Parkinsonism and Related Dementias

Abstract The differential diagnosis for dementia is wide. A slowly progressive course for parkinsonism suggests a degenerative cause and helps to narrow the differential diagnosis considerably. In patients with dementia in combination with parkinsonism (often collectively termed the parkinsonism-related dementias), the 4 most common neurodegenerative entities are 1) Lewy body dementias (which include dementia with Lewy bodies and Parkinson disease with dementia); 2) corticobasal syndrome or corticobasal degeneration; 3) Richardson syndrome or progressive supranuclear palsy; and 4) frontotemporal dementia with parkinsonism.