The relationship between weight and brain health in children is less clear than that of obesity in adults, which has consistently been linked to reduced brain health. But a new Yale study indicates that higher weight and higher body mass index may also affect the brains of children, linking it to both structural and functional brain impairments.
The findings were presented Nov. 28 at the Radiological Society of North America annual meeting.
Previous studies have examined the connection between weight and brain health in children, but findings have been inconsistent, says Simone Kaltenhauser, a research fellow at Yale School of Medicine and lead author of the study. One reason, she says, is because earlier studies had small numbers of participants.
"Instead, we took a population-based approach," said Kaltenhauser. "We used a very large dataset - the study participants closely approximate the U.S. population's sociodemographics and racial and ethnic diversity, making our findings generalizable to the U.S. population."
The dataset was collected through the Adolescent Brain Cognitive Development (ABCD) Study, which initially included children aged 9 or 10 and is tracking their biological and behavioral development through adolescence and into young adulthood. Nearly 12,000 children from across the United States are participating.
Kaltenhauser and her colleagues assessed brain imaging data collected from 5,169 children aged 9 to 10 years old. They used several types of brain images, yielding information on brain structure, the integrity of white matter - nerve fibers that project from one area of the brain to another - and brain network activity.
"Our main finding was that higher weight and body mass index in typically developing 9- to 10-year-olds are associated with poor brain health," said Kaltenhauser.
Specifically, they found children with higher weight had lower cortical thickness, meaning the outer layer of the brain was thinner than it was in children with lower weight. The integrity of their white matter was also impaired, which could have implications for brain function. Their study further revealed that brain networks involved in reward-based decision-making and cognitive control had reduced connectivity in children with higher weight, which could hinder those cognitive abilities.
"We were surprised these changes were visible so early on," said Kaltenhauser.
The researchers repeated their study with data collected two years later than the initial dataset, from the same children then aged 11 or 12, and found similar results.
"One important takeaway of our study is that not only does obesity have consequences for physical health, it's also linked to brain health," said Sam Payabvash, assistant professor of radiology and biomedical imaging at Yale School of Medicine and senior author of the study.
Other studies have reported that obesity in children is linked to reduced cognitive function and poorer academic performance. The findings of this study could help explain why, said the researchers.
The ABCD Study will collect data from participants for several more years, which will allow researchers to track these changes over time.
"At this point, we can't yet say whether weight influences brain health, or if brain health influences weight, or if it's a little of both," said Kaltenhauser. "But we're confident we will be able to do so in the future."
