Autistic kids low on vital social hormone, study suggests

Increasing autistic children’s levels of vasopressin, a hormone that regulates social behaviour, could help treat the social deficits common to autism, research suggests.

Vasopressin is one of two key hormones (together with oxytocin) known to regulate normal social functioning in mammals. Past studies on rodents have shown that disrupting its signalling pathway leads to social impairments.

Published in PLOS ONE, the new study tested whether vasopressin concentrations in autistic children corresponded with their social functioning abilities.

Researchers from Stanford University’s School of Medicine recruited 159 children, some of whom had autism, others who didn’t have autism but had autistic siblings, and a third group who were typically-developing children with no autistic siblings.

They used three standard psychiatric tools to gauge social and behavioural function in participants.

The first calculates social responsiveness; another the ability to recognise others' emotions. The third tool measures the ability to understand that others have values and belief systems different to one’s own – a measure called “Theory of Mind”.

Low levels of vasopressin in the blood of children with autism corresponded with a lower Theory of Mind score. However, there was no correlation seen between vasopressin levels in either group of children and the first two measurements.

The authors concluded that as hormone concentrations weren’t associated with abilities such as recognising emotions, they couldn’t alone explain the vast spectrum of social impairments in autistic children.

But the study’s senior author and Associate Professor of Psychiatry and Behavioural Sciences at Stanford University’s School of Medicine, Karen Parker, said they were hopeful the vasopressin pathway would nevertheless be an “effective therapeutic target”.

“Our reasons for this are that the lower a patient’s blood vasopressin levels, the greater their observed social cognition impairments,” she said.

“This suggests that the brain may have a deficiency of vasopressin, and that vasopressin treatment may enhance social functioning. This is important because there are currently no medications that effectively treat the social deficits in people with autism.”

Theory of Mind deficits create major barriers to communication and closeness. They are typically present in people with autism spectrum disorders, those affected by Asperger’s, schizophrenia and attention deficit hyperactivity disorders (ADHD).

Head of the Autism Research Team at the Telethon Kids Institute, Andrew Whitehouse, said the study was an interesting start in an under-researched area, but was unsure whether the findings were “specific” to children with autism.

“There have been many studies that identified a certain molecule or chemical in the blood, at different levels, in children with autism. But the key point to consider is how much is this specific to autism and not to other conditions?”

He commended the authors for studying the siblings of kids with autism to rule out whether lower levels of vasopressin could have been the result of genetic predisposition or having been raised in the same environment.

“But they didn’t look at whether the levels were different in kids with other difficulties – for example, kids with Down syndrome or kids with ADHD,” he added.

He also said vasopressin’s capacity to predict social abilities in autism remained an open question, given it was found to relate to only one of the three measurements of social ability recorded.

Researcher in Enteric Neuroscience and Autism at the University of Melbourne, Elisa Hill, said the varying traits of autism spectrum disorders made it difficult to “sub-group patients to see who may benefit from various therapeutic approaches”.

“Any potential therapies are likely to be useful for a sub-group of patients. Rather than giving all patients that drug, you might be able to look at blood levels and those who have low vasopressin in their blood are more likely to have a lower Theory of Mind score. So these would be the patients you would target with that potential therapy,” she said.