“Where there is hope, there is life.” And hope is positive expectation, by another name. The scientific study of the placebo effect is usually dated to the pioneering paper published in 1955 on “The Powerful Placebo” by the anesthesiologist Henry K. Beecher (1904-1976). Beecher concluded that, across the 26 studies he analyzed, an average of 32% of patients responded to placebo.
It has been shown that placebos have measurable physiological effects. They tend to speed up pulse rate, increase blood pressure, and improve reaction speeds, for example, when participants are told they have taken a stimulant. Placebos have the opposite physiological effects when participants are told they have taken a sleep-producing drug.
The placebo effect is part of the human potential to react positively to a healer. A patient’s distress may be relieved by something for which there is no medical basis. A familiar example is Band-Aid put on a child. It can make the child feel better by its soothing effect, though there is no medical reason it should make the child feel better.
People who receive a placebo may also experience negative effects. They are like side effects with a medication and may include, for example, nausea, diarrhea and constipation. A negative placebo effect has been called the nocebo effect.
- Placebo response
A positive medical response to taking a placebo, as if it were an active medication.
A term used to describe a method of research in which an inactive substance (a placebo) is given to one group of participants, while the treatment (usually a drug or vaccine) being tested is given to another group. The results obtained in the two groups are then compared to see if the investigational treatment is […]
A temporary organ that joins the mother and fetus, transferring oxygen and nutrients from the mother to the fetus and permitting the release of carbon dioxide and waste products from the fetus. The placenta is roughly disk-shaped, and at full term it measures about 7 inches in diameter and slightly less than 2 inches thick. […]
- Placenta accreta
The abnormal adherence of the chorion of the placenta to the myometrium of the uterus. Normally there is tissue intervening between the chorionic villi and the myometrium, but in ‘placenta accreta, the vascular processes of the chorion grow directly in the myometrium. Placenta accreta can progress into placenta percreta.
- Placenta percreta
A condition in which the placenta invades the uterine wall. In placenta percreta, the vascular processes of the chorion (chorionic villi), a fetal membrane that enters into the formation of the placenta, can invade the full thickness of the myometrium. This can cause an incomplete rupture of the uterus. The chorionic villi can go right […]