More than 57 million people worldwide currently live with dementia, with approximately 10 million new cases diagnosed each year. While there is no cure, global health experts estimate that up to 45% of dementia cases can be prevented or delayed by addressing modifiable health and lifestyle factors.
To translate emerging science into practice, the World Health Organization (WHO) has issued its first major update to its dementia prevention guidelines since 2019.
"Today we know more than ever before about the factors that increase dementia risk, and this guidance translates that knowledge into practical action," WHO Director-General Tedros Adhanom Ghebreyesus stated. "Countries now have clear, evidence-based recommendations they can implement immediately to protect the cognitive health of their populations."
While the update reaffirms foundational advice on exercise and diet, it introduces critical shifts in strategy, highlighting three major areas of focus.
Cutting Air Pollution to Protect the Brain
For the first time, the WHO explicitly identifies air pollution as a key target for dementia prevention. The primary concern is fine particulate matter, specifically ultrafine particles known as PM2.5, which originate from vehicle exhaust, industrial emissions, wildfire smoke, and indoor fuel combustion.
Because PM2.5 particles are small enough to bypass the body’s natural filters and cross into brain tissue, researchers believe they trigger chronic neuroinflammation and oxidative stress—two key drivers of cognitive decline.
With an estimated 99% of the global population exposed to air pollution levels exceeding WHO safety thresholds, environmental exposure represents a major public health challenge. The guidance suggests practical steps such as transitioning to cleaner indoor cooking energy like gas or electricity and supporting policies that cut industrial and vehicular emissions. According to the report, eliminating population-wide air pollution exposure could theoretically prevent roughly 3% of all dementia cases.
Avoiding Supplements Without a Diagnosed Deficiency
While a nutrient-dense diet remains essential for brain health, the WHO cautions against relying on over-the-counter supplements for cognitive protection.
The agency explicitly recommends that individuals without a diagnosed nutritional deficiency avoid taking vitamin B, vitamin E, omega-3 fatty acids, or multivitamin-mineral formulations to prevent cognitive decline. Despite aggressive marketing claims that these products enhance memory and concentration, extensive evidence reviews found no proven benefit in halting or reversing cognitive deterioration among healthy individuals.
The WHO warned that unnecessary supplementation carries potential risks, including metabolic accumulation over time and adverse interactions with prescription medications.
Treating Hearing Loss with Hearing Aids
The guidance also significantly escalates the clinical approach to hearing loss, which affects roughly 1 in 5 people globally. While the 2019 guidelines merely encouraged screening, the updated advice explicitly advocates for the provision of hearing aids to mitigate cognitive decline.
Untreated hearing loss harms brain health through multiple mechanisms. When hearing is impaired, the brain must expend excessive cognitive effort to decode sound, leaving fewer mental resources for processing and memory. Hearing loss also frequently leads to social isolation—an independent risk factor for dementia—and can drive structural changes in the brain over time. The WHO notes that eliminating population-wide hearing loss could theoretically prevent up to 7% of dementia cases.
Beyond these shifts, the updated framework places greater emphasis on structured cognitive training for both healthy adults and those with mild cognitive impairment, alongside active social engagement like volunteering or maintaining close interpersonal relationships. These recommendations complement core health habits, including regular physical exercise, smoking cessation, limiting alcohol intake, and managing underlying chronic conditions such as hypertension, diabetes, and obesity.
