The placebo effect is that remarkable phenomenon where an inactive substance or otherwise fake treatment has a real effect on a patient’s condition. The placebo effect has been investigated since at least 1799. Some of the foundational research on the subject suggests that placebo effects occur in about 35% of people. (“The Powerful Placebo,” Henry Beecher, 1955.) Placebos have documented effects on pain, asthma, tension, anxiety, depression, blood pressure, heart rate, sexual arousal, skin conditions, nausea, vomiting, gastric motility, and angina. Under some circumstances placebos even produce effects that are stronger than those of active drugs. (“Hypnosis and Placebos: Response Expectancy as a Mediator of Suggestion Effects,” Irving Kirsch, 1999.)
While the placebo effect can be powerful, it is sometimes stated incorrectly that hypnosis works as a placebo, and that the effects of hypnosis are merely a placebo effect due to the patient’s beliefs and expectations. While positive expectancy is an important part of hypnosis, hypnosis is not the same as the placebo effect in terms of responsiveness, physiological effect, or administration.
Efficacy, or responsiveness, is the most important consideration from a practical standpoint, and there are significant differences here between hypnosis and the placebo effect. One study found that for subjects insusceptible to hypnosis, some pain reduction may be achieved with hypnosis, but it corresponds to the reduction by placebo. However, for subjects highly susceptible to hypnosis, pain reduction with hypnosis is far greater than by placebo. For these subjects, the average placebo response is negligible or even negative (“The nature of hypnotic analgesia and the placebo response to experimental pain,” McGlashan, Evans, & Orne, 1969). A further difference in responsiveness is that responses to hypnosis are notoriously trait-like , while responses to placebos are comparatively unreliable. There does not appear to be a “placebo reactor” comparable to the “hypnotizable subject.” (Kirsch, 1999.)
In terms of brain activity, there are similarities between hypnotic and placebo when used for analgesia for pain. Both hypnosis and placebo activate the somatosensory cortex, insula, thalamus, anterior cingulate cortex, and prefrontal cortex. However, there are also major differences in brain activity between hypnosis and placebo effects. With placebo, decreased pain is associated with changes in several parts of the limbic system (such as the amygdala, hypothalamus and hippocampus) as well as in the periaqueductal gray and the nucleus accumbens. Instead, hypnotic pain relief is accompanied by changes of activity in the occipital cortex and basal ganglia. (“Brain activity during pain relief using hypnosis and placebo treatments,” Svetlana Kierjanen, 2012.)
Hypnosis is different from a placebo in an important regard, which has to do with ethics. The administration of placebos requires that they be presented deceptively as pharmacological treatments. The use of placebos in medicine is therefore a controversial topic. Hypnosis does not require deception in order to be effective. Hypnosis is a non-deceptive means of exploiting the therapeutic power of suggestion. Doctors and patients can benefit from understanding hypnosis and the power of suggestion. As Voltaire once stated, “there is probably more cure in the doctor’s words than in many of the drugs he prescribes.”