title: The association between aerobic fitness and executive function is mediated by prefrontal cortex volume.
abstract: Aging is marked by a decline in cognitive function, which is often preceded by losses in gray matter volume. Fortunately, higher cardiorespiratory fitness (CRF) levels are associated with an attenuation of age-related losses in gray matter volume and a reduced risk for cognitive impairment. Despite these links, we have only a rudimentary understanding of whether fitness-related increases in gray matter volume lead to elevated cognitive function. In this cross-sectional study, we examined whether the association between higher aerobic fitness levels and elevated executive function was mediated by greater gray matter volume in the prefrontal cortex (PFC). One hundred and forty-two older adults (mean age=66.6 years) completed structural magnetic resonance imaging (MRI) scans, CRF assessments, and performed Stroop and spatial working memory (SPWM) tasks. Gray matter volume was assessed using an optimized voxel-based morphometry approach. Consistent with our predictions, higher fitness levels were associated with: (a) better performance on both the Stroop and SPWM tasks, and (b) greater gray matter volume in several regions, including the dorsolateral PFC (DLPFC). Volume of the right inferior frontal gyrus and precentral gyrus mediated the relationship between CRF and Stroop interference while a non-overlapping set of regions bilaterally in the DLPFC mediated the association between CRF and SPWM accuracy. These results suggest that specific regions of the DLPFC differentially relate to inhibition and spatial working memory. Thus, fitness may influence cognitive function by reducing brain atrophy in targeted areas in healthy older adults.
authors.affiliation: Department of Psychology and the Center for the Neural Basis of Cognition, University of Pittsburgh, PA 15260, USA. andrea.weinstein@gmail.com
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Weinstein
authors.forename: Michelle W
authors.initials: MW
authors.lastname: Voss
authors.forename: Ruchika Shaurya
authors.initials: RS
authors.lastname: Prakash
authors.forename: Laura
authors.initials: L
authors.lastname: Chaddock
authors.forename: Amanda
authors.initials: A
authors.lastname: Szabo
authors.forename: Siobhan M
authors.initials: SM
authors.lastname: White
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Wojcicki
authors.forename: Emily
authors.initials: E
authors.lastname: Mailey
authors.forename: Edward
authors.initials: E
authors.lastname: McAuley
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Kramer
authors.forename: Kirk I
authors.initials: KI
authors.lastname: Erickson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D003071:Cognition / Q000502:physiology; D016001:Confidence Intervals; D003430:Cross-Sectional Studies; D003627:Data Interpretation, Statistical; D019706:Excitatory Postsynaptic Potentials; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D010809:Physical Fitness / Q000523:psychology*; D017397:Prefrontal Cortex / Q000033:anatomy & histology* / Q000502:physiology*; D013028:Space Perception / Q000502:physiology; D057190:Stroop Test