If you want to keep your brain healthy as you age, scientists will be the first to tell you: It might be time to start getting serious about exercise. Studies have shown that physical exercise is one of eight established ways to reduce dementia risk.

Scott Forbes, an associate professor at Brandon University who studies exercise and sports science, says that a growing number of studies show the positive effects of exercise on brain health. Luckily, you don’t need to hit the gym for an hour daily to see an impact.  

“We found benefits when individuals exercised at least 3 times a week,” Forbes said. 

Adding small bursts of high-intensity cardio—researchers call them “exercise snacks”—three to four times throughout the day can have this positive impact. 

So, how exactly does exercise protect the brain? Here are four ways. 

1. Exercise increases blood flow to the brain

In mild cognitive impairment and Alzheimer’s, the brain isn’t receiving enough blood flow, starving the brain cells of oxygen and other nutrients. 

Exercise increases blood flow to regions of the brain, like the hippocampus, which is among the first parts of the brain affected by Alzheimer’s. This keeps the cells healthy longer and prevents them from becoming damaged or dying. Since the cells stay healthy, it also prevents the brain’s immune system from overreacting and causing even more damage. 

2. Exercise promotes the growth of new brain cells and connections

Exercise causes the brain to produce a variety of proteins called growth factors (IGF-1, BDNF, and VEGF ) that may help the brain make new cells to replace old or damaged ones. 

These growth factors can also help the existing brain cells grow in the hippocampus and strengthen existing connections, helping protect the brain against memory problems. Researchers are currently studying some of these growth factors to try and replicate the benefits of exercise in pill form.

3. Exercise helps the brain’s immune system stay healthy

Some researchers even hypothesize that problems with the immune system, and not amyloid or tau, are the key drivers of Alzheimer’s disease. Exercise can help tone down pro-inflammatory processes in the brain that might contribute to Alzheimer’s disease. 

4. Exercise can help you stay social

Loneliness is one of the major risk factors for developing dementia. 

Older individuals who exercise report reduced feelings of social isolation, and it helps people feel more resilient and positive about aging. Many people exercise in groups or play team sports, which might explain these findings.