Up to 45 per cent of dementia cases could be prevented or delayed, according to sweeping new guidelines from the World Health Organisation — the first update to its dementia prevention recommendations in seven years. The guidelines identify a broad range of modifiable risk factors, from tobacco and alcohol use to air pollution and social isolation, and make clear that tackling the global dementia burden will require urgent government action alongside individual lifestyle changes.

More than 57 million people currently live with dementia worldwide, and the disease's prevalence is rising. The updated guidelines, developed by an expert panel drawing on the latest available evidence, offer countries what the WHO's director-general described as "clear, evidence-based recommendations they can put into practice immediately to protect people's cognitive health."

What the new dementia prevention guidelines recommend

The guidelines place particular emphasis on lifestyle factors that individuals and governments can act on now. A healthy diet — rich in leafy greens, berries, nuts and olive oil and low in processed and ultra-processed foods — is among the most strongly supported strategies, alongside regular physical activity and daily cognitive stimulation.

Crucially, cognitive stimulation means genuinely challenging the brain, not simply repeating familiar activities. Examples cited include learning a new language, taking a course, attending public lectures, reading or playing games.

Other key recommendations include:

  • Interventions to address midlife obesity and overweight
  • Hearing aids for people with hearing loss
  • Social engagement programs to reduce loneliness and isolation
  • Managing high blood pressure and diabetes
  • Reducing tobacco and alcohol use

Air pollution joins the dementia risk list

One of the more striking additions to the updated guidelines is a conditional recommendation to reduce exposure to household and ambient air pollution, including fine particulate matter (PM2.5) from vehicle emissions and wood-burning fires.

Scientia Professor Kaarin Anstey, director of the UNSW Ageing Futures Institute and the only Australian member of the WHO's dementia expert panel, said many people underestimate how widespread air pollution exposure actually is.

"What a lot of people don't realise is that the risk isn't just for those living next door to a polluting factory," she said. "A lot of us are exposed to air pollution living in cities. The smoke produced from burning a fire in your fireplace can have negative health effects."

This concern intersects with broader environmental health issues flagged by researchers — including findings explored in coverage of NSW bushfire season air quality risks — underscoring that outdoor air quality has consequences well beyond respiratory health.

Supplements and hormone therapy: what the evidence does and doesn't support

The guidelines take a firm stance against several popular interventions. The WHO strongly recommends against using vitamin and mineral supplements — including vitamins B and E, omega-3 fatty acids, and multivitamins — to reduce the risk of cognitive decline or dementia.

A potentially contentious recommendation is a conditional recommendation against menopausal hormone therapy (MHT) specifically for reducing cognitive decline or dementia risk in post-menopausal women aged 65 and older. Professor Anstey acknowledged the evidence in this area is complex.

"The evidence base for this is very messy," she said. "We're basing these guidelines on the evidence through a very rigorous process. We look at the whole of the literature, its methodologies, and synthesise it all."

Separately, there was found to be insufficient evidence either for or against MHT for women experiencing premature ovarian insufficiency, early menopause or perimenopause for the specific purpose of reducing dementia risk. The guidelines also found insufficient evidence to support specific interventions targeting depression, sleep disorders, stroke, traumatic brain injury, vision impairment or HIV for dementia prevention purposes.

Prevention requires more than personal choices

The WHO panel was explicit that individual behaviour change alone will not be enough to reduce dementia's global toll. Structural government action — on pollution, urban planning, healthcare access and public education — is essential to translating these guidelines into population-level impact.

For older Australians already thinking carefully about long-term health and financial planning, the findings add another dimension to future wellbeing — including considerations explored in reporting on retirement village costs and what they mean for long-term care.

With nearly 10 million new dementia diagnoses recorded globally each year, the WHO's updated guidance arrives as an urgent call to act — at every level of society.