Comparative analysis of cerebrovascular techniques for studying cognitive aging

• Kallie Sweetman, Psychology, University of Delaware

• Christopher Martens, Kinesiology & Applied Physiology, University of Delaware

Cerebrovascular reactivity (CVR) is a dynamic measurement of brain vascular health that may be used to determine age-related increases in cerebrovascular disease risk. CVR may be quantified as the increase in cerebral blood flow (CBF) from rest in response to a vasodilatory challenge, which reflects the ability of cerebral blood vessels to respond to stimuli. Hypercapnia is a vasodilatory stimulus that can be achieved by delivering air supplemented with additional carbon dioxide (CO₂) using an end tidal targeting system or achieved by a breath hold which can naturally increase CO₂. A direct measurement of CBF can be performed using magnetic resonance imaging (MRI). However, this technique requires access to both an MRI and a specialized gas delivery system, which are expensive. An indirect measurement of CBF can be performed using a transcranial Doppler ultrasound (TCD), which is significantly less expensive and requires less equipment. The purpose of this study is to perform a comparative analysis between the breath-hold TCD-CVR technique with a more gold-standard MRI-CVR technique in middle-aged adults. If the breath-hold TCD-CVR technique demonstrates a high reliability and validity with the MRI-CVR technique, then it could serve as a cost-effective and more practical replacement option.