INCIDENCE OF PROGRESSIVE SUPRANUCLEAR PALSY AND MULTIPLE SYSTEM ATROPHY IN OLMSTED COUNTY, MINNESOTA, 1976 TO 1990

Information on the incidence of progressive supranuclear palsy (PSP:, is limited; incidence rates for multiple system atrophy (MSA) are not available. We studied the incidence of PSP and MSA in Olmsted County, Minnesota, for the years 1976 to 1990. This study was part of a larger investigation of all forms of parkinsonism. We used the medical recor ds-linkage system of the Rochester Epidemiology Project to identify al l subjects whose records contained documentation of any form of parkin sonism, related neurodegenerative diseases, or tremor of amy type. A n urse abstractor screened the records and, when applicable, a neurologi st reviewed them to determine the presence]or absence of parkinsonism. Cases of parkinsonism were classified using specified diagnostic crit eria. Population denominators were derived from census data and were c orrected by removing prevalent cases of parkinsonism. Over the 15 year s of the study, we found 16 incident cases of PSP and nine incident ca ses of MSA. No cases of PSP or MSA had onset before age 50 years. The average annual incidence rate (new cases per 100,000 person-years) for ages 50 to 99 years was 5.3 for PSP and 3.0 for MSA. The incidence of PSP increased steeply with age from 1.7 at 50 to 59 years to 14.7 at 80 to 99 years, and was consistently higher in men. Median survival ti me from symptom onset was 5.3 years for PSP and 8.5 years far MSA. The incidence of PSP increases with age and is consistently higher in men at all ages. PSP and MSA are more common than previously recognized.