As obesity is on the rise, not just in America but in different countries around the world, researchers are looking for answers on questions that have been looming for so long. Does excess body weight reduce the brain regions that regulate impulse control and planning? Is obesity a result of that brain difference? Our lifestyle, eating habits, genetics, and family circumstances to blame for this social issue?
The new results from the largest long-term study of children's health and brain development raised these provocative questions about obesity and brain function.
The link between obesity and brain function
The previous studies in adults and children have had conflicting results. The new research does not settle the matter, and outside experts cautioned that misinterpreting the study could unfairly perpetuate weight stigma.
An editorial that was published in JAMA Pediatrics called the study an important addition to the building evidence of a link between brain structure, weight, and mental function.
Follow-up research is being done, and once it confirms the findings, it could easily lead to new ways to help prevent obesity that targets improved brain function.
Dr. Eliana Perrin, a Duke University pediatrics professor who co-wrote the editorial, said that they do not know which direction these links go, nor do they suggest that people with obesity are not as smart as those at a healthy weight.
The study was federally-funded, and it involved 3,190 U.S children ages 9 and 10. They had height and weight measurements, MRI brain scans, and computer-based tests of mental function, including language, memory, reasoning, and impulse control. Almost 1,000 kids were obese or overweight, similar to national statistics of 1 in 3 children who have weight issues.
The researchers found differences in the brain scans of the heaviest children. They had slightly less volume in their brain region behind the forehead that controls the "executive function" tasks. They include things like control impulses, the ability to plan, and handle multiple tasks simultaneously.
Study on brain functions
Study author Scott Mackey, a neuroscientist at the University of Vermont, said that the differences compared with normal-weight kids were subtle.
The heaviest kids also had slightly worse scores on computer-based tests of executive function. But Mackey and the lead author of the study, Jennifer Laurent, a University of Vermont obesity researcher, said that it is unknown whether any of the differences had any significant effect on the academic functioning or behavior of children. It is not clear how they are linked to weight, and Mackey said that it is likely other factors that are not measured in the study, including physical activity and healthy nutrition that plays a far greater role.
The research in adults has linked obesity with low-level inflammation throughout the body that can damage the blood vessels, and it may increase the risks for mental decline and heart disease. Some studies have also found less brain volume in obese adults, and researchers theorize that it could be from inflammation.
The new study raises the possibility that inflammatory changes affecting brain structure, brain function, and weight might begin in childhood.
The latest research confirms previous studies in adults and children, but it leaves a lot of questions unanswered, said Marci Gluck, a research psychologist at the National Institute of Diabetes and Digestive and Kidney Diseases, who was not part of the study. Gluck said that executive function deficits and intelligence are not the same.
Natasha Schvey, an obesity researcher from the University of the Health Sciences, called the study impressively. Still, she noted that eating habits and obesity are influenced by many factors, including metabolic and psychological differences. She also said that there are good researches that states that obesity is not much in a person's control as we think it is. People talk about willpower, which is a very small part of the equation. There is a much bigger contributor to our weight, and a lot of it is genetic. That is not to say it is immutable.
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