Vascular Dementia Is Overdiagnosed

There are different kinds of vascular dementia.¹Ignoring indirect mechanisms (such as hydrocephalus following subarachnoid hemorrhage²), we might hypothesize a pathophysiologic spectrum. At one end would be circumscribed intellectual impairment from destruction of particular brain areas, for example, memory loss after inferior temporal lobe infarction.³This type of dementia seldom produces diagnostic (or conceptual) difficulty. At the other end would be more insidiously progressive dementia from diffuse small-vessel pathology (Binswanger's disease).⁴⁻⁹This type of dementia is understood by no one, and estimates of its prevalence range from infinitesimal to epidemic. Between these two extremes is cognitive loss from multiple lesions, none of which alone would be expected to cause intellectual impairment (multiinfarct dementia).¹⁰This type of dementia is overdiagnosed. Two decades ago Tomlinson et al,¹¹comparing the brains of 50 old people with dementia with those of control subjects without dementia, diagnosed dementia of