Hyperbaric oxygen chamber therapy effective in animal models for improvement of autism - study

Fischer and Barak explained that hyperbaric oxygen therapy (HBOT) is a form of treatment in which patients sit in special chambers where the air consists of 100% oxygen.

 Hyperbaric chamber for hyperbaric oxygen therapy (HBOT). (photo credit: Wikimedia Commons)
Hyperbaric chamber for hyperbaric oxygen therapy (HBOT).
(photo credit: Wikimedia Commons)

Sitting in a hyperbaric (high-pressure) oxygen chamber has been shown, in an animal model, to improve the social functioning and the condition of the autistic brain, according to Tel Aviv University (TAU) researchers.

They identified changes in the brain, including a reduction in neuroinflammation, which is known to be associated with autism. The study’s success, said doctoral student Inbar Fischer and Dr. Boaz Barak of the Sagol School of Neuroscience and School of Psychological Sciences who led the research, could carry implications for understanding and applying pressure-chamber therapy for autism.

Autism spectrum disorder (ASD) is a multifactorial neurodevelopmental disorder characterized by impaired social communication and repetitive behavior, among other symptoms. ASD is highly heritable, with SHANK3 being one of the high-risk genes for ASD.

The research was published in the International Journal of Molecular Sciences under the title “Hyperbaric Oxygen Therapy Alleviates Social Behavior Dysfunction and Neuroinflammation in a Mouse Model for Autism Spectrum Disorders.”

Fischer and Barak explained that hyperbaric oxygen therapy (HBOT) is a form of treatment in which patients sit in special chambers where the air consists of 100% oxygen – way above the 21%, 78% nitrogen and one percent argon in the air we normally breathe – and the atmospheric pressure is higher than the pressure we experience at sea level.

 Tel Aviv University. (credit: MOSHE BEDRASHI) Tel Aviv University. (credit: MOSHE BEDRASHI)

HBOT is widely considered safe, and has already been used to treat a long list of medical conditions, including in Israel. In recent years, scientific evidence has been accumulating that unique protocols of such treatments improve the supply of blood and oxygen to the brain, thereby improving brain function.

According to the US National Institutes of Health, there are currently 14 approved indications for HBOT, including a wide variety of complications like air embolism, severe anemia, certain infectious diseases or sensorial hearing loss for which there is no known cause.

In addition, in the last European Consensus Conference on Hyperbaric Medicine highlighted the use of HBOT as a primary treatment method for certain conditions according to their moderate-to high-degree of evidence, such as after carbon monoxide (CO) poisoning. There has been a “moderate amount” of scientific evidence of success for treating diabetic foot sores, and some suggest it can help COVID-19 patients.

“The medical causes of autism are numerous and varied, and ultimately create the diverse autistic spectrum with which we are familiar. About 20 percent of autistic cases today are explained by genetic causes, that is, those involving genetic defects, but not necessarily ones that are inherited from the parents. Despite the variety of sources of autism, the entire spectrum of behavioral problems associated with it are still included under the single broad heading of ‘autism,’ and the treatments and medications offered do not necessarily correspond directly to the reason why the autism developed,” said Barak.

Preliminary phase of the study

In the preliminary phase of the study, a girl carrying the mutation in the SHANK3 gene was treated by Prof. Shai Efrati, director of the Sagol Center for Hyperbaric Medicine at Tzrifin’s Shamir (Assaf Harofeh) Medical Center and a faculty member at the Sagol School of Neuroscience, which was a partner in the research. Upon completing a series of treatments in the pressure chamber, it was evident that the girl’s social abilities and brain function had improved considerably, Efrati reported.

In the next stage and to more deeply understand the success of the treatment, the team of researchers at Barak’s lab wanted to understand what pressurized pure oxygen does to the brain. They used adult mice carrying the same genetic mutation in the SHANK3 gene as that carried by the girl who had been treated. The experiment comprised a protocol of 40 one-hour treatments in a pressure chamber, which lasted several weeks.

“We discovered that treatment in the oxygen-enriched pressure chamber reduces inflammation in the brain and leads to an increase in the expression of substances responsible for improving blood and oxygen supply to the brain, and therefore brain function. In addition, we saw a decrease in the number of microglial cells, immune system cells that indicate inflammation, which is associated with autism,” Barak reported.

"We saw a decrease in the number of microglial cells, immune system cells that indicate inflammation, which is associated with autism.”

Dr. Boaz Barak

“Beyond the neurological findings we discovered, what interested us more than anything was to see whether these improvements in the brain also led to an improvement in social behavior, which is known to be impaired in autistic individuals,” he explained.

“To our surprise, the findings showed a significant improvement in the social behavior of the animal models of autism that underwent treatment in the pressure chamber compared to those in the control group who were exposed to air at normal pressure, and without oxygen enrichment,” he continued. “The animal models that underwent treatment displayed increased social interest, preferring to spend more time in the company of new animals to which they were exposed in comparison to the animal models from the control group.”

Fischer concluded that “the mutation in the animal models is identical to the mutation that exists in humans. Therefore, our research is likely to have clinical implications for improving the pathological condition of autism resulting from this genetic mutation and likely also of autism stemming from other causes. Because the pressure chamber treatment is non-intrusive and has been found to be safe, our findings are encouraging and demonstrate that this treatment may improve these behavioral and neurological aspects in humans as well, in addition to offering a scientific explanation of how they occur in the brain.”