In the United States, about 25 million children are either overweight or obese. A new study explored how being overweight or obese might affect brain development in children. A report on the study appeared this month in JAMA Pediatrics, a publication of the American Medical Association. The writers suggested a link between body mass index, brain development and “executive functions, such as working memory.” An editorial published with the report called the study an important addition to growing evidence of a link between weight, brain structure and mental function. It also warned against misinterpreting the findings.