A longitudinal mediational investigation of risk pathways among cannabis use, interpersonal trauma exposure, and trauma-related distress

Do traumatic events and substance use co-occur during adolescence? Testing three causal etiologic hypotheses

BACKGROUND

Why do potentially traumatic events (PTEs) and substance use (SU) so commonly co-occur during adolescence? Causal hypotheses developed from the study of posttraumatic stress disorder (PTSD) and substance use disorder (SUD) among adults have not yet been subject to rigorous theoretical analysis or empirical tests among adolescents with the precursors to these disorders: PTEs and SU. Establishing causality demands accounting for various factors (e.g. genetics, parent education, race/ethnicity) that distinguish youth endorsing PTEs and SU from those who do not, a step often overlooked in previous research.

METHODS

We leveraged nationwide data from a sociodemographically diverse sample of youth (N = 11,468) in the Adolescent Brain and Cognitive Development Study. PTEs and substance use prevalence were assessed annually. To account for the many pre-existing differences between youth with and without PTE/SU (i.e. confounding bias) and provide rigorous tests of causal hypotheses, we linked within-person changes in PTEs and SU (alcohol, cannabis, nicotine) across repeated measurements and adjusted for time-varying factors (e.g. age, internalizing symptoms, externalizing symptoms, and friends' use of substances).

RESULTS

Before adjusting for confounding using within-person modeling, PTEs and SU exhibited significant concurrent associations (βs = .46-1.26, ps < .05) and PTEs prospectively predicted greater SU (βs = .55-1.43, ps < .05) but not vice versa. After adjustment for confounding, the PTEs exhibited significant concurrent associations for alcohol (βs = .14-.23, ps < .05) and nicotine (βs = .16, ps < .05) but not cannabis (βs = -.01, ps > .05) and PTEs prospectively predicted greater SU (βs = .28-.55, ps > .05) but not vice versa.

CONCLUSIONS

When tested rigorously in a nationwide sample of adolescents, we find support for a model in which PTEs are followed by SU but not for a model in which SU is followed by PTEs. Explanations for why PTSD and SUD co-occur in adults may need further theoretical analysis and adaptation before extension to adolescents.

The role of interpersonal trauma and substance use in mental health: A large population-based study

Both interpersonal trauma (IPT) and substance use are linked to mental health problems, however their interplay is understudied. This study will investigate the relationship between IPT, substance use and mental health in a large population-based sample. Participants included 3756 individuals, mainly young university students using a snowball sampling method. History of IPT was collected retrospectively using the Traumatic Experiences Checklist. Substance use was examined using the World Health Organization's Alcohol, Smoking and Substance Involvement Screening Test. Mental health symptoms were assessed by the DSM-5 Level 1 Cross-Cutting Symptom Measure. Moderation analyses were performed investigating the relationship between IPT, substance use, and mental health symptoms. Participants exposed to IPT had a higher prevalence of substance use (cannabis, alcohol, tobacco) and had more severe mental health problems than people without IPT. Substance use was associated with a blunted increase of depression, anxiety, and anger in trauma victims. A history of abuse was more strongly linked to substance use than neglect. Moderation analyses further revealed that cannabis use increased psychotic symptoms and psychotic symptoms increased cannabis use in participants with high levels of IPT. Our findings indicate that substance use worsens psychotic symptoms in IPT victims whilst dampening other mental health symptoms.

Trauma exposure among cannabis use disorder individuals was associated with a craving-correlated non-habituating amygdala response to aversive cues

The relationship of cannabis-use disorder and trauma exposure at the level of the brain is not well-understood. Cue-reactivity paradigms have largely focused on characterizing aberrant subcortical function by averaging across the entire task. However, changes across the task, including a non-habituating amygdala response (NHAR), may be a useful biomarker for relapse vulnerability and other pathology. This secondary analysis utilized existing fMRI data from a CUD population with (TR-Y, n = 18) or without trauma (TR-N, n = 15). Amygdala reactivity to novel and repeated aversive cues was examined between TR-Y vs. TR-N groups, using a repeated measures ANOVA. Analysis revealed a significant interaction between TR-Y vs. TR-N and amygdala response to novel vs. repeated cues in the amygdala (right: F (1,31) = 5.31, p = 0.028; left: F (1,31) = 7.42, p = 0.011). In the TR-Y group, a NHAR was evident, while the TR-N group exhibited amygdala habituation, resulting in a significant difference between groups of amygdala reactivity to repeated cues (right: p = 0.002; left: p < 0.001). The NHAR in the TR-Y (but not TR-N) group was significantly correlated with higher cannabis craving scores, yielding a significant group difference (z = 2.1, p = 0.018). Results suggest trauma interacts with the brain's sensitivity to aversive cues, offering a neural explanation for the relationship between trauma and CUD vulnerability. These findings suggest the importance of considering the temporal dynamics of cue reactivity and trauma history in future studies and treatment planning, as this distinction may help decrease relapse vulnerability.