Scientists have pointed out the benefits of walking in Alzheimer's disease

Physical activity may be associated with changes in the brain, even in people who have already shown early signs of Alzheimer's disease. At the same time, it is not necessary to strive for the popular goal of 10,000 steps daily. The study showed that older people who walked more had slower accumulation of certain proteins associated with the disease, and cognitive decline was less pronounced. About how many steps per day improve performance and why the results cannot yet be considered evidence of the preventive effect of walking, see the Izvestia article.

Fewer steps is also a benefit.

The work was published in The Conversation magazine. The researchers followed almost 300 elderly people who already had early signs of Alzheimer's disease in their brains. The participants were examined for 9-11 years, and their physical activity was monitored using pedometers.

The scientists found that higher physical activity was associated with less accumulation of tau proteins in certain areas of the brain and an almost halved decrease in cognitive and daily functions. At the same time, walking did not reduce the number of amyloid plaques — accumulations of protein, which are targeted by many modern methods of treating Alzheimer's disease.

The connection was apparent even with a relatively small number of steps. Approximately 3,000 steps per day, which corresponds to about half an hour of walking at a moderate pace, have already been associated with more favorable indicators. The most pronounced relationship was observed at 5-7.5 thousand steps per day, after which the additional effect ceased to increase noticeably.

Two proteins are different changes

Alzheimer's disease is associated with changes in several proteins in the brain. One of them is beta—amyloid, which can form clusters called amyloid plaques. The other is the tau protein. In case of a disease, it may not fold properly and accumulate in the nervous tissue.

In the described study, physical activity was not associated with a decrease in the number of amyloid plaques. However, among participants who already had them, higher activity was associated with less accumulation of misfolded tau proteins in certain areas of the brain.

These differences are important because the accumulation of tau proteins is more closely associated with a decrease in cognitive and daily functions. In the more active participants, this decrease was almost half as pronounced. Thus, the discovered relationship was not related to the elimination of amyloid plaques, but to changes in tau protein and a slower deterioration in function.

Why 10 thousand steps are not required

According to the study, the most pronounced association with more favorable indicators was observed at 5-7.5 thousand steps per day. After reaching this range, the effect reached a plateau: an increase in the number of steps was not necessarily accompanied by additional benefits.

The authors of the material note that such a goal may be more realistic for older people who lead a sedentary lifestyle than the common recommendation to take 10,000 steps daily. However, the results do not mean that there is a single standard of physical activity suitable for each person.

The article also provides the results of other studies. One study published in the journal Aging & Mental Health involved 1,139 people over the age of 50. Moderate to intense physical activity was associated with a 34-50% reduction in dementia risk during 8-10 years of follow-up. Among participants who developed dementia, physical activity was also associated with less pronounced memory impairment, especially in older women.

In another study published in the journal JAMA Network, 78,430 people were followed for seven years. According to its results, 3.8 thousand steps per day were associated with a 25% reduction in the risk of dementia, and with 9.8 thousand steps, the indicator reached 50%. These results relate to separate studies and should not be confused with the conclusions of the work on the accumulation of tau proteins.

What is Alzheimer's disease?

Alzheimer's disease is a progressive brain disease in which memory and other cognitive functions deteriorate. As the disease progresses, it becomes more difficult for a person to cope with everyday tasks. The changes are associated, in particular, with the accumulation of amyloid plaques and tau proteins in the brain.

The study, highlighted in The Conversation, involved people with early signs of the disease in the brain, so the work allowed us to study the relationship between physical activity and changes even before all participants necessarily developed severe symptoms of dementia.

However, the results do not prove that walking alone prevents Alzheimer's disease. The study had limitations: the sample was relatively small and consisted mainly of well-educated Americans. In addition, the authors of the material note that the study did not take into account other health and lifestyle factors that could affect the results.

Why doesn't the link prove the reason?

People who walked more also had better cardiovascular health outcomes: lower cholesterol levels, better sleep quality and blood pressure, and a lower risk of diabetes. These factors are also associated with the risk of dementia, so it is not easy to separate the effects of physical activity from other lifestyle features.

Healthy habits are often combined. People who engage in regular physical activity can also eat better, smoke less often, and monitor their heart health more closely. Researchers have tried to account for such differences, but the close relationship between habits makes it difficult to determine the independent effect of walking.

The work also examines possible mechanisms of the effect of physical activity on the brain: improving cardiovascular health and blood supply, as well as the production of substances that support connections between nerve cells. Among them are mentioned irisin, a hormone that is produced by muscles, and the brain's neurotrophic factor BDNF. However, these mechanisms do not mean that they explain the results of the study in question.

Feedback is also possible: early symptoms of Alzheimer's disease may make it difficult for a person to remain physically active. For example, hearing problems can limit participation in daily life and reduce the desire to leave the house. As a result, a decrease in activity may be accompanied by a further deterioration in cognitive functions.

Thus, the study links walking with slower accumulation of tau proteins and less pronounced cognitive decline in older people with early signs of Alzheimer's disease. But it does not establish that a certain number of steps is guaranteed to protect the brain: further research is needed to assess the independent effect of physical activity.