BDNF and Alzheimer disease: The relationship between common AD risk variants of the APOE gene and both cognition and the accumulation of Aβ has been consistently shown.7, -, 9 Several other genetic variants (GVs) have been identified for their association with cognition during the course of AD, including Klotho-VS10,11 and brain-derived neurotrophic factor.12,13 In addition, polygenic risk scores have been developed to aggregate genetic risk across the genome for AD and cognitive decline.14,15 Still, a large proportion of the variation in cognitive ability and longitudinal change remains unexplained.