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Hyperbaric oxygen

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By which we mean the medical use of oxygen delivered at greater than atmospheric pressure. It involves the use of a special pressure chamber, which may be for an individual or sometimes it is a larger room that will accommodate several people. The traditional use of hyperbaric oxygen (HBO) is to prevent or treat decompression sickness (‘the bends’) in deep sea divers. That much I knew, until the last few days.

One of the delights of working with the media is that you don’t know what question may come up next, so when I was asked to comment on a recent scientific paper for a national newspaper, I was pleased to oblige. The Telegraph wanted to run a story on a paper from Tel Aviv University whose authors (Shapira et al., 2021) presented data from both animal studies and human volunteers, with evidence that mice that act as a model for Alzheimer’s disease had shown decreased amyloid burden and some improvement in behavioural measures. The six people who had received HBO had ‘significant memory impairment’ though dementia was not specified, and they showed improvements in the memory test scores that were employed.

I couldn’t comment on the animal work (not my sphere) but in relation to the human data, I thought that it was interesting but of course there were likely to be some large non-specific effects of the intervention, and it was not a double-blind randomised controlled trial of the kind that would be required to be regarded as sound medical evidence for a treatment. I also commented that (a) it was an interesting approach and a timely reminder of the importance of vascular factors in the genesis of most dementias, not just vascular dementia, but (b) I doubted that even if the treatment was shown to be effective in dementia it would be difficult to implement at the scale that might be required.

I’ve had an interesting and educational postbag since then, and also done a bit of reading around myself, in case anyone starts to mistake me for a world expert on HBO and dementia. I’m genuinely grateful to everyone who contacted me. Several correspondents gave accounts of how they had arranged HBO for an older relative with dementia and how much the person had benefitted. Someone else was thinking about buying a chamber for domestic use. I was also made aware of a voluntary network of HBO chambers across the UK that provide treatment for people living with multiple sclerosis. Manufacturers of HBO chambers have asked me if I wish to conduct research in this area.

I looked at the medical literature to examine the state of the evidence for benefits of HBO for various conditions. There are a couple of Cochrane reviews; for example, looking at HBO in MS (Bennett & Heard, 2004) which concluded not only that there was no evidence of efficacy but that future trials in this area were not warranted. Other Cochrane reviews have failed to find benefits in acute stroke or in childhood autism. Some side effects are possible, notably pneumothorax, and of course having a large supply of oxygen is potentially a fire hazard.

Whatever the medical evidence, HBO is clearly big business. A pressure chamber may cost around £100,000 or else individual session may cost several hundred pounds for an hour or so. For a long-term condition like dementia, presumably treatment would need to be indefinite. The internet has plenty of suppliers, so chambers are readily available to those who can afford them.

So, HBO for dementia, then? I don’t see it at the moment. It would be hard to do a randomised controlled trial and maybe there are vested interests in not having a trial as it might deter people who would otherwise seek (and pay for) the treatment. There is no evidence anywhere that I have seen that HBO makes a clinically significant or sustainable improvement in people with dementia. I accept that there are anecdotal reports but sometimes simply instilling hope makes a difference. If the benefits that people speak of are mainly placebo effects, then it’s a pretty expensive placebo. It is hard to see the regulators of treatments approving HBO for dementia for a very long time, if ever. Nice idea…but.


And a couple of references:

Bennett  MH, Heard  R. Hyperbaric oxygen therapy for multiple sclerosis. Cochrane Database of Systematic Reviews 2004, Issue 1. Art. No.: CD003057. DOI: 10.1002/14651858.CD003057.pub2. Accessed 16 September 2021. (Hyperbaric oxygen therapy for multiple sclerosis - Bennett, MH - 2004 | Cochrane Library): https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD003057.pub2/full.

Shapira R, Gdalyahu A, Gottfried I, Sasson E, Hadanny A, Efrati S, Blinder P, Ashery U. Hyperbaric oxygen therapy alleviates vascular dysfunction and amyloid burden in an Alzheimer’s disease mouse model and in elderly patients. Aging (Albany NY). 2021; 13:20935-20961. https://doi.org/10.18632/aging.203485 (pdf (aging-us.com))

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