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Author Notes:

Correspondence: Zvinka Z. Zlatar, Department of Psychiatry, Stein Institute for Research on Aging, University of California, San Diego, 9500 Gilman Drive MC 0664, La Jolla, CA 92093-0664, USA e-mail: zzlatar@ucsd.edu

All authors contributed substantially with conception and study design, data acquisition and analyses, data interpretation, manuscript drafting and revisions, and manuscript approval.

We thank Michael Marsiske, Ph.D. and Todd M. Manini, Ph.D. for their help with this project and all the individuals who participated in this study.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


Research Funding:

This work was supported by the National Institutes of Health grants T32 MH019934-21; T32 AG020499-08, and P30 AG028740-03 to Zvinka Z. Zlatar.

This work was also supported by a Department of Veteran Affairs (VA) Rehabilitation R&D Center of Excellence #F2182C and Senior Research Career Scientist (Bruce Crosson: #B6364L) award.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Geriatrics & Gerontology
  • Neurosciences
  • Neurosciences & Neurology
  • physical activity
  • aerobic fitness
  • voxel based morphometry
  • healthy aging
  • MRI
  • gray matter density
  • RISK

Self-reported physical activity and objective aerobic fitness: differential associations with gray matter density in healthy aging


Journal Title:

Frontiers in Aging Neuroscience


Volume 7


Type of Work:

Article | Final Publisher PDF


Aerobic fitness (AF) and self-reported physical activity (srPA) do not represent the same construct. However, many exercise and brain aging studies interchangeably use AF and srPA measures, which may be problematic with regards to how these metrics are associated with brain outcomes, such as morphology. If AF and PA measures captured the same phenomena, regional brain volumes associated with these measures should directly overlap. This study employed the general linear model to examine the differential association between objectively-measured AF (treadmill assessment) and srPA (questionnaire) with gray matter density (GMd) in 29 cognitively unimpaired community-dwelling older adults using voxel based morphometry. The results show significant regional variance in terms of GMd when comparing AF and srPA as predictors. Higher AF was associated with greater GMd in the cerebellum only, while srPA displayed positive associations with GMd in occipito-temporal, left perisylvian, and frontal regions after correcting for age. Importantly, only AF level, and not srPA, modified the relationship between age and GMd, such that higher levels of AF were associated with increased GMd in older age, while decreased GMd was seen in those with lower AF as a function of age. These results support existing literature suggesting that both AF and PA exert beneficial effects on GMd, but only AF served as a buffer against age-related GMd loss. Furthermore, these results highlight the need for use of objective PA measurement and comparability of tools across studies, since results vary dependent upon the measures used and whether these are objective or subjective in nature.

Copyright information:

© 2015 Zlatar, McGregor, Towler, Nocera, Dzierzewski and Crosson.

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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