Cerebral hypoperfusion and inadequate cerebrovascular responses to vasocactive stimuli (cerebrovascular reactivity) may precede the onset of cognitive impairment. Indeed, adults with cognitive impairment, including vascular dementia and Alzheimer’s disease, exhibit inadequate cerebral perfusion. Yet, there is minimal research on how chronic cerebral hypoperfusion may impact cerebrovascular control in humans. This project investigates the connection between cerebral perfusion, blood flow regulation, and cognitive impairment in older adults. Our overarching hypothesis is that chronic hypoperfusion, resulting from a specific variation in cerebrovascular architecture, impacts cerebral blood flow regulation which increases the risk of cognitive impairment. Understanding how chronic hypoperfusion affects cerebrovascular reactivity could be important for the early identification of individuals at elevated risk of cognitive impairment.
Cerebral blood flow responses to hypercapnia and hypoxia will be measured in individuals with vertebral artery hypoplasia (VAH) and those with normal cerebral anatomy (Controls). This study will consist of 2 visits: 1) Screen Day visit to determine eligibility and 2) Study Day visit which will include an MRI to measure brain structure, cerebrovascular reactivity to hypercapnia, and cerebral blood flow responses to hypoxia.