UC Davis

Existing reports on the frequencies of neurodegenerative diseases are typically based on clinical diagnoses. We sought to determine these frequencies in a prospectively assessed, community-based autopsy series. Included subjects had normal cognitive and movement disorder assessments at study entry. Of the 119 cases meeting these criteria, 52% were women; the median age of study entry was 83.5 years (range, 67-99 years), and the median duration from the first visit until death was 4.3 years (range, 0-10 years). At autopsy, clinicopathological diagnoses were made in 30 cases (25%). These diagnoses included 20 with Alzheimer disease (AD) (17%), 7 with vascular dementia (6%), 4 with progressive supranuclear palsy (3%), 3 with Parkinson disease and 1 each with dementia with Lewy bodies, corticobasal degeneration, or multiple system atrophy (0.8% each). Of the 87 subjects still clinically normal at death (73%), 33 had extensive AD pathology (preclinical AD) (38%), 17 had incidental Lewy bodies (20%), and 4 had incidental pathology consistent with progressive supranuclear palsy (5%). The diagnoses were not mutually exclusive. Although limited by a relatively small sample size, the neuropathological outcome of these initially normal elderly subjects represents a rough estimate of the incidence of these neurodegenerative conditions over a defined time period.