Association of cardiorespiratory fitness on interhemispheric hippocampal and parahippocampal functional connectivity.

Interhemispheric functional connectivity is associated with cognitive functioning. Although previous work has evaluated the association of cardiorespiratory fitness on cognitive function, there has been a limited investigation of the association of cardiorespiratory fitness on the functional connectivity of memory-related brain structures. As such, the objective of this study was to examine the association between cardiorespiratory fitness and parahippocampal and hippocampal interhemispheric functional connectivity. Data from the Nathan Kline Institute-Rockland Sample (NKI-RS) were utilized. Our analysis consisted of 284 participants (Mage  = 43 years; 62% female). Cardiorespiratory fitness was objectively measured using a cycle ergometer protocol. Parahippocampal and hippocampal interhemispheric functional connectivity were assessed from fMRI. Higher cardiorespiratory fitness was associated with greater parahippocampal (β = 0.004; CI, 0.00009 to 0.008, p = 0.04), but not hippocampal (β = 0.001; CI, -0.002 to 0.005, p = 0.44) interhemispheric functional connectivity. In conclusion, enhanced cardiorespiratory fitness may facilitate parahippocampal interhemispheric functional connectivity.