Significant link between obesity and cognitive decline revealed by Chinese research

A recent study conducted in China has established a significant connection between obesity and the deterioration of brain health, suggesting that individuals with obesity may suffer from a reduction in brain volume akin to the effects seen after 12 years of ageing.

Researchers from Tsinghua University and Capital Medical University Affiliated Beijing Friendship Hospital undertook a comprehensive study spanning 16 years, during which they monitored the body mass index (BMI) and brain health of over 1,000 Chinese adults across various age groups. The findings of this research were derived from neuroimaging data, which highlighted a distinct association between obesity and several markers of cognitive decline. These markers include diminished brain volume, an increase in white matter lesions, and compromised microstructural integrity of the brain.

In the context of China’s health standards, an individual with a BMI exceeding 24 is categorised as having overweight, and obesity is defined at a BMI threshold of 28. The study, published in the journal Health Data Science, notes a critical finding: individuals under the age of 45 with a BMI over 26.2 exhibit brain volume reductions equivalent to the natural age-related decline observed over 12 years.

This research was spotlighted by the state media outlet Life Times, which stressed the study’s recommendation for younger individuals to maintain a BMI below 26.2 to safeguard their cognitive health. The report emphasised the absence of health benefits in being overweight, stating, “There is no healthy overweight person.”

The implications of obesity on brain health are not unique to China. A related study published in 2023 by a Lancet sub-journal, involving 10,000 participants from across Asia, corroborated these findings. This study illustrated that an increase of 0.27 kilograms in visceral fat correlates with 0.7 years of cognitive ageing for the average person.

Concerns are growing regarding the future health landscape of the Asia-Pacific region, as the authors of the study forecast a surge in dementia cases coinciding with increasing obesity levels and an ageing population. The region, which currently sees approximately 4 million new dementia cases annually—accounting for 40% of the global incidence—is also witnessing a rise in obesity rates that surpass the global average by about 7%.

A separate 2023 study, encompassing nearly 15.8 million adults from more than 240 Chinese cities, reported that 34.8% of the subjects had overweight and 14.1% were classified as having obesity. The study further noted a higher propensity for obesity and overweight conditions among men compared to women, with affected individuals more likely to suffer from health issues such as fatty liver disease, prediabetes, and hypertension.

Sun Dejin, a neurologist from Shenzhen Third People’s Hospital, shared insights with Life Times regarding the severe impact of obesity on cognitive functions. According to Sun, obesity leads to notable cognitive impairments, including deteriorations in thinking, learning, and memory capabilities. He warned that if these cognitive declines are not addressed, they could progress to dementia, posing severe risks to overall health and well-being.

This body of research collectively underscores the critical need for managing obesity to mitigate its profound effects on brain health and cognitive function.