The Dementia Rating Scale in Alzheimer's disease, Huntington's disease and progressive supranuclear palsy.

The Dementia Rating Scale (DRS) comprises a series of five subtests which assess attention, memory, initiation/preservation, construction, and conceptualisation. It can be delivered in full in approximately 30 min, making it a useful test for the detection and estimation of the overall level of dementia. We analysed the pattern of subscale test scores in patients with cortical and subcortical dementias, who were matched for their overall level of dementia on this scale. Patients with dementia of Alzheimer's type were more impaired than patients with Huntington's disease (HD) and progressive supranuclear palsy (PSP) on the memory subtest, whereas patients with HD and PSP were more impaired on the initiation/perseveration subtest. This is evidence in favour of the concept of cortical and subcortical dementias as separate, although overlapping, entities. Qualitative differences in the pattern of cognitive impairment in these disorders can be detected with a brief cognitive status examination.