Hypertension is a major risk factor for cerebral infarction, intracranial hemorrhage, and vascular dementia, particularly among older adults. Prior to clinical manifestations of cerebrovascular disease, subtle neuropsychological deficits are noted in hypertensives of all age ranges. In older adults, hypertension is highly prevalent, and is considered a critical factor in cognitive aging. The underlying pathogenesis of this process is poorly understood. Subtle deficits in neuropsychological performance, and accompanying central nervous system abnormalities, may constitute early markers of elevated cerebrovascular risk among older hypertensives. In this proposal, it is hypothesized that hypertension will be associated with diminished neuropsychological function, increased microvascular disease, greater macrovascular disease, and reduced cerebral perfusion. These three central nervous system mechanisms will result in subtle neuropsychological deficits among non-demented, older hypertensives. The first specific aim of this project is to compare 100 unmedicated, mild-to-moderate essential hypertensives (ages 60-80) to 100 demographically comparable normotensives with respect to: (1) neuropsychological performance; (2) magnetic resonance imaging (MRI) ratings of microvascular disease involving periventricular and deep white matter; (3) magnetic resonance angiography (MRA) ratings of macrovascular disease of the cerebral and cervicocerebral arteries; and (4) relative ratios of cerebral:cerebellar perfusion assessed by single photon emission computed tomography (SPECT).
A second aim i s to examine MRI, MRA, and SPECT indices of microvascular disease, macrovascular disease, and cerebral perfusion as predictors of neuropsychological performance. This study will be the first to examine concomitantly three central nervous system mechanisms as predictors of neuropsychological function in older adults. Understanding the pathogenesis of hypertension-related cognitive impairment in older adults may lead to enhanced efforts in prevention, and intervention to reduce cerebrovascular risk and improve quality of life.
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