A new multi-center study suggests the prescribed antidepressant citalopram is no more effective than placebo in altering obsessive features of autism.

According to background information in the study, the use of antidepressants in children with autism spectrum disorder took off before there was strong scientific proof about its effectiveness.

In the last decade, its use has grown so that today more than 40 percent of autistic children swallow a daily dose of an antidepressant in an attempt to control spinning, rocking and repetitive behavior.

This study, published in the June 2009 issue of Archives of General Psychiatry, should serve to reduce the number of antidepressant prescriptions written for children with autism and similar conditions on the autism spectrum.

“Parents of children with autism spectrum disorders face an enormous number of treatment options, not all of which are research based,” said Thomas R. Insel, MD, Director of the National Institute of Mental Health (NIMH).

“Studies like this help us to better understand which treatments are likely to be beneficial and safe.”

The study was funded by the NIMH and other NIH institutes.

The Feinstein Institute’s Joel D. Bregman, MD, an expert on autism and one of the study investigators, said that the initial use of antidepressants grew out of a belief that some of the repetitive behaviors are similar to those seen among people with obsessive compulsive disorder.

“We can’t rely on apparent similarities to other conditions and clinical experiences to guide our treatment strategies.” Dr. Bregman said. “This was a large double-blind clinical trial that showed that this class of medicine is not effective in reducing these behaviors. These types of studies are essential.”

The study followed 149 children between the ages of five and 17. About half were given a placebo dose and the others received the antidepressant. They were tested repeatedly over the 12-week study period. A positive response was defined by improvement on a number of behavioral measurements.

“There was no significant difference in the rate of positive response” on these tests, the scientists concluded. “Results of the trial do not support the use of citalopram for the treatment of repetitive behavior in children and adolescents with autism spectrum disorder.”

Citalopram is in a class of antidepressant medicines called selective serotonin reuptake inhibitors (SSRIs).

Initial smaller studies reported that SSRIs did make a difference. There is some biologic evidence to suggest that it would. Scientists have reported abnormalities in the brain regions that make the chemical serotonin.

And people with obsessive compulsive disorder (OCD) also have serotonin abnormalities and often respond to the medication that helps the serotonin cells to function more normally. SSRIs are the most frequently prescribed medications for children with autism, Asperger’s disorder, or pervasive developmental disorder-not otherwise specified (PDD-NOS) spectrum disorder.

Part of the explanation for the mixed study results is that the placebo response is very high. In the latest study, one in three children in both groups—32.9 percent of those treated with citalopram and 34.2 percent of those treated with placebo—were reported to have fewer or less severe symptoms.

Source: North Shore-Long Island Jewish (LIJ) Health System