Clinicopathological outcomes of prospectively followed normal elderly brain bank volunteers.

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.