The drug risperidone has been successful in reducing serious behavioral problems in children with autism spectrum disorder (ASD), but researchers have discovered that increased appetite, followed by weight gain, can be a undesirable adverse effect. Rapid weight gain can contribute to insulin resistance and other metabolic alterations that may  predispose patients to diabetes, cardiovascular  disease and liver disease.

The research was recently published online in the Journal of the American Academy of Child and Adolescent Psychiatry. Lead author is Lawrence Scahill, MSN, PhD, professor of pediatrics at Emory University School of Medicine and Marcus Autism Center.

In a 24-week, multisite study, Scahill and colleagues gave risperidone to children ages 4 to 13 who had ASD and serious behavioral problems. The children were randomized to receive either the drug alone or the drug plus parent training. Researchers monitored height, weight, waist circumference and adverse effects, and obtained fasting blood samples before treatment and at week 16. On average, the children gained about 15 percent of weight above baseline over the 24-week trial. The adverse effects of risperidone did not differ significantly between the children in the two randomized groups.

In the 97 children who continued to receive risperidone throughout the study, there was an average 5.4 kg weight gain over 24 weeks, as well as a 6.1 cm  increase in waist circumference. At the beginning of the study, 59 of the 97 children were classified as having normal weight, but by week 24 only 25 children were in the  normal weight category. Negative effects included a significant change in body mass index scores from pretreatment to week 24. This rise was markedly greater in children less than seven years of age compare to those seven years or older.

Weight gain and increase in body mass index were much greater for children with reported increased appetite in the first eight weeks of the study. From before treatment to week 16, there were significant increases in glucose, hemoglobin A1c, insulin, triglycerides and an increase in the biochemical index of insulin resistance in these children.

"This study shows first of all that risperidone should be reserved for serious behavioral problems," says Scahill. "When it is prescribed, however, the prescribing clinician and team should begin discussion with parents about diet and food selection at the very beginning of treatment. Although about 25 percent of children in our study did not show an increase in appetite, parents should be told about the likelihood of an increase in appetite and weight gain and should remove unhealthy foods from the home in anticipation."

The authors conclude: "Appetite, body weight, waist circumference, liver function, blood lipids, and glucose should be measured before starting children on treatment with atypical antipsychotic medications. Appetite, body weight, and waist circumference should be monitored early and regularly during treatment; liver function, blood lipids, and glucose should be monitored periodically."