A multimodal investigation of brain health: cerebral blood flow, cognitive performance and quality of life

Understanding brain health is crucial in diagnosing, preventing and treating neurocognitive conditions (e.g., dementia). However, the literature reveals discrepancies around the interpretation of brain health and differences between populations. This thesis investigates brain health measures from different disciplines, including: resting cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) (using transcranial Doppler (TCD) ultrasound and magnetic resonance imaging (MRI)); cognition (including attention and memory); and quality of life (QoL) questionnaires. Differences between age (younger versus older) and cardiorespiratory fitness (fit versus unfit) groups were also investigated. Importantly, these multimodal brain health measures were completed in the same cohort. Declines were observed between younger and older groups in resting CBF measures (derived using TCD and MRI), and cognitive performance measures (attention-switching, learning and memory). In the older group, higher fitness offset declines in resting CBF and improved markers of cognition. In both groups, fitness significantly positively correlated with better QoL. However, no differences between age or fitness groups were observed in CVR measures. Further, CVR differed significantly depending on the imaging and analysis approach used. Future research is required to elucidate the cause of discrepancies and determine differences between groups (i.e., age/fitness/disease). Further, robust approaches to assess brain vascular health are needed