The fitness versus body fat hypothesis in relation to hippocampal structure. (30th April 2020)

• Record Type: Journal Article
• Authors: Aghjayan, Sarah L.; Jakicic, John M.; Rogers, Renee J.; Esteban‐Cornejo, Irene; Peven, Jamie C.; Stillman, Chelsea M.; Watt, Jennifer C.; Erickson, Kirk I.
• Other Names: Rypma Bart guestEditor.; Gratton Gabriele guestEditor.; Fabiani Monica guestEditor.
• Is Part Of: Psychophysiology. Volume 58:Number 7(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-04-30
• Subjects: anatomical -- fitness -- hippocampus -- middle‐aged adults -- obesity; Psychophysiology -- Periodicals; 612.8
• DOI: 10.1111/psyp.13591
• Languages: English
• ISSNs: 0048-5772

Abstract

Abstract: The Fitness Versus Body Fat Hypothesis argues that cardiorespiratory fitness (CRF) plays a more important role in cardiovascular health than adiposity. It remains poorly understood whether CRF or adiposity accounts for a greater amount of variation in measures of brain health. We examined the contribution of CRF, adiposity, and their interaction with hippocampal structure. This study included 124 sedentary adults ( M = 44.34) with overweight/obesity (Body Mass Index mean = 32.43). FMRIB's Integrated Registration and Segmentation Tool was used to segment the hippocampus. Using hierarchical regression, we examined whether CRF, assessed via a submaximal graded exercise test, or adiposity, assessed as percent body fat using dual‐energy x‐ray absorptiometry (DXA) was associated with left and right hippocampal volume. Vertex‐wise shape analysis was performed to examine regional shape differences associated with CRF and adiposity. Higher CRF was significantly associated with greater left hippocampal volume ( p = .031), with outward shape differences along the surface of the subiculum and CA1 regions. Adiposity was not associated with left or right hippocampal volume or shape. The interaction between adiposity and CRF was not significant. Neither CRF nor adiposity were associated with thalamus or caudate nucleus volumes or shapes, two control regions. Higher CRF, but not adiposity, was related to greater left hippocampal volume, with outward shape differences along the surface of the subiculum and CA1 regions in a midlife sample with overweight/obesity. These findings indicate that, within the context of obesity, CRF is an important contributor to hippocampal structure, highlighting the importance of interventions targeting CRF. Impact Statement: The Fitness Versus Body Fat Hypothesis argues that CRF plays a more important role in cardiovascular health than adiposity. For the first time, we extend the debate to brain health and demonstrate that higher CRF, but not adiposity, is associated with greater volume and outward shape differences along the surface of the subiculum and CA1 regions of the left hippocampus.