It is common sense that you must receive treatment after illness. However, sometimes, patients do not get real treatment, but the symptoms appear to be relieved. Perhaps a more familiar part at home is that when parents are ill, they eat a lot of health care products without taking medicine, and feel their illness is getting better... What's the matter?
Placebo (picture from the Internet)
In the 1980s, neuroscientist Jon Levine recruited a group of volunteers. The volunteers have just undergone surgery. According to the convention, they must use analgesics to reduce postoperative pain. Jon divided the volunteers into two groups. The first group followed the routine practice of injecting morphine; For the second group, it is ostensibly declared that "I will give you a powerful pain killer", but in fact, they are injected with physiological saline.
Morphine is one of the most common analgesics, and its effect has been verified in many aspects. The physiological saline, as its name suggests, is very close to the composition of human body fluid. It is an aqueous solution with a concentration of 0.9% prepared with sodium chloride, and does not have analgesic effect. Generally speaking, the pain level of the first group of patients should be much lighter than that of the second group.
Surprisingly, the results showed that pain was significantly reduced in either group. [1]
The patient did not receive effective treatment and the substance with pharmacological activity, but the symptoms were relieved. This is the placebo effect.
So, how does the placebo work?
The placebo effect has two mechanisms.
The first is to focus on expectations. As long as the doctor tells the patient, "You will get effective treatment", the patient will have expectations for the treatment results. And, out of trust in the doctor, this expectation is usually benign - "I will get effective treatment". Anticipation itself cannot reduce pain. It is just a key. Endorphins are the real pain relievers.
Children often cry to their parents when they knock, touch or fall down. If you pay attention to observation, you will find that parents' embrace can really alleviate children's pain. Because comfort can activate the endogenous opioid system and make the body secrete endorphins. In structure, endorphins are very similar to opium and have a strong analgesic effect. In the follow-up experiment, Jon injected normal saline and naloxone to the second group of patients. Naloxone could block the effect of endorphin. As a result, the placebo effect of normal saline disappeared. [2]
Experimental schematic diagram (drawn by the author)
This shows that the placebo effect is not a pure psychological effect, and the psychological effect is only the initial link. [3]
If the placebo effect comes entirely from expectations, then it is a "deception"; If the patient is explicitly told that "these are some placebos", the patient will not have a benign expectation, and naturally cannot enjoy the role of the placebo.
However, this is not the case. In one study, the doctor gave the patient some sugar pills and clearly told him that "these are some sugar pills", and the patient's pain was still relieved. [4]
Why?
Because there is a second mechanism of placebo effect - conditioned reflex.
Think about the scene when you went to the hospital for the first time. The hospital is a very special place, with distinctive buildings, room layout, interior decoration, and the clothes of doctors and nurses. You receive treatment there, get some medicine, take medicine on time every day, and finally get well. Such scenes will be repeated in a lifetime. Over time, we will link the hospital, doctors and even the action of taking medicine with recovery. Even if you know that you are taking sugar pills, the mere act of taking the medicine can induce the body to release dopamine, thus producing therapeutic effects. [5]
The mechanism of placebo effect (photo source: harvard)
Speaking of this, it is easy to guess which factors are related to the strength of the placebo effect. First, the situation of patients. The more patients believe in medicine and rely on doctors, the stronger the placebo effect will be; [6] The second is the form of placebo. Large pills are better than small ones, and injection is better than pills. [7] Because in public awareness, "injection is better faster"; Finally, it depends on the doctor's performance.
Some hospitals have done experiments, and selected a group of patients with similar conditions in all aspects, and randomly divided into two groups. The first group asked the anesthetist to simply tell them before the operation, "I will help you with anesthesia tomorrow, don't worry"; The anesthesiologists in the second group were much more enthusiastic. They introduced the situation during and after the operation in detail, patiently answered the patients' questions and soothed their emotions. As a result, the demand for postoperative analgesia in the second group was significantly reduced, the average dosage was only 50% of that in the first group, and the hospital stay was also greatly reduced, with an average reduction of 2.6 days. [8] It can be seen that the attitude of doctors has a great impact on the strength of the placebo effect of patients.
Like anything, the placebo effect has two sides. On the one hand, about 35% of patients can benefit from the placebo effect to reduce discomfort and avoid drug abuse; On the other hand, the placebo effect is a natural means of rehabilitation and has nothing to do with the true ingredients of the drug. In the process of drug research, development and testing, we must take this into account and set up a placebo control group; In daily life, we must also take this into account - after eating health care products, we feel good. It may be the placebo effect that plays a role.
Can't sleep at night and feel irritable? Try a placebo. Sugar pills, vitamins and normal saline may work.
reference:
[1] More Than Just a Sugar Pill: Why the placebo effect is real[J]. Science in the News, 2016.
[2] MARCHANT J. Placebos: Honest fakery[J]. Nature, 2016, 535: S14–S15.
[3] VACHON-PRESSEAU E, BERGER S E, ABDULLAH T B, etc Brain and psychological determinants of placebo pill response in chronic pain patients[J]. Nature Communications, 2018, 9(1): 3397.
[4] MD M M. A placebo can work even when you know it’s a placebo[EB/OL]. Harvard Health Blog, 2016-07-07. (2016-07-07)[2018-11-17]. https:// www .health.harvard.edu/blog/placebo-can-work-even-know-placebo-201607079926.
[5] Zhang Ruirui, Guo Jianyou Placebo analgesia and its internal mechanism [J] Chin J Clin Pharmacol Ther 2011Oct, 2011, 16: 10.
[6] Open a book curtain Influencing factors of clinical "placebo effect" [J] Chinese Journal of General Practice, 2008, 11 (9): 825 – 826
[7] The Placebo Effect: How It Works[EB/OL]. Psychology Today, [2018-11-07]. http://www.psychologytoday.com/blog/brain-sense/201201/the-placebo-effect-how-it-works.
[8] Xiao Jianchu Placebo and its application in medicine [J] New Medicine, 2001, 32 (8): 504 – 505
