Childhood adversity interacts separately with 5-HTTLPR and BDNF to predict lifetime depression diagnosis

The serotonin transporter polymorphism (5-HTTLPR) and the brain-derived neurotrophic factor (BDNF) val66met polymorphism have both been linked to depression symptoms and to depression diagnosis (MDD) in interaction with adversity; there have also been failures to find the effects. We reexamined both interactions for lifetime MDD in a college sample. Lifetime MDD was diagnosed by Structured Clinical Interview for DSM-IV in 133 undergraduates; genotypes for 5-HTTLPR and BDNF were assayed from blood, and self-reports were collected concerning childhood adversity (Risk). 5-HTTLPR interacted with Risk such that Risk predicted less likelihood of MDD among ll carriers and tended to predict greater likelihood of MDD among s carriers. BDNF interacted with Risk such that Risk predicted greater likelihood of MDD among met carriers and did not influence val/val carriers. These two interactions were additive: both were significant in a combined model.