Trajectories of cannabis use beginning in adolescence associated with symptoms of posttraumatic stress disorder in the mid-thirties.

Background: Posttraumatic stress disorder (PTSD) symptoms are related to a number of adverse consequences such as substance use and general medical conditions. The present longitudinal study seeks to find the longitudinal patterns of cannabis use as precursors of PTSD symptoms. Such information will serve as a guide for intervention programs for PTSD.

Methods: Growth mixture modeling was conducted to identify the cannabis use trajectory groups using a community sample of 674 participants (53% African Americans, 47% Hispanics of Puerto Rican decent; 60% females) from the Harlem Longitudinal Development Study. Logistic regression analyses were performed to examine the association between earlier trajectories of cannabis use (ages 14 to 36) and later symptoms of PTSD (at age 36) for the full model including the entire sample (N = 674) as well as the reduced model including only participants who had experienced a traumatic event (n = 205).

Results: Five trajectory groups of cannabis use were obtained. The chronic use group (full model: adjusted odds ratio [AOR] = 4.68, P < .01; reduced model: AOR = 4.27, P < .05), the late quitting group (full model: AOR = 6.18, P < .01; reduced model: AOR = 6.67, P < .01), and the moderate use group (full model: AOR = 3.97, P < .01; reduced model: AOR = 3.32, P < .05) were all associated with an increased likelihood of having PTSD symptoms at age 36 compared with the no use group.

Conclusions: The findings provide information that PTSD symptoms in the mid-30s can possibly be reduced by decreasing membership in the chronic cannabis use trajectory group, the late quitting trajectory group, and the moderate cannabis use trajectory group.