Even modest amounts of daily exercise may slow the progression of Alzheimer's disease in older people at risk of developing the condition, researchers have said. A 14-year-long study found that walking 3,000 to 5,000 steps a day delayed cognitive decline by an average of three years, while 5,000 to 7,000 steps delayed it by seven years.
Scientists analysed data from 296 cognitively unimpaired volunteers aged 50 to 90, including annual cognitive assessments, step counts measured by pedometers, and PET imaging to detect levels of amyloid-beta and tau proteins in the brain. Among those with elevated amyloid at the start, higher step counts were linked to slower cognitive decline and a delayed buildup of tau.
Dr Wai-Ying Yau, first author of the study at Mass General Brigham hospital in Boston, said: 'We're encouraging older people who are at risk of Alzheimer's to consider making small changes to their activity levels, to build sustained habits that protect or benefit their brain and cognitive health.' The findings are published in the journal Nature Medicine.
While the researchers cannot rule out reverse causation, where early brain changes cause people to walk less, the data suggests physical activity is protective. How exercise helps is unclear, but it may improve blood flow, reduce inflammation, and raise levels of certain hormones and growth factors.
Dr Julia Dudley of Alzheimer's Research UK said the findings suggest even modest walking, around 5,000 steps daily, is linked to slower tau buildup, a key driver of Alzheimer's. She added that more research, including clinical trials, is needed to confirm the direct impact of physical activity on preventing dementia.
