This paper reflects the research and thoughts of a student at the time the paper was written for a course at Bryn Mawr College. Like other materials on Serendip, it is not intended to be "authoritative" but rather to help others further develop their own explorations. Web links were active as of the time the paper was posted but are not updated.
Imagine you go to your doctor for chronic back pain and she tells you that she's going to give you a drug, yet she's not sure of its effectiveness because only approximately 40% of her patients have found it to be beneficial. How sure will you be that the outcome of this treatment will be positive? However, what if your doctor tells you she is giving you the newest, most beneficial drug treatment on the market and that she is very sure of how helpful it will be? Imagine the difference just a simple positive statement from your doctor will make when you take the pill every day. Not only will you be trusting of your treatment, but that trust will lead you to be confident (Endnote 1) that you will feel better - and in most cases, you will.
This is an example of the placebo effect - a self-made natural healing response of the body. No matter the fact that in both instances your doctor is giving you the same medication, her belief and yours in the treatment will most likely result in more positive effects. Many people argue that alternative methods of healing (such as hypnosis, therapeutic touch, homeopathic remedies, etc) are basically a placebo effect taking place. Yet, doesn't this fact prove the power of our minds both in health and in issues of pain management? Most modern scientists tend to separate the mind from the body, at least implicitly, suggesting the "mind" is simply a construct with little meaning. The one-cause, one- cure philosophy of science today often disregards the role of the mind in health and healing. Yet many of us even daily acknowledge the power of the mind when we say "oh, you're not sick- it's all in your mind". The placebo effect is not totally understood, yet this fact should not lead anyone to believe that its effects should be discounted. The placebo effect has been documented to be very powerful.
A placebo is a medicine or other kind of treatment that seems therapeutic, but in reality is inert and pharmacological inactive (2). The placebo effect is "a change in a patient's illness attributable to the symbolic import of a treatment rather than a specific pharmacologic or physiologic property" (3). Note that a placebo is not even necessary to result in a placebo effect. Basically, the only way this treatment can work is if one believes that it will. No matter the fact that placebos lack actual chemical functioning, it has been documented that 30-40% of patients experience the positive effects of placebo (2, 5, 7). We most often hear of placebos in clinical tests of new medications or treatments, where one group in the study is given the actual medication and the other receives a placebo which feels, tastes, appears exactly like the drug. The placebo group's reactions to the placebo serve as a base-line against which the effects of the drug can be studied. In order for this drug to be considered effective, the treatment being tested much produce results better than those by the placebo. Most often, the patient's belief that the placebo will be positively effective is a self-fulfilling prophecy.
A patient's belief in the treatment and the placebo response are dependent upon a variety of factors. First, the patient's expectations of treatment effects clearly influence the responses. For example, a study in England was done where 100 men were told that they were taking chemotherapy, when in actuality they were taking inactive saline solution. 20% of these men lost their hair, demonstrating the power of the belief of effects of the treatment. (4) Second, the relationship between patient and care-provider is quite important in determining treatment (or placebo) results. If there is a positive rapport between the two, then most often there will be a positive enthusiasm for the treatment, and therefore a positive outcome, no matter if a placebo or pharmacologic treatment was used. The friendliness, interest, sympathy, prestige, and positive attitude of the care- provider toward the patient and toward the treatment are associated with positive effects of placebos as well as of active treatments. For example, in a double- blind study of dental extractions, two groups were compared: the first, where the doctors knew they would administer either a narcotic analgesic, a placebo, or a narcotic antagonistic and the second, where the doctors knew they would administer either a placebo or narcotic antagonist. The patients from the first group who received placebo had significantly less pain. Since the two placebo groups were only different in the doctors' knowledge of possible treatment, this knowledge must have resulted in differences in behaviors by the doctor that influenced patient responses (3). Third, placebos have time- effect curves and peaks, cumulative and carryover effects after end of treatment which are quite similar to those of pharmacologically active medications. For example, "when varying doses of analgesic followed by a placebo are administered, patients' placebo responses correspond in degree of pain relief over time to their original dosage of analgesic" (3). In addition, dose-response effects have also been documented where two placebo pills were demonstrated to have more pronounced effects than one.
How does one explain these trends and effectiveness of a placebo treatment? The physiology of the placebo effect is still largely unknown. A placebo is chemically inactive, yet it has a profound effect on the human mind and body. A possible explanation is that a patient's belief in the treatment will reduce anxiety by allowing the problem to seem more controllable. With regards to the example given at the beginning of the paper, you may feel much more at ease once a doctor has told you that there are effective treatments for your pain, therefore you can reap the benefits of a less-stressed state. Depression and anxiety most often increase subjective complaints of pain (5). Stress adversely affects several physiological processes and increases symptom reporting. Placebos seem "most effective for anxious patients and the effects are often attributed to anxiety reduction and associated decreased pain and suffering" (3). Thus, the patient may benefit from the relief of symptoms of depression, stress, and anxiety. In addition, the placebo does not merely allow the patient's mind to be at ease; the effect extends beyond the psyche. In a 1950 study of routine arterial ligation surgery to treat angina pectoris, 13 patients received the surgery while a placebo group of five had a chest incision made. 76% of those who received the surgery and 100% of the placebo group improved (7).
Another explanation is the idea of conditioned stimuli. Treatment may have a positive effect because of its association with effective treatments (and interactions with the medical field) the patient has had before. Thus, inactive drugs, people, procedures, and places can function as conditioned stimuli for the alleviation of symptoms if powerful unconditioned stimuli has been positively associated repeatedly with the relief of symptoms.
An additional possible explanation for the effects of placebo is that responses may be caused by endogenous opiate release in the central nervous system (3). Pain sensation is subject to circuitry within the nervous system that uses opioid synapses, as suggested by the fact that injection of opiates relieves pain. It is thought that possibly the placebo effect is a stimulation and release of our body's own natural narcotics, such as endorphins and enkephalins. These chemicals are typically released during stress or excitement and it is possible that they either bind to pain receptors or depress neurons in the central nervous system, thus slowing or eliminating pain communication (6). This shows us that, by whatever mechanism, a person's beliefs can either change his biochemistry or functionally mimic a change in biochemistry. However, studies of the exact physiological mechanism of the placebo effect are rare and difficult, especially when in most cases the use of a placebo is to test the effect of another drug. Additionally, since we know that the effect of placebos is dependent upon conditioning, faith and reduction of anxiety, the placebo response is different for everyone and cannot be necessarily predicted.
Indeed, we may not know how the placebo works, yet something which makes such profound therapeutic changes must not be ignored. Many scientists believe that the effectiveness of alternative therapies may simply be a placebo effect. Yet, if the effects of treatments such as hypnosis, meditation, acupuncture, etc... remain and bring about long- lasting health benefits, then we must draw the conclusion that a placebo is more than something against which testing of a "real" drug should be done. Given the positive results of the placebo effect, how can we really say that one type of medicine or therapy is necessarily ineffective? For example, relaxation techniques generally alter sympathetic activity as indicated by decreases in oxygen consumption, respiratory and heart rate, and blood pressure. Increased electroencephalographic slow wave activity has also been reported. Although the mechanism for the decrease in sympathetic activity is unclear, one may infer that decreased arousal (due to alterations in catecholamines or other neurochemical systems) plays a key role. Hypnosis, in part because of its capacity for evoking intense relaxation, has been reported to reduce several types of pain. Finally, acupuncture has gained popularity in its ability to relieve pain, possibly due to the release of endorphins (5). In addition, these types of techniques may alter expectation, which also plays a key role in subjective experiences of pain intensity. They also may augment analgesic responses through behavioral conditioning. Finally, these techniques help patients enhance their sense of self control over their illness enabling them to be less helpless and better able to deal with pain sensations (5). If these are positive effects of alternative therapies (which the medical world claims are placebo effects), then the placebo effect must demonstrate the amazing power of our mind.
Perhaps the placebo decreases anxiety. Perhaps it meets the expectations of the patient. Perhaps it is a conditioned response. Yet, the issue here is that it works. Why does much of the Western world of medicine reject a "technology" that works - the power of our minds? Most doctors shy away from the use of the word because it seems to imply a type of deception. And yet, the deception is all in our heads! "Placebo effects are recognized as an inherent part of any therapeutic intervention outcome, and demonstrate the important and power of the psychological factors in the healing process" (1). The placebo effect is proof of the fact that the mind can influence the body in a powerful and therapeutic way.
1- Fecteau, Danielle, "Placebo Effects", Science et Comportement http://www.ovid.med.virginia.edu/ovidweb/ovidweb.cgi
2- American Cancer Society, Alternative and Complementary Therapies: http://www.cancer.org/alt_therapies/articles/placebo.html
3- Turner, et al, "The importance of placebo effects in pain treatment and research", JAMA, 1994: http://www.ovid.med. virginia.edu/ovidweb/ovidweb.cgi
4- Mining Co. Alternative Medicine Information: http://www.altmedicine.minigco.com/library/weekly/aa100998.htm?terms=placebo+eff ect&COB=home (Note: this link takes you to the Mining Co. search engine)
5- Mind/Body Medicine Discussion: http://www2.trincoll.edu/~rmlee/mindbody_lll/mb2disc_frm.htm
6- Elmer, Debra, "Placebo Use": http://www.nursing.uiowa.edu/sites/Adultpain/MedGen/placebot.htm
7- Imprint Online, "Placebo Power": http://imprint.uwaterloo.ca/issues/012398/3Science/science01.shtml
1- "confident" literally means "with faith" (Lat: con = with; fides = faith)
| Course Home Page
| Back to Brain and Behavior
| Back to Serendip |