The effects of hyperbaric oxygen therapy on oxidative stress, inflammation, and symptoms in children with autism: an open-label pilot study

Abstract

Background: Recently, hyperbaric oxygen therapy (HBOT) has increased in popularity as a treatment for autism. Numerous studies document oxidative stress and inflammation in individuals with autism; both of these conditions have demonstrated improvement with HBOT, along with enhancement of neurological function and cognitive performance. In this study, children with autism were treated with HBOT at atmospheric pressures and oxygen concentrations in current use for this condition. Changes in markers of oxidative stress and inflammation were measured. The children were evaluated to determine clinical effects and safety.

Methods: Eighteen children with autism, ages 3-16 years, underwent 40 hyperbaric sessions of 45 minutes duration each at either 1.5 atmospheres (atm) and 100% oxygen, or at 1.3 atm and 24% oxygen. Measurements of C-reactive protein (CRP) and markers of oxidative stress, including plasma oxidized glutathione (GSSG), were assessed by fasting blood draws collected before and after the 40 treatments. Changes in clinical symptoms, as rated by parents, were also assessed. The children were closely monitored for potential adverse effects.

Results: At the endpoint of 40 hyperbaric sessions, neither group demonstrated statistically significant changes in mean plasma GSSG levels, indicating intracellular oxidative stress appears unaffected by either regimen. A trend towards improvement in mean CRP was present in both groups; the largest improvements were observed in children with initially higher elevations in CRP. When all 18 children were pooled, a significant improvement in CRP was found (p = 0.021). Pre- and post-parental observations indicated statistically significant improvements in both groups, including motivation, speech, and cognitive awareness (p < 0.05). No major adverse events were observed.

Conclusion: In this prospective pilot study of children with autism, HBOT at a maximum pressure of 1.5 atm with up to 100% oxygen was safe and well tolerated. HBOT did not appreciably worsen oxidative stress and significantly decreased inflammation as measured by CRP levels. Parental observations support anecdotal accounts of improvement in several domains of autism. However, since this was an open-label study, definitive statements regarding the efficacy of HBOT for the treatment of individuals with autism must await results from double-blind, controlled trials.

Trial registration: clinicaltrials.gov NCT00324909.

Figure 1

Changes in mean blood values before and after hyperbaric therapy at both 1.3 atm and 1.5 atm. The first column in a-d is the mean value for control children as described by James et al. [51] and is included as a standard reference (labeled as "control"). P-values and blood levels are listed above the bar graphs. a: Changes in mean oxidized glutathione levels. b: Changes in mean tGSH/GSSG.c: Changes in mean fGSH/GSSG. d: Changes in mean adenosine levels

Figure 2

Changes in mean CRP before and after hyperbaric therapy at both 1.3 atm and 1.5 atm. P-values and blood levels are listed above the bar graphs.

Figure 3

Changes in clinical scales at 1.3 atm and 24% oxygen. Declining scores on each scale indicate clinical improvements. Scores are listed above the bar graphs at baseline (0) and after every 10 treatments (10, 20,30, and 40). P-values are listed above the bar graphs. a:Changes in ABC-C subscales at 1.3 atm and 24% oxygen. b:Changes in SRS subscales at 1.3 atm and 24% oxygen. c: Changes in ATEC subscales at 1.3 atm and 24% oxygen.

Figure 4

Changes in clinical scales at 1.5 atm and 100% oxygen. Declining scores on each scale indicate clinical improvements. Scoresare listed above the bar graphs at baseline (0) and after every 10 treatments (10, 20, 30, and 40). P-values are listed above the bar graphs. a: Changes in ABC-C subscales at 1.5 atm and 100% oxygen. b: Changes in SRS subscales at 1.5 atm and 100% oxygen. c: Changes in ATEC subscales at 1.5 atm and 100% oxygen.