A connection between a brain chemistry deficit in children with autism and their difficulties in social situations has been uncovered by Stanford University researchers.
The research team, led by the study’s senior author Karen Parker, Ph.D., an associate professor of psychiatry and behavioral sciences, discovered the correlation between low levels of vasopressin and the “inability of autistic children to understand that other people’s thoughts and motivations can differ from their own,” according to the press release.
Autism, which is characterized by social and communication deficits and repetitive behavior, affects one out of every 68 children in the United States according to the Centers for Disease Control and Prevention.
Vasopressin is a hormone involved in social behavior. It had been previously implicated in regulating social behavior in animals.
“Vasopressin administered into the brain enhances social functioning in rodents, and experimentally blocking the ability of vasopressin to act in the brain induces social impairments in rodents,” Parker said to Healthline in an email. “We theorized that diminished vasopressin levels in people with autism may be associated with social deficits.”
Measuring Brain Chemistry
Parker said that as progress is made in better understanding the biology of autism, scientists will be able to develop laboratory-based biological tests and drugs that specifically target the biological mechanisms that produce, or are altered by, autism.
Parker said vasopressin was tested against several measures of social functioning and the levels were “most strongly related to a measure called ‘theory of mind.’”
The theory of mind measure, according to Parker, is the ability to understand that others have thoughts or intentions different from one’s own.
Parker and her team of researchers, “verified that vasopressin levels in the blood accurately reflected vasopressin levels in the brain by measuring the hormone's levels simultaneously in the blood and cerebrospinal fluid of 28 people who were having the fluid collected for medical reasons,” according to the press release.
Following that verification, they then recruited 159 children for behavioral testing. Of them, 57 had autism, 47 didn’t have autism but had a sibling who did, and 55 were not autistic and had no autistic siblings. All were between the ages of 3 and 12.
The children completed standard psychiatric assessments of their neurocognitive abilities, social responsiveness, theory of mind measures, and ability to recognize others' emotions. All children gave blood samples that were measured for vasopressin.
Levels of Vasopressin
Each group of children had varying ranges of vasopressin levels — high, low, and medium.
“Children without autism had similar scores on theory of mind tests regardless of their blood vasopressin level, but in children with autism, low blood vasopressin was a marker of low theory of mind ability,” wrote researchers.
While the results of the research, published today in PLOS ONE, show autistic children with the lowest vasopressin levels had the greatest social impairment, children without autism can also have low levels of vasopressin without any social impairment.
“Since non-autistic children all scored well on the test, we don’t know whether the relationship between vasopressin levels and theory of mind ability is specific to autism as it appears in this study,” Parker said.
She added that blood vasopressin levels are not a biological marker of autism.
The findings still raise the possibility that treatment with vasopressin could reduce social problems for autistic children with low vasopressin levels. That theory is currently in the testing phase by Parker and her collaborator, Dr. Antonio Hardan, professor of psychiatry and behavioral sciences.
There is no immediate timetable for the tests conducted by Parker, Hardan, and their team of researchers, but there is overall optimism that treatment can be found.
“Our optimistic hypothesis is that vasopressin administration will enhance social functioning in children with autism overall,” Parker noted. “However, since there are likely different subtypes of autism, and different medications will work better for some subtypes of autism over others, it may be that children with the lowest pretreatment vasopressin levels will benefit most from administration of this medication.”