Braak staging, plaque pathology, and APOE status in elderly persons without cognitive impairment

Clinico-pathological studies reveal that some elderly people with no cognitive impairment have high burdens of neurofibrillary tangles (NFTs), a pathology associated with Alzheimer's disease. We examined a total of 123 elderly participants without dementia and free of other neurological disorders or pathologies who at autopsy were classified as Braak NFT stages of I-V. We found that women were significantly more likely to have a high Braak score. Significant associations were found between high Braak scores and entorhinal cortex amyloid load, combined hippocampal and entorhinal cortex amyloid loads with perceptual speed in the low Braak group after adjusting for age, gender and apolipoprotein E ε4 status. Elderly with preserved cognitive function show a wide range of Braak scores and plaque pathology similar to that seen in prodromal and frank Alzheimer's disease at death. These data suggest that some older people with extensive NFT and plaque pathology demonstrate brain resilience or reserve leading to preserved cognitive function.