The Indirect Influence of Cannabis Use Disorder Symptoms on PTSD Symptom Severity Through Psychological Inflexibility

<i>Background:</i> One in five college students (21%) report using cannabis in the past month, and approximately 10% develop cannabis use disorder (CUD). Further, college students have high rates of trauma exposure, and CUD is prospectively linked to posttraumatic stress disorder (PTSD). Given the high rate of co-occurrence, research is needed to understand transdiagnostic, modifiable factors that could account for the relationship between CUD and PTSD. Psychological inflexibility (PI) is one such factor and refers to difficulty adapting thoughts or behaviors to various situations that reflect of one's personal values. <i>Objectives:</i> PI predicts worse PTSD symptom severity and has been established as a maintaining factor between alcohol use and PTSD, albeit no studies have examined this relationship with CUD. <i>Results:</i> College students (<i>N</i> = 336) completed self-report measures of CUD, PI, and PTSD. A cross-sectional mediation model explained 54% of the variance in PTSD symptom severity, <i>F</i>(5, 330) = 78.86, p < .001. After controlling for age, gender, and probable alcohol use disorder, CUD was not directly associated with PTSD symptom severity, yet was indirectly associated with PTSD through higher PI. Specifically, CUD was associated with higher PI (<i>b</i> = 0.31, <i>p</i> < .05, 95% CI [0.07, 0.54]), and higher PI was associated with greater PTSD symptom severity (<i>b</i> = 1.07, <i>p</i> < .001, 95% CI [0.95, 1.19]). <i>Conclusion:</i> Although CUD has been previously linked with worse PTSD symptoms, results suggest that this occurs through PI. Importantly, PI is malleable, and may be an important treatment target for co-occurring CUD and PTSD in college students.