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A study published in Nature Medicine looks at physical activity and preclinical Alzheimer’s disease.
Prof Andrew Doig, Professor in Biochemistry, University of Manchester, said:
“Yau et al. studied nearly 300 people, aged 50-90, to test whether physical activity, measured in the form of number of steps per day, is linked to Alzheimer’s Disease (AD), the most common form of dementia.
“We have known for a long time that AD is likely to be caused by the deposition of the proteins amyloid-b (Ab) and tau in the brain, but which is the most important and how they are linked remains unclear. The patients were divided into two groups – one had significant Ab deposition at the start of the study, known to be a significant risk factor for the disease, and the other had low Ab levels. They were monitored for over 9 years on average, which added a lot of strength to the study, as the progression of AD is so slow. Patients had their daily step count measured, and had regular cognitive tests, as well as brain imaging to track their Ab and tau levels.
“Their results were clear and convincing. In the high AD group, disease progression was a lot slower if the patients were physically active. Cognitive benefits could be seen for only 3000-5000 steps per day; more steps were more effective, with the benefits levelling off at about 7500 steps per day.
“Careful statistical analyses revealed that it was the levels of tau deposits in the brain that were predominantly linked to disease progression, rather than Ab.
“While the exact mechanism that links exercise to dementia is uncertain, this work convincingly shows that a straightforward way to slow down the progression of AD is to take exercise. This does not have to be onerous. Even something as simple as taking a short walk every day shows real benefits. What’s good for the heart is also good for the head.”
Dr Julia Dudley, Head of Research at Alzheimer’s Research UK, said:
“Research has shown that up to 45% of dementia cases could be prevented by addressing factors that may increase our risk, including physical inactivity. This study adds to existing knowledge that being active is good for brain health and could help slow memory and thinking decline as we age.
“Encouragingly, the findings suggest that even a modest amount of walking each day, around 5,000 steps, is linked to a slower build-up of tau protein in the brain, one of the key drivers of Alzheimer’s disease. This gives us a clearer picture of how everyday activity may support brain health and impact the underlying causes of Alzheimer’s.
“It’s important to remember that this study only shows that there is a link, rather than directly proving that walking slows changes in Alzheimer’s. It also did not capture the effect of other types of exercise or changes in walking patterns over time. This research involved a small group of people who did not have dementia symptoms but had proteins linked to Alzheimer’s in their brains.
“More research, including clinical trials, is needed to see the direct impact of physical activity on preventing and slowing the progression of dementia and on underlying disease causes. But studies like this reinforce that simple changes to our lifestyle could help keep our brains healthier for longer.”
Dr Richard Oakley, Associate Director of Research and Innovation at Alzheimer’s Society, said:
“One in three people born today will develop dementia in their lifetime, but evidence shows we can reduce our risk of getting the condition.
“This study reinforces the message that what’s good for our heart is also good for our head and that being more active can support brain health.
“However, because this is an observational study, we can’t draw a conclusive link between step count and changes to cognition or potential signs of Alzheimer’s disease in the brain. The study followed people with raised levels of amyloid in their brain – a potential early sign of Alzheimer’s – but who were not cognitively impaired. We don’t know if these people went on to develop dementia or whether walking 5,000-7,000 steps a day might reduce the risk of or prevent the condition.
“We would encourage everyone to exercise regularly if they can. Other steps like eating a healthy balanced diet, not smoking, drinking less alcohol and keeping on top of health conditions, such as diabetes or high blood pressure, can also help reduce our risk of getting dementia.
“Anyone concerned about their risk of dementia can find out more at alzheimers.org.uk.”
Prof Masud Husain, Professor of Neurology, University of Oxford, said:
“The strength of this research is the combination of serial highly specialized scans that measure amyloid and tau deposition in the brain, with cognitive assessments and baseline step count. This is unique.”
“While the results are really encouraging, the number of participants is relatively small (less than 300 people) and the study is not a clinical trial designed to study the impact of exercise. These limitations mean that we have to be cautious in our interpretation of the findings.”
Prof Tara Spires-Jones, Director of the Centre for Discovery Brain Sciences at the University of Edinburgh, Group Leader in the UK Dementia Research Institute, and Past President of the British Neuroscience Association said:
“This study by Yau and colleagues at Harvard Medical School shows taking over 5000 steps a day is associated with slowing of cognitive decline and slowing the buildup of Alzheimer’s disease pathology in the brain. The study is well-conducted, and the data are an important advance as they indicate that people who already have early Alzheimer’s disease pathology in their brains may still benefit from taking even modest amounts of activity (over 3000 steps per day). However, this type of study cannot fully rule out reverse causation. Instead of increased steps being protective, people could have reduced physical activity because they already had damage to brain circuits caused by early Alzheimer’s disease pathology. While the authors accounted for some aspects of reverse causation by measuring pathology over time, to firmly conclude that increased physical activity slows Alzheimer’s disease progression, randomised trials are needed. So far, trials indicate that exercise is good for cardiovascular function and has small benefits for cognitive function. On balance the data in the field indicate that keeping physically active is good for your brain but is not a guarantee of preventing or slowing dementia.”
Prof Charles Marshall, Professor of Clinical Neurology, Queen Mary University of London, said:
“This research provides strong evidence that moderate levels of physical activity are associated with slower progression of the earliest stages of Alzheimer’s disease, and that this is linked to slower accumulation of tau protein, which is an important cause of brain cell loss.
“With this type of observational study, it is always hard to be sure whether the physical activity is actually the thing causing the observed difference. The authors do a good job of trying to disentangle this, but we cannot be certain whether the people doing more exercise are healthier in other ways, nor whether the development of Alzheimer’s disease changes are influencing activity levels (reverse causality). We also cannot be sure that it is physical activity during this period in later life that makes the difference, or whether those who are more active now have been more active for decades and that the benefits accrue in the much longer term.
“Nevertheless, this study does add to a wealth of evidence suggesting that regular physical activity is good for your brain as well as all of the other physical benefits it brings, and I would have no hesitation in encouraging people to aim for a daily step goal.”
‘Physical activity as a modifiable risk factor in preclinical Alzheimer’s disease’ by Wai-Ying Wendy Yau et al. was published in Nature Medicine at 16:00 UK time on Monday 3rd November.
DOI: https://doi.org/10.1038/s41591-025-03955-6
Declared interests
Prof Andrew Doig: Andrew Doig is a Professor of Biochemistry at the University of Manchester. He is a founder and director of PharmaKure, a spin-out company working on diagnostics and drugs for Alzheimer’s Disease and other neurodegenerative conditions.
Prof Masud Husain: I don’t have any conflicts of interest.
Prof Tara Spires-Jones: I have no conflicts with this study but have received payments for consulting, scientific talks, or collaborative research over the past 10 years from AbbVie, Sanofi, Merck, Scottish Brain Sciences, Jay Therapeutics, Cognition Therapeutics, Ono, and Eisai, and direct a company Spires-Jones Neuroscience, Ltd to act as a consultant. I am also Charity trustee for the British Neuroscience Association and the Guarantors of Brain and serve as scientific advisor to several charities and non-profit institutions.
Prof Charles Marshall: I have no relevant conflicts to declare.
For all other experts, no reply to our request for DOIs was received.