The Effects of Triallelic Serotonin Transporter Gene Polymorphism and Stressful Life Event on Depression in Patients with Alcohol Dependence

ABSTRACT

OBJECTIVES: The purpose of this study is to investigate the relationship between the triallelic serotonin transporter gene and stressful life events to determine their effect on depression with alcohol dependence. METHODS: Ninety-five hospitalized patients with alcohol dependence (73 male, 22 female) were enrolled in this study. Thirty-two (33.7%) of the total patients were diagnosed with major depressive disorder and dysthymic disorder by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders-IV. The characteristics of stress were evaluated using the stressful life events scale, and depressive symptoms were assessed using the depression scale (Beck Depression Inventory, BDI). Alcoholism with depression (n = 32) and alcoholism without depression (n = 63) were genotyped for the triallelic serotonin transporter gene (LA : higher expressing allele, LG/S : lower expressing allele). RESULTS: There was no significant difference in the allele frequency between the depression group and the non-depression group (chi2 = 0.345, p = 0.619). LG/S alleles had more comorbid depression in the higher score of stressful life events scale [Mental-Haenszel (MH)-chi2 = 4.477, p = 0.034]. But there was no significant difference in the comorbidity according to the scores from the stressful life event scale in the LA alleles (MH-chi2 = 0.741, p = 0.399). In the results, alcohol-dependent individuals with LG/S alleles had more comorbid depression than those with LA alleles when they had experienced severe stressful life events (MH-odds ratio = 2.699, p = 0.028). CONCLUSIONS: These results suggest that there is no direct relationship between triallelic serotonin transporter gene and depression in the alcohol dependent patients. But alcohol dependent individuals with the lower expressing alleles of the serotonin transporter gene were more susceptible to depression than those with the higher expressing alleles in response to stressful life events.