Health

Obesity could be linked to mental function: US study

New results from the largest long-term study of brain development and children's health raise provocative questions about obesity and brain function.

Does excess body weight somehow reduce brain regions that regulate planning and impulse control?

Is obesity a result of that brain difference? Or are eating habits, lifestyle, family circumstances and genetics to blame?

Previous studies in children and adults have had conflicting results.

The new research does not settle the matter and outside experts have cautioned that misinterpreting it could unfairly perpetuate weight stigma.

But an editorial published with the study in Jama Pediatrics called it an important addition to mounting evidence of a link between weight, brain structure and mental function.

If follow-up research confirms the findings, it could lead to new ways to prevent obesity that target improved brain function.

"We don't know which direction these relationships go nor do they suggest that people with obesity are not as smart as people at a healthy weight," said Dr Eliana Perrin, a Duke University pediatrics professor who co-wrote the editorial.

The federally-funded study involved 3,190 US children aged nine and 10.

They had height and weight measurements, MRI brain scans and computer-based tests of mental function including memory, language, reasoning and impulse control.

Nearly 1,000 kids - almost one in three - were overweight or obese, similar to national statistics.

Researchers found differences in the heaviest children's brain scans, slightly less volume in the brain region behind the forehead that controls what are known as "executive function" tasks.

They include things like ability to plan, control impulses and handle multiple tasks simultaneously.

The differences compared with normal-weight kids were subtle, said study author Dr Scott Mackey, a neuroscientist at the University of Vermont.

The heaviest kids also had slightly worse scores on computer-based tests of executive function.

But Dr Mackey and lead author Dr Jennifer Laurent, a University of Vermont obesity researcher, said it is unknown whether any of the differences had any meaningful effect on children's academic functioning or behaviour.

It is unclear exactly how they are related to weight and Dr Mackey said it is likely other factors not measured in the study, including physical activity and healthy nutrition, play a far greater role. - AP

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