Prior to 2009, there was a lack of RCTs on the efficacy of HBOT in autism. ABC-C and ATEC aggregate mean scores were improved within the group of children treated with hyperbaric oxygen (but not within the control group). Specifically, improvements were noted in the subscales of irritability, stereotypy, hyperactivity, and speech
with ABC-C, and sociability, sensory/ cognitive awareness, and health/ physical/ behaviour with
ATEC, immediately at the end of the 40 sessions compared with baseline scores. No differences in post-treatment aggregate ABC-C mean score and aggregate ATEC mean score were obtained when directly comparing the treated group and the control group. According to CGI, overall functioning improved in the treated group and not the control group post-treatment, with subscale improvements in receptive language, social interaction, and eye contact. There was no information on the cost-effectiveness of HBOT as no economic evaluations were retrieved.
Hence, findings from the RCT suggest that improvements may be seen in some children with autism treated with HBOT, but when results are compared to a control group, no difference was found as measured by three clinical instruments. Further research is required to determine if HBOT is an effective and cost-effective treatment for autistic children.