[Problems in vascular dementia].

Abstract

Vascular dementia (VD) and Alzheimer's type dementia are two main causes of dementia in the aged. Considering historical backgrounds and ethnic differences, a simplified classification of VD is suggested. First, poststroke dementia of acute onset associated with an infarct that is large enough to impair general cognitive functions, or strategically located. Second, multi-infarct dementia that develops incrementally with increasing numbers of infarcts, and which should be classified as multiple cortical infarct dementia and multiple small infarctor lacunar dementia. Third, vascular dementia of the Binswanger type (VDBT). We compared two types of white matter lesions, periventricular hyperintensity (PVH) and confluent centrum semiovale hyperintensity (CCSH) in lacunar stroke patients with regard to the cerebral blood flow (CBF). In patients with PVH, there was a significant positive correlation between the dementia scores and the CBF in the parietal and temporal areas but not in the frontal area. In CCSH patients, there was a significant positive correlation in the frontal area but not in the parieto-temporal areas. Therefore, dementia in most patients with PVH may not be primarily related to the PVH, but may possibly be due to coexisting Alzheimer's type dementia, and dementia in most CCSH patients may be related to cerebrovascular disease. VDBT is unique clinically in its slowly progressive intellectual deterioration and pathologically in diffuse, confluent, and almost symmetrical white matter lesions. For the pathogenesis of VDBT, our studies suggest that hypertension, short-term variations in blood pressure, and a sustained nighttime elevation of blood pressure promote small vessel disease and cause ischemia of the cerebral white matter that is located in the end-fields of penetrating arteries; this leads to an imparied integrity of the blood-brain barrier and free radical generation, both of which may have important roles in producing diffuse white matter degeneration.