The World Health Organization (WHO) has updated its comprehensive guidance on preventing dementia and cognitive decline, introducing new recommendations and reinforcing existing advice. This marks the first major revision to the organization's global public health strategies on the matter since 2019. With over 57 million people worldwide currently living with dementia and nearly 10 million new cases diagnosed annually, the WHO highlights that up to 45% of dementia cases may be preventable or delayed by addressing modifiable health and lifestyle factors.
Air Quality as a Risk Factor
A significant addition to the updated guidance is the emphasis on limiting exposure to air pollution as a strategy to lower the risk of cognitive decline. The report focuses on fine particulate matter, particularly PM2.5 particles, which can enter the bloodstream and potentially reach the brain, triggering inflammation and oxidative stress. The WHO estimates that 99% of the global population is exposed to air pollution levels exceeding recommended limits. While eliminating pollution entirely is not feasible, the agency suggests that reducing exposure through measures like using cleaner cooking fuels and supporting policies to curb emissions can contribute to brain health. The WHO estimates that if air pollution were reduced to zero at a population level, approximately 3% of dementia cases could be prevented.
Supplements and Nutritional Deficiencies
The WHO is also advising individuals without diagnosed nutritional deficiencies against taking certain vitamins and supplements with the expectation of preventing cognitive decline. The agency found insufficient scientific evidence to support the use of supplements such as vitamins B and E, omega-3 polyunsaturated fatty acids, and multivitamins for dementia prevention in those without deficiencies. The report cautions that unnecessary supplement use may carry risks, including nutrient buildup and potential interactions with medications, which could outweigh any unproven benefits.
Addressing Hearing Loss
Untreated hearing loss, which affects about one in five people globally, is now highlighted as one of the most significant modifiable risk factors for dementia. The WHO's revised guidance specifically supports the provision of hearing aids as a measure to help reduce dementia risk. Hearing loss can impact cognitive health by requiring the brain to expend more resources on processing sound, potentially diverting them from other cognitive tasks. It can also contribute to social isolation, a known factor associated with increased dementia risk, and may lead to structural and functional changes in the brain. The WHO estimates that if hearing loss were eliminated at a population level, approximately 7% of dementia cases could be prevented.
Broader Lifestyle Recommendations
Beyond these updated points, the WHO's guidance continues to emphasize other established strategies for cognitive health. These include engaging in cognitive training activities designed to challenge the brain, maintaining social connections through activities like volunteering and spending time with friends and family, regular physical activity, reducing alcohol consumption, quitting smoking, adhering to a healthy diet, and effectively managing chronic conditions such as obesity, diabetes, and high blood pressure, which are linked to cognitive decline.