Light-intensity exercise improves MRI-measured total brain volume

Analysis from the Framingham Study showed that increasing amounts of light-intensity physical activity was associated with increasing MRI-measured total brain volume (see exercise and brain volume jama2019, or doi: 10.1001/jamanetworkopen.2019.2745)

Details:

-- 2354 participants from the third-generation and offspring groups of the Framingham Heart Study were involved, from 2016-2019.

-- mean age 53, 54% women, 55% college degree/21% some college/23% high school degree, 6.5% current smokers, 31% stage II hypertension, 6% diabetes, 4% cardiovascular disease,

-- median steps/day 7519, moderate-to-vigorous physical activity 20 minutes/day

-- All patients agreed to wear an accelerometer, as well as having repeat brain MRI scans

-- patients were stratified according to whether they met the US Department of Health and Human Services recommend physical activity guidelines of at least 150 minutes of moderate-to-vigorous physical activity (MVPA) per week. 47% of these Framingham participants met these physical activity guidelines

    -- of those meeting the PA guidelines: fewer had hypertension (22% vs 40%), diabetes (2% vs 9%) and cardiovascular disease (2% vs 6%)

Results:

-- each additional hour of light-intensity physical activity (PA) was associated with approximate 1.1 years less brain aging

-- the association with objectively measured physical activity and total cerebral brain volume was particularly impressive in those to age 50-59

-- as compared to those with <5000 steps/d, those achieving >10,000 steps/d had a significant difference on total cerebral brain volume and total white matter volume, the equivalent of about 1.75 years of brain aging

-- among those not meeting the PA guidelines, light-intensity PA and achieving >7500 steps per day were associated with higher total brain volume, equivalent approximate 1.4-2.2 years less brain aging.

-- after adjusting for light-intensity PA, there was no apparent advantage to doing more vigorous activity

-- In terms of specific brain regions:

    -- Both steps/d and light intensity PA were associated with smaller lateral ventricles

    -- 10 to 19 minutes per day of MVPA, vs less than 10 minutes per day, was associated with higher total white matter volume

    -- no association with hippocampal volume or gray matter volume

    -- no significant difference in total cerebral brain volume or any of the specific regions was found based on whether individals met PA guidelines

    -- in the fully adjusted analysis, there was a statistically significant increase in hippocampal volume in those walking 7500-10,000 steps per day

Commentary:

-- in their physical activity guidelines the US Department of Health and Human Services recommends at least 150 minutes of moderate-to-vigorous physical activity per week. However, relatively few people achieve these levels: a 2010 study found that 57% of people aged 40-to 49, and 26% of those 60-69 achieved  these goals

-- the usual total cerebral brain volume decreases at 0.2% per year after age 60

--a Spanish intervention trial of a Mediterranean diet vs a low-fat diet found the following advantages of this diet:

    -- higher total brain volume by 13 mL

    -- higher total gray and white matter volumes

    -- the volumes of certain areas of the brain (cingulate cortex, parietal lobe, temporal lobe, hippocampus) were larger

     --cognitive function was better

    -- decreased development of Alzheimer’s disease

    -- overall, the Mediterranean diet was associated with the equivalent effects of 5 years of decreased aging on the brain architecture, especially those with higher fish and lower meat intake. Seehttps://gmodestmedblogs.blogspot.com/2015/11/mediterranean-diet-and-brain-volume.html). For an array of blogs on the clinical benefits of Mediterranean diet, see http://gmodestmedblogs.blogspot.com/search/label/Mediterranean%20diet 

-- for the large array of blogs on the positive effects of physical activity, both physical as well as psychological, see https://gmodestmedblogs.blogspot.com/search/label/physical%20activity . Even short-term exercise interventions may prevent hippocampal atrophy in older adults and to improve brain connectivity

-- recent US health surveys have suggested that doing only 5 to 10 minutes of light-to-moderate leisure time physical activity a day had significant mortality benefits (seehttps://gmodestmedblogs.blogspot.com/2019/03/5-10-min-of-exercise-may-improve-health.html )

-- as with all such epidemiological studies, the conclusions are limited to suggesting an association and not causality.  since people were not randomized to different lifestyles in the Framingham Study, there is the possibility that there were unmeasured confounders (did those doing more exercise have other unmeasured healthier behavior patterns??). and, this study only looked at brain volume, which may not correlate directly with brain function.  it is impressive that the Mediterranean diet study did find this correlation, but did exercise lead to the same areas of the brain having more volume? and, even within those areas, was there an effect on the quality of the neural connections? and, it is a little un-nerving (so to speak) that there was no additional benefit from doing more than light PA; not sure why there should be such a low threshold effect.

So, to me the real take-home messages of the study are:

-- exercise, as well as diet as noted above, can lead to larger brain volumes, decreasing the progression of brain atrophy from aging by several years. and this is likely to be clinically significant

-- light-intensity exercise seems to confer a major benefit. This level of exercise is significantly less than the guideline-recommended 150 of minutes of moderate-to-vigorous PA per week.

-- In fact, the study suggested that at least in terms of brain volume, increasing from light-intensity to moderate-to-vigorous intensity exercise did not significantly improve brain volume measurements

-- this lower level of exercise is more broadly achievable by larger percentages of the population. Therefore, incremental motivational interviewing may well be able to engage more patients into achieving this level of exercise

-- and, though not documented, it seems likely that the combination of light-intensity exercise with a healthier Mediterranean-type diet may be a significantly important and achievable goal, with a multitude of potential benefits

geoff

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