Placebo, nocebo and psychological effects of drugs

Prim. MUDr. Karel Nešpor, CSc. and MUDr. Hana Karbanová

Introduction

 As evidenced by the placebo effect, drugs work both psychologically and biologically. Some knowledge that concern placebo effect can be used in administration of pharmacologically effective drugs. This topic will be discussed in the latter section of the article. The issue of placebo effect is important particularly for doctors, nurses and pharmacists.

Placebo: the possible mechanism of action

 From a medical perspective, placebo is an inactive substance or procedure that imitates the active substances or procedures. Active placebo is not pharmacologically active but contrary to placebo it has similar side effects as the active substance which increases its plausibility.

 Placebo effect is explained by an increased secretion of endorphins (Benedetti, 2007). Naloxone, the opioid receptors antagonist, weakened the analgesic effect of placebo. In the study by Stern et al. (2011), the placebo effect improved the short-term memory and this effect was blocked by naloxone administration. Other receptor systems can also be affected. It is assumed that the placebo effect has neurophysiological basis and that due to it the stimulation of the body’s ability to heal occurs (Vinař, 2013).

 It would be oversimplifying the situation to understand the placebo efficacy only as a result of the patient’s lack of information. Kaptchuk et al. (2010) report a positive placebo effect in patients with irritable bowel syndrome. The experimental group showed less health difficulties and improved quality of life. The interesting thing about this study was that the subjects were informed that the medication they are taking does not contain the active substance. They were told that “the clinical research has shown that such tablets may affect the health through the mind.”

 The effect of placebo differs significantly at various disorders. Disorders that respond well to placebo include bronchial asthma, sleep disorders, pains, panic disorders, post-traumatic stress disorder and depressions. In contrary, patients with obsessive compulsive disorder do not respond to placebo treatment (Brown, 2006). In placebo effect a number of mechanisms is involved. Some of them are mentioned hereafter.

Volume 2 Issue 3/2013 Full text