Our Baysean Brain and the Placebo Effect

I'm passing on a few clips that give the take home message from a recent NYTimes piece by Haravard Medical School's Ted Kaptchuk, who directs the Harvard-wide program in placebo studies.

...placebos can work even when patients know they are getting a placebo. In 2010 my colleagues and I published a provocative study showing that patients with irritable bowel syndrome who were treated with what we call open-label placebos — as in, we gave them dummy pills and told them so — reported more symptom relief compared with patients who didn’t receive placebos. (These placebos were given with transparency and informed consent.) In another blow to the concept that concealment is required for placebo effects, my team recently published a study comparing open-label placebos and double-blind placebos in irritable bowel syndrome and found no significant difference between the two. A medical myth was overthrown.

Currently, more than a dozen randomized trials demonstrate that open-placebo treatment can reduce symptoms in many illnesses with primarily self-reported symptoms such as chronic low back pain, migraine, knee pain and more. These findings suggest that patients do not have to believe, expect or have faith in placebos to elicit placebo effects. So what’s happening?

To date, the best explanation for the results of open-placebo trials suggests that for certain illnesses in which the brain amplifies symptoms, engaging in a healing drama can nudge the brain to diminish the volume or false alarm of what’s called central sensitization — when the nervous system overemphasizes or amplifies perceptions of discomfort. This mostly involves nonconscious brain processes that scientists call Bayesian brain, which describes how the brain modulates symptoms. The intensification and the relief of symptoms use the same neural pathways. Considerable evidence also shows that placebos, even when patients know they are taking them, trigger the release of neurotransmitters like endorphins and cannabinoids and engage specific regions of the brain to offer relief. Basically, the body has an internal pharmacy that relieves symptoms.

...placebos shouldn’t be a first-line treatment; patients should be given what effective medicines are available. After all, placebos rarely, if ever, change the underlying pathology or objectively measured signs of disease. I like to remind people that they don’t shrink tumors or cure infections.

Crucially, much discussion and reflection is needed among physicians and our health care system as a whole to understand why the act of treatment itself is so powerful to patients even if a pill contains no therapeutic ingredients. Medicine is not only effective drugs and procedures; it’s a human drama of charged engagement. Our team published a study in The BMJ demonstrating that placebo effects can be significantly enhanced in the context of a supportive, respectful and attentive patient-clinician relationship. Acts of human kindness in general are linked to robust placebo effects.