Placebo effect and regression fallacy impacts on dental care

Chemical reason some are more prone to placebo

Scientists don’t know all the details but we do know that placebo treatments work for some issues (especially those that involve brain chemicals like dopamine and endorphins).  Examples of health problems that are altered by those chemicals include chronic pain (in my field that means TMD) and Parkinson’s disease.  New research has shown one of the genetic markers that may dictate the likelihood of a placebo working.  COMT (Catechol-O-methyl transferase) enzyme degrades dopamine in our brain and there are multiple versions of this enzyme.  COMT has some combination of amino acids valine and methionine.  Some people are nearly completely at one end or the other of that spectrum, we call these individuals either met/mets or val/vals.  Val/vals have more valine and degrade dopamine very quickly (about 4x faster than met/mets).  This has the effect of dampening pain perception.  Met/mets are more sensitive to pain and are also more susceptible to placebo treatments.  That’s both a blessing and a curse.  It also means that met/mets should likely be excluded from drug testing or at least viewed as more malleable and susceptible to placebo effects.

Discovery article Aug 2014  by Erik Vance

Where in the brain does the placebo effect work

The prefrontal cortex inhibits the emotional part of the brain (like the insula) where we feel pain. This was found in a fMRI study by Tor Wager at Columbia, which is discussed in the book How we Decide by Lehrer.

Logical reasons we all are prone to placebo and superstition

One reason that placebo treatments “work”, some would say this is proof that they don’t work and also be correct, is due to regression fallacy.  For conditions that naturally ebb and flow people tend to seek treatment at the peak of their symptoms.  If someone “treats” the condition at the peak the patient naturally associates the treatment with the reduction in symptoms when in reality the course of their condition ensures that their symptoms would reduce naturally.  Wikipedia gives the example of back pain but orofacial pain and particularly TMJ pain is the main issue we see in dentistry.

Another reason is the Hawthorne effect.  When people know they are being watched or measured that has an impact on the results you will obtain from them.