This supplement compiles the views of international experts on dementia in parkinsonism. The subject is covered from clinical, morphological and biochemical points of view and the diversity of terminology for dementia with Parkinson's Disease is emphasized. Subjects covered include normal brain function and the influence of age, investigation and treatment of dementia, pathological nomenclature and criteria for diagnosis, the relationship between dementia in Parkinson's Disease and Alzheimer's Disease, and biochemical and morphological substrates of dementia.