541 A Double-Blind Placebo-Controlled Pilot Study of Olanzapine in Childhood/Adolescent Pervasive Developmental Disorder Eric Hollander, M.D., Stacey Wasserman, M.D., Erika N. Swanson, M.A., William Chaplin, Ph.D., Melissa L. Schapiro, B.A.S., Karen Zagursky, and Sherie Novotny, M.D. ABSTRACT Atypical antipsychotics have been shown to improve disruptive and repetitive behaviors in pervasive developmental disorders (PDDs), but they require assessment of potential side ef- fects. This is the first placebo-controlled trial of olanzapine in the treatment of children and adolescents with PDD. Eleven patients with a diagnosis of either autism, Asperger’s syn- drome, or PDD not otherwise specified (PDD-NOS) and aged 6–14 years were randomized into an 8-week double-blind, placebo-controlled, parallel treatment study with olanzapine. There was a significant linear trend  group interaction on the Clinical Global Impres- sions–Improvement (CGI-I) and 50% on olanzapine versus 20% on placebo were responders. Olanzapine was associated with significant weight gain (7.5 ± 4.8 lbs vs. 1.5 ± 1.5 lbs on placebo). Olanzapine may be a promising treatment for improving global functioning of PDDs, but the risk of significant weight gain remains a concern. Additional studies are needed to determine the efficacy and safety of olanzapine in the treatment of children with PDD. JOURNAL OF CHILD AND ADOLESCENT PSYCHOPHARMACOLOGY Volume 16, Number 5, 2006 Mary Ann Liebert, Inc. Pp. 541–548 INTRODUCTION P ERVASIVE DEVELOPMENTAL DISORDERS (PDDs) are characterized by three core domains: im- paired social interaction, poor communicative abilities, and stereotyped, repetitive patterns of behavior. Children with PDDs may also demon- strate disruptive behaviors, such as aggression toward self and others, destruction of property, irritability, and mood instability, as well as diffi- culties with attention, motor control, and sleep. Thus, PDDs pose considerable stress to the af- fected child, family, and community. Currently, there are no medications ap- proved by the U.S. Food and Drug Adminis- tration for the treatment of PDDs. Because there is no “cure” for PDDs and symptoms vary significantly within the population, we often employ targeted pharmacological treat- ments to mitigate associated problem behav- iors (Hollander et al. 2003). Early treatments for these symptoms used typical antipsy- chotics, such as haloperidol, which demon- strated superiority to placebo in improving attention, decreasing stereotypies, and reduc- ing aggressive and disruptive behaviors in Seaver and NY Autism Center of Excellence, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1230, New York, New York.