A nocebo effect is said to occur when negative expectations of the patient regarding a treatment Both placebo and nocebo effects are presumably psychogenic, but they can induce measurable changes in the body. One article that reviewed. Request PDF on ResearchGate | Efecto nocebo: la otra cara del placebo | Administration of drugs is often followed by beneficial (placebo effects) and harmful. This overview focuses on placebo and nocebo effects in clinical trials and routine care. Our goal was to propose strategies to improve.
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Nocebo phenomena are common in clinical practice and have recently become a popular topic of research and discussion among basic scientists, clinicians, and ethicists. The underlying mechanisms include learning by Pavlovian conditioning and reaction to expectations induced by verbal information or suggestion.
Nocebo responses may come about through unintentional negative suggestion on the part of physicians and nurses. Adverse events under treatment with medications sometimes come about by a nocebo effect. Physicians face an ethical dilemma, as they are nodebo not just to inform patients of the potential complications of treatment, but placsbo to minimize the likelihood of these complications, i. Words are the most powerful tool a doctor possesses, but words, like a two-edged sword, can maim as well as heal.
The positive influence of doctor—patient communication, treatment expectations, and sham treatments, termed placebo effect, has been known for many years e2 and extensively studied 1. The efficacy of placebo has been demonstrated plavebo subjective symptoms such as pain and nausea 1.
The Scientific Advisory Board of the German Medical Association published a statement on placebo in medicine in 2. The opposite of the placebo phenomenon, namely nocebo phenomena, have only recently received wider attention from basic scientists and clinicians.
In comparison, the data on the nocebo effect are sparse. Number of studies on the placebo effect olive-green bars, left ordinate and the nocebo effect blue diamonds, right ordinate in PubMed between placfbo Our intention here is to portray the neurobiological mechanisms of nocebo phenomena. Furthermore, in order to sensitize clinicians to the nocebo phenomena in their daily work we present studies on nocebo phenomena in randomized placebo-controlled trials and in clinical nodebo medicinal treatment and surgery.
Finally, we discuss the ethical problems that arise from nocebo phenomena which may be induced by explanation of the proposed treatment in the course of the patient briefing efwcto describe possible solutions. The effects of every medical treatment, for example administration of drugs or psychotherapy, are divided into specific and non-specific. Specific effects are caused by the characteristic elements of the intervention.
The non-specific effects of a treatment are called plavebo effects when they are beneficial and nocebo effects when they are harmful.
Experimental nocebo research aims to answer three central questions:. The proven mechanisms of the placebo response include learning by Pavlovian conditioning and reaction to expectations aroused by verbal information or suggestion 6. Learning experiments with healthy probands have shown placrbo worsening of symptoms of nausea caused by spinning on a swivel chair can be conditioned 7.
Expectation-induced cutaneous hyperalgesia placbeo be produced experimentally through verbal suggestion alone 8. Social learning by observation led to placebo analgesia on the same order as direct experience by conditioning 9. Nocebo responses can also be demonstrated in patients.
In an experimental study, 50 patients with chronic back pain were randomly divided into two groups plaecbo a leg flexion test: One group was informed that the test could lead to a slight increase in pain, while the other group was told that the test had no effect on pain level. The group with negative information reported stronger pain pain intensity It can be concluded from these studies that both placebo and nocebo responses can be acquired via all kinds of learning.
A key part in the mediation of the placebo response is played by a number of central chemical messengers. Especially dopamine and endogenous opiates have been demonstrated to be central mediators of placebo analgesia. These two neurobiological substrates have also been shown to play a part in the nocebo response hyperalgesia: While secretion of dopamine and endogenous opioids is increased in placebo analgesia, this reaction is decreased in hyperalgesia Because worsening of symptoms e.
To date, a genetic predisposition to placebo response has been demonstrated only for depression and social anxiety e3 ; such a predisposition to nocebo response has so far not been shown e4. Sex is a proven predictor of the placebo response and also exerts some influence on the nocebo response. In the above-mentioned study on the aggravation of symptoms of nausea, women were more susceptible to conditioning and men to generated expectations 6.
Identification of predictors of nocebo responses is a central goal of ongoing investigations.
The aim is to pinpoint groups at risk of nocebo responses, for example patients with high levels erecto anxiety, and optimize the therapeutic context accordingly The verbal and non-verbal communications of physicians and nursing staff contain numerous unintentional negative suggestions that may trigger a nocebo response Patients are highly receptive to negative suggestion, particularly in situations perceived as existentially threatening, such as impending surgery, acute severe illness, or an accident.
Persons in extreme situations are often in a natural trance state and thus highly suggestible 15 This nocdbo of consciousness leaves those affected vulnerable to misunderstandings arising from literal interpretations, ambiguities, and negative suggestion Box.
Just as the announcement that a drug is going to be given can provoke its side effects even if it is not actually administered, telling headache patients that they are going to experience a mild electric current or an electromagnetic field e. Researchers distinguish true placebo effects from perceived placebo effects.
The true placebo effect is the whole effect in the placebo group minus non-specific factors such as natural disease course, regression to the mean, and unidentified parallel interventions. The true placebo effect can be quantified only by comparing a placebo group and an untreated group The true nocebo effect in double-blind drug trials thus includes all negative effects in placebo groups minus non-specific factors such as symptoms from the treated disease or comorbid conditions and adverse events of accompanying medication 4.
A systematic review of RCTs of tricyclic antidepressants TCAs; 21 studies and selective serotonin reuptake inhibitors SSRIs; studies revealed a significantly higher rate of adverse events in both the verum and placebo arms of the TCA trials compared to the verum and placebo arms of the SSRI trials. Patients given TCA placebos were significantly more likely to report dry mouth The side effects of medications therefore depend on what adverse events the patients and their treating physicians expect 20 Rates of discontinuation owing to adverse effects of placebo in double-blind trials on patients with various diseases are presented in Table 1.
The methods used for recording adverse events influence the type and the frequency of effects reported: Patients specify more adverse events when checking off a standardized list of symptoms than when they report them spontaneously In a large proportion of double-blind drug trials, the way in which subjective drug side effects were recorded is described inadequately or not at all The robustness of the data on which summaries of product characteristics and package inserts are based must therefore be seen in a critical light.
The problems in evaluating side effects of drugs in RCTs also apply in everyday clinical practice. Is the symptom reported by the patient—nausea, for example—a side effect of medication, a symptom of the disease being treated, a symptom of another disease, or a temporary indisposition unconnected with either the drug or the disease?
Nocebo effects have been described in Table The lactose content of tablets varies between 0. Small amounts of lactose up to 10 g are tolerated by almost all lactose-intolerant individuals. Therefore, complaints of gastrointestinal symptoms by lactose-intolerant patients who have been told by the physician or have found out for themselves that the tablets they are taking contain lactose may represent a nocebo effect In Germany, the aut idem ruling by which pharmacists may substitute a preparation with identical active ingredients for the product named on the prescription and discount agreements have led to complaints from patients and physicians of poor efficacy or increased adverse effects after switching to generic preparations.
A qualitative systematic review showed that patients with increased anxiety, depressivity, and somatization tendency are at greater risk of adverse events after switching to generic preparations In the words of one such statement: Expectations that a treatment will be poorly tolerated, whether based on experience or induced by information from the media or trusted third parties, may bring about nocebo effects.
A systematic review and meta-analysis found a robust association between the expectation and the occurrence of nausea after chemotherapy e However, the studies just cited show that the patient briefing can induce nocebo responses. A study on briefing in the context of influenza vaccination showed that fewer adverse events were reported after vaccination by the group told what proportion of persons tolerated the procedure well than by those informed what proportion experienced adverse events e Based on research, we know that patients who are told about these sorts of side effects are more likely to experience them than those who are not told.
Do you want me to inform you about these side effects or not? A systematic review four studies, patients of patients with chronic pain showed that training from a pharmacist—e.
Skill in conveying positive suggestions and avoiding negative ones should also receive more attention in nurse training. The points that need to be discussed include, for example, whether it is legitimate to express a right of the patient not to know about complications and side effects of medical procedures and whether this must be respected by the physician.
Furthermore, it has to be debated whether some patients might not be left confused and uncertain by their inability to follow the legally mandatory comprehensive information on potential complications of medical treatments that is found, for example, on package inserts or multipage information and consent documents.
Conflict of interest statement. National Center for Biotechnology InformationU. Journal List Dtsch Arztebl Int v.
Published online Jun Author information Article notes Copyright and License information Disclaimer. Received Jan 28; Accepted Mar See letter ” Correspondence letter to the editor: See letter ” Correspondence reply: This article has been cited by other nocevo in PMC.
Abstract Background Nocebo phenomena are common in clinical practice and have recently become a popular topic of research and discussion among basic scientists, clinicians, and ethicists. Conclusion Physicians face an ethical dilemma, as they are required not just to inform patients of the potential complications of treatment, but also to minimize the likelihood of these complications, i.
Method The opposite of the placebo phenomenon, namely nocebo phenomena, have only recently received wider attention from basic scientists and clinicians. Open in a separate window. Experimental nocebo research Experimental nocebo research aims to answer three central questions: Are nocebo effects caused by the same psychological mechanisms as placebo effects, i. Psychological mechanisms The proven mechanisms of the placebo response include learning by Pavlovian conditioning and reaction to expectations aroused by verbal information or suggestion 6.
Neurobiological correlates A key part in the mediation of the placebo response is played by a number of central chemical messengers. Interindividual variation Sex is a proven predictor of the placebo response and also exerts some influence on the nocebo response. Generation of nocebo responses by doctor— patient and nurse—patient communication The verbal and non-verbal communications of physicians and nursing staff contain numerous unintentional negative suggestions that may trigger a nocebo response Box Unintended negative suggestion in everyday clinical practice after 15e5e6.
Nocebo phenomena in drug treatment Researchers distinguish true placebo effects from perceived placebo effects. Table 1 Systematic reviews: Problems in evaluating side effects of drugs The methods used for recording adverse events influence the type and the frequency of effects reported: Nocebo effects during drug treatment in everyday clinical practice Nocebo effects have been described in Table 2: Table 2 Nocebo effects in clinical studies.