Risperidone in Autism Spectrum Disorder: A Weighty Issue
For children with autistic disorder, treatment with risperidone over a 6 month period was associated with an average weight gain of 5.4±3.4kg (P=.0001), those are the findings of a new study published in Journal of the American Academy of Child and Adolescent Psychiatry. Risperidone is approved for treating irritability in children with DSM-IV -defined autistic disorder.
A total of 124 medication-free children were assigned to either a risperidone-only (n=75%) or a risperidone plus parent training group (n=49), for 24 weeks. During the study, weight, height, waist circumference and adverse effect were monitored; fasting blood work was done before treatment was initiated and at Week 16.
At baseline, 60% of the study group was classified as normal weight compared to 29.4% at endpoint. As well as an average weight gain of 5.4±3.4kg from baseline at week 24, researchers found that waist circumference increased from 60.7±10.4 centimeters at baseline to 66.8±11.3 centimeters at Week 24 (P<.0001). The authors hypothesized that this suggests an increase in visceral adipose tissue. Seventy-five participants reported an increase in appetite in the first 8 weeks, while just 22 did not. A faster rise in BMI z-scores were noted in those who had higher appetites after 8 weeks of treatment. The authors note that this is the first study to show that an increased appetite early in treatment precedes rapid weight gain in ASD children.
Although significant, the increases in mean glucose and HbA1c were modest. The number of children with a baseline glucose ≥100mg/dL almost tripled from 4.8% (n=4) at baseline to 12.5% (n=11) at Week 16. There were 12 new cases of metabolic syndrome at week 16, in addition pre-existing or new cases of metabolic syndrome had higher triglyceride/HDL ratio than those not so classified (2.89±1.18 versus 1.02±0.57; P<.0001) and greater waist circumference (68.6±10.6 versus 61.9±9.8; P=.01).
The researchers acknowledge that the study has limitations such as the lack of a placebo control. In addition no MRI or ultrasound tests were used to examine fat deposits in the abdomen, liver, or carotid arteries.
The benefits of risperidone in patients with autism spectrum disorder have been established (N Engl J Med. 2002), but the authors of this study suggest that benefits have to be weighed against the health risks and that "appetite, weight, waist circumference, liver function tests, blood lipids, and glucose warrant monitoring." Previous studies have reported rapid return of serious behavioral problems following gradual dose reduction.
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