The 5-HTTLPR polymorphism moderates the effect of stressful life events on drinking behavior in college students of African descent.

Covault et al. [Covault et al. (2007); Biol Psychiatry 61(5): 609-616] reported that the common functional polymorphism, 5-HTTLPR, in the serotonin transporter gene moderated the association between past-year stressful events and daily reports of drinking in a sample of European-American (EA) college students. We examined this effect in college students of African descent. Students recruited at a Historically Black University (n = 564) completed web-based measures of past-year stressful life experiences and daily reports of drinking and heavy drinking over a 30-day period. Participants were genotyped for the tri-allelic 5-HTTLPR polymorphism and dichotomized as low-activity S' allele carriers or high-activity L' homozygotes. Generalized linear models were used to examine the effects of life stress, genotype, and their interaction on the two drinking measures. In students who completed 15 or more daily surveys (n = 393), there was a significant interaction of past-year stressful events, 5-HTTLPR genotype, and gender on the number of drinking days (P = 0.002). Similar findings were obtained in relation to heavy drinking days (P = 0.007). Men showed a main effect of past-year stressful events on both drinking outcomes (P's < 0.001), but no main or moderator effects of genotype. In women, the S' allele moderated the impact of past-year life stressors on the frequency of drinking and heavy drinking days (P's < 0.001). In college students of African descent, past-year stressful events were associated with more frequent drinking and heavy drinking, an effect that was moderated by the 5-HTTLPR polymorphism. However, in contrast to the findings in EA students, in the current sample, 5-HTTLPR moderated the association only among women.