Project 172226

Cerebral blood flow (CBF) is highly regulated by carbon dioxide and oxygen in the arterial blood. This process becomes impaired with cerebrovascular disease processes and by aging. Aging is associated with a progressive decline in CBF, which is a major risk factor for stroke. In premenopausal women, this decline is not as pronounced as in men but it appears to be accelerated after menopause and persists into old age. This biphasic phenomenon might be explained by ovarian hormone modulation of CBF before menopause, followed by a predominant influence of other factors thereafter. Physical inactivity, a modifiable risk factor for stroke and cognitive decline, may be one of those factors. However, the mechanism by which physical activity exerts its protective effect on the cerebral circulation is unclear. If physical activity is a significant modulator of CBF, one would predict that men and women who are more active would have fewer incidences of cerebrovascular disease than those who are sedentary. A suitable experimental design would require a set of studies in sedentary men and women, followed by the same studies in active men and women, and then placing the sedentary and physically-active groups on similar training programs. This approach would enable the possibility of using this knowledge to impact predictors for stroke, or at least how active living may prevent cardiovascular problems in the brain from occurring. We propose studies in sedentary men and women to address the question: What are the effects of physical activity on CBF and cognitive function in older men and women? This approach will allow us to study the interactions between the cerebral circulation and cognitive function, and may provide powerful diagnostic tools to help identify those individuals at risk of stroke. This work may have a positive impact in helping delay or prevent the onset of disabilities due to diseases like stroke.