Targeting antidiuretic hormone vasopressin shows promise for autism

Autism is a complex neurodevelopmental disorder with no known drug treatment up until now. Researchers have finally found tweaking certain hormones could help patients with autism. There were two independent clinical trials including children and adults with autism that altered the effects of the hormone vasopressin and to assess the effects on social functioning.

Researchers explain the vasopressin is an important hormone in the body that helps to maintain and regulate the kidney functions and blood pressure. Animal studies in the labs revealed that vasopressin has more complex actions in the brains. The hormone can affect social behaviours of the lab animals as well as their bonding with their mates, the researchers noted. There are studies showing the effects of administering vasopressin in healthy humans as well as in humans with dementia and other cognitive problems. The hormone when administered leads to improvement in memory and social skills of the humans, researchers have found.

Image Credit: Zahraa Saleh / Shutterstock
Image Credit: Zahraa Saleh / Shutterstock

Intranasal vasopressin improves social deficits in children with autism

The first study was conducted on children with autism. Karen Parker, a behavioural scientist at Stanford University, explains that the study of the effects hormone on lab voles was one of her earlier research work. Now she works as the director of the university’s Social Neurosciences Research Program and recruited human children with autism for the study. The study results appeared in the latest issue of the journal Science Translational Medicine this week (1st May 2019). The study was titled, “A randomized placebo-controlled pilot trial shows that intranasal vasopressin improves social deficits in children with autism”.

The team writes that they examined the vasopressin levels in the children with autism spectrum disorder. They noted that these children have less amount of vasopressin in their spinal fluid compared to children who were not on the spectrum. They also noted that the symptom severity rose with lower levels of vasopressin. This included severe language and speech difficulties and increase sensitivity, poor IQ and cognitive skills etc.

As a next step, Parker and her colleagues conducted a double blinded randomized controlled trial including 30 children with ASD aged between 6 and 12 years. The children were given a nasal spray containing either vasopressin (17 children) or placebo (13 children) over a period of four weeks.

Results revealed that children with ASD who were given vasopressin nasal spray had significantly improved social skills and had little or no side effects due to the drug. They noted that the children improved on social communication and also improved on assessment of facial emotions of other people. They could better guess the thinking and feelings of other people. Parents as well as doctors assessing the children reported these improvements. “The parents saw improvement, the clinicians saw improvement, and the children's performance on lab tests also improved with vasopressin compared to placebo,” Parker said.

Antonio Hardan, professor of psychiatry and behavioral sciences at Stanford University and co-author of the study said, “Autism is a very heterogeneous disorder. It may be possible, with autism, to see abnormalities that relate to either too much vasopressin or too little.”

Parker in one of her statements said, “This is a pilot trial, so it’s important to acknowledge that. But there were significant improvements in kids on vasopressin. And we saw this convergent evidence on parent ratings, clinician evaluations, and laboratory tests of children’s performance.” She added that large trials with more number of children are necessary to prove the efficacy of the hormonal nasal spray in showing improvement. She explained that in her trial there were only 5 girls on ASD since boys were more commonly diagnosed with ASD than girls. She said that larger trials with equal gender representation may be needed to see if there was any gender specific efficacy of the drug.

Vasopressin V1a receptor antagonist shows improved adaptive behaviors in men with autism spectrum disorder

Researchers at Roche a Swiss-based pharmaceutical company also conducted a double-blinded, randomized, and controlled trial among adult men on the autism spectrum. The study results appeared in the latest issue of the journal Science Translational Medicine this week (1st May 2019). Senior researcher Dr. Paulo Fontoura senior vice president of neuroscience and rare diseases clinical development at Roche Pharmaceuticals led the study titled, “A phase 2 clinical trial of a vasopressin V1a receptor antagonist shows improved adaptive behaviors in men with autism spectrum disorder.”

For their study the team administered an experimental drug balovaptan or placebo to 223 men with autism. Various doses of the experimental drug was administered (1.5, 4 or 10 milligrams of balovaptan). The mechanism by which the drug acts is by blocking one type of cell receptors in the brain that connects with vasopressin. Fontoura said in a statement that balovaptan has the potential “to improve the core characteristics of social interaction and communications in adults with ASD.” The drug therapy was administered for 12 weeks. Social skills and behaviour in this study as well was measured using the Social Responsiveness Scale.

The results of the study showed that there was no significant improvement in the social skills of the men with the drug compared to placebo. The assessment of improvement was made by the primary care givers of the patients. One set of assessment questionnaires were given to patients directly to assess their perception of improvement in the social skills. Results revealed that self-reported benefits in social skills and communication was noted with second-highest and highest doses of the experimental drug.

Expert speak

These two sets of researchers had not collaborated on their studies and the studies were independent. Experts have suggested that although one of the trials did not show an outright success, there is a possibility in exploring vasopressin in autism. As a next step, Parker and her team is working on recruiting a large group of children (100 children) on the spectrum to assess the efficacy and safety of their nasal spray. Similarly Roche is also planning a second set of trials with children on the spectrum aged 5 to 17 years. One of the studies is a Phase II trial among children and adolescents while the other phase III trial is among adults.

Dr. Andrew Adesman, chief of developmental and behavioural pediatrics at Cohen Children's Medical Center in New Hyde Park, was sceptical about the efficacy of vasopressin in autism. He said in a statement, “These two studies, taken together, suggest that treatments to increase vasopressin levels in the brain may be helpful for some patients with ASD. However, much more research is needed in terms of the long-term benefits and safety of this type of treatment.” He warned that vasopressin is approved as an antidiuretic to be prescribed by a physician. The hype caused by these studies may tempt patients to use the medication for autism. He said, “I think families and physicians need to be cautious in using this medication on the basis of a single short-term study.” “Given that there are very few if any good medication options for the treatment of ASD, I am sure there will be great interest in this novel treatment approach. That said, I think much more research is needed before we can feel comfortable recommending vasopressin as a safe and effective treatment for one of the core deficits in children with ASD,” he said.

Kevin Pelphrey, an autism researcher at the University of Virginia in Charlottesville, spoke about the conflicting results saying, “I’ve never seen this before.” He called the results exciting though adding that the role of vasopressin in the brain is to be studied with renewed interest.

Angela Sirigu, neuroscientist at CNRS, in Bron France, is also investigating neurohormones for the management of autism. She called the results exciting.

Eric Hollander, professor of psychiatry and behavioral sciences at Albert Einstein College of Medicine in New York, in his statement regarding the studies aid, “These two studies provide important information that the vasopressin or vasopressin and oxytocin systems are important in social communication. Different agents affecting these systems may ultimately be helpful in terms of new treatments for autism.”

Lawrence Scahill, director of clinical trials at the Marcus Autism Center in Atlanta also warned about misinterpreting the results of these studies. He said, “Both of these studies suggest that the mechanism is worth further study. But I think we want to be careful not to overinterpret the findings.”

Elizabeth Hammock, assistant professor of psychology and neuroscience at Florida State University in Tallahasse added that both the studies looked at two approaches of using vasopressin. She said, “They’re really divergent approaches to targeting the vasopressin system. And we don’t know for sure how either is working.”

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.

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