WHO updates dementia guidance, says up to 45% of risk linked to modifiable factors

The World Health Organization has issued updated guidance on reducing the risk of cognitive decline and dementia, saying up to 45% of dementia risk is linked to modifiable factors that could potentially be prevented or delayed at the population level.

In the guideline, released Tuesday, WHO recommends a set of practical steps for countries, clinicians and the public: cognitive training and stimulation, engagement in social activities, more physical activity, stopping tobacco use, reducing alcohol consumption and adopting a healthy diet. It also calls for managing cardiometabolic conditions including hypertension, diabetes and high cholesterol, and for offering hearing aids as part of risk-reduction strategies. One of the clearest changes from the agency’s earlier guidance is a new recommendation to reduce exposure to air pollution.

The update lands amid a growing global burden. WHO says more than 57 million people worldwide are living with dementia, with nearly 10 million new cases each year. The agency estimates the condition costs the global economy about $1.3 trillion annually, and says roughly half of that burden falls on unpaid care provided by family and friends.

The guideline also tells clinicians what not to offer for prevention. WHO said vitamins B and E, omega-3 polyunsaturated fatty acids, and multivitamin or mineral supplements should not be recommended to reduce dementia risk in people who do not have a diagnosed deficiency. According to WHO, the evidence does not show a net benefit in those cases and some interventions may carry harms.

The document, “Risk reduction of cognitive decline and dementia: WHO guidelines, second edition,” updates WHO’s earlier guidance from 2019 and 2020. It reflects a broader evidence base that has increasingly pointed to preventable or delayable risk. WHO’s “up to 45%” figure is in line with the 2024 Lancet Commission on dementia prevention, intervention and care, which identified 14 potentially modifiable risk factors and estimated that about 45% of dementia cases could theoretically be prevented or delayed if those risks were addressed. WHO presents that figure as an evidence-based population estimate, not as a guarantee for any individual patient.

That distinction matters because the new guidance is less about headline numbers than about turning research into public-health advice. It is aimed at helping health systems prioritize interventions with evidence behind them, while steering patients away from supplements that have not shown clear benefit.

“We know more today than ever before about what drives dementia risk, and these guidelines translate that knowledge into action,” WHO Director-General Dr. Tedros Adhanom Ghebreyesus said in the agency’s announcement. “Countries now have clear, evidence-based recommendations they can put into practice immediately to protect people's cognitive health.”