Advisory Committee Chair
Ronald M Lazar
Advisory Committee Members
Karlene K Ball
Mark S Bolding
Burel R Goodin
Christianne E Strang
Document Type
Dissertation
Date of Award
2022
Degree Name by School
Doctor of Philosophy (PhD) College of Arts and Sciences
Abstract
Cardiorespiratory fitness (CRF) is associated with enhanced cognitive functions in aging. The relationship between fitness and brain function is supported by evidence of improvements or maintenance of gray matter volume, and cerebral blood flow (CBF). Research focused on interactions between CRF and changes in cerebral structure and function have not identified the underlying mechanisms of exercise-induced improvements, and none included the effects of CRF on cerebral oxygen extraction fraction (OEF), which is a measure of the ratio of oxygen that a tissue extracts from the blood to maintain morphological and functional integrity. Here, we present evidence from existing studies that outlines the effects of exercise on the brain and propose to extend our current understanding by interrogating the effects of improved CRF on OEF. We used neuroimaging, transcranial doppler ultrasonography, cognitive assessments, and serum biomarkers to investigate the effects of an 8-week exercise intervention on OEF, hippocampal subfield volumes, CBF, cognition in healthy older sedentary women. The intervention improved CRF, and overall cognitive function, visuospatial memory, and language domains. However, no significant effects of improved fitness were observed on OEF or hippocampal subfields. Similarly, CBF and serum biomarkers were unchanged at follow-up. However, relationships between hippocampal subfields and serum biomarkers were observed: dentate gyrus correlated iv with higher insulin like growth factor-1 and lower c-reactive protein (CRP); subiculum correlated with reduced brain derived neurotrophic factor; and cornu ammonis-3 was associated with higher levels of CRP. Furthermore, we identified a positive relationship between right hemisphere gray matter OEF and language, and subiculum volumes correlated positively with attention and verbal memory. Our findings suggest the selective impact of a short exercise intervention on CRF in older women. Although we did not observe an impact of exercise on CBF, hippocampal subfields or OEF, improvements in cognitive domains were correlated with OEF and hippocampal subfields. Given that CBF was not correlated with any outcomes, our data suggest that blood flow and OEF may not underlie exercise-induced changes in cognition. Indeed, other physiological changes alone or in combination with CBF and OEF or neurotrophins including cerebral waste clearance may underlie the neuroprotective effects of exercise.
Recommended Citation
Norling, Amani M., "Effects of Exercise on Cerebral Oxygen Extraction Fraction, Hippocampal Subfields, and Cognition in Older Women" (2022). All ETDs from UAB. 166.
https://digitalcommons.library.uab.edu/etd-collection/166