Associations of alcohol and cannabis use with change in posttraumatic stress disorder and depression symptoms over time in recently trauma-exposed individuals

Multi-level socioeconomic modifiers of the comorbidity of post-traumatic stress and tobacco, alcohol, and cannabis use: the importance of income

PURPOSE

Post-traumatic stress (PTS) symptoms are highly comorbid with substance use (i.e., alcohol, tobacco, and cannabis). Few studies have investigated potential individual-, household-, and neighborhood-level socioeconomic effect modifiers of this comorbidity in longitudinal analyses. We aim to examine interactions between this multi-level environment and PTS symptoms on future substance use behaviors.

METHODS

Data were drawn from the Advancing Understanding of RecOvery afteR traumA (AURORA) study, including 2943 individuals who presented to the emergency department (ED) within 72 h of a traumatic event. Frequency of tobacco, alcohol, cannabis use, and PTS symptoms were reported at 6 timepoints. Mixed effect Poisson models, clustered by state, were used to generate incidence rate ratios (IRRs) substance use, both cross-sectionally and prospectively. Moderation analysis of PTS and substance use, stratified by household income and area deprivation index (ADI), was conducted using mixed effect models and parallel process growth curves.

RESULTS

Significant associations were observed between PTS with tobacco, alcohol, and cannabis use frequency cross-sectionally, and for tobacco and alcohol and PTS exposure prospectively. Lower income (P < 0.001) and higher deprivation (P < 0.001) were associated with tobacco use, while higher income (P < 0.001) and less deprivation (P = 0.01) were associated with increased alcohol use. We found modest modification by household income for alcohol and tobacco, and little evidence of modification by neighborhood ADI.

CONCLUSIONS

Household income had greater evidence of effect modification for substance use, compared to neighborhood-level ADI. Our findings demonstrate that household indicators of socioeconomic status likely modify the relationship between PTS and substance use.

Cannabis use regimens in trauma-exposed individuals: Associations with cannabis use quantity and frequency

People with trauma histories have an increased odds of cannabis use. Little is known about the frequency or consequences of different cannabis use regimens in cannabis users with trauma histories. Individuals with anxiety disorders tend to administer benzodiazepines in a pro re nata (PRN; i.e., as needed) as opposed to regularly scheduled (RS, e.g., twice daily [BID], three times daily [TID]) manner. Although physicians tend to prescribe benzodiazepines on a PRN regimen to minimize use, this regimen is paradoxically associated with greater use levels. Indeed, PRN administration regimens may increase use via negative reinforcement processes. We extended this older benzodiazepine literature to cannabis by examining regimen of cannabis use among 94 trauma-exposed cannabis users (mean age = 35.1 years; 52.1 % male; 23.4 % with cannabis prescription). Participants reported their initial and current cannabis use regimen (PRN vs. RS vs. both ['PRN+']) and their past month cannabis use frequency (use occasions in last month) and quantity (grams/use occasion). Consistent with patterns in benzodiazepine research, PRN (47.1 % of sample) and PRN+ (43.5 % of sample) were more common than RS regimens (9.4 % of sample). Also consistent with patterns seen with benzodiazepines, our sample moved toward PRN regimens from initial to current use: e.g., 100 % of initial RS users switched to a regimen that included PRN use. Consistent with predictions emerging from learning theory, PRN and PRN+ cannabis users reported significantly higher cannabis use frequencies compared to RS users (p's < 0.01). Unexpectedly, there were no significant differences between cannabis use regimen groups for quantity of cannabis/occasion. While limited by their cross-sectional nature, with longitudinal replication, result may have implications for identifying cannabis use regimens that minimize frequency of use and thereby reduce risk for negative health outcomes.

Herbal Cannabis and Depression: A Review of Findings Published over the Last Three Years

Public perception contrasts scientific findings on the depression-related effects of cannabis. However, earlier studies were performed when cannabis was predominantly illegal, its production was mostly uncontrolled, and the idea of medical cannabis was incipient only. We hypothesized that recent changes in attitudes and legislations may have favorably affected research. In addition, publication bias against cannabis may have also decreased. To investigate this hypothesis, we conducted a review of research studies published over the last three years. We found 156 relevant research articles. In most cross-sectional studies, depression was higher in those who consumed cannabis than in those who did not. An increase in cannabis consumption was typically followed by an increase in depression, whereas withdrawal from cannabis ameliorated depression in most cases. Although medical cannabis reduced depression in most studies, none of these were placebo-controlled. In clinical studies published in the same period, the placebo also ameliorated depression and, in addition, the average effect size of the placebo was larger than the average effect size of medical cannabis. We also investigated the plausibility of the antidepressant effects of cannabis by reviewing molecular and pharmacological studies. Taken together, the reviewed findings do not support the antidepressant effects of herbal cannabis.

Post-traumatic stress and future substance use outcomes: leveraging antecedent factors to stratify risk

Background

Post-traumatic stress disorder (PTSD) and substance use (tobacco, alcohol, and cannabis) are highly comorbid. Many factors affect this relationship, including sociodemographic and psychosocial characteristics, other prior traumas, and physical health. However, few prior studies have investigated this prospectively, examining new substance use and the extent to which a wide range of factors may modify the relationship to PTSD.

Methods

The Advancing Understanding of RecOvery afteR traumA (AURORA) study is a prospective cohort of adults presenting at emergency departments (N = 2,943). Participants self-reported PTSD symptoms and the frequency and quantity of tobacco, alcohol, and cannabis use at six total timepoints. We assessed the associations of PTSD and future substance use, lagged by one timepoint, using the Poisson generalized estimating equations. We also stratified by incident and prevalent substance use and generated causal forests to identify the most important effect modifiers of this relationship out of 128 potential variables.

Results

At baseline, 37.3% (N = 1,099) of participants reported likely PTSD. PTSD was associated with tobacco frequency (incidence rate ratio (IRR): 1.003, 95% CI: 1.00, 1.01, p = 0.02) and quantity (IRR: 1.01, 95% CI: 1.001, 1.01, p = 0.01), and alcohol frequency (IRR: 1.002, 95% CI: 1.00, 1.004, p = 0.03) and quantity (IRR: 1.003, 95% CI: 1.001, 1.01, p = 0.001), but not with cannabis use. There were slight differences in incident compared to prevalent tobacco frequency and quantity of use; prevalent tobacco frequency and quantity were associated with PTSD symptoms, while incident tobacco frequency and quantity were not. Using causal forests, lifetime worst use of cigarettes, overall self-rated physical health, and prior childhood trauma were major moderators of the relationship between PTSD symptoms and the three substances investigated.

Conclusion

PTSD symptoms were highly associated with tobacco and alcohol use, while the association with prospective cannabis use is not clear. Findings suggest that understanding the different risk stratification that occurs can aid in tailoring interventions to populations at greatest risk to best mitigate the comorbidity between PTSD symptoms and future substance use outcomes. We demonstrate that this is particularly salient for tobacco use and, to some extent, alcohol use, while cannabis is less likely to be impacted by PTSD symptoms across the strata.