Weight gain in a controlled study of risperidone in children, adolescents and adults with mental retardation and autism

As part of an ongoing, prospective, ABA design, double-blind crossover stud y of risperidone versus placebo for the treatment of aggressive, destructiv e and self-injurious behavior in persons aged 6-65 years with mental retard ation (MR) and autism, we measured the weight of 19 subjects at each study visit. We compared mean weight gain during the 16-week acute phase and 24-w eek open maintenance phase with that during the initial and middle placebo phases statistically, using a linear mixed model procedure. Results of the linear mixed model analysis showed that relative weight gain observed durin g the acute and maintenance drug phases was significantly greater than that observed during the initial and middle placebo phases respectively (p = .0 001 and p = .0001). Over approximately a year, children aged 8-12 (n = 5) g ained a mean of 8.2 kg (range = 2.7-17.7 kg); adolescents (n = 6) aged 13-1 6 gained a mean of 8.4 kg (range 3.6-15.5 kg); adults aged 21-51 (n = 8) ga ined a mean of 5.4 kg (range 0-9.5 kg). Weight gain observed in this contro lled study of risperidone treatment in children, adolescents, and adults wi th MR and autism was significant. It may be greater in this population than in others reported and in this study was not limited to an acute effect on ly. Rate of weight gain diminished rapidly on tapering and stopping the dru g. Further studies are urgently needed, including those incorporating diet and exercise programming.