Overweight, Not Just Obesity, Linked to Brain Changes, Study Finds

Weight gain beyond normal range may cause subtle changes in the brain even before reaching obesity levels, according to new research from South Korea.

A joint research team led by Professor Park Kang-min of Inje University Haeundae Paik Hospital's neurology department and Professor Kim Jin-seung of Busan Paik Hospital's family medicine department announced on the 19th that they confirmed a tendency for imaging indicators reflecting microstructural damage in brain white matter to increase as body mass index (BMI) rises.

The brain contains a dense network of fine blood vessels. Abnormalities in these vessels can lead to cerebral small vessel disease, which is known to increase the risk of cognitive decline and stroke.

The research team recruited 62 neurologically healthy adults and divided them into three groups according to World Health Organization (WHO) Asia-Pacific criteria: normal weight (BMI 18.5-22.9), overweight (23.0-24.9), and obese (25 and above). They then used diffusion tensor imaging (DTI) from brain magnetic resonance imaging (MRI) to quantitatively analyze subtle damage in brain white matter. The study employed PSMD (Peak Width of Skeletonized Mean Diffusivity), an imaging biomarker that relatively sensitively reflects microstructural changes in brain white matter.

Results showed a significant positive correlation between increasing BMI and rising PSMD values. This trend remained consistent even after adjusting for age.

The researchers noted that PSMD values were significantly higher in the overweight group compared to the normal weight group, not just in the obese category. This suggests that subtle changes in brain white matter may begin at BMI 23 or above in Asian populations. The research team attributed this association to chronic inflammation and metabolic abnormalities. They explained that when inflammatory responses increase alongside weight gain, accompanied by insulin resistance, hypertension, and dyslipidemia, these changes can affect the brain's microvasculature over the long term.

"We have confirmed through imaging that microstructural changes in brain white matter can already appear at the overweight stage," said Professor Park Kang-min. "This research holds important significance in suggesting that weight gain in healthy general adults can be associated with changes in brain microstructure."

Professor Kim Jin-seung emphasized, "These results provide evidence that more proactive weight management is necessary starting from when BMI exceeds 23."

The study was published in the February issue of the international journal Obesity Research & Clinical Practice.