APOE and early-onset autosomal dominant Alzheimer disease: There is a weak association between ApoE4 and BDNF Met on longitudinal PET measurements and the Aβ plaque burden of Alzheimer’s disease-related carriage on cerebral metabolic rate for glucose (CMRgl) decline in cognitively unimpaired late-middle-aged and older adults, without an obvious effect upon the rate of cognitive decline [58].