Being overweight may lead to accelerated cognitive decline, according to new research from the University of Georgia.
Cognitive decline is a normal process. As people age, it often becomes harder to remember things and think as clearly as when they were younger. In otherwise healthy adults, these changes are gradual and subtle.
The new study found higher body mass index over time led to more rapid declines in cognitive functions, memory and executive functioning than what is typically seen in aging adults. That includes things such as managing emotions, organizing and planning tasks, concentrating and more.
The researchers relied on data from a nationally representative study that followed more than 8,200 people over the age of 50 for 24 years.
If people managed their weight, they could significantly lower their rate of cognitive decline in just two years.
Suhang Song, College of Public Health
The present study found that every unit increase in BMI led to a more rapid decline in brain health.
But it's not all bad news.
"We found that if people managed their weight, they could significantly lower their rate of cognitive decline in just two years," said Suhang Song, lead author of the study and an assistant professor in UGA's College of Public Health. "That makes BMI one of the most easily modifiable risk factors when it comes to aging well."
The researchers found the strongest correlation between BMI and cognitive decline at year eight of the study. The effect was most pronounced in adults over 65.
High BMI negatively impacts brain health
Defined as having a BMI of 30 or higher, obesity negatively impacts brain health. But it's not clear exactly how, according to the researchers.
It's likely that extra weight results in inflammation, reduced blood flow and insulin resistance. That may lead to cognitive impairment, Alzheimer's disease and related dementias.
Two out of every five Americans are considered obese based on their BMI alone, according to the Centers for Disease Control and Prevention.
Some researchers are pushing for an expanded definition of obesity that also accounts for additional factors including waist size and weight-related health conditions. Under that definition, the percentage of Americans with obesity jumps to 75%.
Meanwhile, more than 7 million people are living with dementia in the U.S. And that number is predicted to double by 2050, the researchers said.
"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."
Published in the Journal of Neurology, the study was co-authored by the UGA College of Public Health's Meng Hsuan Sung, Zhuo Chen, Janani Rajbhandari, Grace Bagwell Adams, Mahmud Khan, Ye Shen and Xiao Song. Additional co-authors include Qianhui Xu and Xia Song.
