ALZHEIMER'S original description of presenile dementia in 1907 showed the value of clinical-pathological correlation in psychiatry. With his close associate Franz Nissl, the German neuropathologist Alois Alzheimer (1864 to 1915) devoted his career to investigating the anatomical changes underlying dementia.1-3 In the course of these studies, he discovered the disorder now known as Alzheimer's disease, which is characterized clinically by presenile dementia and pathologically by cerebral atrophy, senile plaques, and neurofibrillary degeneration.
Alzheimer was not the first to describe senile plaques.4 These microscopic foci are often found in the brains of the elderly, and some degree of plaque formation seems to accompany normal aging. However, Alzheimer correctly recognized that the presence of senile plaques in large numbers was abnormal. The neurofibrillary changes, consisting of tangles of thick argentophilic fibrils within the cytoplasm of neurons, were new to Alzheimer. Although he considered them specific for presenile dementia, subsequent