To task. I must confess that I was slightly reluctant to write this first post of the new year. Reluctant because I am not an expert on hyperbaric oxygen therapy (HBOT) as a proposed intervention for autism and related conditions. Nevertheless there is a research base to HBOT and autism (albeit currently quite limited), and given that this is a blog supposedly about autism research, the time has come to put pen to paper so to speak.
I got to this post via an interesting report on whether or not a US hospital should be offering HBOT as an intervention option for children with autism. Opinions abound on this topic it seems.
The first thing that comes to my mind (emphasis on the 'my') when talking about anything related to hyperbaric is a scene in the James Bond film, License to Kill. Mr Bond, played by Timothy Dalton, convinces the main villain to pop another villain into a hyperbaric chamber leading to quite a nasty depressurised end. I appreciate that this may not be the best advert for the hyperbaric chamber, but unfortunately that is my recollection, no doubt influenced by my 1980s movie mindset.
The more realistic view of HBOT for treating things like decompression sickness is thankfully a little safer and controlled where the proper expertise is on hand. The technique involves administering oxygen at pressures greater than one atmosphere (atm). Outside of the more traditional uses for HBOT, the theory is that whole body saturation with oxygen administered at pressure might have some onward positive effects for things like brain function particularly where blood flow is impaired and oxygenated levels might be poor. Looking at the evidence base with regards to things like traumatic brain injury and acute migraine, one can perhaps see some promise of effect from HBOT.
Given all the interest in the brain in relation to autism spectrum conditions, it is little wonder that HBOT has been touted as a possible intervention option. More than that however is the potential link between autism and inflammation in all its forms, which might provide another therapeutic target for HBOT.
The research base is, as I said, currently quite small for HBOT use in autism. It started with a few speculative papers published in the journal Medical Hypotheses (here and here). These have been subsequently followed by a few open and more controlled trials on HBOT with some encouraging but mixed results. This paper for example by Dan Rossignol, who seems very much to have lead the advancement of HBOT for autism (more on in him in future posts), suggested some effect on behavioural measures and inflammatory markers (C-reactive protein). The study was an open one and had no control group (either asymptomatic or receiving a sham intervention). Same with this study and same results (behavioural) and this more recent trial which found behavioural improvements but no significant changes to cytokine levels. Other studies have not found any significant effect.
Where a randomised-controlled design has been used, the results did indicate some potential for HBOT for at least some cases of autism. This study came to the conclusion that hyperbaric treatment at 1.3 atmospheres (24% oxygen) over a number of sessions produced a significant effect compared with normal atmosphere, normal oxygen levels. To reiterate my non-professional status with HBOT, I don't know enough about it to say what an increase of 3% over and above normal air oxygen levels administered at 1.3 atmospheres might do. It is difficult to match hyperbaric results with studies for other conditions because parameters can be different (how much oxygen is used and at what pressure). Studies of HBOT for cerebral palsy in children for example, have noted no overall difference between groups when greater oxygen levels were delivered at 1.75 atmospheres compared with only slightly pressurised air being delivered (results were beneficial in both cases). Other studies looking at using HBOT to tackle radiation-induced necrosis in children for example, reported on conditions of 100% oxygen delivered at 2-2.4 atm pressure and noted some potential effect.
On balance, the results obtained for HBOT for autism so far (stress: so far), whilst limited, do tend to suggest that it might be a beneficial intervention option for some. I hasten to add that I am in no way endorsing such an intervention given factors like the accepted uses for HBOT, the price of HBOT and the requirement for multiple sessions. The potential longer-term safety aspects also require a little more study.
To end, a song to reinvigorate you after the post-party/hangover season (although not for any tongue phobics)... "we'll drive you wild.."