Open-label risperidone for Asperger's disorder: Negative symptom spectrum response

Objective: Asperger's disorder consists of negative symptoms similar to those seen in schizophrenia, autism, schizoid personality disorder, and schizotypal personality disorder. We investigated whether risperidone, which is effective in treating the negative symptoms of schizophrenia, would improve such symptoms observed in Asperger's disorder in a prospective, open-label trial. Method: Thirteen male patients aged 6 to 18 years who were diagnosed with Asperger's disorder by DSM-IV criteria were enrolled in a 12-week, prospective, open-label pilot study from March 13, 2002 to August 11, 2003. All subjects were started on risperidone 0.25 mg twice per day. Doses were increased based on clinical indication and tolerability. The primary efficacy variable was the Scale for the Assessment of Negative Symptoms (SANS). Each subject's baseline score served as his control. Secondary efficacy measures included the Positive and Negative Syndrome Scale, Brief Psychiatric Rating Scale, Montgomery-Asberg Depression Rating Scale, Global Assessment Scale, and a modified Asperger Syndrome Diagnostic Scale. Results: We found a statistically significant improvement from baseline for last-observation-carried-forward (LOCF) analyses as well as for analyses of 12-week completers (N = 9) in our primary outcome measure, SANS scores (F = 13.41, p < .0001 for 12-week completers; F = 9.64, p < .0001 for LOCF). We also found statistically significant improvement in all secondary efficacy measurements (F values range, 8.41 to 15.73, p values range, < .0001 to < .005 for 12-week completers; F values range, 6.53 to 7.75, all p < .0001 for LOCF). Conclusions: Subjects' symptoms significantly improved after risperidone. The open-label nature of this small pilot study suggests caution in interpreting these data, but the results suggest that placebo-controlled trials should follow.