How exercise keeps our brains healthy as we age

Every night while you sleep, your brain does something remarkable: it cleans itself. A network called the glymphatic system flushes out the waste and junk that builds up during the day, keeping your mind sharp. But here's the catch — this cleanup system becomes weaker as we grow older, and that's one reason memory and thinking can get harder with age.

Now, a team at Victoria University in Melbourne has found something that might help: exercise.

Dr. James Broatch led a review of existing research — both in animals and humans — looking at how physical activity affects this brain-cleaning system. The findings, published in the journal Trends in Neurosciences, showed that exercise doesn't just strengthen muscles and hearts. It also improves the processes that help the glymphatic system work properly.

Specifically, the research found that people who exercise regularly tend to have lower blood pressure and less stiffness in their blood vessels. Their brains show less inflammation, and they sleep more deeply. All of these changes appear to support the brain's ability to clear out waste.

"If we don't have opportunities for the brain to essentially clean out the junk from the day, we know that buildup is damaging, especially as we age," Dr. Broatch said. "Sleep is more crucial than ever to play this role, but the irony is, good-quality sleep can often be harder to get as we get older. This study asked, what if exercise could support that process?"

The timing matters. More than 10 million people worldwide are diagnosed with dementia each year, and there is still no cure. Understanding how lifestyle choices like exercise might slow that decline could make a real difference for aging populations everywhere.

Dr. Broatch acknowledges there's more to learn. Researchers still don't know exactly how much or what kind of exercise works best, or whether it helps once someone already shows signs of cognitive decline. He is continuing his research to find those answers.

But for now, he says the message is clear: moving your body — especially in ways that get your heart pumping — is one of the best things you can do for your brain at any age.

"The earlier we can develop these good habits, the better as we age," he said.