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Aerobic fitness and obesity: relationship to cerebral white matter integrity in the brain of active and sedentary older adults
  1. BL Marks1,2,3,
  2. LM Katz1,3,
  3. M Styner4,
  4. JK Smith5
  1. 1Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  2. 2Department of Allied Health Sciences, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  3. 3Department of Emergency Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  4. 4Department of Computer Science and Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  5. 5Departments of Radiology and Neuroimaging, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
  1. Correspondence to Dr BL Marks, Department of Exercise and Sport Science, Fetzer Gym, Campus Box #8700, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-8700, USA; marks{at}email.unc.edu

Abstract

Objective Aerobic fitness (VO2 peak) and obesity risk (OR) may impact brain health. This study examined hemispheric and segment specific relationships between VO2 peak, OR and cerebral white-matter (CWM) integrity in the cingulum brain region in healthy older adults.

Methods Fifteen subjects (66±6 years) completed VO2 peak testing and MRI of the brain. OR was determined via body mass index (BMI) and abdominal girth. MRI analysis was performed with a structural 3D T1 MP-Rage and diffusion tensor imaging technique (DTI, 21 directions, repeated four times) on a 3.0 T MR imaging unit. CWM integrity indices, fractional anisotropy (FA) and mean diffusivity (MD), were computed from the tensors. The anterior, middle and posterior cingulum segments were analysed on both sides of the brain. Partial correlations (age and gender controlled) and standard multiple regressions were used to determine significant associations and unique contributions to CWM integrity.

Results VO2 peak was moderately related to FA in the left middle cingulum segment (r partial=0.573, p=0.041) and explained 28.5% of FA's total variance (p=0.10). Abdominal girth (r partial=−0.764, p=0.002) and BMI (r partial=−0.690, p=0.009) were inversely related to FA in the right posterior cingulum (RPC) segment. Abdominal girth and BMI uniquely explained 53.9% of FA's total variance (p=0.012) and 43.9% (p=0.040), respectively, in the RPC.

Conclusion Higher aerobic fitness and lower obesity risk are related to greater CWM integrity but not in the same cingulum segments.

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Footnotes

  • Funding This pilot study was made possible by a seed grant awarded to Dr Marks by the Biomedical Research Imaging Center (BRIC), School of Medicine, University of North Carolina at Chapel Hill.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the University of North Carolina at Chapel Hill, Biomedical Internal Review Board, Study #05-3151.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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