APOLIPOPROTEIN E GENE POLYMORPHISM, ALCOHOL USE, AND THEIR INTERACTIONS IN COMBAT-RELATED POSTTRAUMATIC STRESS DISORDER

BackgroundThe symptomatology of posttraumatic stress disorder (PTSD) is related not only to the intensity of the causative trauma, but also to alcohol use and genetic factors. Among the many candidate genes, the apolipoprotein E gene (APOE) is thought to be associated with stress reactivity. MethodsKorean veterans of the Vietnam War with (n = 128) or without (n = 128) PTSD participated in this study. The Clinician-Administered PTSD Scale and Combat Exposure Scale were administered, and the severity of alcohol use was assessed among these veterans. The APOE polymorphism and clinical variables of the subjects were compared, and associations between PTSD and potential explanatory variables were tested using logistic regression analysis. ResultsHigher frequencies of APOE epsilon 2 alleles and a greater number of individuals with the epsilon 2 allele were found in the PTSD group. Among patients with PTSD, epsilon 2-allele noncarriers consumed alcohol in greater amounts and more frequently than did epsilon 2-allele carriers. Regression analysis revealed a significant interactional effect between harmful drinking and the absence of the epsilon 2 allele associated with PTSD risk. ConclusionsThese results suggest that the APOE epsilon 2 allele operates as a susceptibility gene for combat-related PTSD, with the relationship between alcohol use and PTSD differing according to the epsilon 2-allele status. Future studies should determine the role of the APOE in adaptation to extreme stress, the development of PTSD, and comorbid alcohol-related disorders. (C) 2013 Wiley Periodicals, Inc.