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In a new study, scientists seeking to better understand how physical activity protects against neurodegenerative diseases like Alzheimer’s found it’s because exercise makes the brain larger.
2 to 3 days of moderate to vigorous physical activity was correlated to a significant increase in total brain matter and in specific regions like the temporal lobe and hippocampus.
To ensure the record is understood absolutely clearly—there’s no doubt that physical activity protects the brain from neurodegenerative diseases, including mild and severe cognitive impairment, Alzheimer’s, Parkinsons, and other forms of dementia.
The Canadian/American research team sought to better understand the mechanisms behind this effect.
Light physical activity, number of steps taken per day, and number of city blocks traversed per day, are all modalities that have been used to measure connections between physical activity and preventing these diseases, showing that even pedestrian, non-athletic, non-sportive activity can be neuroprotective in some cases.
One of the main culprits, in a positive sense, for this effect is brain-derived neurotrophic factor (BDNF). BDNF is released into the brain during periods of exercise where it lowers neuro-inflammation, improves synaptic connection, and performs other functions too numerous to list here.
The
study benefitted from the use of a deep-learning neural network that allowed for multiple MRI scans of the same brain to be analyzed rapidly.
10,000 participants (and their brains) with an average age of 54, but ranging from 18 to 97, who were about half men and half women made up the study cohorts.
Exercise was self-reported—an inevitable flaw when conducting large population studies like this one. Participants were asked how many days of the week they engaged in 10 minutes or more of moderate or vigorous intensity exercise.
While previous studies quantified moderate and vigorous intensity through heartbeats per minute, this and other more modern studies simply define moderate as being engaged in physical activity and still being able to talk, but not being able to sing. Vigorous was defined as being in a state where only a few words could be spoken before pausing to breathe.
10,125 brain MRI scans were examined, and it was determined that a higher number of days of moderate to vigorous physical activity “predicted larger normalized brain volumes in multiple regions, including total gray matter volume, total white matter volume, hippocampus, frontal cortex, parietal lobes, and occipital lobe,” the authors wrote.
This was particularly true for the occipital lobe, parietal lobe, hippocampus, posterior cingulate, and temporal lobe, which all had correlative significance (also known as the p-value) of 6 or higher. A result of 6 or higher is typically when scientists begin to take notice of correlations—trained as they are to take them always with a grain of salt.
Brain matter and size are all predictors of better cognitive and neurological health as we age, while neurodegenerative diseases are often found in less-dense brains.
“The study included adults aged 18-97, showing it’s never too early or late to start,” wrote Chris Kresser, founder of the California Center for Functional Medicine, who was not involved in the study.
“While 75% of participants reported doing some regular physical activity, many didn’t meet standard exercise guidelines—yet still showed brain benefits. This adds to growing evidence that even modest physical activity can protect brain health.”
