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HEALTH: The placebo effect: real or imagined?

Placebos, sometimes called sugar pills or dummy pills, are medications or treatments that are benign; that is, they have no pharmacological properties. The condition of patients receiving a placebo should not improve yet, surprisingly, studies have found about 35 percent of patients do.

The most common use of placebos is to test new medications. In these clinical trials the patients are divided into two groups: one is given the medication being tested and the other is given dummy pills. The trials are almost always double blind, meaning that neither patients nor researchers know who has received the real drug and who has received the placebo. This keeps the attitude of the researcher from affecting the condition of the patients and, therefore, the outcome of the study.

Previous studies have shown that patients respond to a placebo according to their expectations. Although they are taking only a sugar pill, they behave very much like the patients who receive the real drug. The symptoms of their illness improve, but they do not feel better overall. They also experience the same side effects. The time effect and dose response curves for patients receiving placebos mimic those of the patients who take the real drug. In addition, placebos are often more effective after the patient has received the actual drug. For example, surgery patients who receive pain medication the first day and a placebo the second day report greater pain relief from the placebo than those who receive the placebo first and the pain medication second. Placebos can also have negative effects; for example, they can make people sick, if that is what they expect.

Scientists can only speculate on how the placebo effect works. One possibility is that taking the placebo reduces the patient’s anxiety and reduced stress levels can contribute to recovery. The placebo may also trigger the release of endorphins, our bodies’ natural painkillers. The evidence for this mechanism is that a patient who has improved due to the placebo effect will regress when given naloxone, a drug that blocks endorphins.

But after nearly 50 years of acceptance, the placebo effect is now being questioned. In a recent paper in the New England Journal of Medicine, Dr. Asbjorn Hrobjartsson and Dr. Peter C. Gotzsche of the University of Copenhagen and Nordic Cochran Center reported the results of their recent study. They reviewed journal articles looking for the original research stating that 35-percent of patients improve if given a placebo. All the papers they looked at did not include original research on the placebo effect but cited a reference. When they looked up the paper being referenced, it cited another reference. It turns out that the original source of the statement was a 1955 article “The Powerful Placebo” published in The Journal of the American Medical Association. The paper was written by Henry Beecher, who had been chief of anesthesiology at Massachusetts General Hospital in Boston. Dr. Beecher had analyzed about a dozen studies and came up with the 35-percent figure.

The Danish doctors had concerns about the validity of Dr. Beecher’s figure and decided to delve into it further. They were concerned that two important facts were being ignored: that the natural course of many diseases is to wax and wane and the statistically-shown observation that a patient who feels terrible one day will almost certainly feel better the next.

To get at this issue they analyzed 114 studies published between 1946 and 1998 that had not two but three groups of patients. In addition to the two groups receiving a medication or a placebo, there was a third group that received nothing — no medication and no placebo. To the doctors’ surprise, patients in the third group improved as often as those in the placebo group. In addition, they could find no objective measure of improvement in the placebo group, such as lowered blood pressure. The studies they used involved about 7,500 patients with 40 different medical conditions, including medical disorders such as high blood pressure, high cholesterol levels and asthma; behavioral disorders and addictions, like alcohol abuse and smoking; neurological diseases like Alzheimer’s disease, Parkinson’s disease, and epilepsy, and infections, like bacterial infections and the common cold.

Additional studies will likely be done to determine the validity of the placebo effect. No matter what the outcome, placebos will continue to be given to people in drug trials since double blind studies prevent the bias of the researchers from influencing the results. —Studyworks

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