Children's Health

Hormone level may be biomarker for autism, study finds

Biotechnology research

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Low levels of the hormone vasopressin have been linked to social deficits in autism, raising the possibility of a treatment for diagnosed children, found a new study from Stanford University School of Medicine.

In a study of 159 children, 57 of whom had autism, researchers found that autistic children who had the lowest vasopressin levels in their blood also had the greatest social impairment.  

“What’s compelling from this study is that if vasopressin levels track this social behavior, it might suggest that kids who have the greatest impairments in these levels might benefit the most from vasopressin treatments,” senior study author Karen Parker, an associate professor of psychiatry and behavioral sciences at Stanford University School of Medicine, told

Vasopressin, a small-protein hormone, is structurally similar to oxytocin and plays a role in social behavior. Researchers studied the “theory of mind” trait, the understanding that people’s intentions, feelings and goals are separate from one’s own Children with typical development understand this idea sometime between ages 6 through 8.

In their study researchers first measured cerebrospinal fluid to determine whether vasopressin levels in the blood reflected the hormone’s levels in the brain.

“Autism is a brain disorder,” Parker said. “If we’re thinking about what we call the biomarkers of disease, ideally we want to take it as close to the origin of disease as possible.”

Because retrieving cerebrospinal fluid typically requires general anesthesia and a lumbar puncture, the team connected with the pediatric clinic at Stanford and collected samples from patients who were having fluid collected for medical reasons.

The 28 sets of samples they collected confirmed that vasopressin is released into the brain and blood, a finding that was a critical step for researchers to move forward to the second study, Parker said.

For the second study, researchers recruited 159 children ages 3 through 12. Of the group, 57 had autism, 47 did not have autism but had a sibling who did, and 55 were children with typical development and no autistic siblings. All children were given standard psychiatric assessments, including measuring their social responsiveness, and had blood samples taken.

In those children with autism, researchers found a strong positive relationship between the level of vasopressin in blood and the child’s performance on the tested social task. Children with autism who had the lowest vasopressin levels also had the largest social impairments. In the non-autism group, low vasopressin levels were not related to displaying social impairment— meaning autism can’t be explained by vasopressin deficit alone.  

“Whenever we do studies in this range of children that have such profound differences in functioning, the idea that even in this range of kids that we could still see this relationship, to me, was pretty powerful. It suggests it’s robust,” Parker said.

The basic biology of autism is poorly understood— unlike many other disorders, there is no biology-based diagnostic test that can lead to treatment with specifically developed medications, Parker said.

A phase 2 clinical trial funded by the National Institutes of Health (NIH) underway at Stanford is analyzing the safety and effectiveness of vasopressin treatment for children with autism.

Because the range of abilities in children with autism varies, neuroscientists like Parker hope that identifying a biological sign may identify different subtypes of autism, and therefore who responds best to different drugs.

“Autism is very heterogeneous— it’s very complicated,” she said. “One of the things we’re really hopeful in doing these studies is asking, ‘Can we streamline this complexity of disorders by understanding the biological substrates that may vary across kids?’”

Parker noted that they may find that vasopressin globally helps most autistic children because it raises social functioning and thus, that a deficit is not necessary. Another possibility is that only children with a vasopressin deficit respond, or perhaps maximally respond, to treatment, she said.

“Our hope is to eventually give a biological profile to these kids and ask which in the arsenal are the therapies, the drugs, that would be the most beneficial for the child,” she said.

Researchers expect to have preliminary data from the ongoing trial this year.

One goal of the group’s newly published findings is to raise awareness of their treatment trial with the aim to quickly enroll patients into their latest  trial.

“The faster we enroll patients, the faster we can get data. It is going to be a game-changer,” she said. “It’s exciting to feel as a group of scientists that we’re starting to understand the biology of a disorder that for so many years we’ve known so little about.”

The study was published Wednesday in PLOS ONE.