Early Family Environment, Current Adversity, the Serotonin Transporter Promoter Polymorphism, and Depressive Symptomatology

Background Mixed evidence has suggested that homozygous carriers of the short allele (s/s) of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) may be at increased risk for depression, if they have also been exposed to early or current adversity/stress. We address this debate by examining the relation of a stressful early family environment, recent adversity/stress, and the 5-HTTLPR to depressive symptomatology in a normal sample. Methods A nonclinical sample of 118 young adult men and women completed assessments of early family environment, recent stressful events, psychosocial resources, and psychological distress, including depressive symptomatology. The 5-HTTLPR was genotyped using a standard protocol with DNA extracted from oral fluid. Results A stressful early family environment was significantly related to depressive symptomatology. In addition, gene-by-environment (G×E) interactions were observed between the 5-HTTLPR and both early family environment and current adversity/stress. Individuals homozygous for the short allele had greater depressive symptomatology if they had experienced early or recent adversity but significantly less depressive symptomatology if they reported a supportive early environment or recent positive experiences, compared with participants with the s/l or l/l genotype. Conclusions Early or current environment, in conjunction with the serotonin transporter polymorphism, predicts depressive symptomatology.