In a newly published study involving autistic adults, half of those who took Prozac (fluoxetine) experienced meaningful declines in repetitive behaviors.
Earlier studies by the same researchers showed the antidepressant to be effective for reducing repetitive behaviors in children with autism spectrum disorder (ASD), although a study from another research team failed to show an effect with the antidepressant Celexa (citalopram).
Prozac and Celexa are both selective serotonin reuptake inhibitor (SSRI) antidepressants.
The latest study shows that treatment with an SSRI can have a positive impact on repetitive, compulsive behavior in autistic adults, just as it can in children, says study researcher Eric Hollander, MD, of the Albert Einstein College of Medicine and Montefiore Medical Center in Bronx, N.Y.
Treating Repetitive Behavior
Autism spectrum disorders are defined by the core symptoms of difficulty communicating and relating with others, repetitive behaviors, and restricted interests.
Inflexible routines or rituals, and repetitive movements such as rocking or hand-wringing, are commonly seen in children and adults with autism.
Antidepressants, especially SSRIs, are sometimes used in the treatment of adults with autism. But they have not been widely studied and their impact on repetitive behaviors had not been studied at all.
The 12-week study by Hollander and colleagues included 37 autistic adults with repetitive behavior symptoms who took either Prozac or a placebo.
Prozac dosages were gradually increased, as tolerated, from 10 milligrams to up to 80 milligrams a day. Repetitive behaviors were assessed using widely accepted measures.
By one such measure, 50% of study participants who took Prozac showed significant improvement in repetitive symptoms at week 12 compared to 8% of those in the placebo group.
The study appears online Dec. 2 in The American Journal of Psychiatry.
Treating Core Autism Symptoms With Drugs
In some cases the drug made a meaningful difference for patients and family members, Hollander says.
"There is a lot of distress and functional impairment associated with narrow restrictive interests and behaviors," he says. "Deviation from routine can cause extreme agitation and explosions that can make things like going to a restaurant or riding public transportation difficult."
The schizophrenia drug Risperdal (risperidone) is approved for the treatment of irritability and agitation in children and adolescents with autism. Autism researcher Fred Volkmar, MD, says the drug also seems to improve repetitive behaviors and other core symptoms in many patients.
Volkmar directs the Child Study Center at Yale University, where he is also a professor of psychiatry.
"The question remains, 'Is fluoxetine better than risperidone for this symptom?'" he tells WebMD. "It would be interesting to see studies comparing these two drugs head to head."