Depression and impulsiveness among soldiers who died by suicide: A psychological autopsy study

Journal of Affective Disorders 235 (2018) 341–347

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Research paper

Depression and impulsiveness among soldiers who died by suicide: A psychological autopsy study

T

Leah Shelefa,b, Neta Koremb, Nirit Yavnaic, Rinat Yedidyab, Keren Ginatb, Golan Shahard, ⁎ Assaf Yacobie,f, a

Psychology Branch, Israeli Air Force, Ramat Gan, Israel Mental Health Unit, Medical Corps, Israel Defense Force, Ramat Gan, Israel c Medical Corps, Israel Defense Force, Ramat Gan, Israel d Department of Psychology, Ben-Gurion University of the Negev, Beer-Sheva, Israel e Department of Psychiatry, Tel Aviv Sourasky Medical Center, Israel f Tel Aviv University Sackler Faculty of Medicine, Tel Aviv, Israel b

A R T I C LE I N FO

A B S T R A C T

Keywords: Depression Impulsivity Suicide Military Soldiers Adolescents

Introduction: Despite the accumulated knowledge about suicide, suicidal acts remain difficult to predict, and many suicides are acted out impulsively. Methods: We performed a psychological autopsy study based on inquiries about the deaths of all male soldiers aged 18–21 years who served in the Israeli army and died by suicide between 2009 and 2013 (n = 69). The study population was first divided into two groups: those who had depressive disorder (n = 31); and those who did not (n = 38). Socio-demographic characteristics of the subjects and the characteristics of the suicidal act were compared. Afterwards, the study population was re-divided by the presence or absence of impulsive personality traits (n = 22, and n = 47, respectively), and investigated for distinct suicidal behavior features. Results: No significant socio-demographic differences were found between the depressed and non-depressed suicide victims. The depressed group had showed more signs of planning the act (47% vs. 23%), and had expressed suicidal ideation in the days preceding the suicide (51.6% vs. 21%). One third of the subjects were found to have an impulsive personality trait, with significantly more histories of disciplinary issues, violence and cluster B personality disorders. Alcohol use during the act was significantly more prevalent among impulsive than non-impulsive subjects (45.4% vs. 14.9%). Conclusion: Identification of distinct clinical groups of suicide victims among young males might help clinicians evaluate high risk cases, and may provide valuable opportunities to alleviate and prevent these events in the future.

1. Introduction Suicide is the second leading cause of death worldwide among adolescents and young adults aged 15–24 (Sullivan et al., 2015). In contrast to the stable trend in the rate of suicide among civilians in the US, the suicide rate in the US army has dramatically increased (Archuleta et al., 2014; Nock et al., 2014). This evidence suggests that soldiers might be a particularly relevant population for suicide research, and Israeli soldiers might be particularly relevant for such research because of compulsory military service for all citizens who reach the age of 18. Hence, most of the country's healthy adolescent population serves in the military and is under army medical surveillance (Shelef et al., 2016). Research on suicide in this population is vital

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owing to the high levels of stress and availability of weapons in the military, and because the risk of suicide is at its peak at these ages (Nock et al., 2008; Shelef et al., 2016). The vulnerability-stress model proposes that an individual has unique biological, psychological, and social elements, including strengths and vulnerabilities for dealing with stress (Zubin and Spring, 1977). This model may be helpful in understanding the phenomenon of suicide, because it distinguishes vulnerability factors that predispose people to be at high risk for suicide (e.g., presence of mental illness, and prior suicidal behavior), as well as stress factors that trigger suicidal behaviors among those who are vulnerable (e.g., hopelessness, adverse life events; (Brown et al., 2000; Buchman-Schmitt et al., 2017; Mann et al., 1999). Unipolar depression features prominently among

Corresponding author at: Department of Psychiatry, Tel Aviv Sourasky Medical Center, 10 Dafna St., Tel-Aviv, Israel. E-mail address: [email protected] (A. Yacobi).

https://doi.org/10.1016/j.jad.2018.04.068 Received 25 October 2017; Received in revised form 14 March 2018; Accepted 7 April 2018 Available online 10 April 2018 0165-0327/ © 2018 Elsevier B.V. All rights reserved.

Journal of Affective Disorders 235 (2018) 341–347

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suicide attempts have yielded conflicting findings. Recent reviews have cast doubt on the role of impulsivity in suicidal behavior (Anestis et al., 2014), although impulsive suicide ideators/attempters might simply constitute a minority group among suicidal individuals. Thus, studies have found that individuals who make impulsive suicide attempts reported lower expectations of death as a result of their attempt, had less suicide ideation, and were less depressed than non-impulsive suicide attempters (Baca-Garcia et al., 2005; Simon et al., 2001; Wyder and De Leo, 2007). Spokas et al. (2012) used the Suicide Intention Scale (SIS) to compare individuals who make impulsive suicide attempts with those who make premeditated attempts, and found that impulsive suicide attempters were less depressed and expected that their attempts to be less lethal. However, the lethality of suicide attempts was similar for both groups. The authors therefore concluded that the presence of impulsive behavior might increase the risk of suicide completion even in the absence of depression and hopelessness (Spokas et al., 2012). However, there is a lack of knowledge about the relationship between impulsive behavior and the characteristics of suicide completers, because only a few studies have been carried out among this population (Brent et al., 1994; Dumais et al., 2005; Maser et al., 2002; Zouk et al., 2006). Existing studies have shown that compared with premeditated suicides, impulsive suicides are characterized by a higher prevalence of aggressive behavior, substance abuse, and psychiatric comorbidity, particularly personality disorders (clusters B and C). The current study aimed to examine mental illness and impulsivity in suicide victims. We examined all cases of male soldiers in the Israeli Defense Force (IDF) who took their lives by suicide during the period 2009–2013 (69 cases). The study hypothesis was that there are two different types of suicides: the first, planned suicides, which are the result from depression; the second, impulsive suicide in cases that had past histories of impulsive pattern of behavior. We began by dividing the study population into two groups: those who had depressive disorder at the time of the suicide, and those who did not. Subjects were characterized in terms of socio-demographic parameters. In the second phase of the study we concentrated on the suicidal act itself, and the two groups were compared in light of their affective state before the act of suicide. Finally, we focused on impulsive personality traits: Specifically, we examined whether the soldiers had prior clinically identifiable features and whether their suicidal act had distinctive features.

these vulnerability factors, as it has been found to constitute the most common diagnosis of individuals who have taken their lives by suicide (Zalsman et al., 2016). Mood disorders, alcohol or substance abuse, psychotic, and personality disorders have also been associated with high risk for suicide in military as well as civilian settings (Mann et al., 1999; Shelef et al., 2017). In addition, there is growing evidence that specific psychological factors which are not related to any particular mental disorder are highly relevant to understanding the association between psychopathology and suicidality (Nock et al., 2014). For example, in our group, cognitive and emotional difficulties were found to be associated with suicidal ideation in mentally healthy soldiers (Shelef et al., 2014). Stressful life events have also been found to have a significant doseresponse effect on the occurrence of suicidal behavior (Stein et al., 2010), and soldiers may experience military-related stressors (e.g., combat exposure and adjustment difficulties) or personal difficulties (Hyman et al., 2012; Kuehn, 2009). In addition to the above-mentioned factors, major risk factors such as male gender, prior suicidal or selfharm behavior, and past family history of suicidal behavior (Borges et al., 2010), as well as protective factors such as social support and mental health treatment are also noteworthy (Beautrais, 2003; Yacobi et al., 2013). The interaction between prior vulnerability and stressful events is still being explored, in an attempt to understand how these factors interact to lead a certain individual to engage in a suicidal act at a given time (Nock et al., 2013; Schapir et al., 2016). Research findings indicate that in the past, it was believed that over 90% of suicides were associated with diagnosable mental illness (Nock et al., 2008) or, at the very least, with subclinical psychiatric symptoms, and that the vast majority of suicidal individuals showed prominent clinical symptoms (Joiner et al., 2017). However, recent psychological-autopsy studies have challenged these findings, and suggest that up to 50% of all suicides are not associated with mental disorders (Milner et al., 2013; Pridmore, 2015). These studies emphasize the role of social and psychological factors in the pathogenesis of suicidal behavior, and argue against using mental disorders as the main target of treatment and preventive interventions. Despite the accumulated knowledge about suicide prevention strategies, it is still difficult to predict suicidal acts (Mann et al., 2005; Zalsman et al., 2016). Research indicates that more than half of all suicide attempters may be characterized as impulsive, and that a significant portion of suicidal acts are carried out impulsively (Rimkeviciene et al., 2015; Simon et al., 2001). Therefore, identification of the factors that are associated with impulsive suicide acts may shed light on different preventive strategies that can be used among this subgroup of suicidal individuals (Baca-Garcia et al., 2005). Studies on the relationship between impulsivity and the medical seriousness of

2. Methods 2.1. Study population & data source The study population included all cases of death by suicide of male soldiers in compulsory military service, during the period 2009–2013 (a

Table 1 Subjects Demographic Divided to Depressive and Non-Depressive Disordersa.

Time in Service (months) Country of Birth Education (years) Religion

Service in combat unit Method of suicide Place of suicide - at the base

Native Immigrant Secular Jewish Religious Non-Jewish shooting hanging

Depressive disorders (n = 31)

Non-depressive disorders (n = 38)

N

%

N

%

17.5 24 7 12 26 3 2 18 30 1 12

( ± 11.59) 77.4 22.6

16 22 16 11.6 30 3 5 19 33 5 19

( ± 11.90) 57.9 42.1

83.9 9.7 6.5 58.0 96.8 3.2 38.7

a

78.9 7.9 13.2 54.0 86.8 13.2 50

P

Χ2

– 0.12 0.06

8.7 –

0.65 0.63

– 0.32

0.21 0.11

6.6 2.6

Based on diagnosis made either before the suicidal event or by post-mortem psychiatric evaluation. Note: Chi-square was used for dichotomous variables. Fisher's Exact Test was used for variables that are not dichotomous. 342

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especially in psychological autopsy studies, specific criteria for determining the impulsivity of the suicidal event as well as an overall SIS score (Beck et al., 1974; Conner, 2004) filled by an independent researcher were used in the present study. Specific criteria for impulsivity included: (1) the level of planning the act known to the others in the victim's environment (not known planning, partial planning, or full planning); (2) suicidal expressions less than three hours before the act or a week before the act, which include suicidal threats, intimation, or gestures; (3) the presence of suicide note; (4) whether the subject was alone during the act; and (5) the possibility of receiving medical attention. In addition, the use of alcohol during the act was examined. Because the use of other substances was found in only one case, it is not mentioned in the Results section. The SIS is an interview-based measure of the seriousness of the intent to attempt suicide among patients who have actually attempted suicide. There is abundant evidence suggesting that the SIS is a reliable tool for assessment of the intent to die and the impulsivity of suicidal acts (Conner, 2004). This questionnaire consists of 15 items (score ranging from 0 to 30), which quantify the verbal and nonverbal behavior of suicide attempters prior to and during the most recent suicide attempt. Based on cut-off values mentioned in prior research literature, as well as on cluster analysis and multidimensional scaling, we used a cut-off score of 20 to distinguish low and high intent to die. The SIS questionnaire has been shown to have a high Cronbach's alpha reliability (0.95). The reliability of the questionnaire used in our study was 0.80 (Beck et al., 1974; Brown et al., 2000). The possible reasons for the suicidal act were categorized as: a desire to end suffering, or a desire to avenge or punish someone else (parents, spouses, commanders).

total of 69 cases). Female suicides were excluded due to the small population size (n = 8). All of the soldiers were single and had no known serious medical or mental conditions. Table 1 shows the demographic characteristics of the study population, which was divided to two groups: depressed subjects, and nondepressed subjects. All of the soldiers were between 18 and 21 years of age, and the average length of their service was 16.7 months (SD = 11.5). Two thirds of the soldiers were Israeli-born; most were secular Jews (81%), and 10% non-Jewish. Seventy-eight percent of the participants had finished high school before enlisting in the military, and 53% had been serving in combat units at the time of the suicide. Almost all of the soldiers (91%) used a rifle to commit suicide, but less than half (44.9%) committed suicide at home. Only 20% had received mental health treatment before recruitment, and 40.5% had received treatment during their service. In the IDF, an independent committee of inquiry is appointed to investigate every case of death by suicide. The committee investigates the history of the solider as well as the events leading up to the suicide, in an attempt to identify the factors that contributed to the event. The committee bases its reports on testimonies given by family members, commanders, and fellow soldiers, as well as on information gathered by the military police about the soldier's character, personal background, and details concerning the last couple of days before the suicide, including the final hours before the act. In this study, we performed retrospective data analysis based on the reports of the committee of inquiry. In addition, data were gathered from the IDF's demographic and medical databases (which include the patient's mental health record). The data collected from these sources were coded by a clinical psychologist, as part of a Master's degree thesis on suicidality of soldiers, who had been blinded as to the hypothesis and aims of this particular study.

2.3. Statistical analysis SPSS version 20.0 for Windows was used for all of the analyses. Univariate analysis included a Chi Square test for categorical independent variables (demographic, personal characteristics and psychiatric diagnosis), which was used to detect differences between groups. Fishers' Exact Test was used to assess high intent- low-intent differences. For categorical variables with more than two groups, each group was compared with the other groups. For continues variables, Mann Whitney test or Ttest were conducted. The level of statistical significance was set to p = .05.

2.2. Measures 2.2.1. Psychiatric and psychological assessment In addition to prior known psychiatric diagnoses, all of the cases examined in the study had undergone a post-hoc psychiatric analysis by the chief military psychiatrist as part of the routine suicide investigation. Notably, psychiatric diagnoses established using proxy-based evaluation has been found to be reliable (Conner et al., 2001). Psychiatric diagnoses were based on the ICD-10 manual. In the present analysis, three main diagnostic groups were used: (1) Cluster B personality disorders are characterized by marked difficulties in impulse control and high levels of sensitivity in interpersonal relationships. These include Narcissistic, Borderline, Histrionic, and Anti-Social Personality Disorders. We decided to focus on this group of personality disorders due to their high prevalence in the present study (49% of the subjects), whereas only 9 subjects (13%) had been diagnosed with other types of personality disorders; (2) Depressive disorders, including major depressive disorder and dysthymia; and (3) Adjustment disorder, defined by the DSM-V as a maladaptive reaction to an identifiable psychosocial stressor or stressors, that occurs within three months after the onset of that stressor. The existence of impulsive personality trait was based on the psychiatric reports investigating the incidents. Impulsive personality trait was defined as having at least one of the following: (1) a psychiatric diagnosis of impulse control disorder; (2) cluster B personality disorders which included specific criteria for impulsivity; (3) impulsive patterns of behavior including: known history of repetitive behaviors of acting without planning or acting with no regards to the consequences (Lewis et al., 2016, Zouk et al., 2006). Other characteristics examined were prior known violent behavior or disciplinary problems recorded in the soldier's military file.

2.4. Ethics approval The institutional review board of the IDF Medical Corps approved the study and waived the requirement for informed consent on the basis of preserving the participants' anonymity. 3. Results The subjects were initially divided into groups – depressive disorder (n = 31; 44.9%), and non-depressive disorder (n = 38; 55.1%). This was based on a diagnosis made either before they died or on a postmortem psychiatric evaluation (Table 1). There were no statistically significant differences in the demographic characteristics of each group, including number of years of education and religiosity, or in the method of suicide used (Table 1). The suicidal attributions of depressive and non-depressive suicides are presented in Table 2. As can be seen in the table, most of the soldiers in both groups did not have a history of prior suicide attempts or selfinjurious behaviors. However, a significantly higher percentage of the soldiers in the non-depressed group had a history of past self-injury than those in the depressed group (18.4% vs. 3.2%; p = .02), whereas only slightly more of the non-depressed soldiers had either threatened suicide or actually made suicide attempts in the past (9.7% vs. 13.1%, p = .42; 12.9% vs. 21%, p = .05). In regard to warning signs and planning, there were no significant

2.2.2. Assessment of the impulsivity of suicidal act In light of the substantial disagreement about the valid criteria for defining an impulsive suicide attempt (Rimkeviciene et al., 2015), 343

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Table 2 Differences in Suicidal Attributions between Depressive and Non-Depressive Disorders Groups.

Prior suicide attempt Prior suicide threat Prior self-injury Physical Complaints (3 months) Suicidal expressions (1–7 days) Suicidal expressions (< 3 h) Level of planning

Without planning Partial planning Full planning

Suicide note Alone during suicide Medical help possible End of suffering as suicide motivation Alcohol use during suicide Cluster A Personality Disorder Cluster B Personality Disorder Cluster C Personality Disorder Anxiety Disorders Impulsive trait SIS Score > 20

Depressive disorders (n = 31)

Non-depressive disorders (n = 38)

N

%

N

%

4 3 1 9 16 31 2 15 14 17 27 3 31 3 2 11 8 1 4 25

12.9 9.7 3.2 29 51.6 100 6.4 48.3 45.2 54.8 87.1 9.7 100 10 6.4 35.4 25 3.2 12.9 80.6

8 5 7 9 8 24 18 11 9 9 25 13 32 14 2 23 7 1 18 16

21.0 13.1 18.4 23.6 21.0 63.1 4704 28.9 23.7 23.7 65.8 34.2 84.2 36.8 5.2 60.5 18.4 2.6 47.4 42.1

P

Χ2

0.05 0.42 0.02 0.39 0.01 <0.001 <0.001 0.04 <0.001 0.01 0.03 0.01 0.01 0.004 0.7 0.04 0.26 0.8 0.001 0.001

2.3 0.65 11.2 0.75 20.2 34.8 42.7 7.9 10.2 20.3 12.6 14.5 17.1 16.6 0.13 12.6 1.3 0. 64 28.3 16.8

Note: Pearson chi-square coefficients are presented.

vs. 19.1%, p = .53). During the week before the suicide, the impulsive subjects had experienced significantly more stressful events that were not related to their military service (an average of 1.82 ± 0.5 vs. 0.98 ± 0.3 events, p = .047), but only slightly more stressful events within their service (1.54 ± 0.4 vs. 1.04 ± 0.5 events, p = .06). During the day of the suicide, 45.4% of the subjects in the impulsive trait group had expressed suicidal ideation, compared to 78.7% of those in the non-impulsive trait group (p < .001). However, during the last three hours before the event 54.4% of those in the impulsive trait group expressed suicidal thoughts, compared to only 21.3% of those in the non-impulsive group (p < .007). Within the period of 3 months before the suicide, impulsive subjects had more changes in behavior (extreme and sudden changes including anger outbursts, becoming reclusive or acting out) and psychomotor agitation (18% vs.6.4%, p = .11; 27.3% vs.12.7%, p = .02, respectively). During the week before the suicide, however, these differences were not significant, and both groups had an increase incidences in behavioral changes and psychomotor agitation. Revenge was found to be a major reason for suicide in the impulsive group, but not in the non-impulsive group (77.3% vs. 25.5%; p = .002), and the use of alcohol was significantly more prevalent among the impulsive subjects (45.4% vs. 14.9%; p = .008). The percentage of nonimpulsive subjects with a high total SIS score (> 20) was significantly higher among the non-impulsive subjects than among the impulsive subjects (70.2% vs. 36.3%; p = .008).

difference in physical complaints between the depressed group and non-depressed groups (29% vs 23.6, p = .39). However, significantly more of the soldiers in the depressed group had expressed suicidal ideation and gestures in the days preceding the suicide than those in the non-depressed group (51.6% vs. 21%; p = .01). Forty five percent of the soldiers in the depressed group had left signs of fully planning the suicide, compared with 23% of the non-depressed group (p < .001). Soldiers in the depressed group left more suicide notes than those in the non-depressed group (54.8% vs. 23.7%, p = .01); more of them had been alone during the act (87% vs. 65.8%, p = .035), they used less alcohol during the act (10% vs. 36.8%, p = .004) and did it in a way that made medical help less possible (9.7% vs. 34.2%, p = .01). There was only one incident of drug use during the suicidal act (marijuana) by a non-depressed subject. Regarding the reason for suicide, the desire to end suffering was appraised as the motivation in 100% of the depressed subjects, compared to 84.2% of those in the non-depressed group (p = .006). As for co-morbid diagnoses, there was no significant difference in the prevalence of anxiety disorders (3.2% vs. 2.6, p = .8) or personality disorders, other than cluster B personality disorders. Overall, the percentage of subjects with a high SIS score (> 20) was significantly higher in the depressed group than in the non-depressed group (80.6% vs. 42.1%, p = .001), and they were found to have significantly fewer impulsive characteristics than their non-depressed peers (12.9% vs. 47.4%. p = .001). Thirty two percent of the subjects in the study were characterized as having impulsive traits (Table 3). A significantly higher percentage of those with impulsive traits had a history of past disciplinary issues in the army and violent behavior records compared with those who did not have impulsive traits (63.6% vs. 19.1%. p < .001; and 18.2% vs. 2.1%. p = .038 of the impulsive and non-impulsive subjects, respectively). Regarding clinical diagnoses, a significantly higher percentage of the subjects in the impulsive trait group had been diagnosed with cluster B personality disorders (77.3% vs. 36.2%, p = .004), but not adjustment disorder (50% vs.48.9, p = .39). As for mental health treatment, the percentage of soldiers with impulsive traits who were treated before military service was significantly higher than the percentage of non-impulsive soldiers (40.9% vs. 10.6%, p = .01). However, the differences between the two groups were not significant with regard to either treatment during their entire military service (45.4% vs. 38.3%, p = .38) or within 3 months of committing suicide (22.7%

3.1. Discussion The findings in our study indicate that the characteristics of young male soldiers who killed themselves and had depression were similar to those who did not have a major depressive disorder in terms of demographic background, education, and religiosity (Table 1). These results are consistent with previous studies that compared demographic characteristics (such as age, gender, marital status and education) of individuals who made suicidal attempts with different levels of depression or levels of intent to die (Spokas et al., 2012; Wojnar et al., 2009). Moreover, the finding that almost all of the subjects used firearms to kill themselves is in accordance with suicide prevention strategies in the Israeli military (Shelef et al., 2016; Zalsman et al., 2016). These strategies hypothesize that reducing availability to firearms 344

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Table 3 Impulsive trait and impulsive suicide. Impulsive trait (n = 22)

Disciplinary problems Violent behavior Cluster B personality disorder Adjustment disorder Mental health treatment before service Mental health treatment during service Mental health treatment within 3 months Average of stressful events within service within 7 days (SD) Average of stressful events outside of service within 7 days (SD) Changes in behavior (3 months) Changes in behavior (7 days) Psychomotor agitation (3 months) Psychomotor agitation (7 days) Suicidal expressions more than 3 h Suicidal expressions less than 3 h Revenge as suicide motivation Alcohol use during suicide SIS Score > 20

Non-Impulsive trait (n = 47)

N

%

N

%

14 4 17 11 9 10 5 1.54 (0.4)

63.6 18.2 77.3 50 40.9 45.4 22.7

9 1 17 23 5 18 9 1.04 (0.5)

19.1 2.1 36.2 48.9 10.6 38.3 19.1

1.82 (0.5) 4 11 6 8 10 12 17 10 8

0.98 (0.3) 18.2 50 27.3 36.4 45.4 54.4 77.3 45.4 36.3

3 19 6 13 37 10 12 7 33

6.4 40.4 12.7 27.6 78.7 21.3 25.5 14.9 70.2

P

Χ2

0.0003 0.04 0.004 0.39 0.01 0.38 0.53 0.06

40.8 12.6 41.6 0.02 24 1.2 3.9 –

0.047

–

0.011 0.17 0.02 0.18 0.004 0.01 0.002 0.01 0.01

6.45 1.9 5.7 1.76 22.5 23.7 53.7 22 29

Note: Chi-square was used for dichotomous variables. Fisher's Exact Test was used for variables that are not dichotomous. SD = Standard Deviation

(Table 2). These findings are congruent with the results of past studies (Marttunen et al., 1998). They support the theory that there are two types of suicidal acts (premeditated and impulsive), which correlate with two types of background characteristics (depressed or impulsive personalities) among young male suicide completers who did not have debilitating mental illness. While in their study, Zouk et al. (2006) included depressive disorder NOS in the depressive group, and concluded that both premeditated and impulsive suicide completers experienced similar depressive symptoms. In this study we included only major depression and dysthymia in the depressive suicide group. Our conclusion is, therefore, that raising the cut-off symptoms to major depression and dysthymia distinguishes effectively between the two groups. Suicidal soldiers with impulsive personality traits were found to have more Cluster B personality disorders as well as histories of violent behavior and disciplinary issues. High prevalence of cluster B disorders has been found in previous research, especially when the suicidal acts were a quick response to an inter-personal conflict (Dumais et al., 2005; Pompili et al., 2011; Zouk et al., 2006). Examination of the days and hours before the suicide reveals that the soldiers in the impulsive group had experienced twice as many stressful events outside of the military than their non-impulsive counterparts (e.g., family disputes, financial difficulties, and difficulties in intimate relationships). Additionally, about half of the soldiers examined in the study, both impulsive and non-impulsive, had experienced adjustment disorder during their service, indicating that they had considerable difficulty conforming to their new environment. Despite these difficulties, it is concerning that only 20% of the soldiers had received any kind of mental health treatment before recruitment, less than half had been treated during their service (Table 3). Only 10% of the non-impulsive group had ever been treated before recruitment, and 38% had been treated during their service. Furthermore, a fifth of the subjects in both groups had met with a mental health professional during the 3 months leading to the suicides, possibly indicating that the mental difficulties of 80% of the subjects in the study had gone unnoticed. These findings might be attributed to well-known difficulties in seeking help by traditional mental health services (Wang et al., 2007). Similar difficulties are described both in other military settings and among populations under stress, therefore alternative prevention models have been implemented, such as peer support, improved

might reduce suicide rates in the military. Among this population of young soldiers, most of the suicide victims in our study did not have past histories of self-injurious behavior (n = 8, 11.6%), suicidal threats (n = 8, 11.6%) or suicide attempts (n = 12, 17.3%). The depressed group had even less of a history of these types of behaviors than the non-depressed group (Table 2). This finding is contradictory with the results of previous studies on suicide, which found that persons with previous self-harm behavior are at higher risk for suicide than the general population (Beautrais, 2001). Moreover, in our study most of the non-depressed subjects and only half of the depressed expressed any suicidal thoughts and intentions during the week before the suicide (Table 2). These findings emphasize the difficulties in identifying high-risk cases for complete suicides, even during the days leading up to the act. The suicidal act performed by the subjects in the depressed group seems to be premeditated with a higher degree of intent to die, including: planning, leaving a note, making sure they are alone during the act and that they will be unlikely to receive medical help (Table 2). This is consistent with previous findings on serious non-impulsive suicide attempts (Spokas et al., 2012), as well as with recent reviews which highlight the planned nature of many suicides (Anestis et al., 2014). Post-mortem analysis revealed that the depressed subjects were all driven by feelings of hopelessness and a desire to end their suffering, complying with similar findings in previous studies (Goldston et al., 2001; Hunter and O'Connor, 2003). The characteristics of the suicidal act among the non-depressed subjects in the current study were found to be different from those of the depressed subjects. Despite the fact that their act was lethal enough to result in death, there are indications that the intent of the non-depressed subjects was not as high as the intent of those in the depressed group (Table 1). This result is consistent with the findings of Spokas et al. (2012) on suicide attempters. They did not plan the act as fully, used more alcohol, and performed the act in a manner that left a greater chance for them to be found and receive medical attention. These findings indicate that the suicides committed by the non-depressed group were more impulsive in nature, and are supported by the lower scores of the non-depressed subjects on the SIS questionnaire (Conner, 2004). Examination of the histories of the non-depressed subjects indicates that almost half of them (47%) had impulsive personality traits, compared with 12.9% of those in the depressed group 345

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research.

handling of suicidal crises by unit command, media, and phone/Internet-based interventions have been recommended (Nock et al., 2014; Shelef et al., 2016). Interestingly, those with impulsive personality trait had shown more behavioral changes (anger outbursts, acting out or becoming reclusive) and psychomotor agitation in the three months period before the suicides compared with non-impulsive subjects (Table 3). In the week before the events, both impulsive and non-impulsive subjects had more behavioral changes and psychomotor agitation, with no significant difference between the groups. On the day of the suicide, most of the non-impulsive soldiers (78.7%) had expressed suicidal ideation, whereas less than half of the impulsive soldiers had expressed such thoughts. This trend was reversed during the last few hours before the act, when only 21% of the non-impulsive group expressed suicidal ideation and intent, as opposed to more than half of the impulsive group. This finding might indicate a sudden onset of suicidal thoughts and urges in the impulsive group, whereas the non-impulsive subjects became quiet because they had already decided to execute their plan (Wyder and De Leo, 2007). The suicide of the impulsive subjects was found to have occurred in the context of interpersonal relationships (Table 3). Most of them (77.3%) acted out of revenge and wanted to punish others for their suffering, in contrast to their non-impulsive peers, who acted out of high suicidal intent. The use of alcohol during the suicidal act perhaps served as an additional risk factor which lowered inhibitions, increased aggression, and focused attention on suicide (Hufford, 2001).

Conflict of Interest Authors declare no conflict of interest. Contributors All of the listed authors in the article have taken an active part in the making of the study or writing the article. The study was designed and planned by Leah Shelef and Assaf Yacobi. Leah Shelef, Neta Corem and Nirit Yavnai had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Statistical analysis was done by Nirit Yavnai and Assaf Yacobi. The analysis of the data, interpretations and drafting of the manuscript were done collectively by all of the authors. The final critical revisions of the manuscript for were prepared by the joint effort of Leah Shelef, Golan Shahar and Assaf Yacobi. Lastly, the data presented in the article has not been published or presented in other places. Funding This study was not funded or supported financially by any group or organization. Acknowledgment

3.2. Study limitations We would like to express our gratitude to the medical corps of the Israeli military for its support in making this study possible.

The Israeli military recruits all healthy 18–21 year-old males in the country, under mandatory law. This unique situation allows for indepth research of rare phenomena such as complete suicide, but also limit the ability to extrapolate to adolescents in other cultures or soldiers in countries where voluntary service is applied. Studies comparing Israeli and American soldiers have found that suicidality is more common among young new male recruits, who also tend to suffer from high rates of mental health difficulties (Bryan and Rudd, 2012; Gilman et al., 2014). Psychological autopsy studies are subject to the inherent methodological limitation of using proxy-based information. To minimize this limitation, much of the information in this study was based either on prior documented data or post-hoc independent psychiatric evaluation. The validity of this procedure with regard to the type of variables used in the current study has been well demonstrated in previous research (Conner et al., 2012). Another limitation of this study is the small size of the study population. Despite the anticipated low power of statistical analysis, statistically significant differences were found in most of the variables examined, which are indicative of marked differences in the factors among the study groups.

Supplementary materials Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.jad.2018.04.068. References Anestis, M.D., Soberay, K.A., Gutierrez, P.M., Hernandez, T.D., Joiner, T.E., 2014. Reconsidering the link between impulsivity and suicidal behavior. Pers. Soc. Psychol. Rev. 18, 366–386. Archuleta, D., Jobes, D.A., Pujol, L., Jennings, K., Crumlish, J., Lento, R.M., Brazaitis, K., Moore, B.A., Crow, B., 2014. Raising the clinical standard of care for suicidal soldiers: an army process improvement initiative. US Army Med. Dep. J. 55–66. Baca-Garcia, E., Diaz-Sastre, C., Garcia Resa, E., Blasco, H., Braquehais Conesa, D., Oquendo, M.A., Saiz-Ruiz, J., de Leon, J., 2005. Suicide attempts and impulsivity. Eur. Arch. Psychiatry Clin. Neurosci. 255, 152–156. Beautrais, A., 2003. Suicide in New Zealand II: a review of risk factors and prevention. N. Z. Med. J. 116, U461. Beautrais, A.L., 2001. Suicides and serious suicide attempts: two populations or one. Psychol. Med. 31, 837–845. Beck, R.W., Morris, J., Lester, D., 1974. Suicide notes and risk of future suicide. JAMA 228, 495–496. Borges, G., Nock, M.K., Haro Abad, J.M., Hwang, I., Sampson, N.A., Alonso, J., Andrade, L.H., Angermeyer, M.C., Beautrais, A., Bromet, E., Bruffaerts, R., de Girolamo, G., Florescu, S., Gureje, O., Hu, C., Karam, E.G., Kovess-Masfety, V., Lee, S., Levinson, D., Medina-Mora, M.E., Ormel, J., Posada-Villa, J., Sagar, R., Tomov, T., Uda, H., Williams, D.R., Kessler, R.C., 2010. Twelve-month prevalence of and risk factors for suicide attempts in the World Health Organization World Mental Health Surveys. J. Clin. Psychiatry 71, 1617–1628. Brent, D.A., Johnson, B.A., Perper, J., Connolly, J., Bridge, J., Bartle, S., Rather, C., 1994. Personality disorder, personality traits, impulsive violence, and completed suicide in adolescents. J. Am. Acad. Child. Adolesc. Psychiatry 33, 1080–1086. Brown, G.K., Beck, A.T., Steer, R.A., Grisham, J.R., 2000. Risk factors for suicide in psychiatric outpatients: a 20-year prospective study. J. Consult. Clin. Psychol. 68, 371–377. Bryan, C.J., Rudd, M.D., 2012. Life stressors, emotional distress, and trauma-related thoughts occurring in the 24 h preceding active duty U.S. soldiers' suicide attempts. J. Psychiatr. Res. 46, 843–848. Buchman-Schmitt, J.M., Chu, C., Michaels, M.S., Hames, J.L., Silva, C., Hagan, C.R., Ribeiro, J.D., Selby, E.A., Joiner Jr., T.E., 2017. The role of stressful life events preceding death by suicide: Evidence from two samples of suicide decedents. Psychiatry Res. 256, 345–352. Conner, K.R., 2004. A call for research on planned vs. unplanned suicidal behavior.

3.3. Conclusions and future directions These days most of the strategies for preventing suicide involve detection and treatment of depression (Mann et al., 2005; Zalsman et al., 2016). It is possible that over-emphasizing depression and psychiatric diagnosis may lead clinicians to underestimate the importance of impulsivity in adolescent and young soldiers at risk for suicide, thus missing valuable opportunities to prevent these events (McGirr and Turecki, 2007; Spirito and Esposito-Smythers, 2006). To our knowledge this study is the first to show a clear connection between levels of suicidal intent and pre-morbid states, either depression or impulsive personality traits, in individuals who died by suicide. We hope that future studies will examine if these patterns reproduce in other populations (civilians, younger adolescents, elderly etc.). Furthermore, the findings in this study emphasize the need for deeper understanding of impulsive personality traits in suicide-prevention 346

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