April 7, 2003 -- Teen and childhood obesity is associated with certain psychological disorders, according to a new Duke University study.
Chronic childhood obesity was associated with a greater likelihood of depression in boys and hostile and defiant behavior in both boys and girls. But it did not appear to increase the risk of chronic anxiety, substance use, attention deficit disorder, or other psychological problems.
The Duke study included almost 1,000 mostly white children between the ages of nine and 16 living in a rural North Carolina region where childhood obesity was at least three times more common than in the nation as a whole. The children were evaluated annually over an eight-year period to determine height, weight, psychiatric disorders, and vulnerabilities to such disorders. The findings are reported in the latest issue of the journal Pediatrics.
Boys who remained obese during childhood and adolescence were four times as likely to experience clinical depression compared with normal-weight boys or those who were overweight only during childhood or their teen years. The association was not seen in girls with chronic childhood obesity, however.
"This is not to say that overweight girls don't have self-esteem issues or depression associated with obesity," lead researcher Sarah Mustillo, PhD, tells WebMD. "We were looking at clinically significant depression, which is not the same as feeling blue. Overall, boys have lower rates of clinical depression, and this is what we found in the other groups. But chronic obesity in boys was associated with an elevated risk of depression."
Childhood obesity was associated with a 2.5 times greater likelihood of a disorder known as oppositional defiant disorder, defined as an ongoing pattern of uncooperative, defiant, hostile behavior toward authority figures. The disorder is more common in boys, but the researchers found it to be elevated in both boys and girls.
Childhood obesity specialist Sarah Barlow, MD, says a child with defiance disorder is less likely to set limits for himself or follow those set by parents, and this could easily lead to obesity. Barlow is an assistant professor of pediatrics at St. Louis University School of Medicine
"For so many families with overweight children, setting limits is a big issue," she tells WebMD. "For these kids, making the lifestyle changes necessary to lose weight may be low on their list of priorities."
Mustillo says it is not clear whether environmental or biochemical factors drive the tendency toward these depressive disorders in kids with childhood obesity. Studies in adults suggest hormonal abnormalities associated with obesity play a role in depression, but little research has been done in children.
The children participating in this study were largely homogeneous, and Mustillo says it is possible different associations would be seen among different ethnic populations.
"From a biochemical standpoint we probably all pretty much have the same makeup," she says. "But if environmental or social factors are involved, you might see a difference. There might be fewer of these problems among ethnic groups where [childhood] obesity is more accepted."