BDNF and early-onset autosomal dominant Alzheimer disease: Interestingly, several of these SNPs are in genes implicated in Alzheimer's disease (AD), such as apolipoprotein E (ApoE), catechol‐O‐methyltransferase (COMT), and brain‐derived neurotrophic factor (BDNF) (Wefel et al., 2016).