WHO Identifies Air Pollution as New Dementia Risk Factor and Advises Against Unproven Supplements
The World Health Organization (WHO) has released its first update since 2019 on guidelines for preventing dementia and cognitive decline, highlighting new risk factors and recommendations that could impact millions globally. Currently, over 57 million people worldwide live with dementia, with approximately 10 million new cases diagnosed annually. Although no cure exists, research suggests that about 45% of dementia cases could be delayed or prevented by modifying risk factors.
A major update in the guidelines is the recognition of air pollution, specifically fine particulate matter (PM2.5), as a significant risk factor for dementia. These particles can enter the brain via the respiratory system, causing inflammation and oxidative stress linked to cognitive decline. Sources include vehicle emissions, industrial pollution, wildfires, and some household cooking methods. The WHO estimates that eliminating air pollution exposure could prevent up to 3% of dementia cases worldwide, urging reductions in pollution through cleaner cooking technologies and emission control policies.
The WHO also cautions against the widespread use of dietary supplements such as omega-3, B vitamins, vitamin E, and multivitamins, stating there is insufficient evidence that they prevent dementia or cognitive decline in people without nutritional deficiencies. Unnecessary supplementation may even cause harm due to accumulation or drug interactions. Instead, the organization recommends focusing on a balanced and varied diet.
Another significant update emphasizes hearing loss as a major modifiable risk factor for dementia. The WHO now explicitly recommends hearing assessments and the use of hearing aids when needed, noting that untreated hearing loss can increase cognitive load and social isolation, both linked to higher dementia risk. Preventing hearing loss could potentially reduce dementia cases by up to 7%.
The guidelines reaffirm lifestyle factors that reduce dementia risk, including regular physical activity, healthy diet, smoking cessation, limited alcohol consumption, management of blood pressure, diabetes, and obesity, maintaining social connections, and engaging in cognitive training activities. The WHO concludes that while dementia cannot be entirely prevented, a combination of healthy lifestyle choices, risk factor management, and early intervention can significantly lower the likelihood of developing the disease in the coming years.
