Posttraumatic Stress Disorder and Alcohol Dependence: Epidemiology and Order of Onset.

Objective: Posttraumatic stress disorder (PTSD) and alcohol dependence (AD) frequently co-occur; however, epidemiologic studies of temporal associations between PTSD and AD are limited. The aims of this study were (a) to investigate the bidirectional associations between PTSD and AD and (b) to examine demographic and clinical correlates of order-of-onset among individuals with PTSD and AD. Method: Participants were 11,103 adults (60.6% women; Mage = 48.7 years, SD = 15.9) from the National Epidemiologic Survey on Alcohol and Related Conditions who endorsed lifetime alcohol consumption and DSM–IV PTSD Criterion A trauma exposure (American Psychiatric Association, 2000). Cox proportional hazards models with time-dependent covariates were used to evaluate bidirectional associations between PTSD and AD. Sex differences were assessed using stratified analyses. Results: After adjusting for demographic, trauma, and alcohol characteristics, PTSD was associated with greater likelihood of subsequent AD (hazard ratio [HR] = 1.359, 95% CI = 1.357–1.362), and AD was associated with greater likelihood of subsequent PTSD (HR = 1.274, 95% CI = 1.271–1.277). Bidirectional associations between PTSD and AD were stronger for women compared with men. Among individuals with PTSD and AD, initial onset of PTSD was associated with younger age of first potentially traumatic event. Initial onset of AD was associated with earlier initiation of alcohol use, earlier onset of heavy alcohol use, family history of alcohol problems, and history of generalized anxiety disorder and social anxiety disorder for women but not men. Initial AD was associated with lifetime panic disorder for men and women. Conclusions: Etiology of PTSD and AD is heterogeneous, and order of onset may reflect differing risk pathways.