A growing body of global research is reinforcing the long-established message that exercise benefits the brain — but new evidence suggests that the timing of physical activity may be just as critical as the activity itself. A recent investigation from the United States, published in JAMA Network Open, has found that people who remain active from midlife onwards show a markedly reduced risk of developing dementia.
Critical Life Stages for Protecting Cognitive Health
The U.S. study monitored more than 4,000 participants from the well-known Framingham Heart Study, assessing adults from early adulthood (26–44 years), midlife (45–64 years), and later life (65–88 years). According to the authors, higher activity levels between ages 45 and 64 were associated with a 41% lower risk of dementia, while maintaining activity into older age corresponded to a 45% reduction.
Experts emphasise that these findings expand the conversation beyond the general recommendation that exercise “is good for the brain”. Professor Sanjula Singh, from Harvard Medical School, noted that this research suggests there may be distinct windows during adulthood when physical activity exerts stronger protective effects.
The global burden of dementia is substantial — the World Health Organization estimates that 57 million people currently live with the condition, a figure expected to almost triple by 2050.
Why Midlife and Later Life May Matter Most
Neurologists point out that many vascular risk factors for dementia — such as hypertension, type 2 diabetes, thyroid disorders, and high cholesterol — tend to emerge from midlife onwards. As physical activity supports vascular health, experts argue that exercise during these stages may provide greater neurological protection.
In addition, physical activity is thought to benefit the brain by:
Improving neurovascular function
Reducing inflammation
Supporting structural integrity of brain tissue
Slowing the accumulation of beta-amyloid proteins, a hallmark of Alzheimer’s disease
Even among older adults carrying the APOE ε4 gene — one of the strongest known genetic risk factors for Alzheimer’s — higher activity levels were tied to a 66% lower risk of dementia.
How Much Exercise Is Needed?
One limitation of the U.S. study is that it did not quantify precise exercise thresholds, relying instead on combined estimates of sleep, sedentary time, and light to vigorous activity.
However, broader scientific literature provides clearer guidance. Research published in 2022 showed that walking 3,800 steps per day was linked to a 25% reduction in dementia risk, with additional benefits as step counts increased. Cycling as a form of transport has also been associated with reduced incidence of dementia and Alzheimer’s disease.
The World Health Organization recommends that adults engage in:
150–300 minutes of moderate aerobic exercise per week, or
75–150 minutes of vigorous aerobic activity, plus
Strength-training sessions on at least two days per week
This may include brisk walking, running, cycling or structured workouts. Harvard researchers involved in brain-health scoring tools, such as the Brain Care Score, highlight that even modest increases in movement can contribute to long-term resilience.
Tips for Those Beginning or Returning to Exercise
Health specialists emphasise the importance of gradual progression. Starting suddenly with high-intensity workouts may lead to injuries that hinder consistency. Neuropsychologists recommend:
Shorter, manageable sessions at first
Gradual increases in duration or intensity
Consistent daily habits, such as walking before work
Brief movement breaks during long sedentary periods
Such routines help embed physical activity into everyday life, supporting both brain and general health.
Important Caveats and the Need for Further Research
Researchers acknowledge that physically active individuals might also engage in other healthy behaviours that contribute to cognitive protection. Additionally, self-reported activity levels may be inaccurate, underscoring the need for future studies using objective measures such as wearable trackers.
Despite these limitations, specialists agree that the evidence strongly supports physical activity as one of the most effective lifestyle factors for reducing dementia risk, especially from midlife onwards.
A Practical Message for Public Health Worldwide
While this research was conducted in the United States, its implications carry global relevance as countries confront rising dementia rates. For individuals reviewing their own lifestyles, experts stress that balanced decision-making — ideally guided by healthcare professionals — remains essential.
As the scientific community continues to examine how lifelong movement shapes brain health, one conclusion stands firm: it is never too late to start being active, but midlife may be one of the most influential moments to do so.