Cannabis use disorder and suicide attempts in Iraq/Afghanistan-era veterans
Introduction
It is estimated that between 125 and 227 million people use cannabis worldwide, making it the most widely used illicit drug in the world (United Nations, 2014, Hoch et al., 2015). Indeed, nearly 20 million Americans report that they have used cannabis in the past month (i.e., 7.5% of Americans 12 years or older; SAMHSA, 2014). Moreover, heavy cannabis use (i.e., cannabis use on 20 or more days during the past month) increased by nearly 60% in the U.S. from 2007 to 2013 (SAMHSA, 2014). Such findings are important because cannabis use has been associated with a wide range of health problems (e.g., Goldman et al., 2010, Joshi et al., 2014). To date, however, there has been only limited attention paid to the relationship between cannabis use and suicidal behavior.
A recent review and meta-analysis (Borges et al., 2016) on cannabis use and suicidal behavior (i.e., suicidal ideation and attempts) identified five studies examining the association between suicidal ideation and heavy cannabis use and six studies examining the association between suicide attempts and heavy cannabis use. Meta-analysis indicated that heavy cannabis use was likely to be associated with both suicidal ideation (OR = 2.53, 95% CI: 1.00–6.39) and suicide attempts (OR = 3.20, 95% CI: 1.72–5.94); however, the authors of this review noted the limited number of studies examined as well as several key issues to be addressed in future research, such as inclusion of more diverse samples, inclusion of patients with and without comorbid mental disorders, and use of clinical interviews to diagnose cannabis use disorders (CUD). Borges et al. (2016) also noted the importance of accounting for the effects of key risk factors (e.g., depression, other drug use problems, and alcohol misuse) that are likely to be associated with both cannabis use and suicidal behavior in statistical analyses.
Death by suicide and suicidal behavior are major concerns among veterans at the present time [Bullman and Kang, 1994, DeBeer et al., 2014, Kang and Bullman, 2008, Kaplan et al., 2007, Kimbrel et al., 2014, Kimbrel et al., 2015, Kimbrel et al., 2016a, Kimbrel et al., 2016b, U.S. Department of Veterans Affairs, 2016]. Indeed, the most recent statistics available from the U.S. Department of Veterans Affairs (2016) suggest that approximately 20 veterans die by suicide each day in the United States. Considerable evidence suggests that veterans with mental health disorders, such as PTSD and depression, are at particularly high risk for suicidal behavior and death by suicide (Bullman and Kang, 1994, DeBeer et al., 2014, Kang and Bullman, 2008, Kaplan et al., 2007, Kimbrel et al., 2014, Kimbrel et al., 2016a; U.S. Department of Veterans Affairs, 2016); however, there has been only limited research on the association between CUD and suicidal behavior among veterans to date. In fact, we are aware of only one other study that has examined the association between CUD and suicide attempts in veterans. Specifically, Kimbrel et al. (2017) recently reported that CUD was significantly associated with suicide attempts (OR = 3.10, p = 0.045) in a sample of 292 Iraq/Afghanistan-era veterans after adjusting for a wide range of covariates, including PTSD, depression, alcohol use disorder, and non-cannabis drug use disorder. This finding is highly consistent with prior research among civilians (e.g., Borges et al., 2016) and suggests that CUD may also increase veterans’ risk for self-injurious behavior; however, this finding has not yet been replicated in an independent sample of veterans.
The objective of the present study was to attempt to replicate Kimbrel et al. (2017) recent finding that lifetime CUD is associated with increased risk for suicidal behavior in a large and diverse sample of Iraq/Afghanistan-era veterans. Consistent with the findings of Borges et al. (2016) and Kimbrel et al. (2017), we hypothesized that CUD would be significantly associated with both current suicidal ideation and lifetime history of suicide attempts in this sample of Iraq/Afghanistan-era veterans, even after accounting for established predictors of suicidal behavior among veterans, including sex, PTSD, depression, alcohol use disorder, non-cannabis drug use disorder, history of childhood sexual abuse, and combat exposure (Ashrafioun et al., 2016, Kimbrel et al., 2014, Kimbrel et al., 2015, Kimbrel et al., 2016a, Kimbrel et al., 2016b, Kimbrel et al., 2017, Maguen et al., 2015).
Section snippets
Participants and procedures
Participants included 3233 Iraq/Afghanistan-era veterans who took part in a cross-sectional, multi-site study conducted by the Department of Veterans Affairs’ (VA) VISN 6 Mid-Atlantic Mental Illness, Research, Education and Clinic Center (MIRECC). Procedures for this study have been fully described elsewhere (Ashley-Koch et al., 2015, Calhoun et al., 2008, Guerra et al., 2011, Kimbrel et al., 2014). To be eligible for the study, participants had to have served in the United States military
Results
CUD was significantly associated with both current suicidal ideation [χ2(1) = 14.695, p < 0.001] and lifetime history of suicide attempts [χ2(1) = 45.053, p < 0.001] at the bivariate level (Fig. 1). Unadjusted logistic regression models revealed that veterans with a lifetime history of CUD had 1.921 times the odds (95% CI: 1.369–2.696) of endorsing current suicidal ideation and 2.831 times the odds (95% CI: 2.065–3.881) of having made a suicide attempt compared to veterans with no lifetime
Discussion
According to Bonn-Miller et al. (2012), rates of CUD diagnoses have increased by more than 50% among veterans receiving care from the Veterans Affairs (VA) Health Care System between 2002 and 2009. Such findings are critically important, as the present research provided further evidence that CUD may be a unique predictor of suicide attempts among veterans. Importantly, the present research begins to address some of the limitations in the extant literature by examining a large and diverse group
Conclusions
In sum, the findings from the present study suggest that CUD may be uniquely associated with suicide attempts in veterans, even after a wide array of relevant covariates are considered. This finding is highly significant given the high rate of suicidal behavior observed among veterans with mental health disorders as well as the increasing rate of CUD observed among veterans in recent years. Additional research aimed at understanding the complex relationship between CUD, other mental health
Role of the funding source
This project was supported in part by the Department of Veterans Affairs’ (VA) Mid-Atlantic Mental Illness Research, Education and Clinical Center (MIRECC) of the VA Office of Mental Health Services, the VA VISN 6 Mid-Atlantic Healthcare Network, and the Research and Development and Mental Health Services of the Durham VA Medical Center. Drs. Kimbrel and Dedert were supported by Career Development Awards #IK2CX000525 and #IK2CX000718, respectively, from the Clinical Science Research and
Acknowledgements
The VA Mid-Atlantic Mental Illness Research, Education, and Clinical Center Workgroup includes John A. Fairbank, Kimberly T. Green, Robin A. Hurley, Angela C. Kirby, Jason D. Kilts, Christine E. Marx, Gregory McCarthy, Scott D. McDonald, Marinell Miller-Mumford, Scott D. Moore, Rajendra A. Morey, Treven C. Pickett, Jared Rowland, Jennifer J. Runnals, Cindy Swinkels, Steven T. Szabo, Katherine H. Taber, Larry A. Tupler, Richard D. Weiner, and Ruth Yoash-Gantz.
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2021, Journal of Psychiatric ResearchCitation Excerpt :Current and lifetime AUD and CUD were each strongly and independently associated with suicide ideation, plan(s), and attempt(s). This finding is consistent with past literature showing associations of AUD and CUD with suicide-related outcomes in veterans (Adkisson et al., 2019; Fuehrlein et al., 2016; Hill et al., 2020; Kimbrel et al., 2017, 2018; Norman et al., 2018). Even after stringent adjustment for sociodemographic, military, trauma, and psychiatric factors, veterans who screened positive for current AUD only and CUD only were nearly 2 and 4 times more likely, respectively, than veterans who screened negative for both disorders to endorse past-year suicide ideation; further, veterans who screened positive for comorbid AUD/CUD were more than 5 times as likely to endorse past-year suicide ideation.
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2021, Clinical Psychology ReviewCitation Excerpt :In a sample of 292 Iraq/Afghanistan-era veterans, CUD was significantly associated with suicidal (OR = 3.10, p = .045) and non-suicidal self-injury (OR = 5.12, p = .009) even after adjusting for a wide variety of covariates including PTSD, depression and non-cannabis drug use disorders (Kimbrel, Meyer, DeBeer, Gulliver, & Morissette, 2018). Another study went on to reveal that CUD was also associated with current suicidal ideation (OR = 1.68, p = .008) and lifetime suicide attempts (OR = 2.30, p < .0001) among 3233 Iraq/Afghanistan veterans even after relevant covariates like sex, history of childhood sexual abuse and combat exposure were considered (Kimbrel et al., 2017). Cannabis dependence was associated with post-deployment suicide attempts regardless of pre-deployment suicide attempts (AOR = 7.96, p = .014) (Adkisson et al., 2018).