The 'love hormone' oxytocin has a tremendous effect on kids' ability to function socially, Stanford University researchers report.
Children blessed with naturally high levels of oxytocin are more savvy at communicating with others and interpreting social signals or situations, said study author Karen Parker, an assistant professor of psychiatry at Stanford.
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"The higher your oxytocin [levels], the better your social functioning," Parker said.
The findings also showed that oxytocin levels are highly inheritable.
Oxytocin is released during most activities that cause people to bond to one another – sex, hugging, kissing, holding hands, giving birth and breast-feeding, among them.
Autism and oxytocin
The researchers noted that the original intent of their study was to determine whether children with autism had lower levels of oxytocin than children without the disorder.
For years, impaired oxytocin function has been suspected as an underlying cause of autism, the researchers explained.
Autism is a developmental disorder that causes significant difficulties in social interaction. It affects one out of every 68 children in the United States, according to the US Centres for Disease Control and Prevention.
Read: Autistic kids have less brain flexibility
While oxytocin levels in the children with autism were similar to those of their unaffected siblings and children without autism in the study, the researchers did find that increasing oxytocin levels improved social functioning in all three groups.
Oxytocin has such a powerful effect on social skills that the hormone could prove a very useful treatment for some people with autism, said Rob Ring, chief science officer for the advocacy and research organisation Autism Speaks.
Read: Girls with autism may need different treatment
"If oxytocin has a general pro-social effect on individuals, it still very much argues for engaging the oxytocin system for therapeutic reasons," Ring said. "This research shows in people with autism that if you have increasing levels of oxytocin, you have increasing ability in social behaviour. That is valuable knowledge."
In their study, the Stanford researchers examined 79 children with autism, 52 of their unaffected siblings and 62 unrelated children without autism. All of the children were between the ages of 3 and 12.
The team checked levels of oxytocin in the children's blood, and used a series of diagnostic tools to test for autism spectrum disorders and overall social ability.
All children with autism have social deficits, but in the study these deficits were worst in those with the lowest blood oxytocin levels and mildest in those with the highest oxytocin levels.
But the social skills of the kids without autism also corresponded to their oxytocin levels, the researchers found.
"Oxytocin appears to be a universal regulator of social functioning in humans," Parker said. "That encompasses both typically developing children as well as those with the severe social deficits we see in children with autism."
Oxytocin levels heritable
Comparisons between siblings with and without autism revealed that oxytocin levels in the blood are more than 85 percent heritable, the study authors noted.
Oxytocin levels are influenced by inheritance to about the same degree as adult height, which is often described as being strongly influenced by genetics, the researchers added.
"We found that social functioning was similar between related siblings, and oxytocin levels were way more similar between siblings," Parker said.
The researchers did not completely rule out a possible link between oxytocin levels and autism. They noted that they only checked oxytocin in the blood, and that levels of the hormone may be different in the cerebrospinal fluid that bathes and protects the brain.
Read: Love hormone may help autistic
In the meantime, oxytocin therapy may prove helpful for children with autism and adults whose levels of the hormone are low, Parker and Ring said.
"It may be there's a subpopulation of people with low oxytocin levels, and they may be the best responders to oxytocin treatment," Parker said. "This may help us handpick the people we think are going to benefit most from this therapy."
The findings are published online in the Proceedings of the National Academy of Sciences.'Love hormone' aids recovery after childbirth
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