The Harvard study

Walking 5,000 steps a day can slow down Alzheimer's

Research in Nature Medicine reveals that even modest physical activity reduces tau protein accumulation and cognitive decline in the elderly at risk

by Francesca Cerati

4 November 2025

2' min read

Translated by AI

Versione italiana

Key points

The study
Tau yes, amyloid no
Why exercise helps

2' min read

Translated by AI

Versione italiana

Walking could be a simple but powerful weapon against Alzheimer's disease. According to research published in Nature Medicine and conducted by a team from Harvard Medical School and Massachusetts General Hospital in Boston, even modest physical activity - around 5,000 steps per day - is associated with a slowdown in cognitive decline and a lower accumulation of tau protein in the brain, a major marker of the disease.

The Studio

The research, which lasted up to 14 years, involved 296 people between the ages of 50 and 90, all of whom had amyloid and tau deposits in their brains but no symptoms of dementia at the outset. The participants wore pedometers to monitor daily activity and regularly underwent PET brain scans and annual cognitive tests.

The results showed that those who walked between 3,000 and 5,000 steps per day experienced a slowdown in cognitive decline of about three years, while those who walked between 5,000 and 7,500 benefited from an average delay of seven years. Beyond this threshold, the benefits seem to reach a plateau.

Tau yes, amyloid no

A key finding was that physical activity was not associated with a reduction in beta-amyloid levels, but with a slower accumulation of tau protein, which is closely linked to memory loss and neuronal death. "For a given amount of amyloid, more steps were linked to lower tau accumulation and slower cognitive decline," explained Wai-Ying Wendy Yau, of Harvard Medical School in Boston and lead author of the study.

According to the researchers, even moderate levels of activity - equivalent to 30-60 minutes of daily walking - could offer tangible benefits, especially in the sedentary elderly. 'This offers a realistic and achievable goal for many people,' Yau points out.

'The study shows that taking more than 5,000 steps a day is associated with a slowing of cognitive decline and Alzheimer's brain pathology, even in those already showing early signs of the disease,' commented Tara Spires-Jones, of the UK's Dementia Research Institute.

Experts stress, however, that this is an observational study and does not prove a cause-and-effect link. 'We can't say that walking prevents dementia, but being active is definitely good for the brain and heart,' commented Richard Oakley, of the British Alzheimer's Society.

Similarly, Charles Marshall, a neurologist at Queen Mary University of London, warns that 'other variables, such as general health status, could influence the results'. However, he adds, 'there is strong evidence that moderate physical activity slows the progression of the early stages of Alzheimer's'.

Why exercise helps

The precise causes of the benefit are not yet clear, but regular physical activity improves blood flow, reduces inflammation and stimulates hormones and growth factors that protect neurons. 'That's the million-dollar question we want to answer in future studies,' says Yau.

According to Julia Dudley, head of research at Alzheimer's Research UK, 'up to 45% of dementia cases could be prevented by addressing modifiable risk factors such as physical inactivity'.

Although walking is not a cure, data suggest that small changes in lifestyle - more exercise, balanced diet, no smoking, little alcohol - can really make a difference in brain health.

"You don't need a marathon, you just need to take the first step," Yau concludes.