A new study counters the idea that low levels of the so-called “love hormone” oxytocin cause autism, as some experts had speculated. However, the same study supports the idea that oxytocin might help individuals whose autism-related social disabilities are worsened by low levels of this hormone.
The investigators looked at blood levels of oxytocin in 79 children with ASD, 52 of their unaffected siblings and 62 children in families not affected by autism. All were between age 3 and 12. Low, medium and high oxytocin blood levels occurred at similar rates in all three groups. This strongly suggests that oxytocin deficiency does not cause autism.
At the same time, the study found that higher oxytocin levels were linked to better social functioning. Among the children with autism, those with the lowest levels of oxytocin had the most-severe social difficulties. Those with the highest levels had the mildest social impairments. Social skills likewise rose and fell with oxytocin levels in the children who didn’t have autism.
“This definitely adds strength to the evidence that oxytocin could improve social behavior in those who have deficits in this area, including those who have autism,” comments Autism Speaks Chief Science Officer Rob Ring. Dr. Ring was not directly involved in this study but ranks among the pioneers in oxytocin research.
Last year, a landmark study funded by Autism Speaks found that short-term use of oxytocin nasal spray improved social abilities in children with autism. The successful results of this pilot study led to an expanded and longer-term study funded by the National Institutes of Health.
In this week’s report, the Stanford investigators conclude that testing for oxytocin blood levels might help identify which individuals would benefit the most from such treatments.
A look at oxytocin cell receptors
In addition to examining oxytocin levels in the blood, the researchers looked at variations in genes that code for oxytocin cell receptors. These receptors determine how the hormone binds to and stimulates brain cells. They found clear associations between variations in receptor genes and higher or lower levels of social ability.
Genetic testing for these variations may further help identify individuals with autism who would benefit from oxytocin or oxytocin-like medicines, they concluded.
“Autism is so heterogeneous,” says Karen Parker, the study’s lead author. “If we can identify biomarkers that help us identify the patients most likely to benefit from a specific therapy, we expect that will be very useful.”
A family trait
Finally, the researchers found that oxytocin levels are highly heritable, or shared by family members, to a degree similar to height. This suggests that social function may likewise be highly heritable in families, Parker says.
“Oxytocin appears to be a universal regulator of social functioning in humans,” she concludes. “That encompasses both typically developing children as well as those with the severe social deficits we see in children with autism.”