Researchers at the University of Georgia found that people with higher body mass index experience faster declines in memory, overall cognitive performance, and executive functioning. The study analyzed data from a nationally representative study that tracked more than 8,200 adults over age 50 for 24 years.
Each one-point increase in BMI was associated with a faster rate of cognitive decline. The association was strongest at the eighth year of the study, and adults older than 65 showed the most pronounced effects.
"We found that if people managed their weight, they could significantly lower their rate of cognitive decline in just two years," said Suhang Song, the study's lead author and an assistant professor at the University of Georgia's College of Public Health. "That makes BMI one of the most easily modifiable risk factors when it comes to aging well."
Excess weight may promote inflammation, impair blood circulation, and contribute to insulin resistance. These changes could increase the likelihood of cognitive impairment, Alzheimer's disease, and other forms of dementia, though scientists are still working to understand the exact mechanisms.
The study does not establish that excess weight directly causes cognitive decline. Song noted that weight management could help protect brain health. "There are no cures for dementia," Song said, "which is why it is critical to identify and address any modifiable risk factors we can find to prevent it."
The research was published in the Journal of Neurology. Coauthors from the University of Georgia College of Public Health include Meng Hsuan Sung, Zhuo Chen, Janani Rajbhandari, Grace Bagwell Adams, Mahmud Khan, Ye Shen, and Xiao Song. Qianhui Xu and Xia Song also contributed to the study.