Hyperbaric oxygen is being used to treat a host of brain conditions, from stroke to cognitive impairment. Celeste McGovern investigates.
Keren Trebelsi, a 46-year-old mother of two and CEO of an international cosmetics company, was on a flight from South Africa to Israel two years ago when she began to feel unwell.
By the time the plane landed, she was “really not well.” Her husband rushed her straight to the hospital, where she was admitted for an ischemic stroke in the right side of her brain.
The left side of her body was paralyzed, and after she underwent a three-hour surgery, the prognosis was not good, she recalls. “They weren’t optimistic. They thought it didn’t look good at all.”
In the months following her stroke, the paralysis in her arm and leg became less concerning than the changes she noticed in her mental function. “It was almost like my mind was playing ping-pong. I was feeling so stupid all the time,” she says. “Filling a form on the internet was such a struggle.”
Keren wondered how she could ever go to back work and function. “I was like, oh my gosh, how will I ever be able to cope in life? It was very, very scary.”
Fortunately, she happens to know Shai Efrati, a professor at the Sackler School of Medicine at Tel Aviv University (TAU), a leading researcher in the field of raising oxygen concentration in patients with brain damage and a founding director of the Sagol Center for Hyperbaric Medicine and Research, which treats up to 200 patients with hyperbaric oxygen each day. He got Keren into hyperbaric oxygen therapy.
Hyperbaric oxygen therapy—or HBOT—is exposure to pure oxygen in a pressurized chamber. It differs from the oxygen delivered through a mask in a hospital, for example, because of the pressure, which forces more oxygen to be dissolved in the blood plasma and diffused into tissues throughout the body.
“If you’ve ever been on a commercial airplane, you’ve been in a hyperbaric chamber,” explains Edward Fogarty, a radiologist from North Dakota who has published papers on HBOT for brain damage. The difference is that with HBOT you are breathing 100 percent oxygen.
The increased air pressure in the chamber leads to improved cellular oxygen delivery, which is why HBOT so effectively treats carbon monoxide poisoning, for example.
The increased pressure of oxygen also compresses bubbles. HBOT has been used for decades to treat conditions in which dangerous gas bubbles develop in people, such as decompression sickness or “the bends,” when deep-sea divers ascend too quickly and develop potentially fatal nitrogen gas bubbles in tissue.
In the past decade, however, a tidal wave of research has shown that oxygen, which affects both oxidative and antioxidant systems in the body, ignites cascades of anti-inflammatory reactions, triggering proliferation of stem cells and a host of growth factors that catalyze the healing process.1
Among its many actions, HBOT stimulates the growth of new blood vessels, or angiogenesis. It promotes brain-derived neurotrophic factor (BDNF), which is like Miracle Gro for new nerve cells in the brain. BDNF increases brain metabolism, improves the blood-brain barrier’s permeability and charges production of glutathione, the body’s super-antioxidant.2 It even improves insulin sensitivity.3
HBOT has also been shown to lengthen telomeres, which are a measure of cellular aging, meaning it slows cellular aging.4
“It’s almost like driving a Ferrari on the road to recovery, versus driving your old beaten-up car,” says Keren. “My physiotherapist couldn’t believe how fast I was improving. It got to a point where one day, I just could walk, with a walker, but I was standing, and I could walk.” Now, Keren walks 4 kilometers every day.
Some changes were completely unexpected. She had been told, for example, that she would never be able to feel sensation in her left hand again, but after her hyperbaric oxygen therapy, she was doing dishes one day when she felt the dishes slipping from her hands and the sensation began to return. Soon she was able to type.
More importantly for Keren, however, was a return of function of her cognitive abilities. “I used to really like doing puzzles, like crosswords and Sudoku . . . this was something I used to do in my free time, and I just couldn’t do it anymore.
“One day, probably halfway through my treatment, I sat down in the chamber, I put on my oxygen mask, and, wow, I could do it! I finished. I was so proud of myself.”
The effort likely paid off in long-term benefits beyond just boosted cognitive function. Since having a stroke significantly raises the risk of dementia, including Alzheimer’s, the oxygen therapy may have averted serious cognitive decline down the road.5
Many larger hospitals are equipped with hyperbaric oxygen chambers, which are used exclusively for 13 specific conditions approved by the US Food and Drug Administration. These include the bends, crush injuries, severe anemia, severe burns, radiation damage from cancer treatment, gangrene and sudden hearing loss. Stroke and many other brain conditions are not on the list.
Most recently, the FDA added non-healing diabetic ulcers to its HBOT indications.6 However, the use of oxygen to heal wounds goes back decades, showing that as many as three-quarters of persistent deep infections resolve with it.
A study published in April this year examined a total of 774 diabetic wounds treated by HBOT. Of those, 472 (61 percent) completely healed, 177 (22.9 percent) partially healed, 41 (5.3 percent) deteriorated, and about 10 percent went on to be amputated.7
In the United Kingdom, about 60,000 people have diabetic foot ulcers, and the National Health Service amputated 27,465 affected lower limbs and toes between 2015 and 2018.8 Nevertheless, health authorities still say they are waiting on more evidence before they approve oxygen therapy.
That, unfortunately, is the stance of most of mainstream medicine regarding HBOT. Since oxygen can’t be patented, oxygen therapy doesn’t have the sponsorship of pharmaceutical companies, and it’s given only a glance in medical school. Hospital hyperbaric chambers are reserved mostly for rare conditions like the bends and as a sort of last-ditch effort for only the most “treatment-resistant” wounds.
In the medical literature, however, emerging evidence is stacking up for HBOT treating a wide range of conditions—from aiding in stroke and heart attack recovery and restoring brain function in children who survived near-drowning accidents to reversing cognitive decline, including even diagnosed Alzheimer’s disease. In animals, HBOT has aided in recovery following spinal cord injury.9
Recent studies point to HBOT’s use in treating COVID-19, including lingering long COVID after-effects of the virus’s lethal spike protein, as well as fibromyalgia and even childhood trauma.
The long practice of using hyperbaric oxygen to treat addictions and damage from drug and alcohol abuse, in the United Kingdom in particular thanks to hyperbaric pioneer Dr Philip James, has new research to support it.10 Dr James, emeritus professor of medicine at the University of Dundee in Liverpool, has studied and promoted HBOT for decades and is a world-renowned expert on the treatment.
In the US, dozens of companies sell hyperbaric chambers for personal use in homes or in private practice. But north of their border, Health Canada so strictly regulates the machines that this is nearly impossible, and there are fewer chambers across Canada than there are in the state of Florida.
In private practices, HBOT is used to treat a variety of conditions that hospitals neglect: wounds, cerebral palsy, multiple sclerosis, blast injuries in veterans, concussions and post-traumatic stress disorder.
Athletic associations like the NFL have hyperbaric oxygen chambers for post-workout recovery, and many players own their own home HBOT chambers. Tennis champion Novak Djokovic even brought his chamber to the US Open in 2019.
Former football superstar Joe Namath swore that HBOT saved his brain after multiple hits to the head in the game over the years, and swimming champ Michael Phelps and boxer Evander Holyfield have sung the praises of hyperbaric oxygen, too.
While ESPN sports network dismissed Namath’s “dubious” HBOT oxygen therapy and his recovery as a placebo effect, one of the hottest emerging fields is its use in the treatment of stroke, traumatic brain injury, cognitive impairment and neurodegenerative diseases, which are all entangled.
Tel Aviv University’s Dr Shai Efrati views many of these conditions as “biological wounds”—the difference being that you can’t see a brain wound with the naked eye. Advanced scanning techniques, including SPECT (single-photon emission computed tomography) and perfusion MRI (magnetic resonance imaging), which shows blood flow to the brain, easily make areas of tissue damage visible in brains that look normal on ordinary MRI scans.
Just as there are areas of dead, necrotic tissue surrounded by living, active wound tissue in diabetic ulcers, so there are dark areas of no activity in the brain, which are necrotized and can’t be revived. Nevertheless, they are surrounded by living tissue that has the potential to rejuvenate.
To heal flesh wounds, such as diabetic ulcers, the area needs to be flooded with oxygen so that stem cells can move in, and new blood vessels will grow and perfuse the area. So too with brain wounds.
In one of his landmark studies a decade ago, Dr Efrati and his colleagues, including Professor Eshel Ben-Jacob of the Tel Aviv University School of Physics and Astronomy and the Sagol School of Neuroscience, recruited post-stroke patients whose condition was no longer improving to undergo hyperbaric oxygen therapy.
Seventy-four participants ranging from six to 36 months post-stroke were split into two groups. The first treatment group received forty 90-minute sessions of HBOT five days a week from the beginning of the study, and the second received no treatment for two months, then received a two-month period of the therapy.
Scans showed increased brain activity after the HBOT treatment compared to after control periods. What’s more, patients reported improvements including reversal of paralysis, increased sensation and improved speaking ability—demonstrating that even years after a stroke, new neurons can grow and brain injury can be ameliorated.11
The changes that HBOT induces in the brain can dramatically impact a person’s life. Cindy Parsons started receiving HBOT therapy at the AVIV clinic—a recently opened Florida satellite of Dr Efrati’s clinic in Israel—four years after she had a stroke and was finally able to improve her speech, comb her own hair and drive a golf cart.
The Israeli researchers confirmed their findings with another study in 2015 of 91 patients who had either ischemic or hemorrhagic strokes three to 180 months before HBOT therapy. The patients showed significant improvements in all memory measures after the treatment, which correlated with improved brain metabolism on images.12
Since then, a growing number of studies and case reports have documented healing of brain injuries and cognitive disorders using HBOT. One case report was published by leading American HBOT doctor Paul Harch of Louisiana State University School of Medicine and radiologist Edward Fogarty of the University of North Dakota in 2018. A 58-year-old woman diagnosed with rapidly progressing Alzheimer’s disease was treated with hyperbaric oxygen for 50 minutes per day, five days a week, for eight weeks.
Before-and-after brain imaging using fluorodeoxyglucose (18FDG) positron emission tomography (PET) scans clearly showed increases of up to 38 percent in brain metabolism in select parts and all of her brain. These changes appeared in tandem with her improved ability to complete cognitive and physical tasks plus a better mood and quality of life.
The paper noted that this was the “first reported case” of HBOT improving Alzheimer’s disease documented by PET scans, suggesting “an effect on global pathology in AD.”13
The Israeli researchers keep bringing more data to the picture. After demonstrating recoveries in cases of traumatic brain injury similar to those following stroke,14 the Israeli researchers, led by Dr Amir Hadanny, published another critical study in 2020, this time looking at cognitive decline.
“The occlusion of small blood vessels, similar to the occlusions which may develop in the pipes of an ‘aging’ home, is a dominant element in the human aging process,” said Dr Efrati. “We found that HBOT induced a significant increase in brain blood flow, which correlated with cognitive improvement, confirming our theory.”15
Chinese researchers confirmed these findings with their own 2020 study of Alzheimer’s patients given just 20 days of “mild” HBOT for under one hour.
Compared to controls, hyperbaric oxygen treatment significantly improved cognition in Alzheimer’s patients at one‐month follow‐up—to a level much greater than that of the current leading drug, donepezil. However, the effect wore off.
In patients with mild cognitive impairment, however, enhanced cognitive function following HBOT lasted longer. Memory and cognitive scores were significantly improved at one‐month and six‐month follow‐ups.
Images also showed improvement of glucose metabolism in brain regions associated with language function and memory. Glucose metabolism seemed to improve more in cognitively impaired patients than in AD patients, leading the researchers to conclude that “hyperbaric oxygen treatment might be a preventive strategy by blocking the conversion of [mild cognitive impairment] to [Alzheimer’s].”16
Research in the past decade points to a dearth of oxygen supply in some diseases that predisposes individuals to neurodegeneration afterward.1 So, hypoxia—or lack of oxygen—from injury, stroke or renal disease, for example, seems to play a major role in neurodegenerative disorders including Alzheimer’s, Parkinson’s, Huntington’s and amyotrophic lateral sclerosis (ALS). Restoring oxygen has become an obvious potential target for therapy.2
Lack of blood flow in the brain leads to hypoxia, which has been observed in the early stages of Alzheimer’s and correlates to a downhill slide, including accumulation of beta-amyloid and degeneration of neurons.3
Similarly, in Parkinson’s, hypoxic brain injury enhances α-synuclein aggregation, a signature of the disease. And hypoxia creates and drives ALS as well. Occupations linked to low oxygen conditions, like being a firefighter, double the risk of developing ALS.
Another factor affecting the development of dementia and age-related cognitive decline is impaired microcirculation of blood in the brain, which has been associated with vascular cognitive decline. It makes sense that restoring blood flow, via flooding the system with oxygen, might help.4
Besides stroke and dementia, hyperbaric oxygen has also been used successfully to treat the following conditions.
Parkinson’s: In one case report, a 45-year-old diagnosed with Parkinson’s, with significant tremors, suicidal depression, insomnia and severe weight loss receiving treatment for one month enjoyed a great reduction in tremors, regained 10 kg (22 lb) and returned to eight or 10 hours a night of sleep. His depression and anxiety scores were nearly halved as well.17
Fibromyalgia: Although many doctors still dismiss fibromyalgia—pain in certain parts of the body—as psychosomatic, advanced imaging has revealed that fibromyalgia originates from damaged areas in the brain that control sensitization.
Dr Efrati’s mother, who had a wracking case of fibromyalgia and was unable to lift her grandbabies, has now recovered thanks to HBOT.
A follow-up study published earlier this year looked at 58 adults with fibromyalgia for more than a year with a triggering event of traumatic brain injury.
“Dramatic,” says Dr Efrati. “Two out of five patients in the hyperbaric treatment group showed such a significant improvement that they no longer met the criteria for fibromyalgia. In the drug treatment group, this did not happen to any patient.”
What’s more, the average improvement in the pain threshold tests was 12 times better in the hyperbaric group than in a control group given medication. “And in terms of quality-of-life indicators, as reported by the patients, we saw significant improvements in all the indicators among the patients who received hyperbaric treatment,” says Dr Efrati.18
Although in this study the brain injury was caused by direct physical injury from an accident or blast wave, in a previous study the Tel Aviv University researchers showed that HBOT could help fibromyalgia patients with a history of childhood sexual abuse. They noted that any severe mental stress—especially if it causes dissociation from memories—can lead to brain injury that is like physical injury.19
Long Covid: Several studies point to the benefits of HBOT for treating Covid-19, and it has also been studied for treating long Covid—the lingering effects of the disease that have been linked to a list of neurological diseases.20 A clinical trial is currently underway at the Karolinska University Hospital in Sweden to further explore the value of HBOT for long Covid.21
The gut has long been considered an anoxic environment where only anaerobic bacteria flourish. However, that dogma is being reconsidered after research has demonstrated that mice exposed to hyperbaric oxygen therapy for nine days experienced a five-fold increase of tissue oxygenation and a shift in gut microbes observed in fecal samples with the growth of aerobic Proteobacteria and Actinobacteria.
It’s not known how these changes might affect the body, but Actinobacteria are pivotal players in maintaining gut homeostasis, so theoretically, HBOT may affect the microbiome beneficially.
While there are many different types of HBOT chambers, the principle is the same: the person breathes oxygen in a mask while sitting or lying in a pressurized chamber.
The pressure ranges from “mild”—just above sea level, which is 1 atmosphere absolute (ata)—to 2.0 or 2.5 ata and should never exceed 3.0 ata.
“Soft” chambers typically reach a pressure of only 1.3 ata, and these are most common in private clinics and homes. They can be rented or purchased in the US and don’t require extensive training to use. Hospitals and many clinicals use “hard” chambers that provide pressure of 2.0 to 2.5 ata.
The number of “dives” that a patient is advised to take varies based on their condition, from one or two for an acute problem to 40 to 60 sessions for a chronic condition. Sessions usually last one to two hours, often with periodic breaks of breathing room air rather than oxygen.
The most common side effect of hyperbaric oxygen treatment is middle ear barotrauma—also known as “airplane ear” because it often occurs while flying in an airplane. It can range from a feeling of fullness or pressure in the ear to muffled hearing but is usually tolerable and resolves within minutes to a few days after HBOT.
Other complications include headache, claustrophobia, reversible myopia (nearsightedness) and, very rarely, seizure. Most of those complications are mild and reversible when the treatment is stopped.
Cataract formation has been described as an extremely rare side effect, most often occurring with a high number of dives, usually more than 150 sessions.1
At lower pressures in “soft chambers” and with dives lasting under an hour, side effects are substantially reduced, but many of the studies on brain conditions are conducted at higher pressures of 2.0 to 2.5 ata.