Also note that the 'nih.gov' link probably unduly impacts credibility - it's just the pubmed central site, not an NIH-supported trial.
> Apart from activating the body’s system of temperature regulation, there is also a hormonal response, which increases body metabolism and the concentrations of adrenaline, noradrenaline, adrenocorticotropic hormone (ACTH), cortisone, pro-opiomelanocortin (POMC), and β-endorphins in blood plasma as well as male testosterone levels
The most awesome head high I've ever experienced was jumping into a icy creek after hiking all day on a hot spring day.
Perhaps it is important. Perhaps it has a negligible effect to cure/improve the condition of the patients.
(You can get adrenalin and testosterone rush seeing an horror movie. Does it also work as a cure?)
If the study is not double blind you have two problems:
1) People want to be cured and want to be nice to the doctors that are making a huge effort to cure them, so they lie. The people don't lie on purpose. They are just a little optimistic and give involuntary an inaccurate answer.
(The effect is bigger in relative questions like "In the scale from 1 to 10, how much does it hurt?" than in objective questions like "How many fingers do you still have?".)
It's difficult to "blind" the patients here, because the placebo treatment must be as indistinguishable as posible for the patients. Perhaps they can put half of the people at -160°C and the other half at -10°C or -20°C. I guess people will not notice the difference if they live in a tropical country. Let's hope hat the effect is triggered in one case and not in the other.
2) Medics want to find a cure, save the humanity, get a Nobel prize, don't see they effort wasted, so they lie. The medics don't lie on purpose. They are just a little optimistic and give involuntary an inaccurate evaluation.
(Also the effect is bigger in relative question than in objective questions)
It's easier to blind the medics using one team to administer the treatment and other to evaluate the outcomes.
3) (There is always a 3.) The threated patients got 15 visits to the medical center to get the treatment. Does the effect come from the freezing or just for the 15 nice trips and warm welcome in the medical center? Did the patients take an additional bath before going to the treatment (to avoid being naked and dirty)? If your control group is not almost equal to the study group, it's difficult to understand what made the difference.
4) And remember to use a randomized group, to avoid cherrypicking the good candidates and putting in the control group the unsolvable cases.
https://news.ycombinator.com/item?id=948637
https://news.ycombinator.com/item?id=2595017
I'm sure there is a placebo aspect, but I wouldn't underwrite the anti-inflammatory component or the sensory stimulation component either.
As is cryotherapy, as a method of inducing heat shock protein release.
So, the controls should also be treated with a series of 15 daily visits to a chamber that is simply the same temperature as its surroundings.
Having 15 daily visits worth of contact with study personnel, in a chamber that exists for a specific purpose, may have a big impact, regardless of temperature. But you won't know unless you use a proper control.
One great challenge in studying complementary/integrative health interventions is selecting the right control group, because practitioners will argue that the control is too much like the active treatment. (So, for example, a cold shower /might/ work, if the mechanism is the same, so it wouldn't be a great control in the initial proof-of-concept experiment.)