Rossignol 2009 RCT positive at 1.3 ATA, challenged on sham design. Larger follow-up trials inconsistent.
Overview
HBOT for autism spectrum disorder (ASD) was a prominent topic in the mid-2000s. A small 2009 RCT (Rossignol et al.) showed benefit, but a larger follow-up trial failed to replicate the results. The current medical consensus is that HBOT for autism lacks sufficient evidence and should not be considered an established therapy. Research continues at lower-pressure protocols.
How HBOT Works
Hypothesised mechanisms include reduction of neuroinflammation and improvement of cerebral perfusion in regions showing hypoperfusion on imaging. Whether these mechanisms are clinically meaningful at the 1.3 ATA pressure typical of ASD trials — vs the 2.0 ATA used in Efrati-lab neurological research — remains debated.
Clinical Protocol
Typical protocol
40 sessions at 1.3–1.5 ATA (soft-shell)
Evidence level
Mixed — Not currently supported
FDA / regulatory status
Not FDA-approved; not recommended by autism medical bodies
Cautions & Considerations
Not an established treatment; evidence is mixed.
Significant out-of-pocket cost without insurance coverage.
Opportunity cost of time and money that could support behavioural interventions.
Marketing claims often overstate the evidence.
Key Research
Rossignol et al. 2009 (positive, 1.3 ATA)
Granpeesheh et al. 2010 (negative replication)
Multiple meta-analyses
Indexed studies
Hyperbaric Treatment for Children with Autism: A Multicenter, Randomized, Double-Blind Controlled Trial (2009, Level 1, 1.3 ATA) — PMID 19284641
Questions to Ask Your Doctor
Am I a candidate for HBOT for this condition given my medical history and current treatments?
What pressure (ATA) and session count would you recommend, and why?
Is treatment at this centre UHMS-accredited? What is the chamber type (monoplace or multiplace)?
What is the expected response rate and typical timeline for improvement?
What are the specific contraindications and side-effect risks in my case?
What is the expected cost and insurance coverage status?
What alternative or complementary treatments should I consider?