A growing body of evidence shows that physical activity — even in small amounts — may help protect the brain as we age.

A major 2025 review in The Lancet Healthy Longevity explores how regular movement and high cardiorespiratory fitness (CRF) can help delay cognitive decline and reduce the risk of dementia by up to 40%.

The researchers describe exercise as “one of the most promising measures we have” for preserving brain health in later life.

What Did the Study Find?

The review, led by researchers at the Norwegian University of Science and Technology (NTNU), evaluated data from both human and animal studies. They found strong evidence that physical activity supports key brain functions that typically decline with age:

• 🧠 Improved blood flow to the brain

• 🔬 Lower levels of inflammation

• 🧬 Healthier mitochondria and energy metabolism

• 🔄 Enhanced ability to repair DNA and remove damaged proteins

• 🧪 Increased release of ‘exerkines’ — protective molecules released during exercise

• 🧠 Better neuroplasticity — the brain’s ability to adapt and form new connections

These changes were linked to a lower risk of Alzheimer’s and other forms of dementia, particularly in people with high cardiorespiratory fitness. In fact, a prospective study of over 30,000 people found that maintaining or improving CRF reduced dementia risk by 40% and dementia-related death by 44%.

“Exercise is not only important for the heart, but also for the brain,” said lead author Dr Atefe Tari. “Even small doses of high-intensity activity… can reduce the risk of dementia by up to 40%.”

How Much Exercise Do You Need?

While the NHS recommends 150 minutes of moderate or 75 minutes of vigorous exercise each week, the researchers argue that even less can make a difference — especially if it's more intense.

What counts?

• Brisk walking

• Climbing stairs

• Dancing

• Cycling

• Swimming — a good alternative for people with joint pain or mobility issues

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Anything that raises your heart rate and leaves you slightly out of breath — but still able to speak — may help.

The study also highlights the concept of microtraining, where short, intense bursts of activity are built into everyday routines. Even this can support brain health, especially when sustained over time.

Why Cardiorespiratory Fitness Matters

CRF refers to how efficiently your heart and lungs deliver oxygen to your muscles — and brain. Unlike general activity levels, it can be directly measured (for example, through a VO₂ max test).

High CRF is a stronger predictor of brain health and longevity than activity levels alone. The good news is that it can be improved at any age through consistent aerobic exercise.

A Final Word

There’s still no cure for Alzheimer’s disease — but this review suggests that fitness may be one of the most effective tools we have for protecting the brain as we age.

Even small amounts of the right kind of movement could make a measurable difference. And it’s never too late to begin.

That said, dementia is a complex condition with many contributing factors — including genetics, sleep, diet, social connection, and overall health. Exercise alone can’t prevent it, but it may reduce risk or delay onset, especially when combined with other healthy lifestyle habits.