Elsevier

Journal of Affective Disorders

Volume 245, 15 February 2019, Pages 412-418
Journal of Affective Disorders

Research paper
Insomnia and risk for suicidal behavior: A test of a mechanistic transdiagnostic model in veterans

https://doi.org/10.1016/j.jad.2018.11.044Get rights and content

Highlights

  • The mechanistic transdiagnostic model posits a central role for psychiatric symptoms in the association between insomnia symptoms and risk for suicidal behavior.

  • In veterans, the association between insomnia symptoms and risk for suicidal behavior may be mediated by symptoms of posttraumatic stress disorder (PTSD) and depression, as well as relationship disruptions.

  • PTSD symptoms may be indirectly associated with risk for suicidal behavior through depressive symptoms and relationship disruptions.

  • Depressive symptoms may be directly associated with risk for suicidal behavior, and indirectly associated with risk through relationship disruptions.

Abstract

Background

Insomnia has been shown to have direct and indirect associations with suicidal ideation, attempts, and death in U.S. military and veteran populations. However, transdiagnostic models of insomnia and psychopathology have not been used to examine the contribution of psychopathology.

Method

The present study is a secondary analysis examining the associations among insomnia symptoms, posttraumatic stress disorder (PTSD) and depressive symptoms, interpersonal theory of suicide variables, and risk for suicidal behavior in community veterans (n = 392). Serial mediation was used to test sequential associations, allowing for examination of direct and indirect associations.

Results

The model with insomnia, PTSD, and depressive symptoms, and thwarted belongingness, accounted for 29% of the variance in risk. Insomnia symptoms had an indirect association through PTSD and depressive symptoms, and thwarted belongingness. The model with insomnia, PTSD, and depressive symptoms, and perceived burdensomeness accounted for 35% of the variance in risk. Insomnia symptoms had an indirect association through PTSD and depressive symptoms, and perceived burdensomeness.

Limitations

Data are cross-sectional, precluding the testing of causal associations.

Conclusions

In veterans, insomnia symptoms may be associated with increased PTSD and depressive symptoms, which may be associated with increased risk for suicidal behavior directly and indirectly through relationship disruptions.

Introduction

Veterans are at higher risk for suicide than the general population in gender and age adjusted analyses (Department of Veterans Affairs, Office of Suicide Prevention, 2016). Psychiatric disorders such as major depression, bipolar disorder, and alcohol abuse and dependence are known to increase risk for suicide in veterans (Britton et al., 2012, Ilgen et al., 2010). Researchers are beginning to examine the contribution of additional factors that may increase psychological distress (Nock et al., 2013), and have found that sleep disturbance increases risk for suicidal thoughts, non-fatal attempts, and death by suicide (Pigeon et al., 2012, Pigeon et al., 2012). There is, however, a paucity of research on the associations among sleep disturbance, psychiatric disorders, and risk for suicidal thoughts and behaviors among veterans, which is critical for effective intervention.

Interest in sleep disturbance in suicide research has been influenced by the recognition that sleep disturbance is a transdiagnostic process relevant to the development and exacerbation of multiple psychiatric disorders (Dolsen et al., 2014). However, the term transdiagnostic is used in multiple ways, which has implications for understanding how sleep relates to the development and exacerbation of psychiatric disorders (Harvey et al., 2011). Sleep disturbance is clearly descriptively transdiagnostic as it frequently co-occurs across a range of psychiatric disorders. Although insomnia is a diagnosis in the Diagnostic and Statistical Manual, 5th edition (American Psychiatric Association, 2013), it is also included as a symptom of multiple psychiatric disorders, including major depression and posttraumatic stress disorder (PTSD), and frequently co-occurs with other psychiatric disorders (Dolsen et al., 2014). However, this tells us very little about the nature of the associations among insomnia and psychiatric disorders. Research also suggests that insomnia is mechanistically transdiagnostic, and that the co-occurrence of insomnia and psychiatric disorders arises through shared causal factors (Harvey et al., 2011). The hypothesized pathway is: a) genetic, such that genes associated with the regulation of circadian rhythms are also associated with psychiatric disorders; b) neurobiological, with disrupted dopaminergic and serotonergic functioning being associated with both insomnia and psychiatric disorders; and, c) psychological, reflected by the reciprocal association between disrupted sleep and emotion regulation, which theoretically explains how sleep disturbance may be a causative agent in the development and exacerbation of psychiatric disorders (Harvey et al., 2011). If the mechanistic transdiagnostic model is relevant to risk for suicidal ideation and behavior, it would suggest that insomnia should be associated with the development or exacerbation of psychiatric symptoms that increase risk. Statistically, this means that the association between insomnia and risk for suicidal ideation and behavior should be mediated by psychiatric symptoms.

Research examining this question has focused on depression, based on evidence that sleep disturbance prospectively predicts depressive symptoms (Baglioni et al., 2011). Despite this association, meta-analysis shows that sleep disturbance is directly associated with suicidal thoughts and behavior in cross-sectional and prospective studies, even after adjusting for symptoms of depression (Pigeon et al., 2012). Unfortunately, the small number of studies included in the meta-analysis prevents sub-analyses in specific populations, and combining different populations with varied psychiatric problems could obscure important findings. For example, research examining these relations among individuals with a military history is inconsistent with meta-analytic results. One study that used semi-structured interviews and self-report measures in young, active duty service members, found that insomnia symptoms were directly associated with suicidal ideation and attempts in cross-sectional and prospective analyses, even after adjusting for depressive symptoms, hopelessness, and PTSD diagnosis (Ribeiro et al., 2012). However, a self-report study with three active duty military samples found that the association between insomnia symptoms and suicidal ideation was mediated by depressive symptoms in prospective analyses, and there was no association between insomnia symptoms and attempts (Bryan et al., 2015). A second self-report study with active duty and veterans also found that the association between insomnia symptoms and suicidal ideation was mediated by depressive symptoms, and found a direct association between insomnia symptoms and attempted suicide (Allan et al., 2017). The sole study examining the association between sleep disturbance and death by suicide in veterans used chart reviews of veteran suicide decedents and showed that documented sleep disturbance had a direct association with time to suicide after the last healthcare contact, even after adjusting for psychiatric symptoms identified by the chart review (Pigeon et al., 2012).

Methodological differences including different samples, measures, shared items across measures, and different outcomes likely contributed to some of the discrepancies among these studies. However, the discrepancies are minor, and the literature generally suggests that insomnia is indirectly associated with risk for suicide ideation, through the development or exacerbation of depression, but is directly associated with suicidal behavior including suicide attempts and death by suicide. The Interpersonal Theory of Suicide (IPT) provides a framework explaining how sleep disturbance may be differentially associated with suicidal ideation and behavior, as it posits that a thwarted sense of belongingness and the perception that one is a burden on loved ones are preconditions for the development of suicidal ideation, but the transition from ideation to attempts is dependent upon the acquired capability to make an actual attempt (Joiner, 2005; Van Orden et al., 2010). The first study examining the associations among thwarted interpersonal needs, insomnia and suicide risk, provided partial support for IPT (Nadorff et al., 2014), as insomnia symptoms were not associated with suicide risk and prior attempts after controlling for thwarted belongingness and perceived burdensomeness in one sample, but was significantly associated with prior attempts after controlling for thwarted belongingness, perceived burdensomeness, and depressive symptoms in a second. A subsequent series of studies has supported the mediation hypothesis for thwarted belongingness. In a self-report study, the impact of insomnia symptoms on suicidal ideation was mediated by thwarted belongingness (Chu et al., 2016), a finding that was replicated in a series of three studies in various populations including a military sample that controlled for anxiety symptoms or diagnosis (Chu et al., 2017b), and a follow-up study with three military samples (Hom et al., 2017). The authors’ explanation was that insomnia increases time in isolation and, thus, loneliness, which increases risk for suicidal ideation (Chu et al., 2016, Chu et al., 2017bb; Hom et al., 2017). However, thwarted belongingness was no longer associated with suicidal ideation when depressive symptoms were covaried (Hom et al., 2017), and analyses controlled for anxiety rather than PTSD symptoms, which is more relevant in military populations.

In general, PTSD has been shown to have a direct association with suicidal ideation, attempts, and suicide, yet it has also been found to be mediated by depression (Krysinska and Lester, 2010, Panagioti et al., 2009, Panagioti et al., 2012). Research among veterans largely reflect these divergent findings, with some studies suggesting that the associations may be direct for suicidal ideation even after adjusting for PTSD diagnosis or symptoms (Ashrafioun et al., 2016, Jakupcak et al., 2011, Pietrzak et al., 2010; Wisco et al., 2016), but with others indicating that its association with suicide-related outcomes is mediated by depression and other psychological variables (Conner et al., 2014, Conner et al., 2014, Jakupcak et al., 2009, Kimbrel et al., 2016, McKinney et al., 2017; Zivin et al., 2007). Despite these findings, the possibility that PTSD symptoms mediate the association of insomnia with risk for suicidal behavior remains understudied. The few studies that have included it as a covariate indicate that it does not eliminate direct associations (Ribeiro et al., 2012), or indirect associations through depressive symptoms (Bryan et al., 2015). Given the lack of research regarding the potential of PTSD symptoms to mediate the association between insomnia and suicide-related outcomes in military samples, effort should be made to understand the potential role of PTSD symptoms in this context.

When applied to suicidal thoughts and behavior, the mechanistic transdiagnostic model proposes a central role for psychiatric symptoms, and posits that insomnia increases individuals’ psychiatric symptoms and emotion dysregulation which disrupts interpersonal relationships (i.e., increasing thwarted belongingness and perceived burdensomeness), and also increases risk for suicidal thinking. The purpose of this study was to examine hypotheses based on a mechanistic transdiagnostic model involving insomnia, psychiatric disorders, and risk for suicidal behavior, in a community sample of veterans. We hypothesized that the association of insomnia symptoms with thwarted belongingness and perceived burdensomeness would be mediated by depressive symptoms in separate analyses for each IPT variable. Based on prior findings (Hom et al., 2017), we further hypothesized that depressive symptoms would mediate the association between insomnia symptoms and risk for suicidal behavior and that thwarted belongingness and perceived burdensomeness would not. Further, given the limited research examining PTSD symptoms as a potential mediator of the association between insomnia symptoms and risk for suicidal behavior, despite its relevance to military and veteran populations, we assessed PTSD symptoms as an early pathway explaining the linkage between symptoms of insomnia and depressive symptoms.

Section snippets

Procedures

Participants were recruited using online invitations distributed through veteran social media outlets (e.g., veteran Facebook pages) and national veteran organizations (e.g., Veterans of Foreign Wars [VFW]). After providing informed consent, participants were invited to complete a battery of questionnaires that was administered via Survey Monkey (www.surveymonkey.com). All analyses were conducted using SPSS 21. For compensation, all participants were entered into a drawing for a chance to win

Descriptive and bivariate analyses

Descriptive and bivariate analyses were used to describe the sample, and correlations indicated that all the variables being studied were significantly associated with each other, with sensitivity analyses indicating all independent variables had Variance Inflation Factor below 4 suggesting no significant collinearity (see Table 2) (Kutner et al., 2004). On the ISI, approximately 50% (198/392) scored 15 or above indicating moderate to severe sleep problems. On the full PCL-M, 42% (164/389,

Discussion

Findings supported the majority of hypotheses that were based on the mechanistic transtheoretical model of sleep disturbance and psychiatric disorders, which posits a central role for psychiatric symptoms. The association of insomnia symptoms with perceived burdensomeness and thwarted belongingness was mediated by depressive symptoms, as expected, but also by PTSD symptoms. Our findings support prior investigations indicating that the association between insomnia symptoms and suicidal ideation

Contributors

Dr. Britton designed the study, conducted the analyses, and wrote the first draft. Ms. McKinney wrote the first draft of the methods section and the figures. Dr. Bishop helped design the study and write the final draft. Dr. Pigeon helped design the study and write the final draft. Dr. Hirsch wrote the protocol, and helped design the study and write the final draft.

Conflicts of interest

PCB, JMM, TMB, WRP, and JKH have no conflicts of interest to declare.

Role of funding source

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Acknowledgments

None.

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