A new study links early childhood obesity to lower IQ scores

Weight watchers
Weight watchers
Image: AP / Patrick Sison
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Childhood obesity comes with a myriad of health risks, ranging from increased risk of heart disease and cancer to asthma and type 2 diabetes. A new study shows how obesity can have an impact on children’s cognitive development as well.

The study, conducted by epidemiologists at Brown University and published in the journal Obesity, found a link between children’s weight in the first two years of life and their cognitive abilities at school age. According to the study authors, ”children on the threshold of obesity or overweight in the first two years of life had lower perceptual reasoning and working memory scores than lean children when tested at ages five and eight.” (The link between weight and working memory was only true for boys, however.) The study also found that overweight or obese children were more likely to have lower IQ scores.

Obesity, which can deregulate certain types of hormones and cause inflammation in the brain, has long been known to be associated with lower cognition in adults, including how they learn, remember information, and manage impulses. But as the researchers explain, “the association between obesity and cognition in children is less well understood.”

The Brown University researchers used data collected from about 200 pairs of moms and their children, measuring their children’s weight and height in their first two years of life. Then the researchers tracked the children’s development, conducting a series of tests that assessed kids’ cognitive skills at ages five and eight.

An important gap in this research is whether children who start out obese or overweight in their early years, but lose weight by the time they reach school age, would still experience the negative associations between weight and cognition. That question exceeded the scope of this particular study: Most children’s weight status hadn’t changed by ages five and eight.

Nan Li, an epidemiologist and the lead researcher on the study, said that the finding linking young children’s weight with IQ was particularly significant: ”This outcome … is very important because it may affect someone’s academic performance, career success, and economic productivity at the population level,” she said.

Many young people are affected by obesity: According to the World Health Organization, 18% of children and adolescents ages five to 19 worldwide were overweight or obese in 2016. ”Our findings,” Li said, “could be a good reminder to parents that they should watch a child’s weight, even in the early life.”

This reporting is part of a series supported by a grant from the Bernard van Leer Foundation. The author’s views are not necessarily those of the Bernard van Leer Foundation.