Clinical Research Directory

Inclusion Criteria: * Meet criteria for probable Parkinson disease dementia or PD-MCI (mild cognitive impairment) * Age greater than 50 * Hoehn and Yahr stage \< 4 in "on" state * Currently taking carbidopa/levodopa * Antiparkinsonian medications stable for at least 4 weeks prior to baseline visit * Cholinesterase inhibitor dose stable for 8 weeks prior to baseline visit Exclusion Criteria: * Meet criteria for dementia with Lewy bodies, including dementia onset prior to or within 1 year of parkinsonism onset * Presence of troublesome dyskinesias * Pregnancy or possibility of becoming pregnant during the study period. * Moderate or severe hepatic impairment * dementia too severe to complete study measures or to adhere to medication schedule