Parkinson-related dementias

Recent advances in neurogenetics, molecular biology, and immunocytochemical staining methods have expanded the spectrum of neurodegenerative disorders now known to cause dementia associated with parkinsonism. A list of these disorders associated with the known dysfunctional proteins is presented in Box 1. This brief review concentrates on those rare disorders in which cognitive impairment/dementia and parkinsonism coexist: corticobasal syndrome (CBS)/corticobasal degeneration (CBD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and frontotemporal dementia with parkinsonism linked to chromosome 17 (FTDP-17); dementia with Lewy bodies (DLB)-a common form of dementia often associated with parkinsonism-is reviewed in an article by Drs. Ferman and Boeve elsewhere in this issue. The clinical, neuropsychologic, neuroradiologic, and neuropathologic similarities and differences in these disorders are compared and contrasted along with Alzheimer's disease, Parkinson's disease, Parkinson's disease with dementia, and dementia with Lewy bodies, highlighting the features critical for identifying the correct diagnosis.