Oct 24, 2017

The Right Chemistry: Placebos, persuasion and all that voodoo

voodoo dolls
So I visited New Orleans and bought a voodoo doll. Can it actually do harm?


October 20, 2017

Bourbon Street in New Orleans features a number of shops selling voodoo dolls.

“Why is that one more expensive than these others,” I asked, pointing at one on the shelf behind the counter.

“Because that one is not just a souvenir — it is real,” came the answer.

Of course, I had to have that one.

The instructions were simple enough. To torment someone, you just have to acquire a piece of fingernail or a strand of hair from the intended victim and place it on the doll before sticking pins into it.

“Is that all?” I asked.

“Well, it helps,” I was told, “if the person knows you intend to inflict harm.”

That argument I can buy, because what we then have is a classic example of the “nocebo effect.”

The term “nocebo” comes from the Latin meaning “I will harm” and can be regarded as the famous placebo’s evil twin.

A placebo produces health benefits in spite of having no plausible scientific merit, while the nocebo effect occurs when something that rationally should have no effect causes real symptoms. “Think sick and be sick” would be an appropriate description.

A study back in 1987 in which patients with unstable angina were treated with aspirin to reduce the risk of a heart attack represents a classic example. Some of the subjects were told that aspirin can cause gastrointestinal side effects, others were not. Six times as many patients withdrew from the study citing gastrointestinal effects in the group that had been told of the possibility of side effects than in the group that had not been so informed. There was no objective evidence such as peptic ulcer or gastrointestinal bleeding in the case of subjects who abandoned the study. Their subjective symptoms, which were very real, were generated by the mind. The nocebo effect in action.

There are numerous other examples. After reading accounts of radiation poisoning following the 2011 Fukushima accident in Japan, people as far away as the U.S. reported experiencing symptoms despite there being no possibility of exposure to radiation from the accident.

The nocebo effect can also be noted in cases of “mobile phone headache syndrome,” a condition in which people claim to suffer from headaches when they are exposed to radio frequencies generated by the device, often triggered by media accounts that raise the spectre of harm. However, when 17 individuals who claimed to be affected took part in a double-blind, randomized trial using sham or actual radio frequencies, no difference was found in reported instances of headache or other discomfort.

There are also some fascinating individual case reports. Take, for example, the man who was involved in a trial of a new antidepressant drug. He had a fight with his girlfriend and decided to end it all by taking all the pills in the bottle he had been given. Soon he started to feel ill, regretted his decision, and asked a neighbour to take him to the hospital where he duly collapsed. All tests came back negative, but the feeling of being unwell persisted. When doctors contacted the organizers of the study, it turned out that their patient had been in the placebo arm of the trial and had tried to kill himself with sugar pills. When informed of this, the man made a rapid recovery.

Now back to my voodoo doll. Can it actually do harm?

In 1942 Dr. Walter Cannon coined the term “voodoo death” to describe demise brought on by a strong emotional shock such as fear. He described a number of cases, albeit anecdotal, in which death occurred as a result of a belief that a curse had been imparted.

When the salesperson noted that I was somewhat skeptical about the evil powers of the doll, she quickly assured me that it can also be used for good. Stroking the doll, she explained, can trigger affection from a person whose picture is placed under the doll. I don’t think I would place too much faith in that, but I do think that a voodoo doll can cause mischief for people who believe in such things. The link between body and mind is indeed a fascinating one.

That relationship is exactly what we will explore further in this year’s “Trottier Public Science Symposium.” On Monday, Oct. 23 at 7 p.m., we will hear from CTV health journalist Dr. Marla Shapiro and McGill placebo expert Dr. Amir Raz. On Oct. 24, also at 7 p.m., our speaker will be Dr. “Patch” Adams, who was portrayed by Robin Williams in a movie about his exploits. He will explore the value of laughter as therapy.

The location is the Centre Mont Royal, 1000 Sherbrooke St. W., corner Mansfield St. The event is free and, of course, everyone is welcome.

Joe Schwarcz is director of McGill University’s Office for Science & Society (mcgill.ca/oss). He hosts The Dr. Joe Show on CJAD Radio 800 AM every Sunday from 3 to 4 p.m.


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