Social adversity, the serotonin transporter (5-HTTLPR) polymorphism and major depressive disorder

Background: Recent evidence has suggested that the short allele of the serotonin transporter (5-HTT) gene-linked polymorpbic region (5-HTTLPR of the human serotonin gene [SLC6A4]) is associated with increased risk of depressive disorder but only among individuals exposed to social adversity. We report an investigation designed to replicate this finding. Methods: Data were available from a non-clinical sample of 4175 adult men and women, ages 41-80 years, selected from participants in the European Prospective Investigation into Cancer and Nutrition in Norfolk (EPIC-Norfolk, United Kingdom) study. Evidence of past-year prevalent episodic major depressive disorder (MDD), defined by restricted DSM-IV diagnostic criteria, was assessed through questionnaire. Adverse experiences in childhood and in adulthood (during the five years preceding assessment) were also assessed through se self report. The 5-HTTLPR variant was genotyped according to published protocols. Results. One-year prevalent MDD criteria were met by 298 study participants. The experience of social adversity (both in childhood and adulthood) was strongly associated with increased rates of past-year prevalent MDD. No gene by environment (GxE) interactions between the 5-HTTLPR genotype, social adversity, and MDD were observed. Conclusions: This study has not replicated a previous finding of a GxE interaction between the 5-HTTLPR genotype, social adversity, and depression.