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特集：医療英語 > 第 18 回：The Mind’s Effect on the Body: The Placebo Effect and White Coat Syndrome(プラシーボ効果及び白衣高血圧症)
According to the American Heritage Science Dictionary, a placebo is a substance containing no medication that is used as a control in a clinical research trial to determine the effectiveness of a potential new drug.1 Those receiving the placebo sometimes get better, a phenomenon known as the placebo effect. Although doctors and researchers have known about the placebo effect for a long time, it is not well understood.
Professor Fabrizio Benedetti of the University of Turin in Italy has shown that a saline placebo can reduce tremors and muscle stiffness in people with Parkinson's disease.2 When measuring the activity of neurons in patients' brains during the administration of saline, they found that individual neurons in the subthalamic nucleus (the part of the brain that is sometimes a target when using surgery in an attempt to relieve Parkinson's symptoms) had the desired affect of firing less often when the saline was given. The neuron activity decreased at the same time as the symptoms improved.
However, it appears that the placebo effect can be either positive or negative and depends on the activities surrounding the medical treatment. In a study performed by Ted Kaptchuk (Assistant Professor of Medicine, Harvard Medical School) et al, researchers compared two placebo treatments: a sham device and inert pills.3 The researchers recruited 270 volunteers suffering from chronic arm pain due to repetitive use that had lasted at least three months despite treatment and who scored three or more on a ten-point scale. The patients were randomized to receive either acupuncture with a sham device (trick needles whose tips retract so they don't penetrate the skin) twice a week for six weeks or blue cornstarch pills once a day for eight weeks. Twenty-five percent of the acupuncture group experienced side effects from the nonexistent needle pricks, including 19 people who experienced pain and four people whose skin became red or swollen. In the cohort taking the sugar pill, 31 percent experienced side effects including dizziness, restlessness, rashes, headaches, nausea and nightmares. Dry mouth and fatigue were the most common complaints, and 3 patients withdrew from the study after reducing the dosage failed to control their symptoms. The side effects reported by the participants exactly matched those described by the physicians when the patients joined the study.
At the end of the study, the patients receiving the fake acupuncture (sham device) reported that their pain decreased an average of 2.64 points on the ten-point scale and those taking the sugar pills said their pain decreased an average of 1.5 points.4 In other words, the sham device had a greater effect than the placebo pill on self reported pain. The researchers believe that the difference may be due to the activities surrounding the medical treatment; performing acupuncture is more elaborate than prescribing pills.
Another phenomenon that illustrates how the mind can affect the body is known as "white coat syndrome" or "white coat hypertension". These terms refer to the situation in which blood pressure measured in a physician's office is consistently higher than when measured at home or at work. Studies suggest that ten to twenty percent of patients may experience white coat syndrome.5 It is believed that white coat syndrome or white coat hypertension is due to the anxiety that some people experience during visits to a physician's office.
The placebo effect and white coat syndrome are just a couple of phenomena that demonstrate how the mind can affect the body. Researchers have a lot to learn regarding these effects, including their causes, mechanisms of action and how to take advantage of the potential positive nature of the placebo effect.
- Please summarize the article. What is the main point of the article?
- What is a placebo and what is the placebo effect?
- How did treatment with saline solution affect Parkinson’s disease patients?
- What happened when researchers compared two placebos?
- What do you think causes the placebo effect?
- What is white coat syndrome?
- What do you think causes white coat syndrome?
- American Heritage Dictionary. Houghton Mifflin and Company. 2002.
- Benedetti F et al. Placebo-responsive Parkinson’s patients show decreased activity in single neurons of subthalamic nucleus. Nature Neuroscience pp. 587-588; volume 7, no 6, 2004. (Accessed 23 March 23, 2007)
- Kaptchuk TJ et al. Sham device v. inert pill: randomized controlled trial of two placebo treatments. BMJ 1 February 2006 (Accessed 23 March 23, 2007)
- Ruvinsky J. Placebo vs. placebo. Discover magazine. 26 April 2006. (Accessed 23 March 23, 2007)
- Davis J. WebMD personal reporter. WebMD.com. (Accessed 23 March 23, 2007)