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Obsessive-compulsive symptom dimensions and insomnia: The mediating role of anxiety sensitivity cognitive concerns
Author’s Accepted Manuscript Obsessive-compulsive symptom dimensions and insomnia: The mediating role of anxiety sensitivity cognitive concerns Amanda M. Raines, Nicole A. Short, Carson A. Sutton, Mary E. Oglesby, Nicholas P. Allan, Norman B. Schmidt www.elsevier.com/locate/psychres
PII: DOI: Reference:
S0165-1781(15)00394-7 http://dx.doi.org/10.1016/j.psychres.2015.05.081 PSY9001
To appear in: Psychiatry Research Received date: 7 October 2014 Revised date: 26 April 2015 Accepted date: 25 May 2015 Cite this article as: Amanda M. Raines, Nicole A. Short, Carson A. Sutton, Mary E. Oglesby, Nicholas P. Allan and Norman B. Schmidt, Obsessive-compulsive symptom dimensions and insomnia: The mediating role of anxiety sensitivity cognitive concerns, Psychiatry Research, http://dx.doi.org/10.1016/j.psychres.2015.05.081 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Obsessive-compulsive symptom dimensions and insomnia: the mediating role of anxiety sensitivity cognitive concerns
Amanda M. Raines Nicole A. Short Carson A. Sutton Mary E. Oglesby Nicholas P. Allan & Norman B. Schmidt*
Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 323064301 USA
Send correspondence to Norman B. Schmidt, Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306-4301 USA, Tel: (850) 645-1766, Fax: (850) 644-7739, email: [email protected] Obsessive-compulsive symptom dimensions and insomnia: the mediating role of anxiety sensitivity cognitive concerns
Abstract
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Existing research on the relationship between obsessive-compulsive disorder (OCD) and insomnia is scarce. Moreover, no research has examined potential mechanisms that may account for the observed relations among OCD and sleep difficulties. The cognitive concerns subscale of anxiety sensitivity (AS), which reflects fears of mental incapacitation, has been linked to both symptoms of OCD and insomnia and may serve as a mechanism for increasing sleep disturbance among patients with OCD. The current study examined the relationship between OCD symptoms and insomnia and the potential mediating role of AS cognitive concerns. The sample consisted of 526 individuals recruited through Amazon’s Mechanical Turk (Mturk), an online crowdsourcing marketplace. Results revealed distinct associations between the unacceptable thoughts domain of OCD and symptoms of insomnia. Additionally, AS cognitive concerns mediated the relationship between these constructs. Future research should seek to replicate these findings using clinical samples and prospective designs. Keywords: obsessive-compulsive disorder; insomnia; anxiety sensitivity cognitive concerns; sleep
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1. Introduction Sleep disturbances are common among the general population, with up to one third of individuals reporting at least occasional difficulties falling or staying asleep (Breslau et al., 1996). These sleep difficulties may become chronic, and develop associated daytime consequences, including fatigue, irritability, and dysphoric mood. About 6% of the population may have such chronic sleep difficulties along with clinically significant distress and impairment, consistent with a diagnosis of insomnia disorder (Ohayon, 2002). Individuals with this disorder often complain of various disruptions to their daytime functioning, including sleepiness interfering with their daily activities, problems focusing, and decreased productivity in personal and occupational roles. In addition to these personal consequences, when direct (e.g., healthcare costs), and indirect (e.g., medical comorbidities, insomnia related alcohol abuse, reduced workplace productivity, motor vehicle and other accidents) insomnia-related costs are combined, they are estimated to range from $92 to $107 billion annually across the United States (Rosekind and Gregory, 2010). These data suggest that insomnia disorder, and symptoms thereof, are prevalent and costly, meriting further research. In addition to the prevalence and consequences associated with sleep disturbances and insomnia disorder in the general population, individuals with mental illness are much more likely to suffer from sleep difficulties and associated problems. Specifically, some degree of sleep disturbance is highly comorbid with nearly all psychiatric disorders (Benca et al., 1992). In fact, a meta-analysis has indicated that objective sleep disturbance (e.g., reduced total sleep time and sleep efficiency, and increased sleep onset latency) as measured by polysomnograpy is linked with the presence of a psychiatric disorder (Benca et al., 1992). In particular, sleep disturbances are present in large proportions of individuals with mood and anxiety disorders. For example, the
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majority (60-84%) of individuals with major depressive disorder (MDD) report some symptoms of insomnia including difficulty falling asleep (Ford and Kamerow, 1989; Hamilton, 1989). In terms of anxiety disorders, generalized anxiety disorder (GAD) has the greatest comorbidity rate with insomnia, with approximately 60% of those with GAD reporting at least occasional symptoms of insomnia (Monti and Monti, 2000; Bélanger et al., 2004). However, sleep disturbances have been found to be present in most, if not all, anxiety-related conditions, including specific phobia, panic disorder, and posttraumatic stress disorder (Ohayon, 1997; Lamarche and De Koninck, 2007). An additional anxiety-related disorder that has received less attention with regard to sleep disturbances, including symptoms of insomnia, is obsessive-compulsive disorder (OCD). OCD is a heterogeneous psychiatric disorder characterized by recurrent and intrusive thoughts, images, or urges (i.e., obsessions) and/or excessive avoidance and repetitive behaviors (i.e., compulsions) aimed at reducing or neutralizing the associated distress and anxiety (American Psychiatric Association, 2013). Approximately 2-3% of the population suffers from this complex and debilitating disorder (Kessler et al., 2005). OCD can lead to substantial impairment in social, occupational, and family domains and is associated with a considerable economic burden to both the individual and society (Markarian et al., 2010). Recent research has begun to closely examine the relationship between obsessivecompulsive (OC) symptoms and sleep disturbances. In a systematic literature review on sleep and OCD, Paterson and colleagues (2013) found that sleep disturbances were common among individuals with OCD (e.g., up to 48% in some samples). Specifically, individuals with OCD had reduced sleep duration and sleep efficiency compared to healthy controls with increased periods of waking after sleep onset, particularly early morning awakenings (Insel et al., 1982; Hohagen
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et al., 1994; Voderholzer et al., 2007). In addition, elevated levels of sleep disturbances among those with OCD were associated with increased severity of OC symptoms. More recently, Timpano, Carbonella, Bernert and Schmidt (2014) extended this research by investigating which aspects of OC symptoms may be related to specific components of sleep disturbances. Here, the authors found that insomnia symptoms (i.e., difficulties initiating and maintaining sleep and associated distress/impairment) were most related to OC symptoms (compared to other sleep disturbances such as delayed bedtime and nightmares). This relationship was particularly strong between insomnia and the obsessions (e.g., sexual, religious or aggressive in nature) dimension of the obsessive-compulsive inventory revised, consistent with the notion that distressing obsessions may interfere with sleep onset (Timpano et al., 2014). There are a number of possible explanations for the relationship between OCD and insomnia. First, direct effects may be present such that individuals suffering from persistent obsessions have more difficulty falling or staying asleep. Other possible explanations include indirect mechanisms such as shared comorbidity or risk factors. One shared risk factor that could help to explain the association between OC symptoms and sleep disturbances is anxiety sensitivity (AS). AS is a well-researched individual difference variable reflecting the tendency to fear bodily sensations associated with anxious arousal (Reiss and McNally, 1985). Research on the dimensional structure of AS has indicated that AS comprises one higher order factor (AS), as well as three lower order factors reflecting fears of the physical, social, and cognitive consequences of anxiety (Taylor et al., 2007). Whereas relations between the various AS subscales and several of the OC symptom domains have been found, the cognitive concerns subscale of AS, which represents fears of mental incapacitation (e.g., “When I cannot keep my mind on a task, I worry that I might be going crazy”) appears to have the strongest associations
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with OC domains (see Robinson and Freeston, 2014 for a review). In particular, research from both clinical and non-clinical samples has demonstrated unique associations between the cognitive concerns subscale of AS and the unacceptable thoughts (e.g., sexual, religious, or aggressive in nature) domain of OCD (Wheaton et al., 2012; Raines et al., 2014b). In addition to the relations between AS cognitive concerns and OC symptoms, research has also found distinct associations between AS cognitive concerns and symptoms of insomnia. For example, Vincent and Walker (2001) examined the relationship between AS and sleeprelated impairment in a sample of individuals with chronic insomnia and found that the cognitive concerns dimension of AS was associated with sleep-related impairment. Calkins, Hearon, Capozzoli, and Otto (2013) extended this research by examining the associations between AS and sleep dysfunction after accounting for two highly relevant sleep related constructs, dysfunctional beliefs about sleep and neuroticism. The authors found that whereas AS total scores did not significantly predict sleep dysfunction, the cognitive concerns subscale did. Given the associations between OC symptoms and AS cognitive concerns, as well as the associations between AS cognitive concerns and insomnia, it is reasonable to assume that AS cognitive concerns could be one factor accounting for the relations between OC symptoms and insomnia. The current study sought to replicate and extend previous research by examining the relationship between OC symptoms and insomnia and the potential mediating role of AS cognitive concerns. Consistent with previous research (Timpano et al., 2014), it was hypothesized that the unacceptable thoughts domain of OCD would be most associated with symptoms of insomnia. Second, mediation procedures were used to test the hypothesis that AS cognitive concerns would mediate the relationship between the unacceptable thoughts domain of OCD and symptoms of insomnia. Finally, in an effort to demonstrate specificity, a multiple
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mediator models approach was used to test the hypothesis that AS cognitive concerns rather than AS physical or AS social concerns would mediate the relationship between unacceptable thoughts and symptoms of insomnia. Because recent reviews have called for the inclusion of relevant covariates (i.e., those associated with both OCD and insomnia) when examining the associations between OCD and sleep disturbances (Paterson et al., 2013), overall levels of worry and number of traumatic life events (TLEs) were controlled for in the current analyses. 2. Methods 2.1 Participants and procedure Individuals were recruited through Amazon’s Mechanical Turk (Mturk). Mturk is an online labor marketplace that allows one to recruit a large number of “workers” to complete various tasks. Workers can browse tasks by title, availability, and reward and are paid upon completion (Shapiro et al., 2013). Mturk is becoming an increasing popular way to collect clinically relevant data as this method lends itself well to the collection of self-report data. Data obtained from Mturk is high in quality (Buhrmester et al., 2011; Paolacci and Chandler, 2014). In addition, individuals are typically white, middle class, educated, underemployed, and approximately 30 years of age (Berinsky et al., 2012; Shapiro et al., 2013). The survey for the current study was made available to individuals living in the United States who were over the age of 18 and demonstrated high quality work on previous tasks as indicated by a Human Intelligence Task rating greater than 90%. After giving informed consent, participants completed a battery of self-report questionnaires that took approximately 1 hour, for which they were compensated $1.00. This payment is consent with the median hourly wage for tasks performed on Mturk (Horton and Chilton, 2010).
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Overall, 526 individuals completed the online survey. Two validity check items (e.g., “Are you reading this questionnaire?”) were included as a safety test against random responses. No individuals missed both of these questions, thus no participants were excluded in the current investigation. The sample was predominantly female (69.2% female, 30.8% male) with ages ranging from 18 to 72 (M= 34.87, SD= 12.41). The majority of participants were Caucasian, identifying as 84.2 % Caucasian, 8% African American, 4.2% Asian, 1.1% American Indian, and 2.5% other (e.g., biracial). A majority of the sample (36.3%) identified their relationship status as married, with 35.9% identifying as single or never married, 15.2% cohabitating, 10.1% divorced, 1.1% widowed, 0.8% separated and 0.6% responded “other”. Regarding highest level of education, 1.1% had completed some high school, 12.9% had a high school diploma or the equivalent to a GED, 3.6% attended a business, trade, or technical school, 35.7% had some college, a 2 year degree, or an AA, 35.2% had a college degree (i.e., BA or BS), and 11.4% had a graduate degree (i.e., MA, MS, JD, MBA, or PhD). 2.2 Measures 2.2.1 Anxiety sensitivity. AS was assessed using the Anxiety Sensitivity Index - 3 (ASI3; Taylor et al., 2007). The ASI-3 is an 18-item self-report measure of AS. This scale provides a more stable measure of the three most widely recognized AS subfactors (cognitive, physical, and social concerns) than the original ASI (Reiss et al., 1986). The measure has shown good psychometric properties (Taylor et al., 2007). In the current study, the ASI-3 subscales demonstrated acceptable to excellent internal consistency (cognitive α = 0.93, physical α = 0.90, social α = 0.87). 2.2.2 Insomnia. Symptoms of insomnia were assed using the Insomnia Severity Index (Bastien et al., 2001). The ISI is a 7-item self-report questionnaire assessing sleep difficulties
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(e.g., falling asleep, staying asleep, waking too early), satisfaction/dissatisfaction with sleep patterns, and/or interference with daily functioning. Respondents were asked to rate each item using a 5-point Likert scale ranging from 0 to 4 with higher scores reflecting more severe sleep problems and greater dissatisfaction with sleep patterns. The ISI has shown evidence of high internal consistency (Bastien et al., 2001). In the present study, the ISI demonstrated excellent internal consistency (α = 0.91). 2.2.3 Obsessive-compulsive symptoms. Obsessive-compulsive symptoms were assessed using the Dimensional Obsessive-Compulsive Scale (DOCS; Abramowitz et al., 2010). The DOCS is a 20-item measure assessing the four dimensions of OC symptoms most reliably replicated in previous structural research. This measure includes four subscales: contamination, responsibility, unacceptable thoughts, and symmetry. In the present study, the DOCS subscales demonstrated acceptable to excellent internal consistency (contamination α = 0.87, responsibility α = 0.91, unacceptable thoughts α = 0.92, and symmetry α = 0.91). 2.2.4 Traumatic life event. The number of traumatic life events was assessed using the Posttraumatic Diagnostic Scale (PDS; Foa, Cashman, Jaycox, & Perry, 1997). This 4-part questionnaire provides a measure of Posttraumatic Stress Disorder symptom severity. In the current investigation, only the 12-item checklist of traumatic event exposure was used. Specifically, participants were asked to indicate all of the traumatic events that they had either witnessed or experienced from a list of 12 options. These options include events such as a serious accident, natural disaster, military combat, and sexual assault. Prior research has shown the PDS to provide both reliable and valid information for both PTSD symptom severity and diagnosis (Foa et al., 1997). A count variable was computed and used as a covariate in all analyses.
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2.2.5 Worry. Symptoms of worry were assessed using the Penn State Worry Questionnaire (PSWQ; Meyer, Miller, Metzger, & Borkovec, 1990). The PSWQ is 16-item selfreport measure assessing an individual's general tendency to engage in excessive worry. Individuals indicate the extent to which each statement is applicable to them on a five-point Likert scale ranging from not at all (1) to very (5). The PSWQ has been reported to have high internal consistency and test-retest reliability (Meyer et al., 1990). Additionally in the present investigation the PSWQ demonstrated excellent internal consistency (α = 0.93). 3. Results 3.1 Sample descriptives Table 1 contains the means, standard deviations, and zero-order correlations for all variables used in the current analyses. The mean PSWQ total score was lower than that found in clinical populations but higher than that found in non-clinical populations (Meyer et al., 1990; Allan et al., 2014). Similarly, the mean DOCS subscale scores were slightly higher than those found in non-clinical samples but lower than those found in clinical populations (Abramowitz et al., 2010). The mean ASI-3 cognitive, physical, and social concerns subscale scores were considerably higher than those found in non-clinical populations but slightly lower than those found in clinical samples (Taylor et al., 2007; Medley et al., 2013). Regarding symptoms of insomnia, 41.2% of the sample scored in the non-clinically significant range, 31.8% scored in the subclinical range, and 27% scored in the clinical range. Finally, 71.1% of the sample endorsed experiencing at least one traumatic life event. 3.2 Primary analyses First, a hierarchical regression analysis was performed to assess the relationship between obsessive-compulsive symptom dimensions (as measured by the DOCS) and symptoms of
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insomnia (as measured by the ISI), after controlling for overall levels of worry (as measured by the PSWQ) and traumatic life events. Preliminary analyses indicated no threats or violations of normality, multicollinearity, or homoscedasticity. In the first step of the model, the TLEs as well as PSWQ scores were entered accounting for 27% of the variance in insomnia (F (2, 523) = 96.72, p < 0.001). In the second step of the model, all four subscales of the DOCS were added accounting for an additional 4% of the variance in insomnia (F Change = 7.98, p < 0.001). Consistent with initial predictions, results revealed that after controlling for TLEs and general worry, the unacceptable thoughts subscale was significantly associated with symptoms of insomnia (β = 0.19, t = 3.82, p < 0.001, sr2 = 0.02) whereas the contamination concerns (β = 0.04, t = 0.81, p = 0.42, sr2 = 0.00), responsibility for harm (β = -0.03, t = -0.49, p = 0.62, sr2 = 0.00), and symmetry/completeness subscales (β = 0.06, t = 1.28, p = 0.20, sr2 = 0.00) were not. Next, asymmetric bootstrapping mediation procedures were used to test the hypothesis that AS cognitive concerns (as measured by ASI-3) would mediate the relationship between the unacceptable thoughts domain of DOCS and insomnia after controlling for overall worry and TLEs. The mediation analysis was conducted using PROCESS with the recommended bootstrap technique of 5,000 bootstrap resamples. Results revealed that there was a significant indirect effect of unacceptable thoughts on insomnia through AS cognitive concerns (B = 0.44, 95% CI [0.33, 0.55]). The full model accounted for 36% of the variance in insomnia and was statistically significant (F (4, 521) = 73.06, p < 0.001). Finally, to demonstrate specificity regarding the mediating role of AS cognitive concerns a multiple mediator models approach was used to test the hypothesis that AS cognitive concerns rather than AS physical or AS social concerns would mediate the relationship between unacceptable thoughts and symptoms of insomnia. Once again, overall levels of worry and TLEs
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were used as covariates in the analysis. Consistent with initial prediction, results revealed that there was an indirect effect of unacceptable thoughts on insomnia through AS cognitive concerns (B = 0.12, 95% CI [0.02, 0.22]) but not through AS physical concerns (B = -0.03, 95% CI [-0.11, 0.05]) or AS social concerns (B = -0.00, 95% CI [-0.09, 0.08]). The full model accounted for 36% of the variance in insomnia and was statistically significant (F (6, 519) = 48.79, p < 0.001). 4. Discussion In line with initial prediction, results revealed that the unacceptable thoughts domain of OCD was significantly associated with symptoms of insomnia whereas the contamination concerns, responsibility for harm, and symmetry/completeness domains were not. These findings are consistent with a growing body of literature identifying associations between various anxietyrelated conditions and sleep difficulties (Ohayon and Roth, 2003; Bélanger et al., 2004; Lamarche and De Koninck, 2007). Moreover, these findings are consistent with recent research demonstrating associations between unacceptable obsessions and sleep disturbances (Timpano et al., 2014). Similar to the way uncontrolled worry in the pre-sleep period can hinder the onset of sleep (Harvey, 2000), extremely distressing obsessions could interfere with one’s ability to fall or stay asleep. Consistent with initial hypotheses, results also revealed that AS cognitive concerns rather than AS physical concerns or AS social concerns, mediated the association between the unacceptable thoughts domain of OCD and symptoms of insomnia. Previous research has indicated distinct associations between AS cognitive concerns and the unacceptable obsessions dimension of OCD (Wheaton et al., 2012; Raines et al., 2014b) as well as symptoms of insomnia (Vincent and Walker, 2001; Calkins et al., 2013). Consistent with this research, the current findings extend the limited empirical work available establishing a link between the unacceptable
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thoughts domain of OCD and sleep disturbances by identifying a potential mechanism that partially accounts for this association. In an effort to better understand the full picture, future investigations should examine other factors that could add explanatory value to the current model. The current results fit within previously proposed cognitive models of OCD. Specifically, individuals with OCD are thought to evaluate intrusive thoughts as especially important or meaningful, leading to increased attempts at suppression (Purdon, 2008). It has been suggested that the recurrent and intrusive nature of these obsessions coupled with unsuccessful attempts at suppression may lead one to conclude that they have lost control over their cognitive capacities (Raines et al., 2014a). Additionally, the tendency to excessively monitor and overvalue one’s thoughts may in turn lead to more negative appraisals as well as increased anxiety and hyperarousal. Similar to the way uncontrolled worry can prevent the onset of sleep among GAD patients (Harvey, 2002), the combination of recurrent and intrusive thoughts coupled with fears of mental incapacitation in the pre-sleep period may lead to increased hyperarousal and the development of insomnia symptoms among individuals with OCD. The present investigation has important clinical implications worth noting. In particular, previous research has shown AS to be a highly malleable construct that is capable of being rapidly reduced (Keough and Schmidt, 2012). For example, in the largest AS intervention to date Schmidt and colleagues (2007) randomized 404 individuals to an anxiety sensitivity amelioration training (ASAT) condition or a health information control. Results indicated significant reductions in overall AS for those individuals in the ASAT condition compared to those in the control condition (30% vs 17%, respectively). These reductions were maintained at two-year follow-up and associated with a lower incidence of Axis I psychopathology (ASAT = 7.5%,
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Control = 12.7%). Recent research has also found promising results for interventions designed to more specifically target the cognitive concerns dimension of AS (Schmidt et al., 2014). In particular, Schmidt et al., 2014 found that individuals randomized to a brief one-session Cognitive Anxiety Sensitivity Treatment (CAST), compared to a health information control, evidenced significant reductions in AS post-treatment and follow-up that were specific to AS cognitive concerns. Moreover, reductions in AS cognitive concerns were associated with symptom improvement for various outcomes including insomnia (Short et al., 2014). Given the somewhat treatment refractory nature of OCD (Jenike, 2004), in particular for individuals elevating the unacceptable thoughts domain (Alonso et al., 2001), future work should determine if interventions aimed at reducing AS cognitive concerns would be effective at treating individuals with symptoms of insomnia and obsessive-compulsive disorder, particularly those with elevated obsessions. The present study should be considered in the context of its limitations and opportunities for future research. First, the current sample included individuals with various levels of OC symptoms rather than clinically diagnosable levels of OCD. Although this is consistent with prior research and a dimensional conceptualization of OCD (Taylor, 2005; Timpano et al., 2014), future research should examine whether these findings generalize to clinical samples. Second, the current investigation is based on cross-sectional data, thus causal inferences cannot be made. Although this is a reasonable first step given the paucity of research in this area, it is important for future research to examine these relationships prospectively. Such an approach would provide the ability to better evaluate potential causal pathways of these relationships. Third, the sample was primarily female and Caucasian. Future investigations should attempt to replicate these findings in more diverse samples of individuals. Finally, we relied on self-report measures
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to assess our constructs of interest. Although we used common and well-validated measures, specifically the DOCS, ISI, and ASI-3 (Taylor et al., 2007; Abramowitz et al., 2010; Morin et al., 2011), future research would benefit from incorporating other methods of assessing these constructs. For example, objective measures of sleep like actigraphy or polysomnography might be complementary to self-report measures of sleep and would provide an additional source of data (Chesson Jr et al., 1997). In spite of the limitations, there are notable strengths of the current study. This study replicated past findings that the unacceptable thoughts domain, and not other OCD symptom domains, was associated with symptoms of insomnia. In addition, an indirect pathway through AS cognitive concerns, and not other lower order dimensions of AS, was found to account for this relation. Therefore, the present study tentatively provides a model explaining the relationship between the unacceptable thoughts domain of OCD and insomnia and highlights the utility of AS cognitive concerns as a potential useful transdiagnostic treatment target.
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Meyer, T., Miller, M., Metzger, R., Borkovec, T., 1990. Development and validation of the penn state worry questionnaire. Behaviour Research and Therapy 28 (6), 487-495. Monti, J.M., Monti, D., 2000. Sleep disturbance in generalized anxiety disorder and its treatment. Sleep Medicine Reviews 4 (3), 263-276. Morin, C.M., Belleville, G., Bélanger, L., Ivers, H., 2011. The insomnia severity index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep 34 (5), 601-608. Ohayon, M.M., 1997. Prevalence of DSM-IV diagnostic criteria of insomnia: distinguishing insomnia related to mental disorders from sleep disorders. Journal of Psychiatric Research 31 (3), 333-346. Ohayon, M.M., 2002. Epidemiology of insomnia: what we know and what we still need to learn. Sleep Medicine Reviews 6 (2), 97-111. Ohayon, M.M., Roth, T., 2003. Place of chronic insomnia in the course of depressive and anxiety disorders. Journal of Psychiatric Research 37 (1), 9-15. Paolacci, G., Chandler, J., 2014. Inside the turk: understanding mechanical turk as a participant pool. Current Directions in Psychological Science 23 (3), 184-188. Paterson, J.L., Reynolds, A.C., Ferguson, S.A., Dawson, D., 2013. Sleep and obsessivecompulsive disorder (OCD). Sleep Medicine Reviews 17 (6), 465-474. Purdon, C., 2008. Unacceptable Obsessional Thoughts and Covert Rituals. Johns Hopkins University Press, Baltimore, MD. Raines, A.M., Capron, D.W., Bontempo, A.C., Dane, B.F., Schmidt, N.B., 2014a. Obsessive Compulsive Symptom Dimensions and Suicide: the Moderating Role of Anxiety Sensitivity Cognitive Concerns. Cognitive Therapy and Research 38 (6), 660-669.
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Raines, A.M., Oglesby, M.E., Capron, D.W., Schmidt, N.B., 2014b. Obsessive Compulsive Disorder and Anxiety Sensitivity: identification of Specific Relations among Symptom Dimensions. Journal of Obsessive-Compulsive and Related Disorders 3 (2), 71-76. Reiss, S., McNally, R., 1985. Expectancy model of fear. In: Reiss, S., Bootzin, R. (Eds.), Theoretical Issues in Behavior Therapy. Academic Press, San Diego, CA, pp. 107-122. Reiss, S., Peterson, R., Gursky, D., McNally, R., 1986. Anxiety sensitivity, anxiety frequency and the prediction of fearfulness. Behaviour Research and Therapy 24 (1), 1-8. Robinson, L.J., Freeston, M.H., 2014. Emotion and internal experience in Obsessive Compulsive Disorder: reviewing the role of alexithymia, anxiety sensitivity and distress tolerance. Clinical Psychology Review 34 (3), 256-271. Rosekind, M.R., Gregory, K.B., 2010. Insomnia risks and costs: health, safety, and quality of life. American Journal of Managed Care 16 (8), 617-626. Schmidt, N.B., Capron, D.W., Raines, A.M., Allan, N.P., 2014. Randomized clinical trial evaluating the efficacy of a brief intervention targeting anxiety sensitivity cognitive concerns. Journal of Consulting and Clinical Psychology 82 (6), 1023-1033. Schmidt, N.B., Eggleston, A.M., Woolaway-Bickel, K., Fitzpatrick, K.K., Vasey, M.W., Richey, J.A., 2007. Anxiety Sensitivity Amelioration Training (ASAT): a longitudinal primary prevention program targeting cognitive vulnerability. Journal of Anxiety Disorders 21 (3), 302-319. Shapiro, D.N., Chandler, J., Mueller, P.A., 2013. Using Mechanical Turk to study clinical populations. Clinical Psychological Science, 2167702612469015. Short, N.A., Allan, N.P., Raines, A.M., Schmidt, N.B., 2014. The effects of an anxiety sensitivity intervention on insomnia symptoms. Sleep Medicine.
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Taylor, S., 2005. Dimensional and subtype models of OCD. In: Abramowitz, J.S., Houts, A.C. (Eds.), Concepts and controversies in obsessive-compulsive disorder. Springer, New
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2
3
4
5
6
7
8
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York, pp. 27-52. Taylor, S., Zvolensky, M.J., Cox, B.J., Deacon, B., Heimberg, R.G., Ledley, D.R., Abramowitz, J.S., Holaway, R.M., Sandin, B., Stewart, S.H., Coles, M., Eng, W., Daly, E.S., Arrindell, W.A., Bouvard, M., Cardenas, S.J., 2007. Robust dimensions of anxiety sensitivity: development and initial validation of the Anxiety Sensitivity Index-3. Psychological Assessment 19 (2), 176-188. Timpano, K.R., Carbonella, J.Y., Bernert, R.A., Schmidt, N.B., 2014. Obsessive compulsive symptoms and sleep difficulties: exploring the unique relationship between insomnia and obsessions. Journal of Psychiatric Research 57, 101-107. Vincent, N., Walker, J., 2001. Anxiety sensitivity: predictor of sleep‐related impairment and medication use in chronic insomnia. Depression and Anxiety 14 (4), 238-243. Voderholzer, U., Riemann, D., Huwig-Poppe, C., Kuelz, A.K., Kordon, A., Bruestle, K., Berger, M., Hohagen, F., 2007. Sleep in obsessive compulsive disorder. European Archives of Psychiatry and Clinical Neuroscience 257 (3), 173-182. Wheaton, M.G., Mahaffey, B., Timpano, K.R., Berman, N.C., Abramowitz, J.S., 2012. The relationship between anxiety sensitivity and obsessive-compulsive symptom dimensions. Journal of Behavior Therapy and Experimental Psychiatry 43 (3), 891-896.
Table 1
10
22
1. TLEs
-
2. PSQW Total
0.08
-
3. DOCS C1
0.08
0.17*
-
4. DOCS C2
0.15*
0.40*
0.62*
-
5. DOCS C3
0.17*
0.49*
0.46*
0.61*
-
6. DOCS C4
0.19*
0.33*
0.57*
0.61*
0.51*
-
7. ASI-3 Cog
0.08
0.55*
0.35*
0.50*
0.54*
0.40*
-
8. ASI-3 Phys
0.11*
0.47*
0.35*
0.47*
0.41*
0.39*
0.70*
-
9. ASI-3 Soc
0.10*
0.55*
0.29*
0.41*
0.44*
0.38*
0.67*
0.70*
-
10. ISI Total
0.32*
0.43*
0.22*
0.31*
0.42*
0.31*
0.42*
0.34*
0.35*
-
Mean
1.95
49.42
2.96
3.49
4.09
3.17
5.85
7.38
9.27
9.88
6.27
6.26
6.90
SD
1.96 15.09 3.41 4.05 4.32 3.85 6.46 Zero-order correlations, means, and standard deviations for all self-report measures.
Note. *p < 0.05. TLEs, Traumatic Life Events; PSWQ Total, Penn State Worry Questionnaire Total Score; DOCS C1, Dimensional Obsessive-Compulsive Scale Category 1 – Concerns about Germs and Contamination; DOCS C2, Dimensional Obsessive-Compulsive Scale Category 2 – Concerns about being Responsible for Harm, Injury, or Bad Luck; DOCS C3, Dimensional Obsessive-Compulsive Scale Category 3 – Unacceptable Thoughts; DOCS C4, Dimensional Obsessive-Compulsive Scale Category 4 – Concerns about Symmetry, Completeness, and the Need for Things to be Just Right; ASI-3 Cog, Anxiety Sensitivity Index-3 Cognitive Subscale; ASI-3 Phys, Anxiety Sensitivity Index-3 Physical Subscale; ASI-3 Soc, Anxiety Sensitivity Index-3 Social Subscale; ISI Total, Insomnia Severity Index Total Score Highlights
23
Examined the relationships between unacceptable thoughts and insomnia. Unacceptable thoughts domain of OCD was associated with insomnia. Anxiety sensitivity cognitive concerns mediated this relationship. Findings support and extend prior research on OCD and sleep.
PII: DOI: Reference:
S0165-1781(15)00394-7 http://dx.doi.org/10.1016/j.psychres.2015.05.081 PSY9001
To appear in: Psychiatry Research Received date: 7 October 2014 Revised date: 26 April 2015 Accepted date: 25 May 2015 Cite this article as: Amanda M. Raines, Nicole A. Short, Carson A. Sutton, Mary E. Oglesby, Nicholas P. Allan and Norman B. Schmidt, Obsessive-compulsive symptom dimensions and insomnia: The mediating role of anxiety sensitivity cognitive concerns, Psychiatry Research, http://dx.doi.org/10.1016/j.psychres.2015.05.081 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Obsessive-compulsive symptom dimensions and insomnia: the mediating role of anxiety sensitivity cognitive concerns
Amanda M. Raines Nicole A. Short Carson A. Sutton Mary E. Oglesby Nicholas P. Allan & Norman B. Schmidt*
Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 323064301 USA
Send correspondence to Norman B. Schmidt, Department of Psychology, Florida State University, 1107 W. Call St., Tallahassee, FL 32306-4301 USA, Tel: (850) 645-1766, Fax: (850) 644-7739, email: [email protected] Obsessive-compulsive symptom dimensions and insomnia: the mediating role of anxiety sensitivity cognitive concerns
Abstract
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Existing research on the relationship between obsessive-compulsive disorder (OCD) and insomnia is scarce. Moreover, no research has examined potential mechanisms that may account for the observed relations among OCD and sleep difficulties. The cognitive concerns subscale of anxiety sensitivity (AS), which reflects fears of mental incapacitation, has been linked to both symptoms of OCD and insomnia and may serve as a mechanism for increasing sleep disturbance among patients with OCD. The current study examined the relationship between OCD symptoms and insomnia and the potential mediating role of AS cognitive concerns. The sample consisted of 526 individuals recruited through Amazon’s Mechanical Turk (Mturk), an online crowdsourcing marketplace. Results revealed distinct associations between the unacceptable thoughts domain of OCD and symptoms of insomnia. Additionally, AS cognitive concerns mediated the relationship between these constructs. Future research should seek to replicate these findings using clinical samples and prospective designs. Keywords: obsessive-compulsive disorder; insomnia; anxiety sensitivity cognitive concerns; sleep
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1. Introduction Sleep disturbances are common among the general population, with up to one third of individuals reporting at least occasional difficulties falling or staying asleep (Breslau et al., 1996). These sleep difficulties may become chronic, and develop associated daytime consequences, including fatigue, irritability, and dysphoric mood. About 6% of the population may have such chronic sleep difficulties along with clinically significant distress and impairment, consistent with a diagnosis of insomnia disorder (Ohayon, 2002). Individuals with this disorder often complain of various disruptions to their daytime functioning, including sleepiness interfering with their daily activities, problems focusing, and decreased productivity in personal and occupational roles. In addition to these personal consequences, when direct (e.g., healthcare costs), and indirect (e.g., medical comorbidities, insomnia related alcohol abuse, reduced workplace productivity, motor vehicle and other accidents) insomnia-related costs are combined, they are estimated to range from $92 to $107 billion annually across the United States (Rosekind and Gregory, 2010). These data suggest that insomnia disorder, and symptoms thereof, are prevalent and costly, meriting further research. In addition to the prevalence and consequences associated with sleep disturbances and insomnia disorder in the general population, individuals with mental illness are much more likely to suffer from sleep difficulties and associated problems. Specifically, some degree of sleep disturbance is highly comorbid with nearly all psychiatric disorders (Benca et al., 1992). In fact, a meta-analysis has indicated that objective sleep disturbance (e.g., reduced total sleep time and sleep efficiency, and increased sleep onset latency) as measured by polysomnograpy is linked with the presence of a psychiatric disorder (Benca et al., 1992). In particular, sleep disturbances are present in large proportions of individuals with mood and anxiety disorders. For example, the
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majority (60-84%) of individuals with major depressive disorder (MDD) report some symptoms of insomnia including difficulty falling asleep (Ford and Kamerow, 1989; Hamilton, 1989). In terms of anxiety disorders, generalized anxiety disorder (GAD) has the greatest comorbidity rate with insomnia, with approximately 60% of those with GAD reporting at least occasional symptoms of insomnia (Monti and Monti, 2000; Bélanger et al., 2004). However, sleep disturbances have been found to be present in most, if not all, anxiety-related conditions, including specific phobia, panic disorder, and posttraumatic stress disorder (Ohayon, 1997; Lamarche and De Koninck, 2007). An additional anxiety-related disorder that has received less attention with regard to sleep disturbances, including symptoms of insomnia, is obsessive-compulsive disorder (OCD). OCD is a heterogeneous psychiatric disorder characterized by recurrent and intrusive thoughts, images, or urges (i.e., obsessions) and/or excessive avoidance and repetitive behaviors (i.e., compulsions) aimed at reducing or neutralizing the associated distress and anxiety (American Psychiatric Association, 2013). Approximately 2-3% of the population suffers from this complex and debilitating disorder (Kessler et al., 2005). OCD can lead to substantial impairment in social, occupational, and family domains and is associated with a considerable economic burden to both the individual and society (Markarian et al., 2010). Recent research has begun to closely examine the relationship between obsessivecompulsive (OC) symptoms and sleep disturbances. In a systematic literature review on sleep and OCD, Paterson and colleagues (2013) found that sleep disturbances were common among individuals with OCD (e.g., up to 48% in some samples). Specifically, individuals with OCD had reduced sleep duration and sleep efficiency compared to healthy controls with increased periods of waking after sleep onset, particularly early morning awakenings (Insel et al., 1982; Hohagen
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et al., 1994; Voderholzer et al., 2007). In addition, elevated levels of sleep disturbances among those with OCD were associated with increased severity of OC symptoms. More recently, Timpano, Carbonella, Bernert and Schmidt (2014) extended this research by investigating which aspects of OC symptoms may be related to specific components of sleep disturbances. Here, the authors found that insomnia symptoms (i.e., difficulties initiating and maintaining sleep and associated distress/impairment) were most related to OC symptoms (compared to other sleep disturbances such as delayed bedtime and nightmares). This relationship was particularly strong between insomnia and the obsessions (e.g., sexual, religious or aggressive in nature) dimension of the obsessive-compulsive inventory revised, consistent with the notion that distressing obsessions may interfere with sleep onset (Timpano et al., 2014). There are a number of possible explanations for the relationship between OCD and insomnia. First, direct effects may be present such that individuals suffering from persistent obsessions have more difficulty falling or staying asleep. Other possible explanations include indirect mechanisms such as shared comorbidity or risk factors. One shared risk factor that could help to explain the association between OC symptoms and sleep disturbances is anxiety sensitivity (AS). AS is a well-researched individual difference variable reflecting the tendency to fear bodily sensations associated with anxious arousal (Reiss and McNally, 1985). Research on the dimensional structure of AS has indicated that AS comprises one higher order factor (AS), as well as three lower order factors reflecting fears of the physical, social, and cognitive consequences of anxiety (Taylor et al., 2007). Whereas relations between the various AS subscales and several of the OC symptom domains have been found, the cognitive concerns subscale of AS, which represents fears of mental incapacitation (e.g., “When I cannot keep my mind on a task, I worry that I might be going crazy”) appears to have the strongest associations
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with OC domains (see Robinson and Freeston, 2014 for a review). In particular, research from both clinical and non-clinical samples has demonstrated unique associations between the cognitive concerns subscale of AS and the unacceptable thoughts (e.g., sexual, religious, or aggressive in nature) domain of OCD (Wheaton et al., 2012; Raines et al., 2014b). In addition to the relations between AS cognitive concerns and OC symptoms, research has also found distinct associations between AS cognitive concerns and symptoms of insomnia. For example, Vincent and Walker (2001) examined the relationship between AS and sleeprelated impairment in a sample of individuals with chronic insomnia and found that the cognitive concerns dimension of AS was associated with sleep-related impairment. Calkins, Hearon, Capozzoli, and Otto (2013) extended this research by examining the associations between AS and sleep dysfunction after accounting for two highly relevant sleep related constructs, dysfunctional beliefs about sleep and neuroticism. The authors found that whereas AS total scores did not significantly predict sleep dysfunction, the cognitive concerns subscale did. Given the associations between OC symptoms and AS cognitive concerns, as well as the associations between AS cognitive concerns and insomnia, it is reasonable to assume that AS cognitive concerns could be one factor accounting for the relations between OC symptoms and insomnia. The current study sought to replicate and extend previous research by examining the relationship between OC symptoms and insomnia and the potential mediating role of AS cognitive concerns. Consistent with previous research (Timpano et al., 2014), it was hypothesized that the unacceptable thoughts domain of OCD would be most associated with symptoms of insomnia. Second, mediation procedures were used to test the hypothesis that AS cognitive concerns would mediate the relationship between the unacceptable thoughts domain of OCD and symptoms of insomnia. Finally, in an effort to demonstrate specificity, a multiple
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mediator models approach was used to test the hypothesis that AS cognitive concerns rather than AS physical or AS social concerns would mediate the relationship between unacceptable thoughts and symptoms of insomnia. Because recent reviews have called for the inclusion of relevant covariates (i.e., those associated with both OCD and insomnia) when examining the associations between OCD and sleep disturbances (Paterson et al., 2013), overall levels of worry and number of traumatic life events (TLEs) were controlled for in the current analyses. 2. Methods 2.1 Participants and procedure Individuals were recruited through Amazon’s Mechanical Turk (Mturk). Mturk is an online labor marketplace that allows one to recruit a large number of “workers” to complete various tasks. Workers can browse tasks by title, availability, and reward and are paid upon completion (Shapiro et al., 2013). Mturk is becoming an increasing popular way to collect clinically relevant data as this method lends itself well to the collection of self-report data. Data obtained from Mturk is high in quality (Buhrmester et al., 2011; Paolacci and Chandler, 2014). In addition, individuals are typically white, middle class, educated, underemployed, and approximately 30 years of age (Berinsky et al., 2012; Shapiro et al., 2013). The survey for the current study was made available to individuals living in the United States who were over the age of 18 and demonstrated high quality work on previous tasks as indicated by a Human Intelligence Task rating greater than 90%. After giving informed consent, participants completed a battery of self-report questionnaires that took approximately 1 hour, for which they were compensated $1.00. This payment is consent with the median hourly wage for tasks performed on Mturk (Horton and Chilton, 2010).
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Overall, 526 individuals completed the online survey. Two validity check items (e.g., “Are you reading this questionnaire?”) were included as a safety test against random responses. No individuals missed both of these questions, thus no participants were excluded in the current investigation. The sample was predominantly female (69.2% female, 30.8% male) with ages ranging from 18 to 72 (M= 34.87, SD= 12.41). The majority of participants were Caucasian, identifying as 84.2 % Caucasian, 8% African American, 4.2% Asian, 1.1% American Indian, and 2.5% other (e.g., biracial). A majority of the sample (36.3%) identified their relationship status as married, with 35.9% identifying as single or never married, 15.2% cohabitating, 10.1% divorced, 1.1% widowed, 0.8% separated and 0.6% responded “other”. Regarding highest level of education, 1.1% had completed some high school, 12.9% had a high school diploma or the equivalent to a GED, 3.6% attended a business, trade, or technical school, 35.7% had some college, a 2 year degree, or an AA, 35.2% had a college degree (i.e., BA or BS), and 11.4% had a graduate degree (i.e., MA, MS, JD, MBA, or PhD). 2.2 Measures 2.2.1 Anxiety sensitivity. AS was assessed using the Anxiety Sensitivity Index - 3 (ASI3; Taylor et al., 2007). The ASI-3 is an 18-item self-report measure of AS. This scale provides a more stable measure of the three most widely recognized AS subfactors (cognitive, physical, and social concerns) than the original ASI (Reiss et al., 1986). The measure has shown good psychometric properties (Taylor et al., 2007). In the current study, the ASI-3 subscales demonstrated acceptable to excellent internal consistency (cognitive α = 0.93, physical α = 0.90, social α = 0.87). 2.2.2 Insomnia. Symptoms of insomnia were assed using the Insomnia Severity Index (Bastien et al., 2001). The ISI is a 7-item self-report questionnaire assessing sleep difficulties
9
(e.g., falling asleep, staying asleep, waking too early), satisfaction/dissatisfaction with sleep patterns, and/or interference with daily functioning. Respondents were asked to rate each item using a 5-point Likert scale ranging from 0 to 4 with higher scores reflecting more severe sleep problems and greater dissatisfaction with sleep patterns. The ISI has shown evidence of high internal consistency (Bastien et al., 2001). In the present study, the ISI demonstrated excellent internal consistency (α = 0.91). 2.2.3 Obsessive-compulsive symptoms. Obsessive-compulsive symptoms were assessed using the Dimensional Obsessive-Compulsive Scale (DOCS; Abramowitz et al., 2010). The DOCS is a 20-item measure assessing the four dimensions of OC symptoms most reliably replicated in previous structural research. This measure includes four subscales: contamination, responsibility, unacceptable thoughts, and symmetry. In the present study, the DOCS subscales demonstrated acceptable to excellent internal consistency (contamination α = 0.87, responsibility α = 0.91, unacceptable thoughts α = 0.92, and symmetry α = 0.91). 2.2.4 Traumatic life event. The number of traumatic life events was assessed using the Posttraumatic Diagnostic Scale (PDS; Foa, Cashman, Jaycox, & Perry, 1997). This 4-part questionnaire provides a measure of Posttraumatic Stress Disorder symptom severity. In the current investigation, only the 12-item checklist of traumatic event exposure was used. Specifically, participants were asked to indicate all of the traumatic events that they had either witnessed or experienced from a list of 12 options. These options include events such as a serious accident, natural disaster, military combat, and sexual assault. Prior research has shown the PDS to provide both reliable and valid information for both PTSD symptom severity and diagnosis (Foa et al., 1997). A count variable was computed and used as a covariate in all analyses.
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2.2.5 Worry. Symptoms of worry were assessed using the Penn State Worry Questionnaire (PSWQ; Meyer, Miller, Metzger, & Borkovec, 1990). The PSWQ is 16-item selfreport measure assessing an individual's general tendency to engage in excessive worry. Individuals indicate the extent to which each statement is applicable to them on a five-point Likert scale ranging from not at all (1) to very (5). The PSWQ has been reported to have high internal consistency and test-retest reliability (Meyer et al., 1990). Additionally in the present investigation the PSWQ demonstrated excellent internal consistency (α = 0.93). 3. Results 3.1 Sample descriptives Table 1 contains the means, standard deviations, and zero-order correlations for all variables used in the current analyses. The mean PSWQ total score was lower than that found in clinical populations but higher than that found in non-clinical populations (Meyer et al., 1990; Allan et al., 2014). Similarly, the mean DOCS subscale scores were slightly higher than those found in non-clinical samples but lower than those found in clinical populations (Abramowitz et al., 2010). The mean ASI-3 cognitive, physical, and social concerns subscale scores were considerably higher than those found in non-clinical populations but slightly lower than those found in clinical samples (Taylor et al., 2007; Medley et al., 2013). Regarding symptoms of insomnia, 41.2% of the sample scored in the non-clinically significant range, 31.8% scored in the subclinical range, and 27% scored in the clinical range. Finally, 71.1% of the sample endorsed experiencing at least one traumatic life event. 3.2 Primary analyses First, a hierarchical regression analysis was performed to assess the relationship between obsessive-compulsive symptom dimensions (as measured by the DOCS) and symptoms of
11
insomnia (as measured by the ISI), after controlling for overall levels of worry (as measured by the PSWQ) and traumatic life events. Preliminary analyses indicated no threats or violations of normality, multicollinearity, or homoscedasticity. In the first step of the model, the TLEs as well as PSWQ scores were entered accounting for 27% of the variance in insomnia (F (2, 523) = 96.72, p < 0.001). In the second step of the model, all four subscales of the DOCS were added accounting for an additional 4% of the variance in insomnia (F Change = 7.98, p < 0.001). Consistent with initial predictions, results revealed that after controlling for TLEs and general worry, the unacceptable thoughts subscale was significantly associated with symptoms of insomnia (β = 0.19, t = 3.82, p < 0.001, sr2 = 0.02) whereas the contamination concerns (β = 0.04, t = 0.81, p = 0.42, sr2 = 0.00), responsibility for harm (β = -0.03, t = -0.49, p = 0.62, sr2 = 0.00), and symmetry/completeness subscales (β = 0.06, t = 1.28, p = 0.20, sr2 = 0.00) were not. Next, asymmetric bootstrapping mediation procedures were used to test the hypothesis that AS cognitive concerns (as measured by ASI-3) would mediate the relationship between the unacceptable thoughts domain of DOCS and insomnia after controlling for overall worry and TLEs. The mediation analysis was conducted using PROCESS with the recommended bootstrap technique of 5,000 bootstrap resamples. Results revealed that there was a significant indirect effect of unacceptable thoughts on insomnia through AS cognitive concerns (B = 0.44, 95% CI [0.33, 0.55]). The full model accounted for 36% of the variance in insomnia and was statistically significant (F (4, 521) = 73.06, p < 0.001). Finally, to demonstrate specificity regarding the mediating role of AS cognitive concerns a multiple mediator models approach was used to test the hypothesis that AS cognitive concerns rather than AS physical or AS social concerns would mediate the relationship between unacceptable thoughts and symptoms of insomnia. Once again, overall levels of worry and TLEs
12
were used as covariates in the analysis. Consistent with initial prediction, results revealed that there was an indirect effect of unacceptable thoughts on insomnia through AS cognitive concerns (B = 0.12, 95% CI [0.02, 0.22]) but not through AS physical concerns (B = -0.03, 95% CI [-0.11, 0.05]) or AS social concerns (B = -0.00, 95% CI [-0.09, 0.08]). The full model accounted for 36% of the variance in insomnia and was statistically significant (F (6, 519) = 48.79, p < 0.001). 4. Discussion In line with initial prediction, results revealed that the unacceptable thoughts domain of OCD was significantly associated with symptoms of insomnia whereas the contamination concerns, responsibility for harm, and symmetry/completeness domains were not. These findings are consistent with a growing body of literature identifying associations between various anxietyrelated conditions and sleep difficulties (Ohayon and Roth, 2003; Bélanger et al., 2004; Lamarche and De Koninck, 2007). Moreover, these findings are consistent with recent research demonstrating associations between unacceptable obsessions and sleep disturbances (Timpano et al., 2014). Similar to the way uncontrolled worry in the pre-sleep period can hinder the onset of sleep (Harvey, 2000), extremely distressing obsessions could interfere with one’s ability to fall or stay asleep. Consistent with initial hypotheses, results also revealed that AS cognitive concerns rather than AS physical concerns or AS social concerns, mediated the association between the unacceptable thoughts domain of OCD and symptoms of insomnia. Previous research has indicated distinct associations between AS cognitive concerns and the unacceptable obsessions dimension of OCD (Wheaton et al., 2012; Raines et al., 2014b) as well as symptoms of insomnia (Vincent and Walker, 2001; Calkins et al., 2013). Consistent with this research, the current findings extend the limited empirical work available establishing a link between the unacceptable
13
thoughts domain of OCD and sleep disturbances by identifying a potential mechanism that partially accounts for this association. In an effort to better understand the full picture, future investigations should examine other factors that could add explanatory value to the current model. The current results fit within previously proposed cognitive models of OCD. Specifically, individuals with OCD are thought to evaluate intrusive thoughts as especially important or meaningful, leading to increased attempts at suppression (Purdon, 2008). It has been suggested that the recurrent and intrusive nature of these obsessions coupled with unsuccessful attempts at suppression may lead one to conclude that they have lost control over their cognitive capacities (Raines et al., 2014a). Additionally, the tendency to excessively monitor and overvalue one’s thoughts may in turn lead to more negative appraisals as well as increased anxiety and hyperarousal. Similar to the way uncontrolled worry can prevent the onset of sleep among GAD patients (Harvey, 2002), the combination of recurrent and intrusive thoughts coupled with fears of mental incapacitation in the pre-sleep period may lead to increased hyperarousal and the development of insomnia symptoms among individuals with OCD. The present investigation has important clinical implications worth noting. In particular, previous research has shown AS to be a highly malleable construct that is capable of being rapidly reduced (Keough and Schmidt, 2012). For example, in the largest AS intervention to date Schmidt and colleagues (2007) randomized 404 individuals to an anxiety sensitivity amelioration training (ASAT) condition or a health information control. Results indicated significant reductions in overall AS for those individuals in the ASAT condition compared to those in the control condition (30% vs 17%, respectively). These reductions were maintained at two-year follow-up and associated with a lower incidence of Axis I psychopathology (ASAT = 7.5%,
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Control = 12.7%). Recent research has also found promising results for interventions designed to more specifically target the cognitive concerns dimension of AS (Schmidt et al., 2014). In particular, Schmidt et al., 2014 found that individuals randomized to a brief one-session Cognitive Anxiety Sensitivity Treatment (CAST), compared to a health information control, evidenced significant reductions in AS post-treatment and follow-up that were specific to AS cognitive concerns. Moreover, reductions in AS cognitive concerns were associated with symptom improvement for various outcomes including insomnia (Short et al., 2014). Given the somewhat treatment refractory nature of OCD (Jenike, 2004), in particular for individuals elevating the unacceptable thoughts domain (Alonso et al., 2001), future work should determine if interventions aimed at reducing AS cognitive concerns would be effective at treating individuals with symptoms of insomnia and obsessive-compulsive disorder, particularly those with elevated obsessions. The present study should be considered in the context of its limitations and opportunities for future research. First, the current sample included individuals with various levels of OC symptoms rather than clinically diagnosable levels of OCD. Although this is consistent with prior research and a dimensional conceptualization of OCD (Taylor, 2005; Timpano et al., 2014), future research should examine whether these findings generalize to clinical samples. Second, the current investigation is based on cross-sectional data, thus causal inferences cannot be made. Although this is a reasonable first step given the paucity of research in this area, it is important for future research to examine these relationships prospectively. Such an approach would provide the ability to better evaluate potential causal pathways of these relationships. Third, the sample was primarily female and Caucasian. Future investigations should attempt to replicate these findings in more diverse samples of individuals. Finally, we relied on self-report measures
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to assess our constructs of interest. Although we used common and well-validated measures, specifically the DOCS, ISI, and ASI-3 (Taylor et al., 2007; Abramowitz et al., 2010; Morin et al., 2011), future research would benefit from incorporating other methods of assessing these constructs. For example, objective measures of sleep like actigraphy or polysomnography might be complementary to self-report measures of sleep and would provide an additional source of data (Chesson Jr et al., 1997). In spite of the limitations, there are notable strengths of the current study. This study replicated past findings that the unacceptable thoughts domain, and not other OCD symptom domains, was associated with symptoms of insomnia. In addition, an indirect pathway through AS cognitive concerns, and not other lower order dimensions of AS, was found to account for this relation. Therefore, the present study tentatively provides a model explaining the relationship between the unacceptable thoughts domain of OCD and insomnia and highlights the utility of AS cognitive concerns as a potential useful transdiagnostic treatment target.
16
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Table 1
10
22
1. TLEs
-
2. PSQW Total
0.08
-
3. DOCS C1
0.08
0.17*
-
4. DOCS C2
0.15*
0.40*
0.62*
-
5. DOCS C3
0.17*
0.49*
0.46*
0.61*
-
6. DOCS C4
0.19*
0.33*
0.57*
0.61*
0.51*
-
7. ASI-3 Cog
0.08
0.55*
0.35*
0.50*
0.54*
0.40*
-
8. ASI-3 Phys
0.11*
0.47*
0.35*
0.47*
0.41*
0.39*
0.70*
-
9. ASI-3 Soc
0.10*
0.55*
0.29*
0.41*
0.44*
0.38*
0.67*
0.70*
-
10. ISI Total
0.32*
0.43*
0.22*
0.31*
0.42*
0.31*
0.42*
0.34*
0.35*
-
Mean
1.95
49.42
2.96
3.49
4.09
3.17
5.85
7.38
9.27
9.88
6.27
6.26
6.90
SD
1.96 15.09 3.41 4.05 4.32 3.85 6.46 Zero-order correlations, means, and standard deviations for all self-report measures.
Note. *p < 0.05. TLEs, Traumatic Life Events; PSWQ Total, Penn State Worry Questionnaire Total Score; DOCS C1, Dimensional Obsessive-Compulsive Scale Category 1 – Concerns about Germs and Contamination; DOCS C2, Dimensional Obsessive-Compulsive Scale Category 2 – Concerns about being Responsible for Harm, Injury, or Bad Luck; DOCS C3, Dimensional Obsessive-Compulsive Scale Category 3 – Unacceptable Thoughts; DOCS C4, Dimensional Obsessive-Compulsive Scale Category 4 – Concerns about Symmetry, Completeness, and the Need for Things to be Just Right; ASI-3 Cog, Anxiety Sensitivity Index-3 Cognitive Subscale; ASI-3 Phys, Anxiety Sensitivity Index-3 Physical Subscale; ASI-3 Soc, Anxiety Sensitivity Index-3 Social Subscale; ISI Total, Insomnia Severity Index Total Score Highlights
23
Examined the relationships between unacceptable thoughts and insomnia. Unacceptable thoughts domain of OCD was associated with insomnia. Anxiety sensitivity cognitive concerns mediated this relationship. Findings support and extend prior research on OCD and sleep.