Placebo, << pluh SEE boh, >> is a substance that doctors sometimes use as a medicine, even though it contains no active ingredient. A placebo brings about an improvement or even a cure in some patients. Placebos look like real drugs but contain only inactive substances, such as sugar. Doctors also may administer placebo injections, which usually contain salt water or sterile water, and may even perform placebo surgery.
Doctors believe the effectiveness of placebos depends on the patient’s belief that the substance is actually medicine. In many cases, this belief provides a psychological boost that can improve the patient’s symptoms. A trusting relationship between the patient and physician can increase the placebo’s effectiveness. In addition, there is some evidence that endorphins and other neurochemicals play a part in the placebo effect. Endorphins may be the body’s natural pain relievers. In 2001, however, a scientific study found that placebos have little or no actual effect.
Placebos are used in research to help determine the effectiveness of new drugs. One group of patients receives the drug. Another group of patients with the same illness, called the control group, gets a placebo. The placebo and the drug look alike. Neither the patients nor the doctors know which is the placebo and which is the drug. Placebo groups are important in studies of diseases with symptoms that worsen or improve over time, such as arthritis or depression. Researchers learn if a new drug is effective by comparing the effects of the drug with those of the placebo.
Physicians have also used placebo groups to test the effectiveness of some surgical operations, such as arthroscopic knee surgery to treat osteoarthritis. In such tests, a number of patients are sent to the operating room and put to sleep. A surgeon makes an incision in all the patients, but only half actually have the surgical operation. Patients and caregivers are not told if real surgery was performed until after the study is completed.
