Study examines Parkinsonism in one county in Minnesota

Walter A. Rocca, M.D., M.P.H., of the Mayo Clinic, Rochester, Minn., and colleagues examined the incidence of dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD) in a JAMA Neurology study of residents in Olmsted County, Minn., over a 15-year period.

Limited information is available about the incidence of DLB or PDD in the general population so researchers used a well-defined population to help better characterize the two disorders, according to the study background.

Among 542 cases of parkinsonism, 64 patients had DLB and 46 had PDD. The overall incidence rate of DLB was 3.5 cases per 100,000 person-years, the incidence rate of PDD was 2.5 and both increased with age, according to the results. Patients with DLB were younger at the onset of symptoms than patients with PDD and had more hallucinations and cognitive fluctuations.

"In conclusion, our study provides unique population-based data on the incidence of DLB and PDD in Olmsted County. Similar to Parkinson disease, the risk of DLB increases with older age and is more frequent in men," the study concludes.