Longitudinal associations of friend-based social support and PTSD symptomatology during a cannabis cessation attempt.

Research supports bidirectional associations between social support and posttraumatic stress disorder (PTSD), whereby social support may buffer against PTSD, and individuals with PTSD may experience decreasing support over time. Research examining contexts that may affect these relations is needed. This study examined the longitudinal associations between PTSD and social support from friends over a 6-month period in 116 veterans with cannabis dependence who had recently initiated an attempt to quit cannabis use. A cross-lagged autoregressive model revealed a significant, negative relation between earlier PTSD symptoms and later support. An exploratory multigroup analysis comparing those with and without a relapse in the first month after their quit attempt revealed that the significant negative association between PTSD and future support was present only in those who relapsed. Although this analysis was limited by a small sample size, results suggest that substance use may be an influential contextual variable that impacts the longitudinal associations between PTSD and support.