How walking may affect Alzheimer’s-related brain changes

Researchers used pedometers to track the activity of about 300 older adults who had early signs of Alzheimer’s disease in their brains. Participants were followed for nine to 11 years.

The researchers found that physical activity did not reduce the accumulation of amyloid plaques, the toxic proteins commonly associated with Alzheimer’s disease. Amyloid plaques are a major target of current Alzheimer’s treatments.

However, among people who already had amyloid plaques, physical activity was associated with less accumulation of misfolded tau protein in certain brain regions. Tau appears later in the development of Alzheimer’s disease and is more closely linked to cognitive and functional decline.

More active participants had almost half as many of these signs associated with dementia. The findings suggest that exercise may help slow the progression of Alzheimer’s-related brain changes even when it does not remove amyloid plaques.

How many steps may help protect brain health?

The study found benefits at around 3,000 steps a day—roughly 30 minutes of walking at a moderate pace. The optimal range appeared to be between 5,000 and 7,500 steps per day, after which the benefits plateaued.

More steps did not necessarily provide greater protection. This suggests that sedentary older adults may be able to achieve meaningful benefits with a realistic, moderate increase in daily activity rather than aiming immediately for the frequently cited goal of 10,000 steps.

What other studies say about exercise and dementia risk

The study had several limitations. It included a relatively small group made up mostly of highly educated white people in the United States. It also did not account for all other lifestyle and health factors that could influence dementia risk.

Other biological defense mechanisms may also be involved in the effects of walking. Nevertheless, the findings support previous research suggesting that physical activity may reduce the risk of dementia.

An English study of 1,139 people aged 50 and older found that those who were moderately to highly active had a 34% to 50% lower risk of dementia during eight to 10 years of follow-up. Among people who already had dementia, staying active was associated with slower memory decline, particularly among older women.

A larger UK study published in 2022 tracked 78,430 people for seven years using wrist-worn accelerometers. It found that approximately 3,800 steps a day was associated with a 25% lower risk of dementia, while 9,800 steps was associated with a 50% lower risk.

However, people who walked more also tended to have better cardiovascular health, lower cholesterol, better sleep and blood pressure, and a lower risk of diabetes. Because these heart and stroke risk factors are also linked to dementia, the relationship is complicated.

Why it is difficult to measure the effect of exercise alone

People who exercise regularly often follow other healthy habits. They may eat a healthier diet, avoid smoking, take better care of their heart health, and experience less financial stress.

These factors are closely connected, making it difficult to determine how much protection comes from exercise itself. Researchers have tried to separate these influences, but it remains challenging to identify which habits have the greatest effect.

There is still strong evidence that exercise can support brain health in several ways. Physical activity improves cardiovascular health, increases blood flow, and stimulates chemicals that help brain cells connect.

One such substance is irisin, a hormone produced by muscles that may affect several biological mechanisms involved in Alzheimer’s disease, including inflammation. Irisin and other exercise-related chemicals, such as BDNF, provide a possible biological explanation for how physical activity could benefit the brain beyond its cardiovascular effects.

Could early Alzheimer’s symptoms reduce physical activity?

The relationship may also work in the opposite direction. Early Alzheimer’s symptoms can make it harder for people to remain active. For example, hearing loss is itself a risk factor for dementia and may create barriers that discourage physical activity.

A vicious cycle between inactivity and cognitive decline

As activity decreases, memory decline may accelerate. This can create a vicious cycle in which early symptoms, such as hearing loss, affect self-esteem and reduce engagement in physical activity, potentially contributing to further cognitive decline.

Could brisk or Nordic walking help people with Alzheimer’s?

Brisk walking may be particularly helpful. In a small trial involving 15 people with mild to moderate Alzheimer’s disease, participants used Nordic walking—an enhanced walking technique involving poles that exercises both the legs and upper body.

After 24 weeks, the Nordic walking group maintained some aspects of brain function and showed improvement in certain functions. The 15 people who received standard treatment alone did not experience a reduction or improvement in their symptoms.

Although the trial was small, it suggests that people who have already been diagnosed with Alzheimer’s disease may also benefit from increasing their physical activity, including through brisk walking.

Why walking outdoors may offer additional benefits

Going outside, particularly into natural environments, may provide additional benefits for dementia prevention. Outdoor activity may improve mood and sleep while reducing loneliness, all of which are linked to dementia risk.

Combining physical movement with natural light and social interaction during an outdoor walk could produce several complementary protective effects.

The challenge is helping people overcome barriers to outdoor activity, including safety concerns, fear of falling, and a preference for staying indoors, especially during cold or wet weather.

Still, the evidence suggests that even a modest amount of walking may help. For older adults, a realistic goal of a 30-minute walk may offer meaningful support for brain health without requiring marathon-level training.

Read more about the research and the potential role of physical activity in reducing Alzheimer’s-related cognitive decline.