How Much Exercise to Lower Your Dementia Risk

Recent data from Johns Hopkins demonstrate just how important exercise is for your brain

By Austin Perlmutter, MD

Exercise Boosts Your Brain

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Most of us know that movement is good for our bodies—but what if just a few minutes of activity each day could also dramatically decrease our chances of developing dementia?

A new study from researchers at Johns Hopkins Bloomberg School of Public Health from March of 2025 offers a hopeful message: even small amounts of exercise may help prevent dementia, including in older adults who are frail. This is big news! In today’s blog we’re diving into the powerful findings from this study in the context of what is known about how exercise enhances brain function.

Just 35 Minutes a Week Made a Big Difference

For this observational analysis, the team reviewed data from nearly 90,000 adults in the U.K. who wore activity trackers as part of the UK Biobank project. Over an average of four years of follow-up, those who engaged in at least 35 minutes of moderate-to-vigorous activity per week—(roughly five minutes a day—had an astonishing 41% lower risk of developing dementia compared to those who did none. What’s remarkable is that these effects held true even for people considered “frail” or “pre-frail”—those often least able to meet traditional exercise goals.

Here's the full breakdown of the exercise benefits to dementia risk:

• 35–70 minutes/week → 60% lower risk

• 70–140 minutes/week → 63% lower risk

• 140+ minutes/week → 69% lower risk

  
  

These data are significant, because in the US, 150 minutes of exercise a week is recommended by the U.S. Department of Health and Human Services. While that’s a great target, it can feel out of reach for many aging adults. The takeaway here is simple: something is infinitely better than nothing.

Why Movement is Key for an Aging Brain

Physical activity improves blood flow, reduces inflammation, and supports the growth of new brain connections (a process called neuroplasticity). Exercise has also been shown to enhance insulin sensitivity and support cardiovascular health—all key factors for protecting cognitive function. Simply put, moving your body is an incredible vote for better brain health. With this in mind, it’s no wonder that studies continue to link movement to lower risks for Alzheimer’s and other dementias.

In one of the most compelling bits of research published in the Proceedings of the National Academy of Sciences on the role of exercise and brain health, researchers in 2011 showed that exercise was able to increase the size of the hippocampus, the brain’s memory center. This type of data is also buttressed by recent data showing that exercise can help prevent brain shrinkage. Exercise of any kind is a great vote for a better brain, but as we learn more about the myriad ways that it affects neurobiology, here a few considerations:

1. Aerobic conditioning (like jogging, swimming and other repetitive “cardio” exercises may be best for improving brain vascular health

2. Resistance training (like lifting weights) may be best for boosting molecules that support neuroplasticity

3. Doing exercises that involve extra brain involvement (like sports or walking while talking with a friend) may provide an added boost to brain rewiring

4. Getting outside while you exercise may also provide additional brain-boosting support.  

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