Neuropathological features of Alzheimer's disease in non-demented parkinsonian patients.

Two patients with levodopa-responsive Parkinson's syndrome had numerous cortical and striatal senile plaques and some neurofibrillary tangles at necropsy. In addition neurons in the pars compacta of the substantia nigra were severely depleted but there were no Lewy bodies or other neuropathological changes to account for parkinsonism. Neither patient was demented. These pathological findings have not previously been described as a cause of Parkinson's syndrome without associated dementia of Alzheimer's disease type.