Given high rates of co-occurring major depression and AUDs (Swendsen & Merikangas, 2000) and evidence that 5-HTTLPR genotype predicts vulnerability to the development of depression following stress exposure (Caspi, Hariri, Holmes, Uher, & Moffitt, 2010), it is noteworthy that only one study considered participants’ neuroticism and depression symptoms in the alcohol-related GxE analyses (Covault et al., 2007). If positive GxE results are mediated by an interaction between 5-HTTLPR genotype and stress on depression risk, inconsistent findings may result from differing levels of comorbid depression across samples. Interestingly, of the two studies that found no evidence for GxE, one excluded participants who met the criteria for major depression (Du & Wan, 2009) and the other found GxE associated with major depression and not AD (Dick et al., 2007b).
