How Much Exercise Do You Need to Lower Your Risk of Dementia?

As people age, the risk of developing dementia increases. Dementia is an umbrella term for symptoms of cognitive decline severe enough to interfere with daily life. Alzheimer’s disease is the most common form of dementia, affecting more than 7 million Americans over 65.

While newer treatments, including donanemab and lecanemab, can help slow the progression of Alzheimer’s disease, staying physically active remains a powerful way to reduce the likelihood of developing memory and cognitive problems over time.

Health Matters spoke with Dr. Wu to better understand why physical activity supports brain health, and how much exercise is enough to reduce the risk of dementia and Alzheimer’s disease.

What happens inside the brain when we exercise?

Dr. Wu: When we exercise and move our bodies, it promotes blood flow throughout the body. Good blood flow is important for getting oxygen and nutrients to the brain. It also flushes out toxins in the brain that build up during the day.

We also know that exercise promotes neurogenesis, which is the production of new brain cells, as well as the release of BDNF (brain-derived neurotropic factor). BDNF is a key molecule that supports neuroplasticity: adaptability, learning, and memory. Research has even shown that physical activity can increase the size of the hippocampus, the part of the brain that is responsible for memory processing and storage.

Lastly, exercise helps us sleep better, which is crucial for brain health. When we’re asleep, it’s an important time for our brain to clear toxins, rebuild energy for the next day, and grow and repair cells.

Can physical activity potentially reduce the risk of developing Alzheimer’s disease?

Dr. Wu: Our understanding of Alzheimer's continues to evolve, but we know there are many factors (such as uncontrolled high blood pressure, diabetes, or smoking) that may make us more vulnerable to Alzheimer's and other dementias. There are also many factors that seem to make us less likely to develop dementia (such as education, social engagement, diet, and exercise.)  

What seems to matter most for brain health: the type of exercise, the intensity, or simply being consistent over time?

Dr. Wu: While cardiovascular exercise, such as running, swimming, or biking, was previously considered the most effective in boosting cognitive health, there’s evidence that other types of exercise, such as strength training and balance training, are just as effective in reducing risk of dementia over time.

What matters most is consistency, so I often tell patients that the best exercise is the one you’ll actually do!

Once someone has been exercising consistently for six months, then we can think about adding variety.

How much exercise is enough to make a difference for brain health and memory?

Dr. Wu: Adults are recommended to engage in at least 150 minutes of moderate-intensity physical activity per week; that said, any amount of exercise is beneficial.

For older adults who may not work out consistently, start by trying to avoid a sedentary lifestyle; even just standing more, going on walks, and stretching throughout the day can all add up to make a difference in reducing the risk of developing or progressing with dementia.