Daily Walking May Slow Tau Buildup Linked to Alzheimer’s Decline

For older adults with early signs of Alzheimer’s in the brain, modest daily walking may be linked to slower buildup of tau proteins and less cognitive decline. The finding shifts attention from amyloid plaques, which many Alzheimer’s treatments target: activity didn’t reduce those plaques in the study, but it was associated with changes in tau, a protein more closely tied to later disease progression.

Modest activity, measurable differences

Researchers followed nearly 300 older adults with early Alzheimer’s brain changes for nine to 11 years, measuring activity with pedometers. Among participants who already had amyloid plaques, those who were more active accumulated tau more slowly in certain brain regions. Their signs of dementia were reduced by almost half compared with less active participants.

The association appeared at around 3,000 steps a day, roughly a half-hour walk at a moderate pace. The strongest range was 5,000 to 7,500 daily steps; beyond that, the observed benefit leveled off. That makes the findings more practical for sedentary older adults than the familiar 10,000-step goal, though the study doesn’t establish a guaranteed minimum or prove that walking caused the difference.

The study’s limits matter. Its participants were mostly white, well educated and based in the US, and the group was relatively small. Researchers also couldn’t fully account for other health and lifestyle factors that tend to accompany physical activity.

Activity and dementia risk

Other studies point in a similar direction. A UK study that followed 1,139 people over age 50 for eight to 10 years found that moderate to vigorous activity was associated with a 34% to 50% lower dementia risk. For participants who developed dementia, staying active was linked to slower memory decline, particularly among older women.

A larger UK study, published in 2022, used wrist accelerometers to track 78,430 people over seven years. It found that dementia risk was 25% lower among those taking about 3,800 steps a day, rising to 50% at 9,800 steps.

Those figures don’t isolate exercise from the rest of a person’s health. More active people in the larger study also tended to have lower cholesterol, better sleep and blood pressure, and a lower risk of diabetes. Those cardiovascular factors are themselves associated with dementia risk.

Healthy behaviors often cluster: people who exercise may also eat well, avoid smoking and have fewer financial stresses. Researchers tried to account for these differences, but it remains difficult to determine how much of the association comes from physical activity alone.

Possible pathways and a feedback loop

There are plausible ways exercise could support brain health directly. It can improve cardiovascular function and blood flow, and it may increase chemicals that help brain cells form connections. One example is irisin, a hormone released by muscles that may affect several processes linked to Alzheimer’s, including inflammation. BDNF is another exercise-associated substance with potential effects on brain function.

The relationship may also run in the opposite direction. Early symptoms can make people less active before dementia is diagnosed. Hearing problems, which are associated with dementia risk, can create barriers to activity. When declining confidence or social engagement leads someone to move less, reduced activity may in turn contribute to faster memory decline. That cycle makes it harder to separate cause from consequence.

Small intervention studies offer a closer look at activity among people who already have Alzheimer’s. In one trial, 15 people with mild to moderate disease took part in Nordic walking, which uses poles to engage the upper body as well as the legs. After 24 weeks, they maintained brain function, with some measures improving. Another 15 participants receiving standard care showed decline or no improvement. The small sample means the result is preliminary, but it suggests physical activity may still matter after diagnosis.

Why the setting may matter

Walking outdoors could add benefits beyond movement. Time in nature may support mood and sleep and reduce isolation, while daylight exposure and social contact can contribute further. These effects may complement one another, although the available evidence doesn’t establish which elements matter most.

For many older adults, getting outside can be difficult because of safety concerns, fear of falling or bad weather. Still, the research makes a modest target seem realistic: a regular half-hour walk may be more attainable than a demanding exercise plan, and the observed benefits didn’t require 10,000 steps a day. The next challenge is helping people build that activity into daily life.

Materials provided by The Conversation. Original written by Eef Hogervorst, Professor of Biological Psychology, Loughborough University. Note: Content may be edited for style and length.