Dataset Information

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study.

ABSTRACT:

Background

Several longitudinal studies found an inverse relationship between levels of physical activity and cognitive decline, dementia, and/or Alzheimer's disease (AD), but results have been inconsistent. We followed an older, community-based cohort for over a decade to examine the association of physical activity with the risk of incident dementia and subclinical brain MRI markers of dementia.

Methods

The physical activity index (PAI) was assessed in the Framingham Study Original and Offspring cohorts, aged 60 years or older. We examined the association between PAI and risk of incident all-cause dementia and AD in participants of both cohorts who were cognitively intact and had available PAI (n = 3,714; 54% women; mean age = 70±7 years). We additionally examined the association between PAI and brain MRI in the Offspring cohort (n = 1,987).

Results

Over a decade of follow-up, 236 participants developed dementia (188 AD). Participants in the lowest quintile of PAI had an increased risk of incident dementia compared with those in higher quintiles (hazard ratio [HR] = 1.50, 95% confidence interval [CI] = 1.04-1.97, p = .028) in a multivariable-adjusted model. Secondary analysis revealed that this relation was limited to participants who were apolipoprotein (APO)E ?4 allele noncarriers (HR = 1.58, 95% CI = 1.08-2.32; p = .018) and strongest in participants aged 75 years or older. PAI was also linearly related to total brain and hippocampal volumes (? ± SE = 0.24±0.06; p < .01 and 0.004±0.001; p = .003, respectively).

Conclusion

Low physical activity is associated with a higher risk for dementia in older individuals, suggesting that a reduced risk of dementia and higher brain volumes may be additional health benefits of maintaining physical activity into old age.

SUBMITTER: Tan ZS

PROVIDER: S-EPMC6075525 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Publications

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study.

Tan Zaldy S ZS Spartano Nicole L NL Beiser Alexa S AS DeCarli Charles C Auerbach Sanford H SH Vasan Ramachandran S RS Seshadri Sudha S

The journals of gerontology. Series A, Biological sciences and medical sciences 20170601 6

<h4>Background</h4>Several longitudinal studies found an inverse relationship between levels of physical activity and cognitive decline, dementia, and/or Alzheimer's disease (AD), but results have been inconsistent. We followed an older, community-based cohort for over a decade to examine the association of physical activity with the risk of incident dementia and subclinical brain MRI markers of dementia.<h4>Methods</h4>The physical activity index (PAI) was assessed in the Framingham Study Origi ...[more]

PMID: 27422439

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Project description:ImportanceDementia 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.ObjectiveTo 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 participantsThis 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.ExposuresPhysical activity achieved using accelerometry-derived total activity (steps per day) and 2 intensity levels (light intensity and moderate to vigorous intensity).Main outcomes and measuresDifferences in total brain volume and other MRI markers of brain aging.ResultsThe 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 (? estimate, 0.22; SD, 0.07; P?=?.003). Among individuals not meeting the PA guidelines, each hour of light-intensity PA (? estimate, 0.28; SD, 0.11; P?=?.01) and achieving 7500 steps or more per day (? 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 relevanceEvery 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.

Project description:IMPORTANCE:In animal studies, brain-derived neurotrophic factor (BDNF) has been shown to impact neuronal survival and function and improve synaptic plasticity and long-term memory. Circulating BDNF levels increase with physical activity and caloric restriction, thus BDNF may mediate some of the observed associations between lifestyle and the risk for dementia. Some prior studies showed lower circulating BDNF in persons with Alzheimer disease (AD) compared with control participants; however, it remains uncertain whether reduced levels precede dementia onset. OBJECTIVE:To examine whether higher serum BDNF levels in cognitively healthy adults protect against the future risk for dementia and AD and to identify potential modifiers of this association. DESIGN, SETTING, AND PARTICIPANTS:Framingham Study original and offspring participants were followed up from 1992 and 1998, respectively, for up to 10 years. We used Cox models to relate BDNF levels to the risk for dementia and AD and adjusted for potential confounders. We also ran sensitivity analyses stratified by sex, age, and education, as well as related BDNF genetic variants to AD risk. This community-based, prospective cohort study involved 2131 dementia-free participants aged 60 years and older (mean [SD] age, 72 [7] years; 56% women). MAIN OUTCOMES AND MEASURES:Ten-year incidence of dementia and AD. RESULTS:During follow-up, 140 participants developed dementia, 117 of whom had AD. Controlling for age and sex, each standard-deviation increment in BDNF was associated with a 33% lower risk for dementia and AD (P?=?.006 and P?=?.01, respectively) and these associations persisted after additional adjustments. Compared with the bottom quintile, BDNF levels in the top quintile were associated with less than half the risk for dementia and AD (hazard ratio, 0.49; 95% CI, 0.28-0.85; P?=?.01; and hazard ratio,?0.46; 95% CI, 0.24-0.86; P?=?.02, respectively). These associations were apparent only among women, persons aged 80 years and older, and those with college degrees (hazard ratios for AD: 0.65, [95% CI, 0.50-0.85], P?=?.001; 0.63 [95% CI, 0.47-0.85], P?=?.002; and 0.27 [95% CI, 0.11-0.65], P?=?.003, respectively). Brain-derived neurotrophic factor genetic variants were not associated with AD risk. CONCLUSIONS AND RELEVANCE:Higher serum BDNF levels may protect against future occurrence of dementia and AD. Our findings suggest a role for BDNF in the biology and possibly in the prevention of dementia and AD, especially in select subgroups of women and older and more highly educated persons.

Dataset Information

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study.

Background

Methods

Results

Conclusion

Publications

Physical Activity, Brain Volume, and Dementia Risk: The Framingham Study.

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