A recent 14 year longitudinal study published in Nature Medicine suggests that walking over 5000 steps per day may be an effective strategy for delaying the progression of Alzheimer's disease in older adults with normal cognitive function. This study reveals for the first time through objective data that moderate exercise can significantly reduce the accumulation rate of tau protein in the brain of preclinical patients and slow down cognitive decline. This discovery provides clear and easily achievable exercise goals for the elderly and opens up new directions for early intervention in Alzheimer's disease. Lack of exercise is a known risk factor for Alzheimer's disease, and there is an urgent need for safe and effective ways to delay disease progression. The team led by Mr. Ma from the American Academic Healthcare System analyzed data from 294 elderly individuals (aged 50-90) with intact cognitive function in the Harvard Aging Brain Study, including exercise volume recorded by pedometers, longitudinal amyloid and tau protein PET imaging data, and cognitive assessment for up to 14 years. The team found that a greater amount of exercise is associated with slower cognitive decline related to amyloid plaques, indicating that exercise may have a protective effect. This benefit is related to the slowing down of tau protein accumulation, rather than pathological changes in amyloid protein. At a moderate activity level of 5001-7500 steps per day, tau protein accumulation and cognitive function tend to stabilize. Encouragingly, even mild activity levels (3001-5000 steps per day) are significantly associated with reduced tau protein accumulation and cognitive decline. These findings suggest that increasing physical activity may help delay the pathological changes of tau protein and cognitive decline in preclinical Alzheimer's disease. In addition, with the popularity of digital wearable devices such as smartwatches, the exercise goals proposed in this study are easier to achieve, which can motivate sedentary elderly people to participate in more exercise. (New Society)