The placebo-nocebo effect: How symbols can heal and kill

The placebo-nocebo effect represents an amazing example of how the mind-brain unit interacts with the body. Whereas placebos have to do with positive symbols that anticipate clinical benefit, nocebos are linked to negative symbols that induce expectations of clinical worsening. Positive symbols can range from empathic doctors and smiling nurses to trust-inducing complex medical machines and apparatuses. Likewise, there are a variety of negative symbols, ranging from shabby doctors to a pain-anticipating dentist’s drill. From an evolutionary perspective, these symbols, and indeed their interpretations by the patients, have evolved from ancient shamanism to modern medicine, whereby the patient’s expectations and beliefs in the healing power of the doctor play a crucial role. By studying placebo and nocebo effects, today we are beginning to understand how medical symbols affect the patient’s brain or, in other words, how positive or negative psychosocial contexts can change the brain and body functioning of the patients. The neuroscientific experimental approach to this issue is paying dividends and promises new therapeutic interventions aimed at enhancing placebo effects and at reducing nocebo effects.