Risperidone has been recommended for the management of disruptive behaviour disorders in children with learning disabilities. This study explored the effects of Risperidone on absolute body weight in children with learning disabilities who received Risperidone for disruptive behaviour disorders.

Data was collected for children (n = 70) with learning disabilities who were prescribed Risperidone for disruptive behaviour disorders in out patient clinic. Weight, height and BMI were recorded at the first appointment and at the follow up for up to one year. Data was analysed to find any changes in weight and BMI during the course of treatment with Risperidone.

Mean weight gain for the sample was 6.1 kg (sd = 2.7), 1.7 kg more than expected in one year which was statistically significant (t = 6.2, df = 69, p < 0.001). Mean BMI change was 1.51 kg; significantly larger than the mean expected BMI change of 0.62 of this sample (t = 4.98, df = 1.6, P = 0.001). Change in BMI was more for girls, 2.17 (sd = 1.00) compared with boys 1.36 (sd = 1.18), but this was not significant (t = 1.90, df = 49, p = 0.06). There is no significant relationship between Risperidone dose and weight gain (Pearson's r = 0.21, p = 0.42) and BMI (Pearson's r = 0.03, p = 1.00).

Risperidone should be used with caution in children where weight gain could have long lasting impact. Prescribing clinicians should obtain baseline measures of weight, height, BMI and monitor them at regular intervals. Emphasis should be placed on life style interventions such as diet, physical activities etc. Further comparable studies with larger sample sizes using more homogenous diagnostic samples are needed.