The Epidemiology of Vascular Dementia

Abstract

The first step in the methodology of modern epidemiology is the definition of the nature of the problem [5]. In the case of vascular dementia, both the definition of the epidemiologic case and the development of adequate diagnostic criteria have been extremely difficult. This is due to several factors: First, the clinical diagnosis of dementia is not a simple procedure since it is influenced by the confounding effect of cultural and educational factors which may mask early and mild cases. Furthermore, the diagnosis requires careful separation from delirium, depression, mental retardation, and psychiatric diseases, as well as from isolated cortical deficits such as aphasia, apraxia, or agnosia. Second, when the diagnosis of dementia is suspected, particularly in early cases, it usually needs confirmation by formal neuropsychologic testing. Third, once the diagnosis of dementia is confirmed, the possible causes — in particular treatable ones — should be investigated [12]. This is a long, complex, and usually unrewarding process which ends in most cases in the trifurcate, dementia of the Alzheimer type (DAT), vascular or multi-infarct dementia (MID), and mixed forms (MIX) resulting from the combination of DAT and MID. The main difficulty with this process of exclusion is that it is virtually impossible to determine if the vascular lesions are simply a marker for vascular dementia, coincidental lesions, the cause of the dementia, or a contributing factor.