Dementia in idiopathic Parkinson's syndrome.

Approximately 25% of patients with idiopathic Parkinson's disease (IPD) later develop dementia, with the typical characteristics as detailed in ICD-10 and DSM-IV. Differential diagnosis has to exclude dementia due to Lewy bodies, subcortical vascular encephalopathy and subcortical dementia due to progressive supranuclear paralysis or corticobasal degeneration. Several studies showed promising results for cholinesterase inhibitors such as donepezile, rivastigmine and galantamine. The demented Parkinsonian patients then present with improvement in cognitive function while motor skills do not deteriorate.