For doctors, the use of placebos to treat medical conditions is explicitly banned by most medical associations but their use is widely debated.
Thousands of clinical trials have shown us that placebo is one of the most effective and safest of medicines (although it is not entirely without side-effects).
However, it is also one of the most misunderstood of treatments.
An article in this month’s Journal of the Royal Society of Medicine (which has been debating placebo over the past year or two) dispels some of the myths.
The placebo effect is usually equated with the average response of patients receiving placebo controls in randomized trials. However, it’s not quite that simple.
For example, not every improvement that happens after someone is given a placebo treatment is the ‘placebo effect’ (some symptoms will just get better by themselves) and not every improvement after medication is the active effect of the drug, some of that will be ‘placebo effect’ too.
Placebos are not ‘ineffective’. In fact, when three condition trials are run (no treatment vs placebo vs medical treatment), placebo consistently out performs ‘no treatment’ and of course, not uncommonly, the medical treatment condition as well.
Placebos are not a ‘non-specific’ treatment. A study on people who take the dopamine-boosting drug L-DOPA for Parkinson’s disease but who took a placebo L-DOPA pill, showed almost identical brain changes, as if they’d taken the real thing.
Furthermore, studies done in the 1970s showed that when heroin users inject water (sometimes done deliberately to alleviate cravings when drugs are in short supply), they can experience drug-like euphoria and have been observed to show opiate-like physiological signs such as pupil constriction.
This last point also demonstrates that placebo is not solely about expectancy, belief or ‘being fooled’, as the heroin users knew they were injecting themselves with water. Conditioned responses play a role.
This can also be seen from the fact that these specific effects of placebo tend to fade after a while, as the conditioning becomes extinguished.
The fact that placebo can be a relatively safe, effective, and sometimes selective treatment has led some to argue that doctors should be able to use it officially (although, of course, many use it unofficially).
Law professor Adam Kolber (who you may know from the excellent Neuroethics and Law blog) wrote a fascinating paper last year that reviewed the research and argued that in limited circumstances, placebos could be ethically used.
The article is available online and I really recommend reading the ‘Avoiding Deception’ section if nothing else – for series of recommendations on how placebo could be used without straight up deception.