Effect of BDNF val66met polymorphism on declarative memory and its neural substrate: A meta-analysis

► In a meta-analysis, we examined the effect of the BDNF val66met polymorphism. ► Declarative memory performance was reduced in carriers of the met allele. ► Hippocampal volume and activation were was reduced in carriers of the met allele. ► BDNF mediates individual variability in hippocampal structure and function.