In medicine, it is not always clear exactly why someone got
better or did not get better. Was it because of something we did or in spite of
something we did? Many illnesses in children get better on their own so it may
not be obvious whether a child’s cough got better because of what I prescribed
or was just going to get better anyway.
One way to help figure this out is to randomly assign patients
with the same problem to receive either the treatment being evaluated or a
placebo. A placebo is something that resembles the actual treatment but is
inactive (the proverbial “sugar pill”). By comparing the results of the
treatment and the placebo, one can ascertain whether the treatment works by
seeing if more people got better with the treatment than with a placebo. The
results are most reliable when the doctors and patients do not know who is in
the treatment group and who is in the placebo group.
But an interesting phenomenon known as the placebo effect
occurs. That is, some people get better with the placebo. And when placebos are
compared to no treatment at all, placebos are often more effective than doing
nothing so it is not always things just getting better on their own.
Or is it? The placebo effect tends to work better for
subjective symptoms which are modulated by the brain. Symptoms such as pain,
fatigue, nausea, and insomnia are more likely to be amenable to the placebo
effect than other signs and symptoms. A placebo will not make your femur
fracture go away or cure a case of Meningococcal meningitis.
A placebo works better if it closely resembles what one
would usually anticipate being the treatment for that symptom. In one study,
50% of participants with migraines improved from a placebo pill, even though
they were told beforehand that it was a placebo. And there is some evidence
that cultural expectations may also influence a person’s response to a placebo.
Is it simply the patient’s perception of their symptom that
changes? We really do not know (at least I do not). But it is interesting to
think about how our expectations can change our experience of our symptoms (as
well as our experience of other things in the world around us).
