Scientific evidence for the effects of non-contact healing
Professor Chris A Roe, Dr Elizabeth Roxburgh and Ms Charmaine Sonnex
Psychology Division, University of Northampton
The value of unconventional health interventions, such as healing, is disputed. Surveys have shown that many members of the general public believe in the power of healing, and there are a large number of healers practising in the UK. However, medical science has been sceptical, citing a lack of robust evidence as a rationale for this scepticism.
The currently accepted ‘best evidence’ for the effects of any health intervention comes from randomised controlled trials. This study design involves randomly allocating participants to a treatment or a no-treatment condition in such a way that they don't know whether they should experience a beneficial effect. This reduces biases and ‘controls’ for the effects of factors such as expectation and the so-called placebo effect, by having an appropriate comparison group to the intervention being tested. However, it is difficult to design a good comparative group for healing interventions, as the effect may depend on factors such as expectation and other elements of what are considered ‘placebo’ in the context of a drug trial.
We were funded by the CHO to carry out an updated review of published trials of healing, and to examine critically whether this literature showed evidence of an effect of healing intention. In order to reduce potential biases from placebo and expectation effects, we examined trials carried out on cell and tissue cultures, small animals and plants, as well as on humans.
We carried out a systematic search of the literature, extracted all relevant trials, carried out a comprehensive assessment of their quality, and combined the data statistically (using standard meta-analysis techniques) in order to calculate an effect size and assess whether it was statistically significant. We also examined the data for evidence of negative publishing bias (non-publication of negative studies), and found that this was positive (i.e. trials of healing that show no effect are less likely to be published than positive trials).
We found 57 trials of healing intention on humans, and 49 trials in other living systems. Combining all the evidence provided us with a fairly small, but highly statistically significant effect size of .193. There was wide variation in the quality of the different trials, and also in the effects reported, with lower quality trials often resulting in apparently better results. However, even when low quality trials were excluded, a significant benefit was found for groups provided with healing intention, in comparison to those not treated. The overall effect size was larger for good quality studies of cell cultures and small animals than it was for plants or humans.
The data need to be treated with some caution in view of the poor quality of many studies and the negative publishing bias; however, our results do show a significant effect of healing intention on both human and non-human living systems (where expectation and placebo effects cannot be the cause), indicating that healing intention can be of value.
In our publication we have provided readers with recommendations for improving the quality of future studies and a bibliography of the published work.