Classification and subtypes of vascular dementia.

Vascular dementia (VaD) is a heterogeneous entity with a large clinicopathological spectrum. It has been classified and subclassified in many different ways. The difficulty in identifying the various subtypes is a problem in the diagnostic process. For clinical purposes, it is desirable to find subtypes of VaD that are homogeneous enough to allow meaningful comparisons across studies. This article presents candidates for such subtypes: poststroke dementia, subcortical VaD, and combined Alzheimer's disease and VaD (AD + VaD). The first two candidates are easy to identify. Poststroke dementia occurs with cognitive decline in close temporal relation to a transient ischemic attack. Subcortical VaD has a relatively homogeneous clinical picture for which detailed criteria are suggested. AD + VaD is more difficult to identify but is possible, sometimes with the aid of neuroimaging and/or biological markers.