Incidence of drug problems in young adults exposed to trauma and posttraumatic stress disorder: do early life experiences and predispositions matter?

CONTEXT: Most estimated associations of posttraumatic stress disorder (PTSD) with DSM-IV drug dependence and abuse are from cross-sectional studies or from prospective studies of adults that generally do not take into account suspected causal determinants measured in early childhood.
OBJECTIVE: To estimate risk for incident drug disorders associated with prior DSM-IV PTSD.
DESIGN: Multiwave longitudinal study of an epidemiologic sample of young adults first assessed at entry to first grade of primary school in the fall semesters of 1985 and 1986, with 2 young adult follow-up assessments.
SETTING: Mid-Atlantic US urban community. PARTICIPANTS: Young adults (n = 988; aged 19-24 years) free of clinical features of DSM-IV drug use disorders at the first young adult assessment and therefore at risk for newly incident drug use disorders during the 1-year follow-up period. MAIN OUTCOME MEASURES: During the 12-month interval between the 2 young adult follow-up assessments, newly incident (1) DSM-IV drug abuse or dependence; (2) DSM-IV drug abuse; (3) DSM-IV drug dependence; and (4) emerging dependence problems (1 or 2 newly incident clinical features of DSM-IV drug dependence), among subjects with no prior clinical features of drug use disorders.
RESULTS: Prior PTSD (but not trauma only) was associated with excess risk for drug abuse or dependence (adjusted relative risk, 4.9; 95% confidence interval, 1.6-15.2) and emerging dependence problems (adjusted relative risk, 4.9; 95% confidence interval, 1.2-20.1) compared with the no-trauma group controlling for childhood factors. Subjects with PTSD also had a greater adjusted relative risk for drug abuse or dependence compared with subjects exposed to trauma only (adjusted relative risk, 2.0; 95% confidence interval, 1.1-3.8) controlling for childhood factors.
CONCLUSIONS: Association of PTSD with subsequent incident drug use disorders remained substantial after statistical adjustment for early life experiences and predispositions reported in previous studies as carrying elevated risk for both disorders. Posttraumatic stress disorder might be a causal determinant of drug use disorders, possibly representing complications such as attempts to self-medicate troubling trauma-associated memories, nightmares, or painful hyperarousal symptoms.