CHICAGO, June 13 (Xinhua) -- A study conducted at Washington University School of Medicine in St. Louis shows that children and adolescents treated with antipsychotics for as little as 12 weeks experience significant gains in body fat and also become less sensitive to insulin.
The findings are published June 13 in the journal JAMA Psychiatry.
Using dual-energy X-ray absorptiometry (DEXA) scans, the researchers measured patients' whole body fat before they were prescribed antipsychotic drugs; after six weeks of treatment; and at 12 weeks when the study concluded. The youths also received MRI scans at the start of the study and 12 weeks later, measuring subcutaneous and visceral fat in the abdomen, known risk factors for diabetes, high blood pressure and cardiovascular disease. The children's sensitivity to insulin also was measured at the beginning and end of the 12-week study period.
The researchers studied 144 St. Louis-area youths aged 6 to 18 who were prescribed antipsychotic drugs to treat disruptive behavior disorders. Children in the study were chosen randomly to receive one of three antipsychotics: aripiprazole, olanzapine or risperidone.
"At the start of the study, about 30 percent of the youths in our sample were overweight or obese, which is exactly the same rate we see in the general population," said John W. Newcomer, the study's principal investigator and an adjunct professor of psychiatry at Washington University.
"But after only 12 weeks of treatment, the rate of those considered overweight or obese had risen to 46.5 percent. We essentially went from one in three children meeting criteria for being overweight or obese, to one in two meeting criteria."
One drug in particular, olanzapine, produced the largest increases in body fat, but fat also increased significantly in children taking the other two medications. The DEXA scans showed that about half of the weight gain was water, and half was new fat.
The gains in body fat and losses in insulin sensitivity were observed whether or not the youths were taking stimulant medications. That's despite the fact many children on Ritalin or other stimulants lose weight or grow more slowly than their peers who don't take those drugs.
"Some clinicians hoped that stimulant treatment might offset antipsychotic-induced weight and fat increases," said Ginger E. Nicol, an associate professor of child psychiatry at the university. "But in our study, stimulants didn't seem to make any difference."
"Antipsychotic medications can be helpful for many as a treatment for behavior disorders," said Nicol. "But we know these drugs also have side effects involving fat gain and insulin resistance, important precursors to diabetes and cardiovascular disease. Our results underscore the need for greater vigilance regarding side effects when prescribing these medications."