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Military unit support, postdeployment social support, and PTSD symptoms among active duty and National Guard soldiers deployed to Iraq
Journal of Anxiety Disorders 28 (2014) 446–453
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Journal of Anxiety Disorders
Military unit support, postdeployment social support, and PTSD symptoms among active duty and National Guard soldiers deployed to Iraq Sohyun C. Han a,1 , Frank Castro a,2 , Lewina O. Lee a,c,e , Meredith E. Charney b,3 , Brian P. Marx a,c , Kevin Brailey b,c , Susan P. Proctor a,d,e , Jennifer J. Vasterling a,c,∗ a
National Center for PTSD at VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, United States VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, United States c Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, United States d U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States e Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, United States b
a r t i c l e
i n f o
Article history: Received 12 September 2013 Received in revised form 16 April 2014 Accepted 16 April 2014 Available online 26 April 2014 Keywords: Social support Unit support Posttraumatic stress disorder Military personnel Deployment Longitudinal
a b s t r a c t Research suggests that military unit support and community postdeployment social support are associated with fewer PTSD symptoms following military deployment. This study extended prior research by examining the associations among predeployment unit support and PTSD symptoms before Iraq deployment as well as unit support, PTSD symptoms, and postdeployment social support after deployment among 835 U.S. Army and 173 National Guard soldiers. Multiple regression analyses indicated that predeployment unit support was not significantly associated with postdeployment PTSD severity in either group of soldiers, whereas higher unit support during deployment was significantly associated with lower postdeployment PTSD severity among active duty soldiers only. Among both groups, higher levels of postdeployment social support were associated with lower levels of postdeployment PTSD symptom severity. These findings suggest that postdeployment social support is a particularly strong buffer against postdeployment PTSD symptoms among both groups of soldiers whereas the effects of unit support may be limited. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Posttraumatic stress disorder (PTSD) is estimated to affect 5 to 20 percent of military service members deployed in support of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF; e.g., Ramchand et al., 2010; Tanelian & Jaycox, 2008). Prior research has identified risk factors for PTSD among military populations including childhood adversity, peritraumatic emotional responses, peritraumatic dissociation, trauma severity and
∗ Corresponding author at: VA Boston Healthcare System (116B-4), 150 South Huntington Avenue, Boston, MA, United States. Tel.: +1 857 364 6522; fax: +1 857 364 4501. E-mail address: [email protected] (J.J. Vasterling). 1 Present address: Department of Psychology, University of Southern California, United States. 2 Present address: VA Palo Alto Healthcare System, United States. 3 Present address: Massachusetts General Hospital, Harvard Medical School, United States. http://dx.doi.org/10.1016/j.janxdis.2014.04.004 0887-6185/© 2014 Elsevier Ltd. All rights reserved.
psychiatric history (Brewin, Andrews, & Valentine, 2000; Ozer, Best, Lipsey, & Weiss, 2008). Less research attention has focused on protective factors for PTSD, such as perceived social support, although social support emerged as one of the strongest predictors for PTSD among military service members in two meta-analyses (Brewin et al., 2000; Ozer et al., 2008). Prior work with military personnel has indicated that unit support, defined as assistance and encouragement obtained specifically from military unit leadership and fellow unit members (King, King, Vogt, Knight, & Samper, 2006), is negatively correlated with PTSD symptom severity and is therefore suggested to protect against PTSD symptom development (Brailey, Vasterling, Proctor, Constans, & Friedman, 2007; Dickstein et al., 2010; Pietrzak et al., 2010). Similarly, general postdeployment social support, defined as the broader social support provided by friends, family members, co-workers, and society to returning service members (King et al., 2006), has been found to be negatively correlated with PTSD symptom severity in Vietnam veterans (King, King, Fairbank, Keane, & Adams, 1998), and more recently, among OEF/OIF veterans
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(Pietrzak, Johnson, Goldstein, Malley, & Southwick, 2009; Pietrzak et al., 2010). Despite the large body of work indicating that both higher levels of unit support and postdeployment social support are associated with less severe PTSD symptoms, most studies have used cross-sectional designs and therefore are more restricted in terms of causal inferences. To date, only one study (Polusny et al., 2011) has prospectively examined the effects of unit support (predeployment) and general postdeployment social support on postdeployment PTSD symptom severity. These investigators assessed a sample of 522 U.S. National Guard soldiers approximately one month prior to, and two months following deployment to Iraq. Results indicated that postdeployment social support was inversely related to new-onset PTSD symptoms after accounting for predeployment PTSD symptoms, predeployment unit support, and combat experiences, whereas predeployment unit support was not significantly associated with postdeployment PTSD. These findings provide compelling support for the potential benefits of postdeployment social support as a buffer for PTSD symptom development following war-zone deployment. However, they did not address the potential effects of unit support specifically during deployment. Given that unit support may change as a function of warzone deployment, it is important to understand the impact of unit support both as service members initially deploy (i.e., predeployment unit support) and during deployment. Furthermore, prior research suggests that the temporal proximity of risk and resilience factors to measurement of outcomes may affect the potency of these factors (Schnurr, Lunney, & Sengupta, 2004); therefore, unit support during deployment may be a stronger predictor of postdeployment PTSD symptoms compared with predeployment unit support. Yet, no studies to date have longitudinally assessed both predeployment unit support and unit support during deployment. It also remains unclear whether the findings of Polusny et al. (2011) based on activated National Guard soldiers generalize to regular active duty personnel, for whom unit support and postdeployment social support may differentially protect against postdeployment PTSD symptom development. For example, whereas regular active duty soldiers continue to work full-time in a military environment after warzone deployment, reservists often return to part-time military responsibilities and a social and occupational context often composed of non-military friends, family members, and co-workers. Therefore, unit support during deployment may exert comparable protection for regular active duty service members and activated reservists in the context of the warzone. However, as reservists transition to civilian life at homecoming, the lasting impact of unit support during deployment, as compared with more non-military postdeployment social support, may diminish. Indeed, other studies have also indicated that homecoming experiences among reservists may be the strongest determinant of their increased risk of PTSD at postdeployment (Browne et al., 2007; Harvey et al., 2011; Thomas et al., 2010). The present study addressed these gaps by examining the independent associations of predeployment unit support, unit support during deployment, and postdeployment social support on postdeployment PTSD symptom severity after adjusting for predeployment PTSD symptom levels among a sample of male U.S. Army regular active duty and activated National Guard soldiers. Based on the literature reviewed previously, we hypothesized that, after taking into account predeployment PTSD symptoms, combat intensity, and stressful life experiences, unit support during deployment would be a more potent predictor of postdeployment PTSD symptoms than predeployment unit support among both active duty and National Guard service members. We also predicted that, after adjusting for predeployment PTSD symptoms, combat intensity, and stressful life experiences, higher levels of general postdeployment social support would be associated with lower
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levels of postdeployment PTSD symptoms. Finally, based on the fact that National Guard soldiers return to a primarily non-military context after deployment, we hypothesized that unit support at both predeployment and during deployment would not be as protective against PTSD symptoms among National Guard soldiers compared with active duty soldiers. 2. Method Human subjects approvals were provided by relevant Tulane University, U.S. Army, and Department of Veterans Affairs oversight committees. All participants provided written informed consent prior to participation. 2.1. Participants The target population was male U.S. Army regular active duty and activated National Guard soldiers who were (a) enrolled in the Neurocognition Deployment Health Study (NDHS; Vasterling, Proctor, Amoroso, Kane, Gackstetter, et al., 2006), a longitudinal cohort study examining neuropsychological outcomes of Iraq War deployment; and (b) deployed in support of OIF between December 2003 and February 2005. As part of the NDHS, participants completed in-person assessments before deployment to Iraq (predeployment) and again following return from deployment (postdeployment). Sampling was conducted at the military battalion level, with diverse units selected to capture heterogeneous deployment experiences and location assignments. Regular active duty units included combat arms (e.g., infantry), combat support (e.g., combat engineers), and service support functions (e.g., supply clerks). National Guard units included combat arms/combat support functions. Further sampling, recruitment, and consent procedures are described elsewhere (Vasterling, Proctor, Amoroso, Kane, Heeren, et al., 2006). A total of 1595 participants enrolled in the NDHS, representing a response rate of almost 94% at baseline enrollment. For the current study, we considered only those soldiers who were either regular active duty or activated Army National Guard and who deployed to Iraq (n = 1128). Because our hypotheses include differential patterns of prediction within regular active duty vs. activated National Guard soldiers, and given that all National Guard personnel were male, female active duty soldiers (n = 91) were also excluded in this report. Of the remaining 1037 potential participants, 72.1% (n = 748) participated in the postdeployment assessment. Soldiers most commonly did not participate in the postdeployment assessment because they were no longer with their originating unit (of 289 non-participants, 69% relocated to another unit, 25% separated from service). Less than 2% of the participants declined participation in the postdeployment assessment. Individuals who did not participate in the postdeployment assessment were included in the final sample in data analysis (see Section 2.4.3 for methods on handling attrition). From the 1037 potential participants, individuals were only excluded for internally inconsistent questionnaire responses (e.g., providing all extreme responses in the same direction on a scale with bi-directional items; n = 21) or not completing a questionnaire at predeployment (n = 8). The final sample (n = 1008) consisted of 835 regular active duty and 173 activated National Guard soldiers who deployed to Iraq. 2.2. Measures Demographic characteristics (e.g., age, education) and deployment history were acquired through both interview and written survey responses. Deployment history was verified through service records. More comprehensive descriptions of primary assessment data and secondary data obtained from automated military
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databases are provided elsewhere (Vasterling, Proctor, Amoroso, Kane, Gackstetter, et al., 2006; Vasterling, Proctor, Amoroso, Kane, Heeren, et al., 2006). 2.2.1. PTSD symptom severity We assessed PTSD symptom severity at both pre- and postdeployment using the Posttraumatic Stress Disorder Checklist, Civilian Version (PCL-C; Weathers, Litz, Herman, Huska, & Keane, 1993). This widely used, 17-item self-report scale is congruent with the Diagnostic and Statistical Manual of Mental Disorders (DSM-IVTR; APA, 2000) symptom criteria and uses a 1-month time frame. Item scores on this measure were summed (range = 17–85), with higher scores indicating greater PTSD symptom severity. Internal consistency was excellent in both the active duty sample (˛ = 0.93 and 0.94 for pre- and postdeployment PCL, respectively) and the National Guard sample (˛ = 0.90 and 0.95 for pre- and postdeployment PCL, respectively). Furthermore, in a prior report, the PCL-C has correlated highly with the Clinician-Administered PTSD Scale (r = 0.93) and is widely acknowledged as a good screening measure of PTSD (Blanchard, Jones-Alexander, Buckley, & Forneris, 1996). 2.2.2. Stress exposures We assessed the extent of combat exposure at postdeployment using a modified version of the Combat Experiences Scale of the Deployment Risk and Resilience Inventory (DRRI; King et al., 2006). The modified scale consists of the same 15 items from the original measure except that it utilizes a 5-point Likert-type scale (1 = never and 5 = daily or almost daily) to determine the extent of combat intensity. It also included an additional item to assess the extent to which soldiers participated in a support convoy. Sample items include, “While deployed, I went on combat patrols or missions” and “While deployed, my unit engaged in battle in which it suffered casualties.” Item scores on this measure were summed (range = 16–80), with higher scores indicating greater combat intensity. We assessed postdeployment stressful life events using the Postdeployment Life Events Scale of the DRRI (King et al., 2006). This scale consists of 17 dichotomous items (0 = no and 1 = yes). Sample items include “Since returning home, I have been robbed or had my home broken into” and “Since returning home, I have had problems getting access to adequate healthcare.” Item scores on this measure were summed (range = 0–17), with higher scores indicating more stressful life events experienced. 2.2.3. Military unit and postdeployment social support We assessed unit support using the Unit Support Scale of the DRRI (King et al., 2006). Predeployment unit support was assessed at baseline, with questions referenced to current levels of support. Unit support during deployment was assessed at the postdeployment assessment with the same items but with questions referenced to level of support during deployment. The scale consists of 12 items measured on a 5-point Likert type scale (1 = strongly disagree and 5 = strongly agree). Sample items include, “My unit is like a family to me,” and “The commanding officer(s) in my unit were supportive of my efforts.” Item scores on this measure were summed (range = 12–60), with higher scores indicating stronger unit support. Internal consistency was excellent in both the active duty sample (˛ = 0.93 and 0.94 for unit support measured at preand postdeployment, respectively) and the National Guard sample (˛ = 0.91 and 0.91 for unit support measured at pre- and postdeployment, respectively). We assessed the level of general (e.g., community, family, coworker) social support veterans receive after deployment using the Postdeployment Social Support scale of the DRRI (King et al., 2006). This scale consists of 15 items measured on a 5-point Likert type scale (1 = strongly disagree and 5 = strongly agree). Sample
items include “The reception I received when I returned from my deployment made me feel appreciated for my efforts” and “The people I work with respect the fact that I am a Veteran.” Item scores on this measure were summed (range = 15–75), with higher scores indicating stronger social support. Internal consistency was good in both the active duty sample (˛ = 0.88) and the National Guard sample (˛ = 0.86).
2.3. Procedure Predeployment assessments were conducted between April 2003 and July 2004 and occurred on average 91.6 days (SD = 91.2) prior to deployment for active duty soldiers and 111.0 days (SD = 12.3) prior to deployment for National Guard soldiers. Postdeployment assessments were administered between January 2005 and September 2006 and occurred on average 73.0 days (SD = 18.5) after deployment for active duty soldiers and 197.5 days (SD = 34.0) after deployment for National Guard soldiers. National Guard soldiers were assessed at longer intervals compared with active duty soldiers due to military scheduling constraints inherent to duty status.
2.4. Data analysis 2.4.1. Data preparation and sample characteristics Missing values for specific items (occurring in <4% of the sample) were replaced for the PCL only if greater than 50% of the items on the entire PCL were completed and greater than 50% of the items relevant to each DSM-IV-TR PTSD symptom cluster were completed. The greatest number of items missed for any given case was 5 of a possible 17. Each missing value was replaced by the mean value of the individual’s completed items within the same DSM-IV-TR symptom cluster. For all other measures, missing values for specific items were replaced by the mean of the individual’s completed items for that measure, but only when 50% or more of the items for that measure was completed by the individual. This occurred in approximately 3% of the participants. Given the clustering of individuals within battalions, intraclass correlations (ICCs) were used to quantify the amount of variation in each independent and dependent variable that is attributable to battalion characteristics vs. individual differences within battalions. Because all ICCs did not reach statistical significance (ICC range: .00–.27, ns), we determined that battalion membership did not meaningfully explain individual differences in the variables of interest. As a result, subsequent analyses were conducted without clustering by battalion membership.
2.4.2. Associations between social support and deployment-related PTSD symptoms In preliminary analysis, we examined differences between active duty and National Guard samples on all covariates, independent variables and dependent variables via t-test. We used hierarchical multiple regression analyses to examine associations between social support variables and postdeployment PTSD symptom severity. Separate analyses were performed for active duty and National Guard subsets to determine whether patterns of association differed according to duty status. Within the regression analyses, the order of variables entry reflected our desire first to adjust for demographic variables, pre-existing (i.e., predeployment) PTSD symptoms, and deployment and postdeployment stressor severity (entered in Step 1). Social support measures were then stepped in individually to examine their incremental impact on postdeployment PTSD symptom severity. Specifically, DRRI unit support (predeployment) summary scores were entered in Step 2;
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DRRI unit support (deployment) summary scores in Step 3; and DRRI postdeployment social support summary scores in Step 4.
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Participants in the final sample generally reflected the deployed U.S. Army population at the time of study enrollment with the exception of (a) commissioned officers, who comprised 2% of our study compared with 13% of active duty and 10% of National Guard Army soldiers serving overseas, and (b) female soldiers, who were excluded in our sample but who typically comprise of 9% of regular active duty and 6% of the National Guard deployed Army forces. As shown in Table 1, individuals who did not return for the postdeployment assesssment were somewhat older, slightly more educated, had spent more time in the Army, more likely to be officers than enlisted soldiers, more likely to report a history of psychiatry disorders, and had higher levels of PTSD symptoms at predeployment. Group differences on other demographic, military, and health variables were nonsignificant. Duty status comparisons revealed that regular active duty soldiers were younger, had fewer years of education, reported more severe predeployment PTSD symptoms on the PCL, more extensive combat exposure, fewer postdeployment life events, and lower unit support before and during deployment, compared with National Guard soldiers (Table 2). Given that National Guard soldiers were assessed at a relatively longer interval from Iraq return to the postdeployment assessment compared with active duty soldiers, we examined the correlation between interval duration and postdeployment PTSD symptoms within both samples. The correlations were weak and failed to reach statistical significance for both the active duty sample, r(607) = −.03, ns, and National Guard sample, r(101) = .18, ns.
with lower postdeployment PTSD symptom severity in Step 3 and added 0.9% to the total explained variance. In the final model, higher postdeployment social support was associated with lower postdeployment PTSD symptom severity. This variable added 2.9% to the explained variance of postdeployment PTSD symptom severity, resulting in a total R2 of 41.4%. The effect of unit support during deployment was no longer significant. Results of the hierarchical multiple regression analyses for National Guard soldiers are presented in Table 3. Among National Guard soldiers, demographic variables, baseline PTSD, and stressful combat and life experiences together explained 56.6% of the variance in postdeployment PTSD symptom severity. Unit support at predeployment (Step 2) and during deployment (Step 3) were not significantly associated with postdeployment PTSD symptom severity, contributing only 0.4% and 0.8% to the explained variance. In the final model, higher postdeployment social support was associated with lower postdeployment PTSD symptom severity. This variable added 3.6% to the explained variance of postdeployment PTSD symptom severity, resulting in a total R2 of 61.4%. We conducted post hoc analyses to explore whether specific facets of postdeployment social support were associated with postdeployment PTSD symptoms. We conducted confirmatory factory analyses, with items treated as continuous and using maximum likelihood estimation. We first conducted a confirmatory factor analysis of postdeployment social support based on literature indicating that social support is commonly conceptualized as emotional and instrumental support (Cohen & Wills, 1985). Compared with a unidimensional model and a 2-factor (instrumental vs. emotional) model of social support, a 3-factor model provided the best fit to the data (CFI = 0.93, TLI = 0.90; RMSEA = 0.10), with the factors representing (a) emotional support with family and friends; (b) emotional support from community and workplace; and (c) instrumental support from family and friends (results available from corresponding author upon request). For each component, item scores were summed to yield a subscale score that were subsequently entered as a predictor in regression analyses. In structuring the regression models, due to the moderately high correlations among social support subscale scores in both active duty (.57–.67) and National Guard samples (.55–.56), we considered models that included only covariates (i.e., variables in Step 1) with individual entry of each social support subscale score into a separate model. In active duty soldiers, we found all three social support components to be negatively correlated with postdeployment PTSD symptom severity (emotional support with family and friends B = −.71, SE B = .14, ˇ = −.16, p < .001; emotional support from community and workplace B = −.57, SE B = .13, ˇ = −.15, p < .001; instrumental support from family and friends B = −.46, SE B = .13, ˇ = −.12, p < .001). In National Guard soldiers, emotional support from family and friends (B = −.62, SE B = .31, ˇ = −.13, p = .05) and instrumental support from family and friends (B = −.73, SE B = .30, ˇ = −.17, p = .02) were negatively correlated with PTSD symptom severity, but emotional support from community and workplace was not significantly associated with postdeployment PTSD symptom severity (B = −.47, SE B = .36, ˇ = −.09, p = .19).
3.2. Association of social support with postdeployment PTSD symptom severity
4. Discussion
Results of the hierarchical multiple regression analyses for active duty soldiers are presented in Table 3. Among regular active duty soldiers, demographic variables, baseline PTSD, and stressful combat and life experiences together explained 37.2% of the variance in postdeployment PTSD symptom severity. In Step 2, predeployment unit support did not predict postdeployment PTSD symptom severity; it only added 0.4% to the explained variance. However, higher unit support during deployment was associated
This study examined the independent associations of predeployment unit support, unit support during deployment and postdeployment social support with postdeployment PTSD symptom severity in a sample of regular active duty and activated National Guard soldiers deployed to Iraq in support of OIF. After accounting for predeployment PTSD symptoms, combat severity and stressful life events, as expected and consistent with a prior study of National Guard soldiers (Polusny et al., 2011),
2.4.3. Missing data due to attrition All individuals who participated in the predeployment assessment (n = 1008) were included in the analyses. In analyses examining key variables by duty status and in multiple regression analyses, missing data due to attrition (28.7% of sample) were handled with multiple imputation (MI). Before conducting MI, we compared individuals who participated in the postdeployment assessment with those who did not on predeployment demographic, military, and mental health characteristics via t-test or 2 , as appropriate. Because group differences on these variables may lead to differential predictions of postdeployment survey response, variables on which the two groups differed were included as auxiliary variables in MI to facilitate the estimation of attritionrelated missingness (Graham, 2012). MI also included all variables in the regression model. Forty complete datasets were generated wherein imputed values replaced missingness. The 40 datasets were analyzed, and the results were combined to yield estimates that incorporate missing data uncertainty (Rubin, 1996). Analyses were conducted using SAS version 9.3 (SAS Institute Inc., 2011). 3. Results 3.1. Sample characteristics
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Table 1 Comparison of postdeployment participants and non-participants on baseline characteristics. Variable
Participants (n = 719)
Age, years, M, SD Ethnic minority, % Education, years, M, SD Time in Army, years, M, SD Enlisted rank, % Junior enlisted (E1–E4), % Non-commissioned officers (E5–E9), % Officers (commissioned or warrant), % Previous operational deployment, prior to 2001,% Married, % Reported prescribed psychoactive or anticonvulsant medication use, past 48 h, % Reported psychiatric history (lifetime), % Reported alcohol use disorder (lifetime), % PTSD screen positive, % PCL summary score, M, SD
25.8 (6.0) 267 (37.1) 12.5 (1.4) 4.7 (4.9) 702 (97.6) 519 (72.2) 183 (25.5) 17 (2.3) 68 (9.7) 341 (47.4) 13 (1.8) 42 (5.9) 30 (4.2) 54 (7.5) 28.3 (11.9)
Non-participants (n = 289)
p
26.8 (7.4) 93 (32.3) 12.7 (1.7) 5.9 (5.9) 270 (93.8) 194 (67.4) 76 (26.4) 18 (6.2) 36 (12.7) 150 (52.1) 9 (3.1) 28 (9.7) 16 (5.6) 26 (9.0) 30.1 (13.4)
.03 .15 .04 .002 .002
.17 .18 .20 .03 .37 .42 .05
Note. PCL = civilian version PTSD Checklist.
Table 2 Descriptive statistics of demographic, baseline PTSD, external stressor, and social support variables between active duty and National Guard participants. Variable Demographic factors: Age at pre-deployment (years) Education (years) Predeployment PTSD symptoms: Predeployment PCL: External stressors: DRRI combat experiences DRRI postdeployment life events Social support variables: DRRI predeployment unit support DRRI unit support during deployment DRRI postdeployment social support Postdeployment PTSD symptoms: Postdeployment PCL
Active Duty (n = 835)
National Guard (n = 173)
p
25.1 (5.4) 12.5 (1.4)
30.6 (8.8) 12.8 (1.7)
<.001 .009
29.4 (12.8)
25.9 (9.7)
<.001
19.0 (10.7) 1.0 (1.4)
11.6 (7.7) 1.5 (1.5)
<.001 <.001
36.9 (11.2) 38.2 (11.3) 56.7 (9.9)
40.3 (10.0) 42.5 (9.1) 57.2 (9.4)
<.001 <.001 .54
32.8 (13.7)
33.9 (13.6)
.35
Note. DRRI, Deployment Risk and Resilience Inventory; PCL, civilian version PTSD Checklist.
predeployment unit support was not significantly associated with postdeployment PTSD symptom severity among either active duty or National Guard soldiers. Unit support during deployment was significantly and inversely associated with postdeployment PTSD symptom severity among active duty soldiers, but only before the inclusion of postdeployment social support. Unit support during deployment was not significantly related to postdeployment PTSD symptoms among National Guard soldiers. As hypothesized, postdeployment social support was inversely associated with postdeployment PTSD symptom severity among both active duty and National Guard soldiers. To the best of our knowledge, this is the first study to examine the effects of predeployment unit support and unit support experienced during deployment on posttraumatic symptomatology among both regular active duty and activated National Guard soldiers. These results extend prior cross-sectional findings on the relationship between unit support and PTSD symptoms (e.g., Brailey et al., 2007; Dickstein et al., 2010; Pietrzak et al., 2009) and suggest that unit support during deployment may buffer against postdeployment PTSD symptomatology among active duty soldiers, above and beyond the effects of predeployment PTSD symptoms and predeployment unit support. Our results suggest that perceptions of unit support during deployment may particularly affect soldiers’ reactions to potentially life-threatening situations during warzone deployment. Unit support is likely to prevent individuals from perceiving stressful situations as unmanageable or overwhelming, as fellow soldiers and military leaders offer a sense of social identity and provide instrumental and emotional support (Cobb, 1976; Cohen & Wills, 1985). Therefore, soldiers who experienced higher levels of unit support during
deployment may have been better equipped to manage stressful experiences during combat, subsequently lowering the risk for PTSD following deployment. That the relationship between unit support during deployment and postdeployment PTSD symptoms was no longer significant after including general postdeployment social support may simply suggest that postdeployment social support is a particularly potent buffer in protecting against adverse mental health consequences after warzone deployment. Unlike active duty soldiers, for whom unit support during deployment was found to be beneficial in buffering the effects of deployment, unit support at neither time period was significantly associated with PTSD symptoms among National Guard soldiers. This was suprising, given that National Guard members reported significantly more support from their units both at predeployment and during deployment compared with regular active duty soldiers. These results may suggest differences between active duty and National Guard soldiers in the importance of unit support. Unit support may be essential to active duty soldiers, who receive rigorous training with their units before deployment and whose identity and morale during deployment may be closely tied to their units. On the other hand, National Guard personnel typically train with their units only one weekend a month and two weeks in the summer (e.g., La Bash, Vogt, King, & King, 2008), and carry out predominantly civilian lifestyles, including civilian occupations. Therefore, National Guard soldiers may have lower expectations for support from their unit and greater expectations for support from their non-military family, friends, and co-workers, especially after deployment. Our findings are consistent with other studies that have found that homecoming experiences among reservists are stronger risk factors for PTSD than deployment-related
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Table 3 Hierarchical multiple regression analysis for demographic, baseline PTSD, external stressor, and social support variables predicting postdeployment PTSD in regular active duty and National Guard soldiers. Active Duty (n = 835) B Step 1 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Step 2 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Step 3 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Unit support during deployment Step 4 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Unit support during deployment Postdeployment social support
National Guard (n = 173) SE B
ˇ
**
F (5,829) = 98.45 R2 = .37 .12 .13 .48 .32 1.73 F (6,828) = 83.19** R2 = .38 .13 .17 .46 .33 1.71 −.07 F (7,827) = 73.95** R2 = .39 .12 .24 .45 .34 1.63 −.01 −.13 F (8,826) = 73.03** R2 = .41 .14 .30 .44 .31 1.45 −.00 −.01 −.28
B
SE B
ˇ
.11 .54 .11 .18 .62
.18* −.01 .31** .37** .45**
.12 .54 .12 .18 .61 .10
.19* −.01 .29* .37** .45** −.04
.12 .54 .12 .17 .60 .11 .12
.20* −.01 .28* .38** .44** −.01 −.08
.11 .52 .12 .17 .62 .11 .12 .13
.16* .02 .27* .37** .37** .08 −.01 −.26*
**
.09 .35 .04 .04 .30
.05 .01 .46** .26** .18**
.09 .35 .04 .04 .30 .04
.05 .01 .43** .26** .18** −.06
.09 .35 .04 .04 .31 .05 .05
.05 .02 .43** .27** .17** −.00 −.11*
.09 .34 .04 .04 .31 .05 .05 .05
.06 .03 .41** .25** .15** .00 −.01 −.20**
F (5,167) = 44.08 R2 = .57 .32 −.02 .46 .98 4.12 F (6,166) = 37.02** R2 = .57 .33 −.03 .42 .98 4.12 −.08 F (7,165) = 32.58** R2 = .58 .35 −.03 .41 .99 3.98 −.03 −.16 F (8,264) = 32.91** R2 = .61 .29 .28 .38 .97 3.37 .11 −.03 −.40
*
p < .05. p < .001. Statistics were generated from a dataset imputed using an expectation-maximization (EM) algorithm and based on the full sample. **
factors (Browne et al., 2007; Harvey et al., 2011; Thomas et al., 2010). Inferences about our findings should be interpreted with caution given that our National Guard sample was smaller than our active duty sample and therefore represented differences in the statistical power to detect significant associations. Overall, the effect of unit support during deployment was small in both the active duty and the National Guard samples (R2 < 1% for both groups), therefore, the difference in results between samples should be interpreted with this consideration in mind. The association of postdeployment social support with postdeployment PTSD symptom severity was robust, in that it was observed across both regular active duty and activated National Guard soldiers and after adjustment for demographic variables, stress exposures, predeployment PTSD symptoms, predeployment unit support, and unit support during deployment. These findings replicate prior literature (e.g., Pietrzak et al., 2010; Polusny et al., 2011) and highlight the important role of general postdeployment social support obtained from a variety of sources including friends, family members, and co-workers in the adjustment to life following deployment. As active duty and National Guard soldiers who deployed to Iraq and other war zones transition to the home front, stronger postdeployment social support may help lead to more compliance with treatment, improved coping mechanisms, and greater opportunities for soldiers to express their thoughts and feelings, thereby reducing vulnerability to PTSD (Price, Gros, Strachan, Ruggiero, & Acierno, 2013). Our findings suggest that both active duty and National Guard soldiers may benefit from stronger postdeployment social support.
Post hoc analyses suggest that both instrumental and emotional support coming from both relatively intimate sources (family, friends) and broader sources (community, workplace) may influence PTSD symptoms. Among National Guard members, however, support from family and friends was more strongly related to post-deployment PTSD symptoms than support from community and workplace. These results are tentative but suggest that further exploration of various facets of social support among active duty vs. National Guard soldiers may prove useful. An implication of these findings is that it may be beneficial to seek mechanisms to increase social support among war-zone returnees. Sherman, Fischer, Sorocco, and McFarlane (2009), for example, developed an intervention, Reaching Out to Educate and Assist Caring, Healthy Families program (REACH), to strengthen emotional and instrumental support provided by family members of veterans with PTSD and affective disorders. The program aims to increase communication skills, minimize stress at home, improve coping strategies, and provide education about the disorder and its impact on relationships. However, even in the absence of a specific intervention, our findings point to the importance in clinical settings of evaluating the social support structure for returning veterans as part of a more comprehensive assessment of potential resources and threats to recovery in veterans’ lives. Our findings contribute to the growing literature on risk and resilience among veterans indicating that perceptions of social support is one of the strongest predictors of PTSD among military populations (Brewin et al., 2000). As previously reported in another paper using an overlapping sample (Vasterling et al.,
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2010), predeployment PTSD, postdeployment life events, and combat experiences were strongly associated with postdeployment PTSD (see Vasterling et al., 2010, for a more in depth discussion of these findings). However, the current study extends these findings to demonstrate that even after taking into account predeployment symptoms, combat severity, and postdeployment life stressors, postdeployment social support remains strongly associated with PTSD outcomes. Interventions that include a more comprehensive approach may have a greater effect on mitigating postdeployment PTSD than interventions that target only one of these factors. Contrary to prior findings indicating that younger age is inversely correlated with PTSD (e.g., Brewin et al., 2000), our findings unexpectedly indicated that age is positively correlated with postdeployment PTSD severity in both active duty and National Guard soldiers. Although we do not have an explanation for this finding, it is noteworthy that earlier studies were conducted prior to the conflicts in Iraq and Afghanistan. A recent review of PTSD among OEF/OIF returnees indicated that age was not significantly associated with PTSD (Ramchand et al., 2010), suggesting that findings from the prior literature may not replicate in contemporary military populations. The study had several limitations. First, we did not assess for general (i.e., non-military-specific) social support prior to deployment, and it is therefore unknown whether pre- vs. postdeployment non-military social support may exert differential effects on PTSD symptoms. However, we were primarily interested in postdeployment social support, which prior literature has identified as a particularly potent buffer against PTSD symptoms (e.g., Polusny et al., 2011). Second, postdeployment social support and postdeployment PTSD were assessed concurrently. Prior work points to the evidence of a social selection model, in which PTSD may lead to an erosion of social support over time (Kaniasty & Norris, 2008; King et al., 2006). Therefore, it is possible that more severe PTSD symptoms at postdeployment led to lower perceptions of, or actual, postdeployment social support. Third, unit support during deployment was measured retrospectively and may be subject to reporting biases related to current emotional functioning. Real-time assessment of unit support during deployment was not feasible in this study, but given the short amount of time that elapsed between deployment and the postdeployment assessment, it is likely that potential biases were reduced to some extent. Fourth, PTSD symptom scores were derived from a self-report measure and were not tied to a specific traumatic experience, which may lead to decreased specificity of the measure. However, the PCL has shown strong agreement with the Clinician-Administered PTSD Scale (CAPS; Blanchard et al., 1996), the gold standard diagnostic interview for PTSD. Finally, although the PCL-C is not specific to military PTSD, our prospective analyses controlled for predeployment PTSD symptoms that may have been attributable to other sources (e.g., child abuse). Further, we were interested in the service member’s PTSD symptoms in their totality at postdeployment, reflecting both the real-life clinical presentation as well as acknowledging the interactive nature of many PTSD symptoms, regardless of their source (Macdonald, Proctor, Heeren, & Vasterling, 2013). These limitations are offset by the study’s strengths, which include the availability of prospective data to draw stronger causal inferences and the ability to account for predeployment PTSD symptoms. Furthermore, this was the first study to assess unit support both prospectively before deployment and longitudinally following deployment. This was also the first study to prospectively assess unit support, postdeployment social support, and PTSD among both active duty and National Guard subsets. In summary, our study suggests that postdeployment social support is a particularly potent buffer against postdeployment PTSD symptom development among active duty and National
Guard soldiers. Our results also suggest that unit support during deployment may help protect against postdeployment PTSD among active duty soldiers. This study advances the literature on the relationships between interpersonal protective factors and postdeployment PTSD symptoms among active duty and National Guard Army soldiers who deployed to contemporary war zones. Increasing social support after deployment appears vital to reducing the consequences of war-zone experiences. Acknowledgements Funding was provided by the U.S. Army Medical Research and Material Command (DAMD 17-03-0020) and Department of Veterans Affairs (VA) Clinical Sciences Research and Development. Lewina Lee’s efforts on this project were supported by awards from the National Institute on Aging (AG039343, AG032037). The manuscript underwent scientific and administrative review at the U.S. Army Research Institute for Environmental Medicine. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Army or Department of Veterans Affairs. We thank the soldiers for volunteering their time to participate in the study and for their military service. References American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders IV-TR. Washington, DC: American Psychiatric Association. Blanchard, E. B., Jones-Alexander, J., Buckley, T. C., & Forneris, C. A. (1996). Psychometric properties of the PTSD checklist (PCL). Behaviour Research and Therapy, 34, 669–673. Brailey, K., Vasterling, J. J., Proctor, S. P., Constans, J. I., & Friedman, M. J. (2007). PTSD symptoms, life events, and unit cohesion in U.S. soldiers: baseline findings from the Neurocognition Deployment Health Study. Journal of Traumatic Stress, 20, 495–503. Brewin, C. R., Andrews, B., & Valentine, J. D. (2000). Meta-analysis of risk factors for posttraumatic stress disorder in trauma-exposed adults. Journal of Consulting and Clinical Psychology, 68, 748–766. Browne, T., Hull, O. H., Jones, M., Murphy, D., Fear, N. T., Greenberg, N., et al. (2007). Explanations for the increase in mental health problems in UK reserve forces who have served to Iraq. British Journal of Psychiatry, 190, 484–489. Cobb, S. (1976). Presidential Address-1976. Social support as a moderator of life stress. Psychosomatic Medicine, 38, 300–314. Cohen, S., & Wills, T. A. (1985). Stress, social support, and the buffering hypothesis. Psychological Bulletin, 98, 310–357. Dickstein, B. D., McLean, C. P., Mintz, J., Conoscenti, L. M., Steenkamp, M. M., Benson, T. A., et al. (2010). Unit cohesion and PTSD symptom severity in Air Force medical personnel. Military Medicine, 175, 482–486. Graham, J. W. (2012). Missing data: analysis and design. NY: Springer. Harvey, S. B., Hatch, S. L., Jones, M., Hull, L., Jones, N., Greenberg, N., et al. (2011). Coming home: social functioning and the mental health of UK reservists on return from deployment to Iraq or Afghanistan. Annals of Epidemiology, 21, 666–672. Kaniasty, K., & Norris, F. H. (2008). Longitudinal linkages between perceived social support and posttraumatic stress symptoms: sequential roles of social causation and social selection. Journal of Traumatic Stress, 21, 274–281. King, L. A., King, D. W., Fairbank, J. A., Keane, T. M., & Adams, G. A. (1998). Resilience and recovery factors in post-traumatic stress disorder among female and male Vietnam veterans: hardiness, postwar social support, and additional stressful life events. Journal of Personality and Social Psychology, 74, 420–434. King, L. A., King, D. W., Vogt, D. S., Knight, J., & Samper, R. E. (2006). Deployment Risk and Resilience Inventory: a collection of measures for studying deploymentrelated experiences of military personnel and veterans. Military Psychology, 18, 89–120. La Bash, H. A., Vogt, D. S., King, L. A., & King, D. W. (2008). Deployment stressors of the Iraq war: insights from the mainstream media. Journal of Interpersonal Violence, 24, 231–258. MacDonald, H. Z., Proctor, S. P., Heeren, T., & Vasterling, J. J. (2013). Associations of postdeployment PTSD symptoms with predeployment symptoms in Iraqdeployed Army soldiers. Psychological Trauma: Theory, Research, Practice, and Policy, 5, 470–476. Ozer, E. J., Best, S. R., Lipsey, T. L., & Weiss, D. S. (2008). Predictors of posttraumatic stress disorder and symptoms in adults: a meta-analysis. Psychological Trauma: Theory, Research, Practice, and Policy, 3–36. Pietrzak, R. H., Johnson, D. C., Goldstein, M. B., Malley, J. C., Rivers, A. J., Morgan, C. A., et al. (2010). Psychosocial buffers of traumatic stress, depressive symptoms, and psychosocial difficulties in veterans of Operations Enduring Freedom and Iraqi Freedom: the role of resilience, unit support, and postdeployment social support. Journal of Affective Disorders, 120, 188–192.
S.C. Han et al. / Journal of Anxiety Disorders 28 (2014) 446–453 Pietrzak, R. H., Johnson, D. C., Goldstein, M. B., Malley, J. C., & Southwick, S. M. (2009). Psychological resilience and postdeployment social support protect against traumatic stress and depressive symptoms in soldiers returning from Operations Enduring Freedom and Iraqi Freedom. Depression and Anxiety, 26, 745–751. Polusny, M. A., Erbes, C. R., Murdoch, M., Arbisi, P. A., Thuras, P., & Rath, M. B. (2011). Prospective risk factors for new-onset post-traumatic stress disorder in National Guard soldiers deployed to Iraq. Psychological Medicine, 41, 687–698. Price, M., Gros, D. F., Strachan, M., Ruggiero, K. J., & Acierno, R. (2013). The role of social support in exposure therapy for Operation Iraqi Freedom/Operation Enduring Freedom veterans: a preliminary investigation,. Psychological Trauma: Theory, Research, Practice, and Policy, 5, 93– 100. Ramchand, R., Schell, T. L., Karney, B. R., Osilla, K., Burns, R. M., & Caldarone, L. (2010). Disparate prevalence estimates of PTSD among service members who served in Iraq and Afghanistan: possible explanations. Journal of Traumatic Stress, 23, 59–68. Rubin, D. B. (1996). Multiple imputation after 18+ years. Journal of American Statistical Association, 91, 473–489. SAS Institute Inc. (2011). Version 9.3. Cary, NC: SAS Institute Inc. Schnurr, P. P., Lunney, C. A., & Sengupta, A. (2004). Risk factors for the development versus maintenance of posttraumatic stress disorder. Journal of Traumatic Stress, 17, 85–95.
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Sherman, M. D., Fischer, E. P., Sorocco, K., & McFarlane, W. R. (2009). Adapting the multifamily group model to the Veterans Affairs System: the REACH program. Professional Psychology: Research and Practice, 40, 593–600. Tanelian, T., & Jaycox, L. H. (2008). Invisible wounds: mental health and cognitive care needs of America’s returning veterans. Santa Monica, CA: Rand Corporation. http://veterans.rand.org. Accessed 06.02.13 Thomas, J. L., Wilk, J. E., Riviere, L. A., McGurk, D., Castro, C. A., & Hoge, C. W. (2010). Prevalence of mental health problems and functional impairment among active component and National Guard soldiers 3 and 12 months following combat in Iraq. Archives of General Psychiatry, 67, 614–623. Vasterling, J. J., Proctor, S. P., Amoroso, P., Kane, R., Gackstetter, G., Ryan, M. A., et al. (2006). The Neurocognition Deployment Health Study: a prospective cohort study of army soldiers. Military Medicine, 171, 253–260. Vasterling, J. J., Proctor, S. P., Amoroso, P., Kane, R., Heeren, T., & White, R. F. (2006). Neuropsychological outcomes of army personnel following deployment to the Iraq war. Journal of the American Medical Association, 296, 519–529. Vasterling, J. J., Proctor, S. P., Friedman, M. J., Hoge, C. W., Heeren, T., King, L. A., et al. (2010). PTSD symptom increases in Iraq-deployed soldiers: comparison with nondeployed soldiers and associations with baseline symptoms, deployment experiences, and postdeployment stress. Journal of Traumatic Stress, 23, 41–51. Weathers, F., Litz, B., Herman, D., Huska, J., & Keane, T. (1993). The PTSD Checklist (PCL): reliability, validity, and diagnostic utility. In Paper presented at the Annual Convention of the International Society for Traumatic Stress Studies San Antonio, TX.
Contents lists available at ScienceDirect
Journal of Anxiety Disorders
Military unit support, postdeployment social support, and PTSD symptoms among active duty and National Guard soldiers deployed to Iraq Sohyun C. Han a,1 , Frank Castro a,2 , Lewina O. Lee a,c,e , Meredith E. Charney b,3 , Brian P. Marx a,c , Kevin Brailey b,c , Susan P. Proctor a,d,e , Jennifer J. Vasterling a,c,∗ a
National Center for PTSD at VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, United States VA Boston Healthcare System, 150 South Huntington Avenue, Boston, MA 02130, United States c Boston University School of Medicine, 72 East Concord Street, Boston, MA 02118, United States d U.S. Army Research Institute of Environmental Medicine, Natick, MA, United States e Boston University School of Public Health, 715 Albany Street, Boston, MA 02118, United States b
a r t i c l e
i n f o
Article history: Received 12 September 2013 Received in revised form 16 April 2014 Accepted 16 April 2014 Available online 26 April 2014 Keywords: Social support Unit support Posttraumatic stress disorder Military personnel Deployment Longitudinal
a b s t r a c t Research suggests that military unit support and community postdeployment social support are associated with fewer PTSD symptoms following military deployment. This study extended prior research by examining the associations among predeployment unit support and PTSD symptoms before Iraq deployment as well as unit support, PTSD symptoms, and postdeployment social support after deployment among 835 U.S. Army and 173 National Guard soldiers. Multiple regression analyses indicated that predeployment unit support was not significantly associated with postdeployment PTSD severity in either group of soldiers, whereas higher unit support during deployment was significantly associated with lower postdeployment PTSD severity among active duty soldiers only. Among both groups, higher levels of postdeployment social support were associated with lower levels of postdeployment PTSD symptom severity. These findings suggest that postdeployment social support is a particularly strong buffer against postdeployment PTSD symptoms among both groups of soldiers whereas the effects of unit support may be limited. © 2014 Elsevier Ltd. All rights reserved.
1. Introduction Posttraumatic stress disorder (PTSD) is estimated to affect 5 to 20 percent of military service members deployed in support of Operation Iraqi Freedom (OIF) and Operation Enduring Freedom (OEF; e.g., Ramchand et al., 2010; Tanelian & Jaycox, 2008). Prior research has identified risk factors for PTSD among military populations including childhood adversity, peritraumatic emotional responses, peritraumatic dissociation, trauma severity and
∗ Corresponding author at: VA Boston Healthcare System (116B-4), 150 South Huntington Avenue, Boston, MA, United States. Tel.: +1 857 364 6522; fax: +1 857 364 4501. E-mail address: [email protected] (J.J. Vasterling). 1 Present address: Department of Psychology, University of Southern California, United States. 2 Present address: VA Palo Alto Healthcare System, United States. 3 Present address: Massachusetts General Hospital, Harvard Medical School, United States. http://dx.doi.org/10.1016/j.janxdis.2014.04.004 0887-6185/© 2014 Elsevier Ltd. All rights reserved.
psychiatric history (Brewin, Andrews, & Valentine, 2000; Ozer, Best, Lipsey, & Weiss, 2008). Less research attention has focused on protective factors for PTSD, such as perceived social support, although social support emerged as one of the strongest predictors for PTSD among military service members in two meta-analyses (Brewin et al., 2000; Ozer et al., 2008). Prior work with military personnel has indicated that unit support, defined as assistance and encouragement obtained specifically from military unit leadership and fellow unit members (King, King, Vogt, Knight, & Samper, 2006), is negatively correlated with PTSD symptom severity and is therefore suggested to protect against PTSD symptom development (Brailey, Vasterling, Proctor, Constans, & Friedman, 2007; Dickstein et al., 2010; Pietrzak et al., 2010). Similarly, general postdeployment social support, defined as the broader social support provided by friends, family members, co-workers, and society to returning service members (King et al., 2006), has been found to be negatively correlated with PTSD symptom severity in Vietnam veterans (King, King, Fairbank, Keane, & Adams, 1998), and more recently, among OEF/OIF veterans
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(Pietrzak, Johnson, Goldstein, Malley, & Southwick, 2009; Pietrzak et al., 2010). Despite the large body of work indicating that both higher levels of unit support and postdeployment social support are associated with less severe PTSD symptoms, most studies have used cross-sectional designs and therefore are more restricted in terms of causal inferences. To date, only one study (Polusny et al., 2011) has prospectively examined the effects of unit support (predeployment) and general postdeployment social support on postdeployment PTSD symptom severity. These investigators assessed a sample of 522 U.S. National Guard soldiers approximately one month prior to, and two months following deployment to Iraq. Results indicated that postdeployment social support was inversely related to new-onset PTSD symptoms after accounting for predeployment PTSD symptoms, predeployment unit support, and combat experiences, whereas predeployment unit support was not significantly associated with postdeployment PTSD. These findings provide compelling support for the potential benefits of postdeployment social support as a buffer for PTSD symptom development following war-zone deployment. However, they did not address the potential effects of unit support specifically during deployment. Given that unit support may change as a function of warzone deployment, it is important to understand the impact of unit support both as service members initially deploy (i.e., predeployment unit support) and during deployment. Furthermore, prior research suggests that the temporal proximity of risk and resilience factors to measurement of outcomes may affect the potency of these factors (Schnurr, Lunney, & Sengupta, 2004); therefore, unit support during deployment may be a stronger predictor of postdeployment PTSD symptoms compared with predeployment unit support. Yet, no studies to date have longitudinally assessed both predeployment unit support and unit support during deployment. It also remains unclear whether the findings of Polusny et al. (2011) based on activated National Guard soldiers generalize to regular active duty personnel, for whom unit support and postdeployment social support may differentially protect against postdeployment PTSD symptom development. For example, whereas regular active duty soldiers continue to work full-time in a military environment after warzone deployment, reservists often return to part-time military responsibilities and a social and occupational context often composed of non-military friends, family members, and co-workers. Therefore, unit support during deployment may exert comparable protection for regular active duty service members and activated reservists in the context of the warzone. However, as reservists transition to civilian life at homecoming, the lasting impact of unit support during deployment, as compared with more non-military postdeployment social support, may diminish. Indeed, other studies have also indicated that homecoming experiences among reservists may be the strongest determinant of their increased risk of PTSD at postdeployment (Browne et al., 2007; Harvey et al., 2011; Thomas et al., 2010). The present study addressed these gaps by examining the independent associations of predeployment unit support, unit support during deployment, and postdeployment social support on postdeployment PTSD symptom severity after adjusting for predeployment PTSD symptom levels among a sample of male U.S. Army regular active duty and activated National Guard soldiers. Based on the literature reviewed previously, we hypothesized that, after taking into account predeployment PTSD symptoms, combat intensity, and stressful life experiences, unit support during deployment would be a more potent predictor of postdeployment PTSD symptoms than predeployment unit support among both active duty and National Guard service members. We also predicted that, after adjusting for predeployment PTSD symptoms, combat intensity, and stressful life experiences, higher levels of general postdeployment social support would be associated with lower
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levels of postdeployment PTSD symptoms. Finally, based on the fact that National Guard soldiers return to a primarily non-military context after deployment, we hypothesized that unit support at both predeployment and during deployment would not be as protective against PTSD symptoms among National Guard soldiers compared with active duty soldiers. 2. Method Human subjects approvals were provided by relevant Tulane University, U.S. Army, and Department of Veterans Affairs oversight committees. All participants provided written informed consent prior to participation. 2.1. Participants The target population was male U.S. Army regular active duty and activated National Guard soldiers who were (a) enrolled in the Neurocognition Deployment Health Study (NDHS; Vasterling, Proctor, Amoroso, Kane, Gackstetter, et al., 2006), a longitudinal cohort study examining neuropsychological outcomes of Iraq War deployment; and (b) deployed in support of OIF between December 2003 and February 2005. As part of the NDHS, participants completed in-person assessments before deployment to Iraq (predeployment) and again following return from deployment (postdeployment). Sampling was conducted at the military battalion level, with diverse units selected to capture heterogeneous deployment experiences and location assignments. Regular active duty units included combat arms (e.g., infantry), combat support (e.g., combat engineers), and service support functions (e.g., supply clerks). National Guard units included combat arms/combat support functions. Further sampling, recruitment, and consent procedures are described elsewhere (Vasterling, Proctor, Amoroso, Kane, Heeren, et al., 2006). A total of 1595 participants enrolled in the NDHS, representing a response rate of almost 94% at baseline enrollment. For the current study, we considered only those soldiers who were either regular active duty or activated Army National Guard and who deployed to Iraq (n = 1128). Because our hypotheses include differential patterns of prediction within regular active duty vs. activated National Guard soldiers, and given that all National Guard personnel were male, female active duty soldiers (n = 91) were also excluded in this report. Of the remaining 1037 potential participants, 72.1% (n = 748) participated in the postdeployment assessment. Soldiers most commonly did not participate in the postdeployment assessment because they were no longer with their originating unit (of 289 non-participants, 69% relocated to another unit, 25% separated from service). Less than 2% of the participants declined participation in the postdeployment assessment. Individuals who did not participate in the postdeployment assessment were included in the final sample in data analysis (see Section 2.4.3 for methods on handling attrition). From the 1037 potential participants, individuals were only excluded for internally inconsistent questionnaire responses (e.g., providing all extreme responses in the same direction on a scale with bi-directional items; n = 21) or not completing a questionnaire at predeployment (n = 8). The final sample (n = 1008) consisted of 835 regular active duty and 173 activated National Guard soldiers who deployed to Iraq. 2.2. Measures Demographic characteristics (e.g., age, education) and deployment history were acquired through both interview and written survey responses. Deployment history was verified through service records. More comprehensive descriptions of primary assessment data and secondary data obtained from automated military
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databases are provided elsewhere (Vasterling, Proctor, Amoroso, Kane, Gackstetter, et al., 2006; Vasterling, Proctor, Amoroso, Kane, Heeren, et al., 2006). 2.2.1. PTSD symptom severity We assessed PTSD symptom severity at both pre- and postdeployment using the Posttraumatic Stress Disorder Checklist, Civilian Version (PCL-C; Weathers, Litz, Herman, Huska, & Keane, 1993). This widely used, 17-item self-report scale is congruent with the Diagnostic and Statistical Manual of Mental Disorders (DSM-IVTR; APA, 2000) symptom criteria and uses a 1-month time frame. Item scores on this measure were summed (range = 17–85), with higher scores indicating greater PTSD symptom severity. Internal consistency was excellent in both the active duty sample (˛ = 0.93 and 0.94 for pre- and postdeployment PCL, respectively) and the National Guard sample (˛ = 0.90 and 0.95 for pre- and postdeployment PCL, respectively). Furthermore, in a prior report, the PCL-C has correlated highly with the Clinician-Administered PTSD Scale (r = 0.93) and is widely acknowledged as a good screening measure of PTSD (Blanchard, Jones-Alexander, Buckley, & Forneris, 1996). 2.2.2. Stress exposures We assessed the extent of combat exposure at postdeployment using a modified version of the Combat Experiences Scale of the Deployment Risk and Resilience Inventory (DRRI; King et al., 2006). The modified scale consists of the same 15 items from the original measure except that it utilizes a 5-point Likert-type scale (1 = never and 5 = daily or almost daily) to determine the extent of combat intensity. It also included an additional item to assess the extent to which soldiers participated in a support convoy. Sample items include, “While deployed, I went on combat patrols or missions” and “While deployed, my unit engaged in battle in which it suffered casualties.” Item scores on this measure were summed (range = 16–80), with higher scores indicating greater combat intensity. We assessed postdeployment stressful life events using the Postdeployment Life Events Scale of the DRRI (King et al., 2006). This scale consists of 17 dichotomous items (0 = no and 1 = yes). Sample items include “Since returning home, I have been robbed or had my home broken into” and “Since returning home, I have had problems getting access to adequate healthcare.” Item scores on this measure were summed (range = 0–17), with higher scores indicating more stressful life events experienced. 2.2.3. Military unit and postdeployment social support We assessed unit support using the Unit Support Scale of the DRRI (King et al., 2006). Predeployment unit support was assessed at baseline, with questions referenced to current levels of support. Unit support during deployment was assessed at the postdeployment assessment with the same items but with questions referenced to level of support during deployment. The scale consists of 12 items measured on a 5-point Likert type scale (1 = strongly disagree and 5 = strongly agree). Sample items include, “My unit is like a family to me,” and “The commanding officer(s) in my unit were supportive of my efforts.” Item scores on this measure were summed (range = 12–60), with higher scores indicating stronger unit support. Internal consistency was excellent in both the active duty sample (˛ = 0.93 and 0.94 for unit support measured at preand postdeployment, respectively) and the National Guard sample (˛ = 0.91 and 0.91 for unit support measured at pre- and postdeployment, respectively). We assessed the level of general (e.g., community, family, coworker) social support veterans receive after deployment using the Postdeployment Social Support scale of the DRRI (King et al., 2006). This scale consists of 15 items measured on a 5-point Likert type scale (1 = strongly disagree and 5 = strongly agree). Sample
items include “The reception I received when I returned from my deployment made me feel appreciated for my efforts” and “The people I work with respect the fact that I am a Veteran.” Item scores on this measure were summed (range = 15–75), with higher scores indicating stronger social support. Internal consistency was good in both the active duty sample (˛ = 0.88) and the National Guard sample (˛ = 0.86).
2.3. Procedure Predeployment assessments were conducted between April 2003 and July 2004 and occurred on average 91.6 days (SD = 91.2) prior to deployment for active duty soldiers and 111.0 days (SD = 12.3) prior to deployment for National Guard soldiers. Postdeployment assessments were administered between January 2005 and September 2006 and occurred on average 73.0 days (SD = 18.5) after deployment for active duty soldiers and 197.5 days (SD = 34.0) after deployment for National Guard soldiers. National Guard soldiers were assessed at longer intervals compared with active duty soldiers due to military scheduling constraints inherent to duty status.
2.4. Data analysis 2.4.1. Data preparation and sample characteristics Missing values for specific items (occurring in <4% of the sample) were replaced for the PCL only if greater than 50% of the items on the entire PCL were completed and greater than 50% of the items relevant to each DSM-IV-TR PTSD symptom cluster were completed. The greatest number of items missed for any given case was 5 of a possible 17. Each missing value was replaced by the mean value of the individual’s completed items within the same DSM-IV-TR symptom cluster. For all other measures, missing values for specific items were replaced by the mean of the individual’s completed items for that measure, but only when 50% or more of the items for that measure was completed by the individual. This occurred in approximately 3% of the participants. Given the clustering of individuals within battalions, intraclass correlations (ICCs) were used to quantify the amount of variation in each independent and dependent variable that is attributable to battalion characteristics vs. individual differences within battalions. Because all ICCs did not reach statistical significance (ICC range: .00–.27, ns), we determined that battalion membership did not meaningfully explain individual differences in the variables of interest. As a result, subsequent analyses were conducted without clustering by battalion membership.
2.4.2. Associations between social support and deployment-related PTSD symptoms In preliminary analysis, we examined differences between active duty and National Guard samples on all covariates, independent variables and dependent variables via t-test. We used hierarchical multiple regression analyses to examine associations between social support variables and postdeployment PTSD symptom severity. Separate analyses were performed for active duty and National Guard subsets to determine whether patterns of association differed according to duty status. Within the regression analyses, the order of variables entry reflected our desire first to adjust for demographic variables, pre-existing (i.e., predeployment) PTSD symptoms, and deployment and postdeployment stressor severity (entered in Step 1). Social support measures were then stepped in individually to examine their incremental impact on postdeployment PTSD symptom severity. Specifically, DRRI unit support (predeployment) summary scores were entered in Step 2;
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DRRI unit support (deployment) summary scores in Step 3; and DRRI postdeployment social support summary scores in Step 4.
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Participants in the final sample generally reflected the deployed U.S. Army population at the time of study enrollment with the exception of (a) commissioned officers, who comprised 2% of our study compared with 13% of active duty and 10% of National Guard Army soldiers serving overseas, and (b) female soldiers, who were excluded in our sample but who typically comprise of 9% of regular active duty and 6% of the National Guard deployed Army forces. As shown in Table 1, individuals who did not return for the postdeployment assesssment were somewhat older, slightly more educated, had spent more time in the Army, more likely to be officers than enlisted soldiers, more likely to report a history of psychiatry disorders, and had higher levels of PTSD symptoms at predeployment. Group differences on other demographic, military, and health variables were nonsignificant. Duty status comparisons revealed that regular active duty soldiers were younger, had fewer years of education, reported more severe predeployment PTSD symptoms on the PCL, more extensive combat exposure, fewer postdeployment life events, and lower unit support before and during deployment, compared with National Guard soldiers (Table 2). Given that National Guard soldiers were assessed at a relatively longer interval from Iraq return to the postdeployment assessment compared with active duty soldiers, we examined the correlation between interval duration and postdeployment PTSD symptoms within both samples. The correlations were weak and failed to reach statistical significance for both the active duty sample, r(607) = −.03, ns, and National Guard sample, r(101) = .18, ns.
with lower postdeployment PTSD symptom severity in Step 3 and added 0.9% to the total explained variance. In the final model, higher postdeployment social support was associated with lower postdeployment PTSD symptom severity. This variable added 2.9% to the explained variance of postdeployment PTSD symptom severity, resulting in a total R2 of 41.4%. The effect of unit support during deployment was no longer significant. Results of the hierarchical multiple regression analyses for National Guard soldiers are presented in Table 3. Among National Guard soldiers, demographic variables, baseline PTSD, and stressful combat and life experiences together explained 56.6% of the variance in postdeployment PTSD symptom severity. Unit support at predeployment (Step 2) and during deployment (Step 3) were not significantly associated with postdeployment PTSD symptom severity, contributing only 0.4% and 0.8% to the explained variance. In the final model, higher postdeployment social support was associated with lower postdeployment PTSD symptom severity. This variable added 3.6% to the explained variance of postdeployment PTSD symptom severity, resulting in a total R2 of 61.4%. We conducted post hoc analyses to explore whether specific facets of postdeployment social support were associated with postdeployment PTSD symptoms. We conducted confirmatory factory analyses, with items treated as continuous and using maximum likelihood estimation. We first conducted a confirmatory factor analysis of postdeployment social support based on literature indicating that social support is commonly conceptualized as emotional and instrumental support (Cohen & Wills, 1985). Compared with a unidimensional model and a 2-factor (instrumental vs. emotional) model of social support, a 3-factor model provided the best fit to the data (CFI = 0.93, TLI = 0.90; RMSEA = 0.10), with the factors representing (a) emotional support with family and friends; (b) emotional support from community and workplace; and (c) instrumental support from family and friends (results available from corresponding author upon request). For each component, item scores were summed to yield a subscale score that were subsequently entered as a predictor in regression analyses. In structuring the regression models, due to the moderately high correlations among social support subscale scores in both active duty (.57–.67) and National Guard samples (.55–.56), we considered models that included only covariates (i.e., variables in Step 1) with individual entry of each social support subscale score into a separate model. In active duty soldiers, we found all three social support components to be negatively correlated with postdeployment PTSD symptom severity (emotional support with family and friends B = −.71, SE B = .14, ˇ = −.16, p < .001; emotional support from community and workplace B = −.57, SE B = .13, ˇ = −.15, p < .001; instrumental support from family and friends B = −.46, SE B = .13, ˇ = −.12, p < .001). In National Guard soldiers, emotional support from family and friends (B = −.62, SE B = .31, ˇ = −.13, p = .05) and instrumental support from family and friends (B = −.73, SE B = .30, ˇ = −.17, p = .02) were negatively correlated with PTSD symptom severity, but emotional support from community and workplace was not significantly associated with postdeployment PTSD symptom severity (B = −.47, SE B = .36, ˇ = −.09, p = .19).
3.2. Association of social support with postdeployment PTSD symptom severity
4. Discussion
Results of the hierarchical multiple regression analyses for active duty soldiers are presented in Table 3. Among regular active duty soldiers, demographic variables, baseline PTSD, and stressful combat and life experiences together explained 37.2% of the variance in postdeployment PTSD symptom severity. In Step 2, predeployment unit support did not predict postdeployment PTSD symptom severity; it only added 0.4% to the explained variance. However, higher unit support during deployment was associated
This study examined the independent associations of predeployment unit support, unit support during deployment and postdeployment social support with postdeployment PTSD symptom severity in a sample of regular active duty and activated National Guard soldiers deployed to Iraq in support of OIF. After accounting for predeployment PTSD symptoms, combat severity and stressful life events, as expected and consistent with a prior study of National Guard soldiers (Polusny et al., 2011),
2.4.3. Missing data due to attrition All individuals who participated in the predeployment assessment (n = 1008) were included in the analyses. In analyses examining key variables by duty status and in multiple regression analyses, missing data due to attrition (28.7% of sample) were handled with multiple imputation (MI). Before conducting MI, we compared individuals who participated in the postdeployment assessment with those who did not on predeployment demographic, military, and mental health characteristics via t-test or 2 , as appropriate. Because group differences on these variables may lead to differential predictions of postdeployment survey response, variables on which the two groups differed were included as auxiliary variables in MI to facilitate the estimation of attritionrelated missingness (Graham, 2012). MI also included all variables in the regression model. Forty complete datasets were generated wherein imputed values replaced missingness. The 40 datasets were analyzed, and the results were combined to yield estimates that incorporate missing data uncertainty (Rubin, 1996). Analyses were conducted using SAS version 9.3 (SAS Institute Inc., 2011). 3. Results 3.1. Sample characteristics
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Table 1 Comparison of postdeployment participants and non-participants on baseline characteristics. Variable
Participants (n = 719)
Age, years, M, SD Ethnic minority, % Education, years, M, SD Time in Army, years, M, SD Enlisted rank, % Junior enlisted (E1–E4), % Non-commissioned officers (E5–E9), % Officers (commissioned or warrant), % Previous operational deployment, prior to 2001,% Married, % Reported prescribed psychoactive or anticonvulsant medication use, past 48 h, % Reported psychiatric history (lifetime), % Reported alcohol use disorder (lifetime), % PTSD screen positive, % PCL summary score, M, SD
25.8 (6.0) 267 (37.1) 12.5 (1.4) 4.7 (4.9) 702 (97.6) 519 (72.2) 183 (25.5) 17 (2.3) 68 (9.7) 341 (47.4) 13 (1.8) 42 (5.9) 30 (4.2) 54 (7.5) 28.3 (11.9)
Non-participants (n = 289)
p
26.8 (7.4) 93 (32.3) 12.7 (1.7) 5.9 (5.9) 270 (93.8) 194 (67.4) 76 (26.4) 18 (6.2) 36 (12.7) 150 (52.1) 9 (3.1) 28 (9.7) 16 (5.6) 26 (9.0) 30.1 (13.4)
.03 .15 .04 .002 .002
.17 .18 .20 .03 .37 .42 .05
Note. PCL = civilian version PTSD Checklist.
Table 2 Descriptive statistics of demographic, baseline PTSD, external stressor, and social support variables between active duty and National Guard participants. Variable Demographic factors: Age at pre-deployment (years) Education (years) Predeployment PTSD symptoms: Predeployment PCL: External stressors: DRRI combat experiences DRRI postdeployment life events Social support variables: DRRI predeployment unit support DRRI unit support during deployment DRRI postdeployment social support Postdeployment PTSD symptoms: Postdeployment PCL
Active Duty (n = 835)
National Guard (n = 173)
p
25.1 (5.4) 12.5 (1.4)
30.6 (8.8) 12.8 (1.7)
<.001 .009
29.4 (12.8)
25.9 (9.7)
<.001
19.0 (10.7) 1.0 (1.4)
11.6 (7.7) 1.5 (1.5)
<.001 <.001
36.9 (11.2) 38.2 (11.3) 56.7 (9.9)
40.3 (10.0) 42.5 (9.1) 57.2 (9.4)
<.001 <.001 .54
32.8 (13.7)
33.9 (13.6)
.35
Note. DRRI, Deployment Risk and Resilience Inventory; PCL, civilian version PTSD Checklist.
predeployment unit support was not significantly associated with postdeployment PTSD symptom severity among either active duty or National Guard soldiers. Unit support during deployment was significantly and inversely associated with postdeployment PTSD symptom severity among active duty soldiers, but only before the inclusion of postdeployment social support. Unit support during deployment was not significantly related to postdeployment PTSD symptoms among National Guard soldiers. As hypothesized, postdeployment social support was inversely associated with postdeployment PTSD symptom severity among both active duty and National Guard soldiers. To the best of our knowledge, this is the first study to examine the effects of predeployment unit support and unit support experienced during deployment on posttraumatic symptomatology among both regular active duty and activated National Guard soldiers. These results extend prior cross-sectional findings on the relationship between unit support and PTSD symptoms (e.g., Brailey et al., 2007; Dickstein et al., 2010; Pietrzak et al., 2009) and suggest that unit support during deployment may buffer against postdeployment PTSD symptomatology among active duty soldiers, above and beyond the effects of predeployment PTSD symptoms and predeployment unit support. Our results suggest that perceptions of unit support during deployment may particularly affect soldiers’ reactions to potentially life-threatening situations during warzone deployment. Unit support is likely to prevent individuals from perceiving stressful situations as unmanageable or overwhelming, as fellow soldiers and military leaders offer a sense of social identity and provide instrumental and emotional support (Cobb, 1976; Cohen & Wills, 1985). Therefore, soldiers who experienced higher levels of unit support during
deployment may have been better equipped to manage stressful experiences during combat, subsequently lowering the risk for PTSD following deployment. That the relationship between unit support during deployment and postdeployment PTSD symptoms was no longer significant after including general postdeployment social support may simply suggest that postdeployment social support is a particularly potent buffer in protecting against adverse mental health consequences after warzone deployment. Unlike active duty soldiers, for whom unit support during deployment was found to be beneficial in buffering the effects of deployment, unit support at neither time period was significantly associated with PTSD symptoms among National Guard soldiers. This was suprising, given that National Guard members reported significantly more support from their units both at predeployment and during deployment compared with regular active duty soldiers. These results may suggest differences between active duty and National Guard soldiers in the importance of unit support. Unit support may be essential to active duty soldiers, who receive rigorous training with their units before deployment and whose identity and morale during deployment may be closely tied to their units. On the other hand, National Guard personnel typically train with their units only one weekend a month and two weeks in the summer (e.g., La Bash, Vogt, King, & King, 2008), and carry out predominantly civilian lifestyles, including civilian occupations. Therefore, National Guard soldiers may have lower expectations for support from their unit and greater expectations for support from their non-military family, friends, and co-workers, especially after deployment. Our findings are consistent with other studies that have found that homecoming experiences among reservists are stronger risk factors for PTSD than deployment-related
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Table 3 Hierarchical multiple regression analysis for demographic, baseline PTSD, external stressor, and social support variables predicting postdeployment PTSD in regular active duty and National Guard soldiers. Active Duty (n = 835) B Step 1 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Step 2 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Step 3 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Unit support during deployment Step 4 Age (years) Education (years) Predeployment PTSD Combat experience Postdeployment life events Predeployment unit support Unit support during deployment Postdeployment social support
National Guard (n = 173) SE B
ˇ
**
F (5,829) = 98.45 R2 = .37 .12 .13 .48 .32 1.73 F (6,828) = 83.19** R2 = .38 .13 .17 .46 .33 1.71 −.07 F (7,827) = 73.95** R2 = .39 .12 .24 .45 .34 1.63 −.01 −.13 F (8,826) = 73.03** R2 = .41 .14 .30 .44 .31 1.45 −.00 −.01 −.28
B
SE B
ˇ
.11 .54 .11 .18 .62
.18* −.01 .31** .37** .45**
.12 .54 .12 .18 .61 .10
.19* −.01 .29* .37** .45** −.04
.12 .54 .12 .17 .60 .11 .12
.20* −.01 .28* .38** .44** −.01 −.08
.11 .52 .12 .17 .62 .11 .12 .13
.16* .02 .27* .37** .37** .08 −.01 −.26*
**
.09 .35 .04 .04 .30
.05 .01 .46** .26** .18**
.09 .35 .04 .04 .30 .04
.05 .01 .43** .26** .18** −.06
.09 .35 .04 .04 .31 .05 .05
.05 .02 .43** .27** .17** −.00 −.11*
.09 .34 .04 .04 .31 .05 .05 .05
.06 .03 .41** .25** .15** .00 −.01 −.20**
F (5,167) = 44.08 R2 = .57 .32 −.02 .46 .98 4.12 F (6,166) = 37.02** R2 = .57 .33 −.03 .42 .98 4.12 −.08 F (7,165) = 32.58** R2 = .58 .35 −.03 .41 .99 3.98 −.03 −.16 F (8,264) = 32.91** R2 = .61 .29 .28 .38 .97 3.37 .11 −.03 −.40
*
p < .05. p < .001. Statistics were generated from a dataset imputed using an expectation-maximization (EM) algorithm and based on the full sample. **
factors (Browne et al., 2007; Harvey et al., 2011; Thomas et al., 2010). Inferences about our findings should be interpreted with caution given that our National Guard sample was smaller than our active duty sample and therefore represented differences in the statistical power to detect significant associations. Overall, the effect of unit support during deployment was small in both the active duty and the National Guard samples (R2 < 1% for both groups), therefore, the difference in results between samples should be interpreted with this consideration in mind. The association of postdeployment social support with postdeployment PTSD symptom severity was robust, in that it was observed across both regular active duty and activated National Guard soldiers and after adjustment for demographic variables, stress exposures, predeployment PTSD symptoms, predeployment unit support, and unit support during deployment. These findings replicate prior literature (e.g., Pietrzak et al., 2010; Polusny et al., 2011) and highlight the important role of general postdeployment social support obtained from a variety of sources including friends, family members, and co-workers in the adjustment to life following deployment. As active duty and National Guard soldiers who deployed to Iraq and other war zones transition to the home front, stronger postdeployment social support may help lead to more compliance with treatment, improved coping mechanisms, and greater opportunities for soldiers to express their thoughts and feelings, thereby reducing vulnerability to PTSD (Price, Gros, Strachan, Ruggiero, & Acierno, 2013). Our findings suggest that both active duty and National Guard soldiers may benefit from stronger postdeployment social support.
Post hoc analyses suggest that both instrumental and emotional support coming from both relatively intimate sources (family, friends) and broader sources (community, workplace) may influence PTSD symptoms. Among National Guard members, however, support from family and friends was more strongly related to post-deployment PTSD symptoms than support from community and workplace. These results are tentative but suggest that further exploration of various facets of social support among active duty vs. National Guard soldiers may prove useful. An implication of these findings is that it may be beneficial to seek mechanisms to increase social support among war-zone returnees. Sherman, Fischer, Sorocco, and McFarlane (2009), for example, developed an intervention, Reaching Out to Educate and Assist Caring, Healthy Families program (REACH), to strengthen emotional and instrumental support provided by family members of veterans with PTSD and affective disorders. The program aims to increase communication skills, minimize stress at home, improve coping strategies, and provide education about the disorder and its impact on relationships. However, even in the absence of a specific intervention, our findings point to the importance in clinical settings of evaluating the social support structure for returning veterans as part of a more comprehensive assessment of potential resources and threats to recovery in veterans’ lives. Our findings contribute to the growing literature on risk and resilience among veterans indicating that perceptions of social support is one of the strongest predictors of PTSD among military populations (Brewin et al., 2000). As previously reported in another paper using an overlapping sample (Vasterling et al.,
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2010), predeployment PTSD, postdeployment life events, and combat experiences were strongly associated with postdeployment PTSD (see Vasterling et al., 2010, for a more in depth discussion of these findings). However, the current study extends these findings to demonstrate that even after taking into account predeployment symptoms, combat severity, and postdeployment life stressors, postdeployment social support remains strongly associated with PTSD outcomes. Interventions that include a more comprehensive approach may have a greater effect on mitigating postdeployment PTSD than interventions that target only one of these factors. Contrary to prior findings indicating that younger age is inversely correlated with PTSD (e.g., Brewin et al., 2000), our findings unexpectedly indicated that age is positively correlated with postdeployment PTSD severity in both active duty and National Guard soldiers. Although we do not have an explanation for this finding, it is noteworthy that earlier studies were conducted prior to the conflicts in Iraq and Afghanistan. A recent review of PTSD among OEF/OIF returnees indicated that age was not significantly associated with PTSD (Ramchand et al., 2010), suggesting that findings from the prior literature may not replicate in contemporary military populations. The study had several limitations. First, we did not assess for general (i.e., non-military-specific) social support prior to deployment, and it is therefore unknown whether pre- vs. postdeployment non-military social support may exert differential effects on PTSD symptoms. However, we were primarily interested in postdeployment social support, which prior literature has identified as a particularly potent buffer against PTSD symptoms (e.g., Polusny et al., 2011). Second, postdeployment social support and postdeployment PTSD were assessed concurrently. Prior work points to the evidence of a social selection model, in which PTSD may lead to an erosion of social support over time (Kaniasty & Norris, 2008; King et al., 2006). Therefore, it is possible that more severe PTSD symptoms at postdeployment led to lower perceptions of, or actual, postdeployment social support. Third, unit support during deployment was measured retrospectively and may be subject to reporting biases related to current emotional functioning. Real-time assessment of unit support during deployment was not feasible in this study, but given the short amount of time that elapsed between deployment and the postdeployment assessment, it is likely that potential biases were reduced to some extent. Fourth, PTSD symptom scores were derived from a self-report measure and were not tied to a specific traumatic experience, which may lead to decreased specificity of the measure. However, the PCL has shown strong agreement with the Clinician-Administered PTSD Scale (CAPS; Blanchard et al., 1996), the gold standard diagnostic interview for PTSD. Finally, although the PCL-C is not specific to military PTSD, our prospective analyses controlled for predeployment PTSD symptoms that may have been attributable to other sources (e.g., child abuse). Further, we were interested in the service member’s PTSD symptoms in their totality at postdeployment, reflecting both the real-life clinical presentation as well as acknowledging the interactive nature of many PTSD symptoms, regardless of their source (Macdonald, Proctor, Heeren, & Vasterling, 2013). These limitations are offset by the study’s strengths, which include the availability of prospective data to draw stronger causal inferences and the ability to account for predeployment PTSD symptoms. Furthermore, this was the first study to assess unit support both prospectively before deployment and longitudinally following deployment. This was also the first study to prospectively assess unit support, postdeployment social support, and PTSD among both active duty and National Guard subsets. In summary, our study suggests that postdeployment social support is a particularly potent buffer against postdeployment PTSD symptom development among active duty and National
Guard soldiers. Our results also suggest that unit support during deployment may help protect against postdeployment PTSD among active duty soldiers. This study advances the literature on the relationships between interpersonal protective factors and postdeployment PTSD symptoms among active duty and National Guard Army soldiers who deployed to contemporary war zones. Increasing social support after deployment appears vital to reducing the consequences of war-zone experiences. Acknowledgements Funding was provided by the U.S. Army Medical Research and Material Command (DAMD 17-03-0020) and Department of Veterans Affairs (VA) Clinical Sciences Research and Development. Lewina Lee’s efforts on this project were supported by awards from the National Institute on Aging (AG039343, AG032037). The manuscript underwent scientific and administrative review at the U.S. Army Research Institute for Environmental Medicine. The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Army or Department of Veterans Affairs. We thank the soldiers for volunteering their time to participate in the study and for their military service. References American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders IV-TR. Washington, DC: American Psychiatric Association. Blanchard, E. B., Jones-Alexander, J., Buckley, T. C., & Forneris, C. A. (1996). Psychometric properties of the PTSD checklist (PCL). Behaviour Research and Therapy, 34, 669–673. Brailey, K., Vasterling, J. J., Proctor, S. P., Constans, J. I., & Friedman, M. J. (2007). PTSD symptoms, life events, and unit cohesion in U.S. soldiers: baseline findings from the Neurocognition Deployment Health Study. Journal of Traumatic Stress, 20, 495–503. Brewin, C. R., Andrews, B., & Valentine, J. D. (2000). Meta-analysis of risk factors for posttraumatic stress disorder in trauma-exposed adults. Journal of Consulting and Clinical Psychology, 68, 748–766. Browne, T., Hull, O. H., Jones, M., Murphy, D., Fear, N. T., Greenberg, N., et al. (2007). Explanations for the increase in mental health problems in UK reserve forces who have served to Iraq. British Journal of Psychiatry, 190, 484–489. Cobb, S. (1976). Presidential Address-1976. Social support as a moderator of life stress. Psychosomatic Medicine, 38, 300–314. Cohen, S., & Wills, T. A. (1985). Stress, social support, and the buffering hypothesis. Psychological Bulletin, 98, 310–357. Dickstein, B. D., McLean, C. P., Mintz, J., Conoscenti, L. M., Steenkamp, M. M., Benson, T. A., et al. (2010). Unit cohesion and PTSD symptom severity in Air Force medical personnel. Military Medicine, 175, 482–486. Graham, J. W. (2012). Missing data: analysis and design. NY: Springer. Harvey, S. B., Hatch, S. L., Jones, M., Hull, L., Jones, N., Greenberg, N., et al. (2011). Coming home: social functioning and the mental health of UK reservists on return from deployment to Iraq or Afghanistan. Annals of Epidemiology, 21, 666–672. Kaniasty, K., & Norris, F. H. (2008). Longitudinal linkages between perceived social support and posttraumatic stress symptoms: sequential roles of social causation and social selection. Journal of Traumatic Stress, 21, 274–281. King, L. A., King, D. W., Fairbank, J. A., Keane, T. M., & Adams, G. A. (1998). Resilience and recovery factors in post-traumatic stress disorder among female and male Vietnam veterans: hardiness, postwar social support, and additional stressful life events. Journal of Personality and Social Psychology, 74, 420–434. King, L. A., King, D. W., Vogt, D. S., Knight, J., & Samper, R. E. (2006). Deployment Risk and Resilience Inventory: a collection of measures for studying deploymentrelated experiences of military personnel and veterans. Military Psychology, 18, 89–120. La Bash, H. A., Vogt, D. S., King, L. A., & King, D. W. (2008). Deployment stressors of the Iraq war: insights from the mainstream media. Journal of Interpersonal Violence, 24, 231–258. MacDonald, H. Z., Proctor, S. P., Heeren, T., & Vasterling, J. J. (2013). Associations of postdeployment PTSD symptoms with predeployment symptoms in Iraqdeployed Army soldiers. Psychological Trauma: Theory, Research, Practice, and Policy, 5, 470–476. Ozer, E. J., Best, S. R., Lipsey, T. L., & Weiss, D. S. (2008). Predictors of posttraumatic stress disorder and symptoms in adults: a meta-analysis. Psychological Trauma: Theory, Research, Practice, and Policy, 3–36. Pietrzak, R. H., Johnson, D. C., Goldstein, M. B., Malley, J. C., Rivers, A. J., Morgan, C. A., et al. (2010). Psychosocial buffers of traumatic stress, depressive symptoms, and psychosocial difficulties in veterans of Operations Enduring Freedom and Iraqi Freedom: the role of resilience, unit support, and postdeployment social support. Journal of Affective Disorders, 120, 188–192.
S.C. Han et al. / Journal of Anxiety Disorders 28 (2014) 446–453 Pietrzak, R. H., Johnson, D. C., Goldstein, M. B., Malley, J. C., & Southwick, S. M. (2009). Psychological resilience and postdeployment social support protect against traumatic stress and depressive symptoms in soldiers returning from Operations Enduring Freedom and Iraqi Freedom. Depression and Anxiety, 26, 745–751. Polusny, M. A., Erbes, C. R., Murdoch, M., Arbisi, P. A., Thuras, P., & Rath, M. B. (2011). Prospective risk factors for new-onset post-traumatic stress disorder in National Guard soldiers deployed to Iraq. Psychological Medicine, 41, 687–698. Price, M., Gros, D. F., Strachan, M., Ruggiero, K. J., & Acierno, R. (2013). The role of social support in exposure therapy for Operation Iraqi Freedom/Operation Enduring Freedom veterans: a preliminary investigation,. Psychological Trauma: Theory, Research, Practice, and Policy, 5, 93– 100. Ramchand, R., Schell, T. L., Karney, B. R., Osilla, K., Burns, R. M., & Caldarone, L. (2010). Disparate prevalence estimates of PTSD among service members who served in Iraq and Afghanistan: possible explanations. Journal of Traumatic Stress, 23, 59–68. Rubin, D. B. (1996). Multiple imputation after 18+ years. Journal of American Statistical Association, 91, 473–489. SAS Institute Inc. (2011). Version 9.3. Cary, NC: SAS Institute Inc. Schnurr, P. P., Lunney, C. A., & Sengupta, A. (2004). Risk factors for the development versus maintenance of posttraumatic stress disorder. Journal of Traumatic Stress, 17, 85–95.
453
Sherman, M. D., Fischer, E. P., Sorocco, K., & McFarlane, W. R. (2009). Adapting the multifamily group model to the Veterans Affairs System: the REACH program. Professional Psychology: Research and Practice, 40, 593–600. Tanelian, T., & Jaycox, L. H. (2008). Invisible wounds: mental health and cognitive care needs of America’s returning veterans. Santa Monica, CA: Rand Corporation. http://veterans.rand.org. Accessed 06.02.13 Thomas, J. L., Wilk, J. E., Riviere, L. A., McGurk, D., Castro, C. A., & Hoge, C. W. (2010). Prevalence of mental health problems and functional impairment among active component and National Guard soldiers 3 and 12 months following combat in Iraq. Archives of General Psychiatry, 67, 614–623. Vasterling, J. J., Proctor, S. P., Amoroso, P., Kane, R., Gackstetter, G., Ryan, M. A., et al. (2006). The Neurocognition Deployment Health Study: a prospective cohort study of army soldiers. Military Medicine, 171, 253–260. Vasterling, J. J., Proctor, S. P., Amoroso, P., Kane, R., Heeren, T., & White, R. F. (2006). Neuropsychological outcomes of army personnel following deployment to the Iraq war. Journal of the American Medical Association, 296, 519–529. Vasterling, J. J., Proctor, S. P., Friedman, M. J., Hoge, C. W., Heeren, T., King, L. A., et al. (2010). PTSD symptom increases in Iraq-deployed soldiers: comparison with nondeployed soldiers and associations with baseline symptoms, deployment experiences, and postdeployment stress. Journal of Traumatic Stress, 23, 41–51. Weathers, F., Litz, B., Herman, D., Huska, J., & Keane, T. (1993). The PTSD Checklist (PCL): reliability, validity, and diagnostic utility. In Paper presented at the Annual Convention of the International Society for Traumatic Stress Studies San Antonio, TX.