BDNF and Mental deterioration: There is now strong and well-replicated evidence that allelic variation in the brain-derived neurotrophic factor (BDNF) Val66Met (rs6265) polymorphism exerts substantial influence on rates of neurodegeneration and cognitive decline in adults with elevated levels of Aβ (Aβ+) (Boots, et al., 2017; Franzmeier, et al., 2021; Lim, et al., 2013; Lim, et al., 2014a; Lim, et al., 2015; Lim, et al., 2016; Lim, et al., 2017a; Lim, et al., 2018; Lim, et al., 2021; Lim, et al., 2022; van, den, Bosch, et al., 2021).