Hyperbaric oxygen therapy may improve symptoms in autistic children

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Summary

Autism is a neurodevelopmental disorder that currently affects as many as 1 out of 166 children in the United States. Recent research has discovered that some autistic individuals have decreased cerebral perfusion, evidence of neuroinflammation, and increased markers of oxidative stress. Multiple independent single photon emission computed tomography (SPECT) and positron emission tomography (PET) research studies have revealed hypoperfusion to several areas of the autistic brain, most notably the temporal regions and areas specifically related to language comprehension and auditory processing. Several studies show that diminished blood flow to these areas correlates with many of the clinical features associated with autism including repetitive, self-stimulatory and stereotypical behaviors, and impairments in communication, sensory perception, and social interaction. Hyperbaric oxygen therapy (HBOT) has been used with clinical success in several cerebral hypoperfusion syndromes including cerebral palsy, fetal alcohol syndrome, closed head injury, and stroke. HBOT can compensate for decreased blood flow by increasing the oxygen content of plasma and body tissues and can even normalize oxygen levels in ischemic tissue. In addition, animal studies have shown that HBOT has potent anti-inflammatory effects and reduces oxidative stress. Furthermore, recent evidence demonstrates that HBOT mobilizes stem cells from human bone marrow, which may aid recovery in neurodegenerative diseases. Based upon these findings, it is hypothesized that HBOT will improve symptoms in autistic individuals. A retrospective case series is presented that supports this hypothesis.

Section snippets

Overview of autism

Autism is a neurodevelopmental disorder currently affecting as many as 1 out of 166 children in the United States [1] that is characterized by impairments in social interaction, difficulty with communication, and restrictive and repetitive behaviors [2]. It affects children from all socioeconomic and ethnic backgrounds [3]. Autism was considered a rare condition before the 1990’s with a prevalence of approximately 1 in 2500 children [4]. However, according to the US Department of Developmental

Hypothesis

Multiple studies have revealed that autism is a neurodegenerative disease characterized by cerebral hypoperfusion, neuroinflammation, and increased oxidative stress. HBOT helps overcome hypoperfusion, has potent anti-inflammatory effects and reduces oxidative stress. Furthermore, HBOT mobilizes stems cells from human bone marrow. Therefore, HBOT will improve symptoms of autism.

Evidence of decreased cerebral blood flow in autism and possible mechanisms of hypoperfusion

Even in the presence of normal magnetic resonance imaging (MRI) findings, focal areas of decreased cerebral blood flow occur in children with autism [26]. Multiple independent single photon emission computed tomography (SPECT) and positron emission tomography (PET) research studies have demonstrated hypoperfusion to several areas of the autistic brain, most notably the temporal lobes [26], [27], [28], [29], [30], [31], [32], [33], [34], [35], [36], [37], [38], [39]. Several studies show that

Evidence of neuroinflammation in autism

Recent studies reveal that autism is characterized by neuroinflammation. Autopsy brain samples of autistic patients demonstrate an active neuroinflammatory process in the middle frontal gryus, anterior cingulate gryus, and cerebellar hemispheres including increased microglial and astroglial activation and increased proinflammatory cytokines. Furthermore, cerebrospinal fluid obtained from living autistic patients also “showed a prominent proinflammatory profile” [49]. Previous studies of

Evidence of increased oxidative stress in autism

Recent studies have shown that autistic children have evidence of increased oxidative stress including lower serum glutathione levels [100]. Sogut et al. [101] demonstrated that autistic children had increased red blood cell nitric oxide, which is a known reactive free radical and is toxic to the brain [101]. James et al. [100] recently showed that total serum glutathione levels were 46% lower and oxidized glutathione was 72% higher in autistic children when compared to neurotypical controls.

Improving stem cell mobilization in autism

Recently, HBOT at 2.0 ATA and 100% oxygen for 2 h was shown to mobilize stem/progenitor cells from the bone marrow of humans. Elevations were found in the number of colony-forming cells as demonstrated by an increase in the number of CD34+ cells by almost 2-fold [126]. This finding is relevant because autism and hypoxic brain injuries are considered by many to be permanent conditions. However, new research is revealing that even long-standing brain disorders may be partially reversible [13], [14]

Testing the hypothesis

There is a strong possibility that HBOT could play an integral role in improving brain disorders associated with hypoxia, hypoperfusion, inflammation, and/or oxidative stress, including autism, through the improvement of oxygen supply, decreased inflammation and oxidative stress, and/or the recruitment of new stem cells (see Table 1). This in turn should lead to improved clinical outcomes. Some physicians have begun using HBOT in autistic children and anecdotal reports indicate that HBOT has

Acknowledgments

The authors thank the following for reviewing this manuscript and offering advice: Dr. John Battiston, Dr. Bentley Calhoun, Mr. Michael Haynes, Dr. Elizabeth Mumper, Dr. David Slawson, and Dr. Kyle Van Dyke. Written consent was obtained from the children’s parent(s) for publication of case series data. The authors have two autistic sons who participated in the case series.

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