Autistic Disorder (autism), along with Asperger syndrome and pervasive developmental disorder–not otherwise specified, comprise a spectrum of neurode-developmental disorders (collectively termed autism spectrum disorders or ASD) that are characterized by restrictive and repetitive behaviors along with impairments in communication and social interaction. The number of children diagnosed with ASD has increased over the last decade and ASD currently affects as many as 1 out of 150 individuals in the United States (U.S.). ASD is generally considered a “static” neurological disorder without any known cure. The use of hyperbaric treatment in children with ASD has increased in recent years and traditionally involves inhaling up to 100% oxygen at a pressure greater than one atmosphere (atm) in a pressurized chamber. Most typical indications for hyperbaric treatment involve the use of hyper-baric pressures above 2.0 atm. Higher atmospheric pressures are generally required to treat conditions such as carbon monoxide poisoning and to improve wound healing. However, improvements have been observed via treatments with 95–100% oxygen and hyperbaric pressures of 1.5–2.0 atm for some chronic neurological conditions, including autism, fetal alcohol syndrome, cerebral palsy, and chronic or traumatic brain injury. Furthermore, improvements in some of these conditions, including autism and cerebral palsy, have been observed with the use of hyperbaric pressures of 1.3 atm and oxygen levels of 21–24%.
In one study, significant improvements were observed in children with autism with the use of hyperbaric treatment at both 1.5 atm/100% oxygen and 1.3 atm/24% oxygen; neither hyperbaric protocol worsened markers of oxidative stress and both reduced C-reactive protein (a marker of inflammation). Rationales for the use of hyperbaric treatment in autism include decreasing inflammation, improving cerebral hypoperfusion, and modulating immune dysregulation, all reported as problems in some individuals with autism. Several case reports and three uncontrolled studies enrolling between 6 and 18 children with autism have reported clinical improvements with hyperbaric treatment at 1.3 atm.