The antipsychotic drug Risperdal may cut aggressive behavior in children with autism.

That effect was reported in The American Journal of Psychiatry. Researchers including James McCracken, MD, of the University of California at Los Angeles (UCLA), studied Risperdal and autism.

However, Risperdal doesn't cure autism, and it may not be right for all autistic children. Only those with severe tantrums and aggressive or self-hurtful behaviors were studied. In the new study, improvements in behavior were maintained for over four months in more than 80 percent of those taking Risperdal (about 52 children).

Risperdal is an antipsychotic used to treat schizophrenia in adults. Antipsychotic drugs do not cure schizophrenia; they reduce psychotic symptoms suffered by these patients.

The drug showed "very good tolerability," but its long-term effects aren't known, say McCracken and colleagues.

About Autism

Autism is part of a spectrum of developmental disabilities caused by brain abnormalities, says the CDC.

People with autism spectrum disorders tend to have problems with social and communication skills. They may engage in repetitive behaviors. Some experience tantrums or aggression. These behaviors can be severe enough to limit educational and developmental progress, write the researchers.

Between two and six out of a thousand people have an autism spectrum disorder, says the CDC.

Read WebMD's "More on Autism Symptoms and Causes"

Researcher's Comments

"Our findings support adding [Risperdal] to the small arsenal of intermediate-term medication options for the tens of thousands of children with autism who display aggressive and destructive behaviors," says McCracken in a news release.

He says the response to Risperdal "ranks among the most positive ever observed in children with autism for a drug treatment."

However, more studies are needed, say the researchers.

Tracking Risperdal's Impact

The study included 101 children with autism. They were 5 to 17 years old. Their autism was accompanied by severe tantrums, aggression, and/or self-injurious behavior.

They were assigned to take Risperdal or a placebo for eight weeks. A total of 63 children who responded well agreed to continue for four more months.

Irritability scores dropped 59 percent, on average, with Risperdal. About 83 percent were rated "much" or "very much" improved throughout the study, say the researchers.

They also tracked 38 children as they were weaned off the drug. Gradually, Risperdal was substituted for a placebo. When that happened, symptoms often returned.

Read WebMD's "On the Cutting Edge of Autism Treatment"

Side Effects

Side effects -- especially mild to moderate increased appetite, tiredness, and drowsiness -- were "common," say the researchers.

Weight gain was also reported. Kids taking Risperdal gained about 11 pounds during the six-month study.

That's more than what would be expected for normal development, say the researchers.

Previous Study

An earlier study on Risperdal and autism appeared in The New England Journal of Medicine's Aug. 1, 2002, edition.

That study only lasted eight weeks. It included 101 autistic children. They were given Risperdal or a placebo.

Negative behaviors were "much" or "very much" improved in 69 percent of the Risperdal group, compared with 12 percent of those taking the placebo.

At the time, researcher Lawrence Scahill, PhD, MSN, told WebMD that Risperdal "does not appear to have much impact on the core symptoms of autism."

"What we want to avoid is the mistaken notion that it is appropriate for all children with autism and that pushing the doses will make all of their problems go away," said Scahill.

Scahill is an associate professor of nursing and child psychiatry at Yale University School of Nursing and Child Study Center.

Read WebMD's "Early Signs of Autism Identified in Infants"

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Aman, M. The American Journal of Psychiatry, July 2005; vol 162: pp 1361-1369. CDC: "Autism Information Center." WebMD Medical News: "Schizophrenia Drug Helps Autistic Kids." News release, UCLA.