Changes in blood flow to the brain is mediated by cerebrovascular reactivity, where blood can be diverted to specific areas of need. Dejan Jakimovski, MD, PhD, Buffalo Neuroimaging Analysis Center, Buffalo, NY, describes the link between systemic arterial blood flow and cerebral perfusion in multiple sclerosis (MS). Patients with MS may have impaired cerebrovascular reactivity, resulting in blood not being directed to specific areas in the brain from the heart. The brain cannot consequently restrict blood flow in certain areas where blood is not high demand. This interview took place at the American Academy of Neurology 2022 Congress in Seattle, WA.