Placebo effects: a power of self-fulfilling prophecy and caring
Updated: Aug 10, 2020
If you are not familiar with placebo effects, they are worth noticing. It is no secret that the patients' belief that the pills they are taking would work can account for as much as 50% of the therapeutic effects of the medicine.
Many parents may have their own version of stories regarding placebo effects. Some kids experience sudden stomach aches, when their school begins after a long break. If parents give their children a vitamin pill without revealing its true identity and tell them that this pill will let the stomach pain go away, it often becomes a self-fulfilling prophecy. I find it AMAZING.
Placebo effects alone may not cure cancer, but they are the cherry on the cake. If we focus on positive outcomes, can we expedite our body’s recovery? Why are we wired that way?
Modern neurobiologists explain our perception as a prediction process, based on inputs (sensory cues or experience), as suggested by Bayesian models. For example, small children may be afraid of going to bed, thinking about monsters lurking in the dark. However, as they never run into such monsters in real life, children learn that it is safe to sleep through the night. These mismatches between “data” and predictions continue to revise our set of hypotheses, shaping our perceptions throughout our lifetime.
This Bayesian brain can offer us some explanation about Placebo effects. Repeated experience in a certain context (e.g. feeling better after taking a sugar pill) serves as the basis of our prediction in the future (e.g. Taking a sugar pill always makes me feel better). Next time, when the brain perceives intake of a sugar pill, it will tell the body to feel better in an attempt to realize its prediction despite the fact that the sugar pill does not have any ingredient that takes care of the symptom biochemically.
This phenomenon is quite similar to the well-known Pavlovian conditioning, where dogs would salivate in response to a ring bell without food, following repeated encounters with food (unconditioned stimulus) in association with the ring bell (conditioned stimulus). This associative learning has been shown to be effective as a dose-reduction strategy for renal transplantation patients, who need to take immunosuppressive drugs during their lifetime. After the patients had learned to associate immunosuppressive drugs (unconditioned stimulus) with a special drink (conditioned stimulus), intake of the special drink alone could suppress the patients’ immune response.
(Source of the image components: Media Assets Repository System)
Even more intriguing are honest placebo effects. An honest placebo group, who was told that their pills have no active medicine, still benefited greatly from taking those pills. Some patient had to keep taking these fake pills because her symptoms (irritable bowel syndrome) came back at full force once she stopped taking them.
These patients “knew” that these pills would not improve their symptoms due to a lack of active ingredients. So it was not their conscious belief that produced these honest placebo effects. It is thought that traditionally beneficial rituals (e.g. taking pills) combined with patients’ interactions with caring doctors may trick our Bayesian brain subconsciously to “predict and prepare” the body for recovering from illness.
Knowing that our Bayesian brain is conditioned to associate a fast recovery with encouraging information about treatments or inert pills given by caring doctors, perhaps we can harness the ability of our body to heal itself by taking advantage of placebo effects. Self-fulfilling prophecy and bedside manner matter after all!