Walking more in your 40s and 50s can lower your risk of Alzheimer’s disease

Walking more in midlife may do more than protect the heart—it may also guard the brain. A recent study suggests that increasing physical activity between the ages of 45 and 65 can help lower the risk of Alzheimer’s disease, while remaining inactive could raise the chances of decline later in life.

This research, published in the journal Alzheimer’s & Dementia, was carried out by scientists from the Barcelona Institute for Global Health and the Barcelonaβeta Brain Research Center. The findings add to a growing body of work showing that exercise is not just about muscle and stamina—it may help prevent the buildup of harmful proteins that damage the brain.

Alzheimer’s is the most common form of dementia, and it affects millions of people worldwide. The condition slowly erodes memory and thinking skills, often leading to a complete loss of independence. While aging is the greatest risk factor, researchers have long searched for ways to delay or prevent the disease.

One promising area is lifestyle. According to the World Health Organization, about 13% of Alzheimer’s cases worldwide may be linked to physical inactivity. In other words, more than one in ten cases could be avoided if people were more active during their lives. That is a striking number, given that Alzheimer’s currently has no cure.

The WHO recommends at least 150 to 300 minutes of moderate activity per week, or 75 to 150 minutes of vigorous exercise. These guidelines are based on decades of data showing how activity improves cardiovascular health, mental well-being, and metabolism. But until recently, less was known about how exercise directly impacts the brain.

The new research focused on 337 middle-aged volunteers who were part of the ALFA+ study, a long-term project tracking families with a history of Alzheimer’s disease. Participants were all residents of Catalonia and were followed over four years. “We conducted a four-year follow-up of middle-aged residents of Catalonia with a family history of Alzheimer's disease,” explains Müge Akıncı, the first author of the paper and a doctoral researcher at the time of the study.

To measure physical activity, the researchers used detailed questionnaires. They also used neuroimaging scans to see how exercise might affect brain structure and function. People were grouped into three categories: adherent (meeting WHO recommendations), non-adherent (doing some but less than the recommended activity), and sedentary (doing none at all). This design allowed the team to explore how changes in physical activity—not just a single snapshot—might be linked to Alzheimer’s-related changes in the brain.

One of the earliest hallmarks of Alzheimer’s disease is the buildup of beta-amyloid, a sticky protein that collects between nerve cells. When these deposits grow, they can disrupt communication between neurons and trigger a cascade of damage.

The researchers found that participants who increased their activity during the study period showed less accumulation of beta-amyloid. The effect appeared to be dose-dependent: the more people increased their activity, the less amyloid they had. This is striking because amyloid buildup is thought to occur decades before memory problems appear. By slowing or reducing this buildup, exercise may protect the brain long before symptoms begin.

Beyond protein buildup, the team also examined structural changes in the brain. One area of interest was cortical thickness, especially in the medial temporal region. This part of the brain is critical for memory and learning, and its thinning is one of the earliest signs of neurodegeneration.

The scans revealed that people who were physically active—whether they met official guidelines or not—had greater cortical thickness than those who were fully sedentary. “Even those who did less physical activity than recommended had greater cortical thickness than sedentary people, suggesting that any amount of exercise, no matter how minimal, has health benefits,” says Akıncı. This reinforces the idea that it is better to move some than not at all. Small lifestyle changes, such as regular walking or cycling, may provide measurable protection for the brain.

The study’s emphasis on middle age is important. Many brain changes linked to Alzheimer’s begin decades before symptoms appear. By the time memory loss is noticeable, it is often too late to reverse the damage. This is why researchers stress prevention rather than treatment. “These findings reinforce the importance of promoting physical activity in middle age as a public health strategy for Alzheimer's prevention,” says lead investigator Eider Arenaza-Urquijo.

Public health experts argue that this prevention window is critical. Encouraging more activity in adults between 45 and 65 may have a stronger impact than focusing only on older populations. It is in midlife that exercise habits may influence whether harmful proteins take hold in the brain.

The message from this research is not that people must suddenly run marathons. Instead, increasing activity in any form—walking, swimming, cycling, or even gardening—can bring benefits. The most important factor is consistency and progress over time.

The scientists observed that benefits were linked more to increasing activity rather than hitting a fixed threshold. This means that even people who start late can still make a difference by gradually moving more. For those who already exercise regularly, the findings suggest that staying active is essential. For those who have been sedentary, small steps can matter. Adding a daily walk, standing more often, or replacing short car trips with cycling may all contribute to better brain health.

With global Alzheimer’s cases expected to rise sharply as populations age, prevention strategies are urgently needed. Exercise is one of the most accessible tools available. Unlike expensive treatments or complex medications, physical activity is low-cost, widely available, and carries benefits for nearly every system in the body.

As Arenaza-Urquijo puts it, “Interventions aimed at promoting increased physical activity could be key to reducing the incidence of the disease in the future.” Encouraging midlife adults to move more may not only improve individual health but also reduce the social and economic burden of Alzheimer’s worldwide.

This study adds to mounting evidence that the brain and body are deeply linked. Cardiovascular health, mental resilience, and metabolic balance all play roles in protecting against neurodegeneration. Exercise, as it turns out, touches all of these systems at once.

While no single lifestyle change can guarantee protection from Alzheimer’s, staying active appears to be one of the strongest defenses available today. For middle-aged adults, every step taken now could mean sharper memory and stronger independence decades later.

Note: The article above provided above by The Brighter Side of News.

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