Cardiorespiratory fitness predicts cortical thickness of medial temporal brain areas associated with spatial cognition in young but not older adults

Cardiorespiratory fitness (CRF) has been shown to have a potent effect on neurocognitive health. However, less is known about the impact of CRF on extrahippocampal neocortical regions in the medial temporal lobes (MTL). Specifically, it is unclear whether CRF modulates these MTL regions in young adulthood and if these brain areas are differentially related to CRF in young vs. older adults. The primary goal of the current study was to investigate if CRF predicted cortical thickness of MTL neocortical regions that, along with the hippocampus, are critical for spatial learning and memory. Additionally, given the established role of the MTL cortices in spatial navigation, we sought to determine if CRF and MTL cortical thickness would predict greater subjective sense of direction in both young and older adults. Cross-sectional data from 56 young adults (20-35 years) and 44 older adults (55-85 years) were included. Using hierarchical multiple regression analyses, we confirmed significant positive relationships between greater CRF and greater left entorhinal, left parahippocampal, and left perirhinal cortical thickness in young, but not older, adults. Left parahippocampal thickness interacted with age group to differentially predict sense of direction in young and older adults. Young adults displayed a positive, and older adults a negative, relationship between left parahippocampal thickness and sense of direction. Our findings extend previous work on the association between CRF and hippocampal subfield structure in young adulthood to left MTL neocortical regions. HighlightsO_LICardiorespiratory fitness assessed in young and older adults using a submaximal treadmill test. C_LIO_LISurface-based structural analysis of cortical thickness of medial temporal regions. C_LIO_LICardiorespiratory fitness predicted left medial temporal cortical thickness in young but not older adults. C_LIO_LILeft parahippocampal thickness differentially predicted sense of direction in young and older adults. C_LI