Accept psychological effects, urges Michael Hyland

Modern medicine is based on the assumption that there are specific causes of disease, and that specific treatments have a therapeutic effect by ‘correcting’ that specific cause.

Any treatment has a specific effect (e.g., the biochemical effect of a drug) and a non-specific effect (e.g., the psychological effect of knowing that you are taking a treatment).  In medicine this non-specific effect is termed a placebo and, at least from the perspective of research, is treated as a kind of nuisance variable.

The relative contribution of the non-specific (placebo) effect and specific effect varies substantially in conventional medicine. Whereas placebos are ineffective for setting broken bones, 80 per cent of the effect of modern anti-depressants is placebo mediated and only 20 per cent due to the active effect of the drug.

Non-specific effects

Homeopathy has been tested as though it were a conventional medical treatment using the randomised controlled trial (RCT), and results have by and large been equivocal. The lack of clear RCT evidence to support homeopathy must lead to the conclusion that homeopathy is working in some different way to conventional medicine, i.e., that it is primarily a non-specific effect.

The conclusion that homeopathy is effective due to a placebo effect often leads to the unwarranted conclusion that homeopathy is useless. Because conventional medicine has nailed its colours to the mast of specific effects, it often fails to appreciate the importance of non-specific effects.

The conventional psychological view is that placebos work through expectancy. However, expectancy does not seem to explain outcome well in the case of homeopathy. In my own research, I have found that spirituality is a better and independent predictor of outcome compared with expectancy in flower essences (which are related to homeopathy in that there are normally no ‘active’ biochemicals).

Mechanisms

Two possible mechanisms underlie the effectiveness of homeopathy.  One is that it works through some conventional psychological mechanism that is yet to be understood. The other is there is some other ‘unconventional’ mechanism, such as quantum entanglement or electromagnetic radiation. In either case, the best evidence is that it is a non-specific effect, and one which is particularly helpful for many diseases and not just those which have psychological symptoms – but homeopathy will not set broken bones.

Homeopathy is useful – but we need to stop pretending that it is a specific treatment, and we need to accept that there is role both for specific and non-specific treatments in medicine.

Michael E. Hyland is Professor of Health Psychology at the University of Plymouth