[Pathogenesis and pathophysiology of ischemic leukoencephalopathy]

The cerebral white matter is highly susceptible to ischemic damage because of its location in the end-fields of penetrating arteries. Our studies have shown that hypertension, short-term variability of blood pressure, decreased oxygen dissociation of hemoglobin, and increased resistance of cerebral arterioles play important roles in the pathogenesis of Binswanger type dementia. While hypoperfusion was most remarkable in the frontal area and dopamine metabolism in the cerebrospinal fluid was impaired in Binswanger type dementia, cerebral blood flow decreased most conspicuously in the parietal area and there was an impairment of noradrenaline metabolism in the cerebrospinal fluid in senile dementia of Alzheimer type. Previous anatomical studies have indicated that the ascending dopaminergic system predominantly innervates the frontal cortex, while the noradrenergic system projects all cortical areas, including the parietal cortex. Our findings suggest frontally-dominant dysfunctions in Binswanger type dementia.