An association study of the brain-derived neurotrophic factor Val66Met polymorphism and amphetamine response

Although genetic factors are known to be important in addiction, no candidate genes have yet been consistently linked to drug use or abuse. Brain-derived neurotrophic factor (BDNF), which has been implicated in the behavioral response to psychomotor stimulants and potentiates neurotransmitters that are strongly linked to addiction, is a logical candidate gene to study. Using a drug challenge approach, we tested for association between BDNF G196A (val66met) genotype and subjective responses to amphetamine (AMPH). Healthy volunteers participated in a double blind, crossover design in which they received placebo, 10 mg, and 20 mg oral d-amphetamine in random order. Subjective and physical responses to ingestion of AMPH were measured at 30-min intervals after drug ingestion. Each subject was genotyped for the BDNF G196A polymorphism and grouped and analyzed accordingly. The effects of AMPH on ratings of arousal, energy, and heart rate were compared in subjects with the val/val genotype (N = 67) and the subjects with either the val/met or met/met genotypes (N = 32). AMPH produced less pronounced self-ratings of arousal and energy, yet higher increases in heart rate, in the val/met and met/met compared to the val/val group. These results suggest that BDNF is related to the subjective and physical response to low doses of AMPH.