The placebo effect, sleep difficulty, and side effects: a balanced placebo model

When describing harms and benefits to potential trial participants, participant information leaflets are inadequate

BACKGROUND

Providing informed consent for trials requires providing trial participants with comprehensive information about the trial, including information about potential risks and benefits. It is required by the ethical principle of respecting patient autonomy. Our study examines the variation in the way information about potential trial benefits and harms is shared in participant information leaflets (PILs).

METHODS

A total of 214 PILs and informed consent forms from clinical trials units (CTUs) and Clinical Research Facilities (CRFs) in Ireland and the UK were assessed by two authors independently, to check the extent to which they adhered to seven recently developed principles. Discrepancies were resolved by a third.

RESULTS

Usage of the seven principles varied widely between PILs regardless of the intended recipient or trial type. None of the PILs used more than four principles, and some (4%) used none. Twenty-seven per cent of PILs presented information about all known potential harms, whereas 45% presented information on all known potential benefits. Some PILs did not provide any potential harms or potential benefits (8%). There was variation in the information contained in adult and children PILs and across disease areas.

CONCLUSION

Significant variation exists in how potential trial benefits and harms are described to potential trial participants in PILs in our sample. Usage of the seven principles of good practice will promote consistency, ensure informed ethical decision-making and invoke trust and transparency. In the long term, a standardised PIL template is needed.

Reduction in caffeine withdrawal after open-label decaffeinated coffee

BACKGROUND

Withdrawal from addictive drugs can be reduced by administering placebo deceptively, but in the clinic it is unethical to deceive the patient. Open-label placebo effects have been observed across a range of psychophysiological phenomena, and may also apply to drug withdrawal.

METHOD

24-hour abstinent heavy coffee drinkers (N = 61) rated their caffeine withdrawal symptoms before being allocated to one of three groups. The Deceptive group was given decaffeinated coffee (decaf) and told it was caffeinated, the Open-Label group given decaf and told it was decaf and the Control group given water and told it was water. After 45 min, caffeine withdrawal was measured again. All participants rated their expectancies of withdrawal reduction from caffeinated coffee, decaf and water prior to being randomised and the end of the study.

RESULTS

There was a significant 9.5-point reduction in caffeine withdrawal in the Open-Label group (95% confidence interval (CI): 4.7, 14.3; p = 0.002), which was 8.6 points less than the Deceptive group (95%CI: 0.4, 16.8; p = 0.014) but 8.9 points greater than the Control group (95%CI: 0.6, 17.2; p = 0.012). Pre-randomisation, participants expected caffeinated coffee to reduce their withdrawal symptoms the most, followed by water and decaf, Pre-randomisation expectancy of withdrawal was only associated with amount of withdrawal reduction in the Deceptive group.

CONCLUSION

It appears as if open-label placebo caffeine (i.e. decaf) can reduce caffeine withdrawal symptoms, even when people do not hold a conscious expectancy it will do so. There may be ways to integrate open-label placebo procedures into clinical interventions for drug dependence without violating informed consent.

Social communication pathways to COVID-19 vaccine side-effect expectations and experience

OBJECTIVE

Negative beliefs about medication and vaccine side-effects can spread rapidly through social communication. This has been recently documented with the potential side-effects from the COVID-19 vaccines. We tested if pre-vaccination social communications about side-effects from personal acquaintances, news reports, and social media predict post-vaccination side-effect experiences. Further, as previous research suggests that side-effects can be exacerbated by negative expectations, we assessed if personal expectations mediate the relationships between social communication and side-effect experience.

METHOD

In a prospective longitudinal survey (N = 551), COVID-19 vaccine side-effect information from three sources-social media posts, news reports, and first-hand accounts from personal acquaintances-as well as side-effect expectations, were self-reported pre-vaccination. Vaccination side-effect experience was assessed post-vaccination.

RESULTS

In multivariate regression analyses, the number of pre-vaccination social media post views (β = 0.17) and impressions of severity conveyed from personal acquaintances (β = 0.42) significantly predicted an increase in pre-vaccination side-effect expectations, and the same variables (βs = 0.11, 0.14, respectively) predicted post-vaccination side-effect experiences. Moreover, pre-vaccination side-effect expectations mediated the relationship between both sources of social communication and experienced side-effects from a COVID-19 vaccination.

CONCLUSIONS

This study identifies links between personal acquaintance and social media communications and vaccine side-effect experiences and provides evidence that pre-vaccination expectations account for these relationships. The results suggest that modifying side-effect expectations through these channels may change the side-effects following a COVID-19 vaccination as well as other publicly discussed vaccinations and medications.

Beliefs About Medicines Predict Side-Effects of Placebo Modafinil

BACKGROUND

Patients receiving placebo in clinical trials often report side-effects (nocebo effects), but contributing factors are still poorly understood.

PURPOSE

Using a sham trial of the cognition-enhancing "smart pill" Modafinil we tested whether medication beliefs and other psychological factors predicted detection and attribution of symptoms as side-effects to placebo.

METHODS

Healthy students (n = 201) completed measures assessing beliefs about medication, perceived sensitivity to medicines, negative affectivity, somatization, and body awareness; 66 were then randomized to receive Deceptive Placebo (told Modafinil-given placebo, 67 to Open Placebo (told placebo-given placebo, and 68 to No Placebo. Memory and attention tasks assessed cognitive enhancement. Nocebo effects were assessed by symptom checklist.

RESULTS

More symptoms were reported in the Deceptive Placebo condition (M = 2.65; SD = 2.27) than Open Placebo (M = 1.92; SD = 2.24; Mann-Whitney U = 1,654, z = 2.30, p = .022) or No Placebo (M = 1.68; SD = 1.75, Mann-Whitney U = 1,640, z = 2.74, p = .006). Participants were more likely to attribute symptoms to Modafinil side-effects if they believed pharmaceuticals to be generally harmful (incidence rate ratio [IRR] = 1.70, p = .019), had higher perceived sensitivity to medicines (IRR = 1.68, p = .011), stronger concerns about Modafinil (IRR = 2.10, p < .001), and higher negative affectivity (IRR = 2.37, p < .001).

CONCLUSIONS

Beliefs about medication are potentially modifiable predictors of the nocebo effect. These findings provide insight into side-effect reports to placebo and, potentially, active treatment.

Using Positive Attribute Framing to Attenuate Nocebo Side Effects: A Cybersickness Study

BACKGROUND

Side effect warnings can contribute directly to their occurrence via the nocebo effect. This creates a challenge for clinicians and researchers, because warnings are necessary for informed consent, but can cause harm. Positive framing has been proposed as a method for reducing nocebo side effects whilst maintaining the principles of informed consent, but the limited available empirical data are mixed.

PURPOSE

To test whether positive attribute framing reduces nocebo side effects relative to negative framing, general warning, and no warning.

METHODS

Ninety-nine healthy volunteers were recruited under the guise of a study on virtual reality (VR) and spatial awareness. Participants were randomized to receive positively framed ("7 out of 10 people will not experience nausea"), negatively framed ("3 out of 10 people will experience nausea"), general ("a proportion of people will experience nausea"), or no side effect warnings prior to VR exposure.

RESULTS

Receiving a side effect warning increased VR cybersickness relative to no warning overall, confirming that warnings can induce nocebo side effects. Importantly, however, positive framing reduced cybersickness relative to both negative framing and the general warning, with no difference between the latter two. Further, there was no difference in side effects between positive framing and no warning.

CONCLUSIONS

These findings suggest that positive framing not only reduces nocebo side effects relative to negative framing and general warnings, but actually prevents nocebo side effects from occurring at all. As such, positive attribute framing may be a cheap and ethical way to reduce nocebo side effects.

The Unintended Consequences of Adverse Event Information on Medicines' Risks and Label Content

Patients and prescribers need to be aware of adverse drug events to minimize the risk of their occurrence and the severity with which they appear. However, numerous studies show that being informed about adverse events can increase the possibility of suffering from them. Patients tend to overestimate the likelihood of experiencing the adverse events included in the label, and this can contribute to worsening the negative expectations which are at the root of the nocebo effect. In fact, patients can become anxious after reading the undesirable effects section of the leaflet and, in addition to suffering from the nocebo effect, might not take a drug they could benefit from due to the fear of experiencing adverse events. In addition, patients' attention can focus towards non-specific symptoms of daily living that can be misattributed to the drug and included in the labelling. This article proposes a number of suggestions to reduce the abovementioned unintended effects associated with labelling, namely, an increased focus on the excess risk of experiencing adverse events rather than crude incidence, using attribute framing to help patients to better understand the risk of experiencing adverse events, dividing the undesirable effect section of the leaflet into subsections according to the level of evidence supporting causal relationships and, finally, restricting the addition of non-specific adverse events that are also symptoms of daily living to only those where there is enough evidence to show they have been caused by the drug. More studies on how to minimize the nocebo effect induced by adverse event information should be performed, and these should be done in collaboration with health authorities, to reach a shared consensus on how to better present adverse event information in the label.

Why we need more research into the placebo response in psychiatry

Placebos are not inert, but exert measurable biological effects. The placebo response in psychiatric illness is important and clinically relevant, but remains poorly understood. In this paper, we review current knowledge about the placebo response in psychiatric medicine and identify research directions for the future. We argue that more research is needed into the placebo response in psychiatric medicine for three broad reasons. First, awareness of factors that cause placebo response, for whom, and when, within clinical trials will allow us to better evidence efficacy of new treatments. Second, by understanding how placebo mechanisms operate in the clinic, we can take advantage of these to optimise the effects of current treatments. Finally, exploring the biological mechanisms of placebo effects might reveal tractable targets for novel treatment development.

A Positive Mood Induction for Reducing the Formation of Nocebo Effects from Side Effect Information

BACKGROUND

Providing treatment side effect information can increase the occurrence of side effects through nocebo effects. Nocebo effects from side effect information raise a dilemma for health care, as there is an ethical obligation to disclose potential unpleasant treatment information to patients.

PURPOSE

To test the hypothesis that a positive mood induction can block the development of nocebo effects that result from treatment side effect information.

METHODS

In a laboratory setting, healthy participants were assigned to one of four conditions in a between-subjects randomized factorial trial. First, participants took part in a mood induction procedure, with half receiving a positive mood induction and the other half a neutral mood induction. Next, participants were told they would experience transcranial direct current stimulation (tDCS). Prior to a sham tDCS task, half of the participants were informed that headache pain is a side effect of tDCS, whereas the other half were not given this information.

RESULTS

In the neutral mood condition, the provision of headache side effect information lead to a greater occurrence of headaches, more frequent headaches, and a higher maximum level of headache pain as compared to those given no side effect information. In the positive mood condition, a similar increase in headache pain did not manifest from the provision of side effect information.

CONCLUSIONS

This is the first experiment to find that a positive mood induction can block the formation of nocebo effects that arise from side effect information. Inducing positive moods may be an effective strategy for reducing nocebo effects in a variety of clinical settings.

The Influence of Side Effect Information Framing on Nocebo Effects

BACKGROUND

One contributing factor to the development of nocebo effects is information provided about possible side effects. However, nondisclosure of information can be problematic.

PURPOSE

We assessed whether positively framed side effect information (highlighting likelihood of not experiencing side effects) can reduce nocebo effects compared to negatively framed information (highlighting likelihood of experiencing side effects).

METHODS

One hundred twelve participants took part in research ostensibly assessing the influence of benzodiazepines (actually sham capsules) on anxiety. Participants were randomized to receive a sham capsule with positively or negatively framed information about four side effects, or a no-treatment control condition. Side effect expectations were assessed after information provision. Framed side effects and other unmentioned symptoms were assessed during the session and 24-hr follow-up.

RESULTS

Nocebo effects occurred in symptoms presented as side effects (regardless of framing) during the study session and follow-up (ps < .003). At follow-up, there was also a nocebo effect in other unmentioned symptoms (p = .018). Positive framing reduced side effect symptoms compared with negative framing during the study session (p = .037), but this effect was no longer present at follow-up (p = .53). Side effect expectations did not differ between the framing conditions (p = .14).

CONCLUSIONS

Positive framing reduced side effects short-term, but not at follow-up. Expectations did not differ between negative and positive framing. Nocebo effects appeared to generalize to other unmentioned symptoms over a 24-hr period. Further research is needed to determine whether the initial impact of positive framing can be maintained over time.

Prescribing Placebos: An Experimental Examination of the Role of Dose, Expectancies, and Adherence in Open-Label Placebo Effects

Background

Recent evidence indicates that placebo effects can occur even when patients know that they are taking a placebo, termed the open-label placebo effect.

Aim

To assess whether placebo dose (one pill per day vs. four pills per day), treatment expectancies, and adherence contribute to open-label placebo effects.

Method

Healthy undergraduate participants were randomly assigned to take one or four open-label placebo pills per day or to a no-treatment control group. Placebo-treated participants took a 5-day course of an open-label placebo described as enhancing physical (symptoms and sleep) and psychological (positive and negative emotional experience) well-being. Expectancies about placebo effectiveness and well-being were assessed at baseline, and well-being and adherence were assessed after the 5-day course of treatment.

Results

Medium-to-large open-label placebo effects were evidenced in all well-being outcomes including sleep quality. Dose did not influence these effects. Both treatment expectancies and adherence were significant independent predictors of enhanced well-being in the two psychological well-being outcomes and the experience of physical symptoms, but sleep quality improved independently.

Conclusions

This is the first study to demonstrate the effect of open-label placebos in improving well-being and sleep quality and to show that open-label placebo reposes do not appear to be dose-dependent, but for most well-being outcomes are independently predicted by both positive expectancies and treatment adherence.

Choice, Expectations, and the Placebo Effect for Sleep Difficulty

BACKGROUND

Choice has been found to facilitate placebo effects for single-session treatments where standard placebo treatment without choice failed to elicit a placebo effect. However, it is unknown whether choice can enhance the placebo effect for treatments occurring over a period of days and where placebo effects are readily established without choice.

PURPOSE

We tested whether single or daily choice between two (placebo) treatments enhanced the placebo effect for sleep difficulty relative to no choice and no treatment over a 1 week period.

METHODS

One-hundred and seventeen volunteers self-identifying with sleep difficulty were recruited under the guise of a hypnotic trial and randomized to one of the four groups. Self-reported outcomes included insomnia severity, fatigue, total sleep time (TST), sleep onset latency (SOL), perceived sleep quality (PSQ), and treatment satisfaction. Objective TST and SOL were assessed in a subsample via actigraphy.

RESULTS

Overall, placebo treatment significantly improved insomnia severity, fatigue, and PSQ, confirming a placebo effect on these outcomes. However, both traditional and Bayesian analysis indicated no benefit of choice on the placebo effect on any sleep outcome. Mediation analysis of the overall placebo effect indicated that expectancy completely mediated the placebo effects for insomnia severity and PSQ and partially mediated the placebo effect for fatigue.

CONCLUSION

These findings suggest that choice does not enhance the placebo effect over longer treatment periods (up to 7 days) when placebo effects are readily established without choice. As such, any benefit of choice on placebo effects may be confined to quite specific circumstances.

CLINICAL TRIALS REGISTRATION

ACTRN12618001199202.

Healthy Sleepers Can Worsen Their Sleep by Wanting to Do so: The Effects of Intention on Objective and Subjective Sleep Parameters

PURPOSE

Sleep is regulated by homeostatic and circadian factors. In addition, psychological factors have a strong modulatory impact on our sleep, but the exact underlying mechanisms are still largely unknown. Here, we examined the role of intentions on subjective and objective sleep parameters. Young healthy sleepers were instructed to voluntarily either worsen or improve their sleep. We predicted that participants would be capable of worsening, but not improving, their sleep compared to a regular sleep condition. In addition, we predicted that the instruction to alter sleep would lead to a higher discrepancy between subjective and objective sleep variables.

PARTICIPANTS AND METHODS

Twenty-two healthy students participated in one adaptation and three experimental nights. Polysomnography and subjective sleep parameters were measured during all four nights. Participants were instructed to sleep regularly ("neutral"), better ("good") or worse ("bad") than normal, in a counterbalanced order.

RESULTS

The instruction to sleep "bad" increased objective sleep onset latency and the number of awakings during the night. The effects were stronger on subjective sleep variables, resulting in a higher sleep misperception in the "bad" condition as compared to the other two conditions. The instruction to sleep "good" did not improve sleep nor did it affect sleep misperception.

CONCLUSION

We conclude that intention is sufficient to impair (but not improve) subjective and objective sleep quality and to increase sleep misperception in healthy young sleepers. Our results have important implications for the understanding of the impact of psychological factors on our sleep.

Nocebo effects of a simplified package leaflet compared to unstandardised oral information and a standard package leaflet: a pilot randomised controlled trial

BACKGROUND

The term "nocebo effect" describes the phenomenon that the mere knowledge and anticipation of possible negative consequences of an intervention can increase the probability of experiencing these consequences. Our objective was to assess whether different information presentations on adverse events (AEs) in package information leaflets (PILs) could influence the nocebo effect.

METHODS

We included patients undergoing orthopaedic surgery in this pilot randomised controlled trial (pRCT). Patients were assigned by random, computerised and centralised allocation to one of three groups: Simplified-PIL, No-PIL or Standard-PIL on ibuprofen. The Simplified-PIL was written in plain language, and AEs were reported with a focus on avoiding biased risk perception. Only the outcome assessment was blinded.

RESULTS

We included 35, 33 and 34 patients in the Simplified-PIL, No-PIL and Standard-PIL groups, respectively. All patients were included in the intention-to-treat analysis. Six patients in the Simplified-PIL, four in the No-PIL and eight in the Standard-PIL group reported an AE. This corresponds to relative risks of 0.80 (95% confidence interval (CI) 0.27-1.90) for the Simplified-PIL and 0.50 (95% CI 0.14-1.46) for the No-PIL compared with the Standard-PIL group. The Simplified-PIL increased knowledge, reduced anxiety and improved adherence, although statistical uncertainty was high for all of these outcomes.

CONCLUSIONS

This pRCT provides the first hints on the way information on AEs is reported in PILs can affect the nocebo effect. This pRCT shows that a definitive RCT is feasible. If the results are confirmed in a definitive large RCT, a revision of the current practice for designing PILs should be considered.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03428035. Registered 2 February 2018.

How does music aid sleep? literature review

With the growth of interest in using music to treat insomnia, there is a need to collect and evaluate the literature. This paper reviews disparate literature and assesses the various kinds of assertions and hypotheses made by researchers about music's efficacy in assisting sleep. Six main researcher proposed reasons (RPR) for how music aids sleep were identified in the literature: (1) relaxation, where music encourages physiological or psychological relaxation; (2) distraction, where music acts as a focal point to distract from inner stressful thoughts; (3) entrainment, synchronization of biological rhythms to beat structures in music; (4) masking, obscuring noxious background noise with music; (5) enjoyment, listening to preferred, emotionally relatable or pleasant music; and (6) expectation, individuals cultural beliefs around music. We evaluated each RPR in terms of the evidence available in the extant literature. Masking RPR was identified as having support for improving sleep. Relaxation, distraction and enjoyment RPR had mixed levels of support. Expectation RPR had possible support. Entrainment had mixed possible support. The paper discusses interactions between RPRs, and a call is made to turn research attention to sequencing the RPRs and possible RPR mediators, with relaxation being a likely mediator of several RPRs.

Effectiveness of Chinese herbal medicine for patients with primary insomnia: A PRISMA-compliant meta-analysis

BACKGROUND

Traditional medicine is widely used for patients with primary insomnia, but the studies showed inconsistent results. We performed a meta-analysis of randomized controlled trials (RCTs) to evaluate the effectiveness of Chinese herbal medicine (CHM) versus placebo for primary insomnia patients.

METHODS

The electronic databases including PubMed, EmBase, Cochrane library, and China National Knowledge Infrastructure were searched to identify the RCTs published from inception till July 2018. The summary weighted mean difference (WMD) with its 95% confidence interval (CI) for Pittsburgh sleep quality index (PSQI), sleep onset latency, total sleep duration, Athens insomnia scale (AIS), and sleep efficiency were calculated using random-effects model.

RESULTS

Fifteen RCTs comprising 1500 patients were finally included in the meta-analysis. Overall, patients who received CHM had lower levels of PSQI (WMD: -2.36; 95% CI: -4.02 to -0.70; P = .005), sleep onset latency (WMD: -11.54; 95% CI: -20.55 to -2.54; P = .012), and AIS (WMD: -0.59; 95% CI: -0.97 to -0.22; P = .002) as compared with placebo. Moreover, the summary WMDs of CHM versus placebo were associated with higher total sleep duration (WMD: 0.79; 95% CI: 0.56-1.02; P < .001), and sleep efficiency (WMD: 9.72; 95% CI: 6.49-12.96; P < .001). The treatment effect on PSQI might be affected by publication year, sample size, mean age, percentage male, diagnostic tool, duration of insomnia, treatment duration, and study quality.

CONCLUSION

The findings of this meta-analysis indicated that CHM could significantly improve the symptoms of insomnia than placebo for patients with primary insomnia.

Can Positive Framing Reduce Nocebo Side Effects? Current Evidence and Recommendation for Future Research

Although critical for informed consent, side effect warnings can contribute directly to poorer patient outcomes because they often induce negative expectations that trigger nocebo side effects. Communication strategies that reduce the development of nocebo side effects whilst maintaining informed consent are therefore of considerable interest. We reviewed theoretical and empirical evidence for the use of framing strategies to achieve this. Framing refers to the way in which information about the likelihood or significance of side effects is presented (e.g., negative frame: 30% will experience headache vs. positive frame: 70% will not experience headache), with the rationale that positively framing such information could diminish nocebo side effects. Relatively few empirical studies (k = 6) have tested whether framing strategies can reduce nocebo side effects. Of these, four used attribute framing and two message framing. All but one of the studies found a significant framing effect on at least one aspect of side effects (e.g., experience, attribution, threat), suggesting that framing is a promising strategy for reducing nocebo effects. However, our review also revealed some important open questions regarding these types of framing effects, including, the best method of communicating side effects (written, oral, pictorial), optimal statistical presentation (e.g., frequencies vs. percentages), whether framing affects perceived absolute risk of side effects, and what psychological mechanisms underlie framing effects. Future research that addresses these open questions will be vital for understanding the circumstances in which framing are most likely to be effective.

Minimizing Drug Adverse Events by Informing About the Nocebo Effect-An Experimental Study

Relevance: Informing patients about potential adverse events as part of the informed consent may facilitate the development of nocebo-driven drug adverse events (nocebo side effects). Objective: To investigate whether informing about the nocebo effect using a short information sheet can reduce nocebo side effects. Methods: A total of N = 44 participants with weekly headaches for at least 6 months were recruited using the cover story of a clinical trial for a headache medicine. In reality, all participants took a placebo pill and were randomized to the nocebo information group or the standard leaflet group. Participants were instructed to read the bogus medication leaflet entailing side effects information shortly before pill intake. The nocebo group additionally received an explanation about the nocebo effect as part of the leaflet. Questionnaires were completed at baseline, 2 min, and 4 days after the pill intake. We conducted general linear models with bootstrap sampling. Baseline symptoms were included as a covariate. Results: Most participants (70.5%) reported nocebo side effects at 2 min. Participants who received the nocebo information (n = 24) reported less nocebo symptoms than the control group (n = 20) (estimated difference: 3.3, BCa 95% CI [1.14; 5.15], p = 0.01, Cohen's d = 0.59). Baseline symptoms, perceived sensitivity to medicine, and side effect expectations each moderated the group effect (estimated difference in slope: 0.47, BCa 95% CI [0.19; 0.73], p = 0.001, d = 0.75; 1.07 [0.27; 1.61], p = 0.006, d = 0.73; 1.57 [0.38; 2.76], p = 0.02, d = 0.58). No group differences were found at 4-day follow-up. After revealing the actual aim of the study, 86% of the participants evaluated the nocebo information to be helpful in general. Conclusions: Results provide the first evidence that informing about the nocebo effect can reduce nocebo side effects.

The nocebo effect: a clinical challenge in the era of biosimilars

INTRODUCTION

The nocebo effect is defined as a negative effect of a pharmacological or non-pharmacological medical treatment that is induced by patients' expectations, and that is unrelated to the physiological action of the treatment. The nocebo effect is an important clinical challenge in the current era of biosimilars. Areas covered: This review aims to answer five key questions about the nocebo effect, namely to reveal its definition, pathophysiology, clinical relevance, contributing factors, and management. Expert commentary: The nocebo effect lowers patients' quality of life and negatively affects treatment adherence rates in biosimilar-treated patients. It may negatively impact on the cost-savings of biosimilars. Health-care providers in charge of biosimilar-treated patients need to be aware of the nocebo effect and adopt strategies to minimize it. They have to be well-informed and confident about the existing evidence about biosimilars. A good patient-physician relationship will improve patients' acceptance of biosimilars, and limits the risk of inappropriate negative bias and the nocebo effect.

Effect of Genetic Information and Information About Caffeine Content on Caffeine Withdrawal Symptoms

This study sought to test the effect of genetic information and information about the caffeine content of a beverage on caffeine withdrawal, specifically if: (1) being informed that one has tested positive for a gene related to caffeine withdrawal can produce an exaggerated caffeine withdrawal response during abstinence; (2) belief that one has consumed caffeine leads to a reduction in withdrawal symptoms when no caffeine is consumed. Regular coffee drinkers were given a bogus genetic test and were told either that they had tested positive or negative for a gene related to withdrawal. After 24-hour caffeine abstinence withdrawal symptoms were measured using a self-report caffeine withdrawal scale, and then again after a cup of decaffeinated coffee. Half the participants were told their coffee was caffeinated and half were told truthfully that it was decaffeinated. Participants told the coffee was caffeinated reported a greater reduction in withdrawal symptoms than those told it was decaffeinated. Differing genetic test result information produced no difference in reported withdrawal symptoms. These results indicate that information about the dose of caffeine administered can influence withdrawal symptoms, but that genetic information does not have a universal ability to produce nocebo effects across all sensory and cognitive domains.

Placebo caffeine reduces withdrawal in abstinent coffee drinkers

BACKGROUND

Expectancies have been shown to play a role in the withdrawal syndrome of many drugs of addiction; however, no studies have examined the effects of expectancies across a broad range of caffeine withdrawal symptoms, including craving.

AIMS

The purpose of the current study was to use caffeine as a model to test the effect of expectancy on withdrawal symptoms, specifically whether the belief that one has ingested caffeine is sufficient to reduce caffeine withdrawal symptoms and cravings in abstinent coffee drinkers.

METHODS

We had 24-h abstinent regular coffee drinkers complete the Caffeine Withdrawal Symptom Questionnaire (CWSQ) before and after receiving decaffeinated coffee. One-half of the participants were led to believe the coffee was regular caffeinated coffee (the 'Told Caffeine' condition) and one-half were told that it was decaffeinated (the 'Told Decaf' condition).

RESULTS

Participants in the Told Caffeine condition reported a significantly greater reduction in the factors of cravings, fatigue, lack of alertness and flu-like feelings of the CWSQ, than those in the Told Decaf condition.

CONCLUSIONS

Our results indicated that the belief that one has consumed caffeine can affect caffeine withdrawal symptoms, especially cravings, even when no caffeine was consumed.

The placebo effect: From concepts to genes

Despite its initial treatment as a nuisance variable, the placebo effect is now recognized as a powerful determinant of health across many different diseases and encounters. This is in light of some remarkable findings ranging from demonstrations that the placebo effect significantly modulates the response to active treatments in conditions such as pain, anxiety, Parkinson's disease, and some surgical procedures. Here, we review pioneering studies and recent advances in behavioral, neurobiological, and genetic influences on the placebo effect. Consistent with recent conceptualizations, the placebo effect is presented as the product of a general expectancy learning mechanism in which verbal, conditioned, and social cues are centrally integrated to change behaviors and outcomes. Examples of the integration of verbal and conditioned cues, such as instructed reversal of placebo effects are also incorporated into this model. We discuss neuroimaging studies that have identified key brain regions and modulatory mechanisms underlying placebo effects using well-established behavioral paradigms. Finally, we present a synthesis of recent genetics studies on the placebo effect, highlighting a promising link between genetic variants in the dopamine, opioid, serotonin, and endocannabinoid pathways and placebo responsiveness. Greater understanding of the behavioral, neurobiological, and genetic influences on the placebo effect is critical for evaluating medical interventions and may allow health professionals to tailor and personalize interventions in order to maximize treatment outcomes in clinical settings.