In many medical studies, even people who take “fake” treatments, such as sugar pills with no active ingredients, can still feel better. These are the puzzling “placebo effects”. They are common, diverse and powerful and they raise an interesting ethical question – can doctors justifiably prescribe placebos to their patients? The standard answer is no. Doing so patronises the patient, undermines their trust, and violates the principles of informed consent. It compromises the relationship between doctor and patient. At worst, it could do harm.
But many of these arguments are based on the idea that placebo effects depend on belief; people must expect that treatments will work in order to experience any benefits. For a doctor to prescribe a placebo, they’d need to deceive. But according to Ted Kaptchuk from Harvard Medical School, deception may not be necessary. In a clinical trial, he found that patients with irritable bowel syndrome (IBS) felt that their symptoms improved when they took placebo pills, even if they were told that the pills were inactive.
Fabrizio Benedetti, a placebo researcher at Turin Medical School who wasn’t involved in the study, says, “Although several studies suggested that placebos can be equally effective without deception, this is the first rigorous study that provides scientific evidence for this.”
Referring to an earlier study published in the British Medical Journal, he says, “We did the study because we knew that physicians were giving placebo to patients secretly without informed consent. Our study was designed to test whether placebo effects could be harnessed without this secret deception.”
The placebo effect – the phenomenon where fake medicines sometimes work if a patient believes that they should – is a boon to quacks the world over. Why it happens is still a medical mystery but thanks to a new study, we have confirmation that the spine is involved.
Frank Eippert from the University Medical Center Hamburg-Eppendorf used a technique caled functional magnetic resonance imaging (fMRI) to scan the backbones of volunteers as they experienced the placebo effect. Eippert heated the recruits’ forearms to the point of pain and he gave them cream to soothe the sting. The creams were all shams with no pain-relieving properties, but only half of the recruits were told this. The others were told that they’d been given lidocaine, an anaesthetic.
Sure enough, the volunteers who used the alleged “anaesthetic” felt about a quarter less pain than those who were aware that they were using an ordinary cream – the placebo effect in action. But Eippert also found that the activity of neurons in the spine (specifically an area near the back called the “dorsal horn”) was also strongly allayed.
The dorsal horn is the gateway of pain. It controls the passage of pain impulses from our senses into our central nervous system. Eippert’s results provide direct evidence that our belief in the effectiveness of a fake medicine can close this gate, blocking pain signalling in this all-important area.
Of course, it’s still unclear how this happens, but the answer probably lies with opioids, natural pain-relieving chemicals used by the brain that have been linked to the placebo effect for over 30 years. These chemicals are probably responsible for closing the dorsal horn’s gate.
Eippert’s results build upon, and support, earlier research linking the spine to the placebo effect. Nonetheless, it’s very unlikely that this is the only explanation behind the mysterious placebo effect. For a start, people who suffer from fibromyalgia – a condition characterised by long-term pain all over the body – can still experience in the placebo effect but in a way that doesn’t involve the spine.
Reference: Science 10.1126/science.1180142