An estimate of the prevalence of dementia in idiopathic Parkinson's disease
R. Mayeux, Y. Stern, R. Rosenstein, K. Marder, A. Hauser, L. Cote and S. Fahn
Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, NY.
A review of the records for evidence of dementia using criteria adapted
from the third edition of the Diagnostic and Statistical Manual of Mental
Disorders in every patient (hospitalized and outpatient) with parkinsonism
at a major medical center during an 18-month period revealed an overall
prevalence of 10.9% in 339 patients with idiopathic Parkinson's disease.
Demented patients were older, had a later age at onset of motor
manifestations, and a more rapid progression of physical disability than
nondemented patients. Duration of illness and levodopa use and the presence
of tremor or depression were similar in demented and nondemented patients.
Demented patients more often responded poorly or developed adverse effects
to levodopa than nondemented patients. When Parkinson's disease began after
age 70 years, dementia was noted over three times more frequently than when
the disease began at an earlier age. The age-specific prevalence rate of
dementia for patients older than 70 years was more than twice that for
younger patients. Moreover, the number of records with evidence for
dementia with idiopathic Parkinson's disease was 3.75 times greater than
expected in comparison with data from a study of the prevalence of dementia
in the elderly.
