Is subcortical vascular dementia a clinical entity for clinical drug trials?

Several therapeutic trials have been performed for vascular dementia, with drugs differing in type and mechanism of action. The results have been almost invariably inconclusive. Given the current notion that there are different subtypes of vascular dementia according to pathophysiological mechanisms, it is reasonable to suspect that one of the main causes of the disappointing results was that the study samples included patients not fitting with the rationale of selective treatments. Testing this hypothesis is difficult because characterization of patients in relation to different subtypes of vascular dementia is not available for most studies. However, attempts are ongoing to reclassify patients entered in some trials for post hoc subgroup analyses with some preliminary interesting results. We propose that (1) specific subtypes of vascular dementia should be the target in any single trial using a treatment with a proper rationale; and (2) subcortical vascular dementia, caused by small vessel disease leading to lacunar infarcts and subcortical white matter changes, represents a clinically and radiologically well-defined entity to be considered for future trials designed specifically for testing adequate drugs.