Longevity Briefs: How Does Exercise Protect Against Dementia?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: It’s becoming quite clear that exercise can protect the brain against neurodegenerative diseases such as Alzheimer’s. Combined evidence from multiple studies suggests that regular exercise during midlife is associated with a roughly 30% reduced risk of dementia later on. That’s a pretty substantial reduction for a group of currently incurable diseases, but scientists don’t have a clear picture of how exercise is protecting the brain. Some general ideas exist, but the effects of exercise are complicated and many remain to be discovered. If we understood the systems and molecules involved with more precision, we might be able to design drugs that could mimic the ways in which exercise protects the brain.

What did the researchers do: In an issue of Brain Plasticity, researchers explore what we currently know about how exercise can affect the brain, what organs are involved, and how the communication between these organs and the brain occurs.

Key takeaway(s) from this research: The article discusses how the liver, fat tissue, the gut microbiome, and especially skeletal muscle tissue seem to be important in the exercise – brain relationship. Muscle tissue ‘talks’ to the brain via signalling molecules called myokines, as well as using enzymes, metabolic products and exosomes (small packages containing various molecules and genetic material). These signals can affect the brain in various beneficial ways, such as improving blood flow, encouraging the growth of new neurons and reducing inflammation.

The authors also raise the possibility that this system could work both ways. While exercise appears to protect the brain, sedentary behaviour could trigger the release of harmful signalling molecules from muscle tissue. This could help to explain some previous research suggesting that certain behaviours like sitting may be actively harmful to our health, rather than simply representing a lack of physical exercise. The authors also discuss the effects that fat tissue, the bacteria in the gut and by extension, our diets, can have on the brain.

In practice, this means we should all exercise more and eat healthier diets if we want to avoid dementia, which most people reading this probably already know. It’s typically difficult to convince someone (or even to convince yourself!) to change their lifestyle as a preventative measure when they feel healthy here and now. It’s sometimes worth reminding ourselves that exercise can have more immediate benefits for our brains – who doesn’t want better memory and cognitive performance?