Research suggests gut microbiome plays a role in lifestyle impact on dementia risk

The gut microbiome may play a role in how diet and exercise affect brain health and dementia risk, according to a recent Baycrest study. This knowledge can help scientists and clinicians optimize strategies to prevent dementia.

Lifestyle intervention to reduce risk of dementia often involve diet and exercise, which are known to affect the gut microbiome— a community of bacteria and other microorganisms that live in our intestines.

“We know that imbalances in the microbiome are associated with impaired cognition,” says lead study author Noah Koblinsky, an exercise physiologist and project coordinator at Baycrest’s Rotman Research Institute (RRI).

“However, we know little about the role of the microbiome when we use it lifestyle interventionssuch as diet and exercise, for support the brain health. Can we tailor lifestyle interventions to specifically target the gut microbiome, and will this help optimize their impact on cognition? In this review study, we sought to address this knowledge gap.”

To that end, Koblinski and his team analyzed all existing studies of diet and exercise that looked at both the microbiome and brain health. The study was published in Journals of Gerontology: Series A.

They found that the gut microbiome does play a role in how diet and exercise affect brain health, although more research is needed to fully understand how.

Diet studies have shown a large effect of diet on the microbiome, with foods associated with the Mediterranean diet (such as fiber and healthy fats) appearing to have the greatest benefits for a healthy gut and brain microbiome. One study of 1,200 older adults looked at the effects of diet on both cognition and the microbiome.

Half of the participants were asked to follow a Mediterranean diet for 12 months, while the other half were not. Those who followed the Mediterranean diet showed significant improvements in cognition. Additionally, those who followed a more mindful diet had healthier microbiomes associated with better brain health.

In another study, researchers used antibiotics to “kill” the gut microbiome in a sample of rats. They then transplanted these rats with microbiomes (feces) from rats that were fed either an unhealthy diet or a healthy diet. Rats that received transplants from the junk food group showed poorer memory as well as inflammation in the gut and brain.

These findings support the idea that the microbiome plays a role in how diet affects brain health.

The researchers found fewer studies focusing on exercise. However, those who have hypothesized that starting exercise, particularly aerobic exercise, can simultaneously lead to changes in the gut microbiome and brain health.

This area of ​​research is still in its infancy, and most of the studies reviewed by the researchers looked at rodents and individual dietary components (such as fiber) rather than complete dietary patterns (such as the Mediterranean diet). Overall, the researchers found a clear need for more studies on wholesome diet and exercise that address both the microbiome and brain health, particularly in older adults at risk of dementia.

Researchers are now running a diet and are conducting a randomized controlled trial and seeking funding to analyze microbiome changes.

“Better understanding how changes in the gut microbiome influence the relationship between lifestyle and brain healthwe can enhance existing lifestyle interventions and create new strategies to reduce the risk of dementia by helping elderly people are aging fearlessly everywhere,” says Dr. Nicole Anderson, RRI senior research fellow, associate research director of Baycrest’s Kimmel Center for Family Brain Health and Well-being, and senior author of the study.