Subcortical vascular dementia.

Vascular dementia (VaD) incorporates different vascular mechanisms and changes in the brain, and has different causes and clinical manifestations. Current criteria for VaD select an aetiologically and clinically heterogeneous group and this definitional heterogeneity has affected clinical trial results. Focus on a more homogeneous group, such as that with subcortical (ischaemic) VaD, could be an alternative in clinical drug trials. This subtype incorporates two small vessel clinical entities - 'Binswanger's disease' and 'the lacunar state'. It comprises small vessel disease as the primary vascular aetiology, lacunar infarct(s) and ischaemic white matter lesions as the primary type of brain lesions, subcortical location as the primary location of lesions, and the subcortical clinical syndrome as the primary clinical manifestation. Subcortical VaD is expected to show a more predictable clinical picture, natural history, outcome and treatment responses.