Pam Harrison

May 10, 2013

DONOSTIA / SAN SEBASTIÁN, Spain — Intranasal oxytocin appears to normalize fixated or restricted interest, a core deficit in autistic spectrum disorder (ASD), new research shows.

This expands the spectrum of normalizing effects now being reported for intranasal oxytocin, essentially "completing the picture" of how the neuropeptide ameliorates the 3 key distinguishing features of ASD.

"In autism, there are 3 basic deficits — social communication, repetitive behavior, and fixated or restricted interest, where children get fixated on a particular pattern or sensory stimulation and have difficulty paying attention to other, more socially relevant cues," Lane Strathearn, MD, PhD, assistant professor of pediatrics, psychiatry and behavioral sciences, Baylor College of Medicine, Houston, Texas, told Medscape Medical News.

"So this is the first time that this particular aspect of autistic behavior has been examined in relation to oxytocin, and we've shown that oxytocin has some effect on all 3 aspects of autism behavior, including now fixated interest."

The study was presented here at the 12th Annual International Meeting for Autism Research (IMFAR).

Impact on the Amygdala?

As part of a randomized, double-blind, placebo-controlled crossover study, a total of 32 individuals, 16 with ASD and 16 matched control participants, were given either intranasal oxytocin or placebo on their first study visit. They were given the alternate solution on a subsequent visit 2 weeks later. The mean age of the study group was 13 years, and all participants were male.

On each occasion, participants viewed 14 slides, each containing 4 related pictures of real-life scenes. Within that set of related pictures, participants were shown some that were highly organized, such as football players lined up straight across the field, and some that were disorganized, such as crowd shots at a football game.

Researchers then tracked participants' gaze using an automated eye tracker as they examined each set of pictures and documented which pictures those with ASD preferred compared with which pictures the normal control participants preferred.

"Our hypothesis was that individuals with ASD would like the highly structured, organized pictures more than pictures that were less organized, and under normal conditions, that's exactly what we found," Dr. Strathearn said.

In contrast, participants without ASD showed no preference for any type of picture, giving each picture equal attention.

However, when researchers assessed picture preference following administration of intranasal oxytocin, "the difference between ASD subjects and normal controls was eliminated — there was no difference between the 2 groups in their gaze preference when looking at the same pictures," said Dr. Strathearn.

Dr. Strathearn noted that oxytocin has been shown to enhance social bonding and attachment. It has subsequently been explored in a range of studies involving mother-infant attachment, social development and exchange, and recognition of facial emotion.

"It's not completely clear where or how oxytocin is acting in these particular situations, but functional MRI [magnetic resonance imaging] studies suggest that oxytocin does affect the amygdala, which is the emotional center in the brain," Dr. Strathearn said.

Studies have shown that blood levels of oxytocin are lower in children with ASD as well.

Research also indicates that ASD children process facial emotions differently from typically developing children, and if they are missing out on information about facial emotion, "that is a lot of information they're not able to take in, so this may have a cascading effect on developing appropriate emotional responses," Dr. Strathearn suggested.

Growing Evidence of Therapeutic Effect

Asked by Medscape Medical News to comment on this study, Daniel Smith, PhD, senior director, Autism Speaks, New York City, noted that findings from this study build on the growing body of literature that oxytocin appears to elicit a therapeutic response in individuals with ASD.

"We need larger studies to confirm if this is a reliable finding," Dr. Smith told Medscape Medical News. "But it is interesting that they are showing a difference in attention and in response to organized pictures vs unorganized ones, and in a larger study, it would be useful to incorporate a more objective functional endpoint to complement the typical clinical scales we typically use in ASD studies."

Dr. Strathearn and Dr. Smith report no relevant financial relationships.

12th Annual International Meeting for Autism Research (IMFAR). Abstract 122.007. Presented May 3, 2013.

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