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JAMA Netw Open. 2019 Apr 5;2(4):e192745. doi: 10.1001/jamanetworkopen.2019.2745.

Association of Accelerometer-Measured Light-Intensity Physical Activity With Brain Volume: The Framingham Heart Study.

Author information

1
Department of Endocrinology, Diabetes, Nutrition and Weight Management, Boston University School of Medicine, Boston, Massachusetts.
2
Framingham Heart Study, Framingham, Massachusetts.
3
Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts.
4
Department of Neurology, Boston University School of Medicine, Boston, Massachusetts.
5
Department of Internal Medicine, Glostrup Hospital, Glostrup, Denmark.
6
Melbourne Dementia Research Centre, The Florey Institute for Neuroscience and Mental Health, Melbourne, Victoria, Australia.
7
Faculty of Medicine, Dentistry, and Health Sciences, The University of Melbourne, Melbourne, Victoria, Australia.
8
Centre for Human Psychopharmacology, Swinburne University of Technology, Melbourne, Victoria, Australia.
9
Department of Neurology and Center for Neuroscience, University of California, Davis.
10
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts.
11
Department of Epidemiology, Boston University School of Public Health, Boston, Massachusetts.
12
Glenn Biggs Institute for Alzheimer's and Neurodegenerative Diseases, University of Texas Health Sciences Center, San Antonio.

Erratum in

Abstract

Importance:

Dementia risk may be attenuated by physical activity (PA); however, the specific activity levels optimal for dementia prevention are unclear. Moreover, most older adults are unable to meet the nationally recommended PA guidelines, set at 150 minutes of moderate to vigorous PA per week.

Objective:

To assess the association of total steps walked per day and total dose (intensity × duration) of PA with brain volumes on magnetic resonance imaging (MRI) among Framingham Heart Study participants.

Design, Setting, and Participants:

This cross-sectional, community-based cohort study of the association of accelerometry-determined PA with brain MRI measures in Framingham, Massachusetts, included the Framingham Heart Study third-generation (examination 2, 2008-2011) and offspring (examination 9, 2011-2014) cohorts. Of 4021 participants who agreed to wear an accelerometer and had valid data (≥10 hours/day for ≥3 days), 1667 participants who did not undergo brain MRI (n = 1604) or had prevalent dementia or stroke (n = 63) were excluded. Data analysis began in 2016 and was completed in February 2019.

Exposures:

Physical activity achieved using accelerometry-derived total activity (steps per day) and 2 intensity levels (light intensity and moderate to vigorous intensity).

Main Outcomes and Measures:

Differences in total brain volume and other MRI markers of brain aging.

Results:

The study sample of 2354 participants had a mean (SD) age of 53 (13) years, 1276 (54.2%) were women, and 1099 (46.7%) met the PA guidelines. Incremental light-intensity PA was associated with higher total brain volume; each additional hour of light-intensity PA was associated with approximately 1.1 years less brain aging (β estimate, 0.22; SD, 0.07; P = .003). Among individuals not meeting the PA guidelines, each hour of light-intensity PA (β estimate, 0.28; SD, 0.11; P = .01) and achieving 7500 steps or more per day (β estimate, 0.44; SD, 0.18; P = .02) were associated with higher total brain volume, equivalent to approximately 1.4 to 2.2 years less brain aging. After adjusting for light-intensity PA, neither increasing moderate to vigorous PA levels nor meeting the threshold moderate to vigorous PA level recommended by the PA guidelines were significantly associated with total brain volume.

Conclusions and Relevance:

Every additional hour of light-intensity PA was associated with higher brain volumes, even among individuals not meeting current PA guidelines. These data are consistent with the notion that the potential benefits of PA on brain aging may accrue at a lower, more achievable level of intensity or duration.

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