In contrast to the assumptions of some doctors, new research suggests that the antidepressant Celexa does not help relieve repetitive behaviors often seen in children and teens with autism.
But the findings still need to be confirmed by other studies, and at least one autism specialist said the drug has worked well in his patients of preschool age, who are younger than those in the study.
"The jury is still out on how autism should be treated," said the specialist, Dr. Andrew Zimmerman, a pediatric neurologist and director of medical autism research at the Kennedy Krieger Institute in Baltimore.
Antidepressants known as selective serotonin reuptake inhibitors, or SSRIs, are a common treatment for autism and given to perhaps 30 percent of children with the condition, said Dr. Bryan King, lead author of the study. Other common treatments, he said, include antipsychotic drugs, which calm people who use them, and stimulants such as Ritalin, which reduce hyperactivity and impulsive behaviors.
Celexa, also known by the generic name citalopram, is lesser known than similar antidepressants such as Prozac and Paxil. But it's easier to prescribe to autistic children because it comes in a liquid form, meaning that parents don't have to force their children to take pills, said King, a researcher and director of psychiatry and behavioral medicine at Seattle Children's Hospital and the University of Washington.
Also, the drug spends less time in the body before being flushed out, making it easier for doctors to quickly adjust the dosage, he said.
King's research team assumed that Celexa reduces symptoms of autism in children, such as repetitive motions, but they wanted to understand more about its powers.
"We didn't expect it to work for everyone, but we were hoping that we'd be able to drill down into the population for whom it was very helpful and begin to identify the predictor of what a positive response would be," he said.
They randomly gave either 16.5 milligrams, on average, of Celexa or a placebo to 149 children with autism who were 5 to 17 years old. The children took the drug or fake drug for three months, and 123 of them finished the study.
The number of children who improved -- defined as not engaging in as many repetitive behaviors -- was about a third in both groups.
In other words, Celexa appeared to make no difference compared with a placebo. And children on Celexa were more likely to suffer from apparent side effects such as diarrhea, insomnia, hyperactivity and repetition of movements, the study found.
In a statement, Forest Laboratories, the maker of Celexa, said that it "was not involved in this study and therefore cannot provide comment."
The results are in the June issue of Archives of General Psychiatry.
The finding raises questions about whether similar antidepressants are also not providing benefit, or as much benefit as doctors had assumed, King said.
Zimmerman, the Baltimore autism specialist, said he's successfully treated younger autistic children, ages 3 to 5, with the drug. He added that he uses smaller doses, which appear to not create as many side effects.