Posttraumatic stress disorder and the incidence of nicotine, alcohol, and other drug disorders in persons who have experienced trauma

Background: We examine whether exposure to traumatic events increases the risk for nicotine dependence or alcohol or other drug use disorders, independent of posttraumatic stress disorder (PTSD). Methods: Data come from a longitudinal epidemiologic study of young adults in southeast Michigan. Prospective data covering a 10-year period and retrospective lifetime data gathered at baseline were used to estimate the risk for onset of substance use disorders in persons with PTSD and in persons exposed to trauma without PTSD, compared with persons who have not been exposed to trauma. The National Institute of Mental Health Diagnostic Interview Schedule for DSM-III-R was used. Logistic regression was used to analyze the prospective data, and Cox proportional hazards survival analysis with time-dependent variables was applied to the lifetime data. Results: The prospective and retrospective data show an increased risk for the onset of nicotine dependence and drug abuse or dependence in persons with PTSD, but no increased risk or a significantly (P = .004) lower risk (for nicotine dependence, in the prospective data) in persons exposed to trauma in the absence of PTSD, compared with unexposed persons. Exposure to trauma in either the presence or the absence of PTSD did not predict alcohol abuse or dependence. Conclusions: The findings do not support the hypothesis that exposure to traumatic events per se increases the risk for substance use disorders. A modestly elevated risk for nicotine dependence might be an exception. Posttraumatic stress disorder might be a causal risk factor for nicotine and drug use disorders or, alternatively, the co-occurrence of PTSD and these disorders might be influenced by shared risk factors other than traumatic exposure.