APOE and Cognitive impairment: AD, Alzheimer’s disease; AS, asymptomatic Alzheimer’s disease; CT, control; MCI, mild cognitive impairment; CERAD, Consortium to Establish a Registry for Alzheimer’s Disease amyloid-β plaque load score; Braak, Braak stage for tau tangle burden; PMI, post-mortem interval; ApoE, apolipoprotein E isoform genotype; MMSE, Mini-Mental State Examination; NA, not available.