Previous studies have associated genetic polymorphisms, in particular apolipoprotein E (APOE) ε2/ε3/ε4 genotype (see review4,5) and the non-synonymous rs6265 (Val66Met) SNP in brain derived neurotropic factor (BDNF)6–9, with altered rates of episodic memory decline and hippocampal atrophy. This evidence concerns the gene APOE and hippocampal atrophy.