Neuropsychology of subcortical dementias.

Subcortical dementias are a heterogeneous group of disorders that share primary pathology in subcortical structure and a characteristic pattern of neuropsychological impairment. This article describes the neurobiological and cognitive features of three prototypical subcortical dementias, Parkinson's disease, Huntington's disease, and progressive supranuclear palsy, concentrating of traits shared by disorders. Clinical features are also discussed, especially those which differentiate subcortical dementias from cortical dementias, such as Alzheimer's disease. The cortical-subcortical nomenclature has been criticized over the years, but it continues to provide an effective means of classifying dementia profiles in clinically and theoretically useful ways.