Cannabis use and posttraumatic stress disorder: prospective evidence from a longitudinal study of veterans

Abstract

Background Posttraumatic stress disorder (PTSD) is the most highly co-occurring psychiatric disorder among veterans with cannabis use disorder (CUD). Despite some evidence that cannabis use prospectively exacerbates the course of PTSD, which in turn increases the risk for CUD, the causal nature of the relationship between cannabis and psychiatric comorbidity is debated. The longitudinal relationship between PTSD diagnosis and traumatic intrusion symptoms with cannabis use and CUD was examined using cross-lagged panel model (CLPM) analysis. Methods Prospective data from a longitudinal observational study of 361 veterans deployed post-9/11/2001 included PTSD and CUD diagnoses, cannabis use, and PTSD-related traumatic intrusion symptoms from the Inventory of Depression and Anxiety Symptoms. Results A random intercept CLPM analysis that leveraged three waves (baseline, 6 months and 12 months) of cannabis use and PTSD-related intrusion symptoms to account for between-person differences found that baseline cannabis use was significantly positively associated with 6-month intrusion symptoms; the converse association was significant but reduced in magnitude (baseline use to 6-month intrusions: β = 0.46, 95% CI 0.155–0.765; baseline intrusions to 6-month use: β = 0.22, 95% CI −0.003 to 0.444). Results from the two-wave CLPM reveal a significant effect from baseline PTSD to 12-month CUD (β = 0.15, 95% CI 0.028–0.272) but not from baseline CUD to 12-month PTSD (β = 0.12, 95% CI −0.022 to 0.262). Conclusions Strong prospective associations capturing within-person changes suggest that cannabis use is linked with greater severity of trauma-related intrusion symptoms over time. A strong person-level directional association between PTSD and CUD was evident. Findings have significant clinical implications for the long-term effects of cannabis use among individuals with PTSD.

Sociodemographic Characteristics Associated With and Prevalence and Frequency of Cannabis Use Among Adults in the US

“…[21][22][23][24][25] Cannabis use may negatively affect mental health treatment outcomes for patients with anxiety and depression, and use is associated with suicidal ideation. [26][27][28][29][30][31][32][33][34] Finally, recent data suggests that that 1 out of 5 individuals who use cannabis have a cannabis use disorder. 35 Studies that have examined the health effects of cannabis have used various measures of exposure (eg, ever use, past-year use, monthly use, daily and almost daily use); however, there is a wide spectrum of outcomes for use frequency within the past month.…”

“… 21 , 22 , 23 , 24 , 25 Cannabis use may negatively affect mental health treatment outcomes for patients with anxiety and depression, and use is associated with suicidal ideation. 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 Finally, recent data suggests that that 1 out of 5 individuals who use cannabis have a cannabis use disorder. 35 …”

Longitudinal associations between impulsivity and alcohol and cannabis use frequency, quantity, and problems among military veterans.

“…Indeed, military veterans not only vary in their sociodemographic composition (cf. college students), but are also distinguished by unique experiential factors (e.g., count/type of trauma exposure; Baker et al, 2009; Dedert et al, 2009) and psychological morbidities (e.g., posttraumatic stress disorder [PTSD]; Dursa et al, 2014) known to be associated with both impulsivity and substance use indices (Armour et al, 2016; James et al, 2014; Metrik et al, 2020). Future research with military veterans is needed to replicate the current findings.…”

“…The sample was comprised of 361 returning OEF/OIF/OND veterans deployed post 9/11/2001 ( M age = 33.56, 93.4% male) who completed a battery of interviews as part of a larger prospective study on cannabis use and affective disorders (Metrik et al, 2020). Participants who reported using cannabis at least once in their lifetime were recruited from a Veteran’s Health Administration (VHA) facility in the Northeast region of the United States via study advertisements and the VHA OEF/OIF/OND Roster—an accruing database of combat veterans who recently returned from military service in Iraq and Afghanistan and were enrolled in VHA.…”

Longitudinal course of mental health symptoms among veterans with and without cannabis use disorder.

“…The added value of their longitudinal follow-up study is that it offers novel insight into the prospective association between CUD and depression but also suggests the possibility that these associations are nonlinear. In a related study, researchers found that cannabis use among veterans was associated with significantly worse PTSD intrusion symptoms in the future (Metrik et al, 2020). There are many notable strengths of these studies, particularly as they relate to naturalistic longitudinal design, which is needed to evaluate natural recovery and change.…”