Think Yourself Unhealthy

The Nocebo Effect


Sep Meyer [1] 


The Nocebo Effect (or Nocebo Phenomenon as it is also termed) came vividly to public attention in the last decade of the 1990s.  Medical research revealed that women who believed they had a tendency to heart disease were nearly four times as likely to die as women with similar risk factors who didn't hold such negative views.

In 2002, psychiatrist A.J. Barsky  wrote[2] "They're convinced that something is going to go wrong, and it's a self-fulfilling prophecy."   Four years earlier, Robert & Michele Root-Bernstein had written: "Research has . . . shown that the nocebo effect can reverse the body's response to true medical treatment from positive to negative" [3].

In a similar way to which Placebo derives from the Latin for "I will heal", Nocebo is Latin for "I will harm".  Thus a nocebo effect is an ill effect caused by the suggestion or belief that something is harmful.

Dr Barsky (op cit.) speculated that the effect occurs when people reassign existing chronic symptoms, such as anxiety, backache, headaches and insomnia to the drug they have just begun taking.  He suggests that when a patient with a history of vague, difficult-to-diagnose complaints believes that any prescribed drug  will do little to help, those low expectations are inevitably met.

The nocebo effect has been described as the placebo effect's evil twin. While the placebo effect refers to health benefits produced by a treatment that should have no effect, patients experiencing the nocebo effect experience the opposite. They presume the worst, health-wise, and that's just what they get.

There have been some interesting experiments conducted over the years to demonstrate the power of the nocebo effect.  Inevitably medical research has been less profound than into the placebo effect, since medical practitioners have an ethical obligation to cure their patients and not to induce illness in them.

In one experiment, college students were told that an electric current would be passed through their heads and that this might cause a headache.  Although not a single volt of electricity was actually transmitted, more than two-thirds of the students reported headaches.

In another experiment in the 1980s, researchers at three separate medical centres conducted a study of aspirin and another blood thinner in heart patients and made an astonishing discovery.  In two of the centres patients were warned of possible gastrointestinal problems.  At the third location, no such caution was issued.  When the data was reviewed it revealed that the patients who had received the warning were almost three times more likely to have the side effect than the other patients.  Although the actual incidence of stomach damage, such as ulcers, was the same for all three groups, those who had been warned about the possibility of minor discomfort were the ones most likely to experience the pain.

And in a study published long before the word nocebo had been coined, it was demonstrated that producing an artificial rose to a patient allergic to the plant resulted in a display of the same symptoms as would have been produced by the genuine flower.

Perhaps the most bizarre of all the experiments was that conducted with a group of asthmatic patients.  They inhaled a vapour that they believed to be a chemical irritant or allergen.  Nearly half of the patients experienced breathing problems with several developing full-blown attacks.  They were then "treated" with a substance they believed to be a bronchodilating medicine and recovered immediately.  In fact, both the irritant and the medicine were the same substance: a nebulized salt water solution.  Both the attack and the cure resulted from the patients expectations.

Analysis of experiments conducted over the years, and examination of the symptoms displayed by nocebo-effect patients, has resulted in several telling conclusions and points the way ahead for further study.

For example: the behaviour of physicians and hospital staff, the colours that are worn, or the ambience in which tests and treatment are conducted, all can have an effect on the patients' mental state.  This effect can be positive or negative - a placebo or a nocebo - depending on and influencing the patients' reactions.   Many patients, for example, react badly when confronted by medical practitioners dressed in white.  It has even been called "white-coat hypertension".  Green, however, has been found to have a calming effect.  A Dutch study found that most people considered red and orange pills to be stimulating, with blue and green pills more likely to have a depressant effect.

It was ascertained that when anaesthetists visited patients the night before surgery and were warm, chatty and sympathetic, the patients subsequently required half the postoperative pain medication than those whose anaesthetists were peremptory and businesslike.  They were also released from hospital on average two and a half days earlier.

A book published some years ago, reviewed by me for another journal, was entitled Think Yourself Healthy.  It was concerned with the benefit to health of positive thinking.  It was published before the nocebo effect per se was officially recognised, but inevitably, the consideration of positive energy on physical health acknowledged the corollary of Think sick - be sick.  Think the worst and you may just end up getting it.


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[1] Sep Meyer is a graduate of the London School of Economics and, since his retirement from a commercial life, has been devoting his time to a totally non-commercial activity, writing poetry, magazine articles, book reviews and drama. 

[2] Department of Psychiatry, Brigham and Women's Hospital, Maryland, USA, writing in the Journal of the American Medical Association, February 2002 on Nonspecific medication side effects and the nocebo phenomenon.

[3] Honey, Mud, Maggots and Other Medical Marvels: The Science Behind Folk Remedies and Old Wives' Tales  (Houghton Mifflin Co., 1998).