Thursday, May 21, 2009
Placebo's "Evil Twin"Nocebo
The nocebo effect was discussed recently in an article:
"The idea that believing you are ill can make you ill may seem far-fetched, yet rigorous trials have established beyond doubt that the converse is true - that the power of suggestion can improve health. This is the well-known placebo effect. Placebos cannot produce miracles, but they do produce measurable physical effects.
The placebo effect has an evil twin: the nocebo effect, in which dummy pills and negative expectations can produce harmful effects. The term "nocebo", which means "I will harm", was not coined until the 1960s, and the phenomenon has been far less studied than the placebo effect. It's not easy, after all, to get ethical approval for studies designed to make people feel worse.
What we do know suggests the impact of nocebo is far-reaching. "Voodoo death, if it exists, may represent an extreme form of the nocebo phenomenon," says anthropologist Robert Hahn of the US Centers for Disease Control and Prevention in Atlanta, Georgia, who has studied the nocebo effect.
In clinical trials, around a quarter of patients in control groups - those given supposedly inert therapies - experience negative side effects. The severity of these side effects sometimes matches those associated with real drugs. A retrospective study of 15 trials involving thousands of patients prescribed either beta blockers or a control showed that both groups reported comparable levels of side effects, including fatigue, depressive symptoms and sexual dysfunction. A similar number had to withdraw from the studies because of them.
Occasionally, the effects can be life-threatening "Beliefs and expectations are not only conscious, logical phenomena, they also have physical consequences," says Hahn.
Nocebo effects are also seen in normal medical practice. Around 60 per cent of patients undergoing chemotherapy start feeling sick before their treatment. "It can happen days before, or on the journey on the way in," says clinical psychologist Guy Montgomery from Mount Sinai School of Medicine in New York. Sometimes the mere thought of treatment or the doctor's voice is enough to make patients feel unwell. This "anticipatory nausea" may be partly due to conditioning - when patients subconsciously link some part of their experience with nausea - and partly due to expectation.tching
Alarmingly, the nocebo effect can even be catching. Cases where symptoms without an identifiable cause spread through groups of people have been around for centuries, a phenomenon known as mass psychogenic illness. One outbreak (see "It's catching") inspired a recent study by psychologists Irving Kirsch and Giuliana Mazzoni of the University of Hull in the UK.
They asked some of a group of students to inhale a sample of normal air, which all participants were told contained "a suspected environmental toxin" linked to headache, nausea, itchy skin and drowsiness. Half of the participants also watched a woman inhale the sample and apparently develop these symptoms. Students who inhaled were more likely to report these symptoms than those who did not. Symptoms were also more pronounced in women, particularly those who had seen another apparently become ill - a bias also seen in mass psychogenic illness.
The study shows that if you hear of or observe a possible side effect, you are more likely to develop it yourself. That puts doctors in a tricky situation. "On the one hand people have the right to be informed about what to expect, but this makes it more likely they will experience these effects," says Mazzoni.
This means doctors need to choose their words carefully so as to minimise negative expectations, says Montgomery. "It's all about how you say it."
Medical professionals be careful what you say.We all have known patients who undergo relatively simple surgeries saying before they will die and against all odds do..and some surrgeons who will not operate in such situations...
Wonder how many gwt the side effects advertisThe Fortune Telling ed with the billion dollar drug commercials seen regularly?
The Fortune Of Note Earrings are used in the illustration