Up to 45% of dementia cases worldwide can be attributed to modifiable risk factors, the World Health Organization has concluded in its first update to prevention guidelines since 2019. The assessment, drawn from a review of evidence accumulated over five years, places new emphasis on controlling hypertension, diabetes, hearing loss and exposure to air pollution, alongside established targets such as smoking, alcohol use and physical inactivity. With more than 57 million people living with dementia and annual global economic costs estimated at $1.3 trillion, the finding reframes the condition not as an inevitable consequence of ageing but as a process that health systems can actively slow.

A growing body of research now illuminates the biological pathways through which everyday habits reach the brain. Scientists at the National Autonomous University of Mexico (UNAM) have presented data suggesting that periodontitis—a severe gum infection affecting an estimated one billion people globally—may contribute to neuroinflammation when oral bacteria and their toxins enter the bloodstream. In parallel, a study from the University of Campinas (Unicamp) in Brazil, conducted in mice and published in Life Sciences, shows that eight weeks of resistance training reprograms the liver epigenetically, reducing fat accumulation and inflammation while restoring insulin sensitivity. The work demonstrates how muscle contraction alters DNA methylation of the MTCH2 gene, effectively switching off a cellular emergency mode that, when chronically activated by obesity, drives metabolic and cognitive damage.

Viewed from Latin America, where public-health data reveal that over 50% of Mexican adults have periodontal disease and four in ten adolescents carry excess weight, the implications are immediate. A separate investigation by the Metropolitan Autonomous University (UAM) in Mexico City found that adolescent obesity directly impairs cognitive performance, with hypercaloric diets triggering central neuroinflammation during a critical window of brain development. Meanwhile, researchers at Harvard University have quantified the protective effect of specific foods: regular consumption of berries, they report, can delay memory loss by up to 2.5 years, while fatty fish and leafy greens supply the omega-3 fatty acids and B vitamins that lower beta-amyloid levels and support neuronal structure.

The convergence of these findings challenges a healthcare model that treats oral health, metabolic disease and cognitive decline in separate silos. The WHO guideline explicitly advises against routine supplementation with B vitamins, vitamin E or omega-3s in the absence of deficiency, steering resources instead toward behavioural and environmental interventions. The next practical milestone will be the translation of these updated recommendations into national prevention programmes, particularly in middle-income countries where dental care access is limited and ultra-processed food environments are expanding rapidly.