Alzheimer's Disease Pathology in Non-Demented Elderly

The purpose of this study was to quantitate the extent of neuropathological lesions (neurofilbrillary tangles and senile plaques) characteristic of Alzheimer's disease in cognitively intact elderly control subjects. The subjects included twenty-six elderly individuals who were autopsied at a university-based Alzheimer's Disease Center. The mean age at autopsy was 78 years (range 51-99 years); there were 15 males and 11 females. All of these control subjects had a few neurons containing neurofibrillary tangles in the hippocampus, but no neurofibrillary tangles in the neocortex. Twelve of the 26 subjects (46%) had some senile plaques in the neocortex, while fourteen (54%) did not. Six subjects (23%) had substantial numbers of senile plaques in the neocortex. Neither the number of neurons containing neurofibrillary tangles nor the number of senile plaques correlated with age in these subjects. Possible conclusions are that there are many elderly individuals with incipient Alzheimer's Disease, or that one can have some degree of these lesions and still be cognitively normal. These data point out the need to have better pathological markers of the disease process and better diagnostic criteria to define Alzheimer's Disease.