Cardiorespiratory fitness is associated with cerebral myelin content in aging

Motivation: While higher cardiorespiratory fitness (CRF) is recognized as vital for brain health, its specific connection with white matter integrity, especially cerebral myelination, remains unclear. Goal(s): This study aims to investigate the association between CRF and myelin in cognitively unimpaired adults spanning a wide age range. Approach: We employed our advanced multicomponent MR relaxometry method to measure myelin water fraction, a direct proxy of myelin content, while CRF was assessed using the maximum rate of oxygen consumption, peak VO2. Results: Our results indicate that higher peak VO2 is associated with greater myelin content across several white matter structures, particularly among older adults. Impact: This work lays the foundation for future investigations to further elucidate the mechanisms underlying the relationship between cardiorespiratory fitness and cerebral myelination, as well as its potential as an interventional target in addressing age-related neurodegeneration, including in Alzheimer’s disease.