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Pontifications on Poison

Being some ramblings on events associated with poisonous plants.

Wednesday 7th September 2011

One of my favourite radio programmes is BBC Radio 4’s ‘More or Less’. I’m so interested in it that I have been known to switch it off, because I couldn’t give it my full attention, and listen to it later on the BBC website.

It is supposed to about numbers and how they are wrongly used by people who don’t know any better or misused by people who should. I put ‘supposed to be’ because an item on the latest programme had only a tangential relationship to numbers but it was very interesting.

Apparently, a recent report said that trials showed that acupuncture was effective in reducing pain. The producers of ‘More or Less’ asked a doctor who blogs about the subject to look at the stated results and see if the claimed improvements could be justified. The first, and most important, thing the doctor found was that there had been no control group during the trial.

If you are doing a trial to see if a drug or procedure works it is not enough to just give some people the procedure and compare them to people who have not had it. You have to have a group of people who are made to think they have had the procedure. This is because an essential principle of measuring things scientifically is to have only one variable. That is the only way to be certain that what you are measuring or observing is the result of the changes in that variable.

If you are testing a new drug, for example, it is easy to make up one set of pills containing the substance under test and a visually identical set made of all the same ingredients except for the test substance. Obviously, if you are examining a procedure rather than a drug the challenge is to find something that seems to be the procedure but isn’t. This is not always possible, for example, if you want to know if a surgical intervention is effective it is hard to create the impression that an operation has been performed.

With acupuncture, however, there are sham techniques that give the subject the belief that they have had acupuncture even though there is no penetration of the skin. There remains a drawback to this, however, which is that you cannot make a trial of acupuncture versus sham acupuncture double blind. Double blinding means that the person dealing with the trial subject does not know if that subject is having the actual test or is a control. This helps to eliminate any inadvertent communication to the subject that could tell them what they are receiving.

Clearly, there is no way for a person administering acupuncture or sham acupuncture not to know which procedure they are using. Nonetheless, having a control group receiving sham acupuncture is essential if you want to claim that any observed results are the result of the acupuncture and not the placebo effect.

Cannabis sativa

Cannabis sativa

Most people these days have heard of the placebo effect but a lot still think of it as just some sort of magic. It may seem like magic; the idea that people feel better in spite of not being given any actual medicine or treatment does seem inexplicable but, in fact, we do now have a pretty good understanding of what can trigger a placebo effect even if it remains hard to know why.

There have been trials showing that the way a medicine is given can make a difference to its effects; subjects told to ‘try this’, when given a sugar pill, reported less benefit that those given the same sugar pill but told ‘this has been very successful with other people’. There have been trials showing that simply taking an interest in someone’s condition without any intervention of any sort can produce a reduction in symptoms.

In spite of what has been claimed for acupuncture the largest effect* seems to be a result of the attention paid to the patient. If you go to your GP you get five minutes and, because your history is known, that is all that is needed to prescribe a remedy. If you go to an acupuncturist, they will spend quite a while taking your history so that they know what treatment to apply. Plus, of course, they are, usually, charging for their service so they feel the need to be seen to give value for money.

This last is one of the more worrying aspects of the placebo effect. Trials have shown that people respond better to expensive treatment. Subjects in one trial were treated identically except that one group were told the ‘medication’ (a sugar pill) was cheap and the other believed the pills to be costly. I find the cost effect worrying because, if a way can be found for doctors to harness the placebo effect without going against their ethical requirement not to lie to patients, you can’t be sure of getting the best effect from a free consultation.

Urtica dioica, stinging nettle

Urtica dioica, stinging nettle

Naturally, people who believe in things like homeopathy, are reluctant to accept that it is all placebo effect. If they believed the truth about homeopathic substances it could diminish the placebo effect so I tend not to bother to argue with them. I do, however, give them what to me is a telling example of the placebo effect.

Some years ago, in the USA, a trial was sanctioned for a substance derived from Cannabis sativa thought to be useful in reducing the nausea associated with chemotherapy. In trials, all the subjects are warned about any possible side effects from the drug being tested and, in this trial ‘getting high’ counted as a side effect. One of the trial subjects pulled out early because he said the medicine was making him high and he was not a drug type person and he did not like the experience of intoxication from cannabis. The trial records showed that he had been part of the control group, in other words the substance that got him high contained no cannabis whatever.

*I said ‘largest effect’ because I think there may be useful things about acupuncture that are still to be discovered. Trials conducted in Plymouth suggest that Urtica dioica, stinging nettle, might produce a reduction in pain though a great deal more work is needed to be sure it is the stinging that is creating the effect. To my simple mind it seems possible that causing mild pain, from nettles or needles, may cause the brain to wake up to the more serious pain it has been ignoring.


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