Neuro-Bio-Behavioral Mechanisms of Placebo and Nocebo Responses: Implications for Clinical Trials and Clinical Practice

A Preliminary Study of the Effectiveness of an Allostatic, Closed-Loop, Acoustic Stimulation Neurotechnology in the Treatment of Athletes with Persisting Post-concussion Symptoms

BACKGROUND

Effective interventions are needed for individuals with persisting post-concussion symptoms. High-resolution, relational, resonance-based, electroencephalic mirroring (HIRREM®) is an allostatic, closed-loop, acoustic stimulation neurotechnology, designed to facilitate relaxation and self-optimization of neural oscillations.

METHODS

Fifteen athletes (seven females, mean age 18.1 years, SD 2.6) with persisting post-concussion symptoms received 18.7 (SD 6.0) HIRREM sessions over a mean of 29.6 (SD 23.2) days, including 11.3 (SD 4.6) in office days. Pre- and post-HIRREM measures included the Rivermead Post-Concussion Symptoms Questionnaire (RPQ, n = 12), the Insomnia Severity Index (ISI, n = 15), the Center for Epidemiologic Studies Depression Scale (CES-D, n = 10), short-term blood pressure and heart rate recordings for measures of autonomic cardiovascular regulation (n = 15), and reaction time by the drop-stick method (n = 7). All participants were asked about their physical activity level and sports participation status at their post-HIRREM data collection visit and 1 to 3 months afterward.

RESULTS

At the post-HIRREM visit, subjects reported improvements in all three inventories (RPQ mean change 19.7, SD 11.4, Wilcoxon p = 0.001; ISI mean change -4.1, SD 4.1, Wilcoxon p = 0.003; CES-D mean change -12.0, SD 10.0, Wilcoxon p = 0.004), including statistically significant reductions in 14 of the 16 individual items of the RPQ. There were also statistically significant improvements in baroreflex sensitivity, heart rate variability in the time domain (SDNN), and drop-stick reaction testing (baseline mean distance of 23.8 cm, SD 5.6, decreased to 19.8 cm, SD 4.6, Wilcoxon p = 0.016). Within 3 months of the post-HIRREM data collection, all 15 had returned to full exercise and workouts, and ten had returned to full participation in their athletic activity.

CONCLUSIONS

The use of HIRREM by a series of athletes with persisting post-concussion symptoms was associated with a range of improvements including, for the majority, return to full participation in their sport. The findings do not appear to be consistent with constituents of the placebo effect. A larger controlled trial is warranted.

Can Psychological Expectation Models Be Adapted for Placebo Research?

Placebo responses contribute substantially to the effect and clinical outcome of medical treatments. Patients' expectations have been identified as one of the major mechanisms contributing to placebo effects. However, to date a general theoretical framework to better understand how patient expectations interact with features of medical treatment has not been developed. In this paper we outline an expectation model that can be used as framework for experimental studies on both placebo and nocebo mechanisms. This model is based on psychological concepts of expectation development, expectation maintenance, and expectation change within the typical paradigms used in placebo research. This theoretical framework reflects the dynamic aspects of the interaction between expectations and medical treatment, and offers a platform to combine psychological and neurophysiological research activities. Moreover, this model can be used to identify important future research questions. For example, we argue that the dynamic processes of expectation maintenance vs. expectation changes are not sufficiently addressed in current research on placebo mechanisms. Therefore, the question about how to change and optimize patients' expectations prior to treatment should be a special focus of future clinical research.

Placebo and Nocebo Effects in Sexual Medicine: An Experimental Approach

Few studies have investigated placebo and nocebo effects in a human sexuality context. Studying placebo and nocebo responses in this context may provide insight into their potential to modulate sexual drive and function. To examine such effects in sexual medicine, 48 healthy, male heterosexual participants were divided into four groups. Each group received instruction to expect stimulating effects, no effect, or an inhibitory effect on sexual functions. Only one group received the dopamine agonist cabergoline; all other groups received placebo or nocebo. Modulations in sexual experience were examined through an established experimental paradigm of sexual arousal and masturbation-induced orgasm during erotic film sequences with instruction to induce placebo or nocebo effects. Endocrine data, appetitive, consummatory, and refractory sexual behavior parameters were assessed using the Arizona Sexual Experience Scale (ASEX) and the Acute Sexual Experience Scale (ASES). Results showed increased levels of sexual function after administration of cabergoline with significant effects for several parameters. Placebo effects were induced only to a small degree. No negative effects on sexual parameters in the nocebo condition were noted. This paradigm could induce only small placebo and nocebo effects. This supports the view that healthy male sexual function seems relatively resistant to negative external influences.

Purslane Extract and Glucose Homeostasis in Adults with Type 2 Diabetes: A Double-Blind, Placebo-Controlled Clinical Trial of Efficacy and Safety

Purslane extract (PE) is derived from Portulaca oleracea L., a medicinal plant used in traditional medicine for its antidiabetic properties. This randomized, placebo-controlled clinical trial was designed to evaluate the efficacy and safety of PE in improving glucose control, blood pressure, and lipid profile in adults with type 2 diabetes mellitus (T2DM) treated with a single oral hypoglycemic agent at baseline. Subjects were randomized to treatment with three capsules of PE/day or a matched placebo. Change from baseline to the week 12 end-of-follow-up visit measures of glucose homeostasis, hemodynamics, and lipid profile was compared by treatment assignment. In addition, these measures were evaluated in a subgroup of "responders," defined as patients whose week 12 HbA1c was lower than baseline values, regardless of treatment assignment. This group was further assessed in subgroups of baseline oral hypoglycemic treatment. A total of 63 participants were treated with either PE (n = 31, 11 females, mean age 52.4 ± 7.9 years) or matched placebo (n = 32, 11 females, mean age 58.3 ± 10.8 years). In the total cohort, systolic blood pressure declined significantly more in the PE group than the placebo group: -7.5 ± 5.0 versus -0.01 ± 0.3 mmHg, P < .0001. In the responders' subgroup, HbA1c declined significantly more in the PE group than the placebo group: -0.8% ± 0.4% versus -0.6% ± 0.5%, P = .03. Few adverse events were reported. These were mild and did not differ by treatment assignment. PE appears to be a safe, adjunct treatment for T2DM, significantly reducing systolic blood pressure in the total cohort and HbA1c in the subgroup of responders.

A take-home placebo treatment can reduce stress, anxiety and symptoms of depression in a non-patient population

BACKGROUND

With a healthcare system burdened by symptomatic and mental-health related conditions, the placebo effect may represent a useful clinical tool. First, however, there is a need to broaden research attention and investigate placebo effects outside laboratories and beyond experimental pain. This study investigated the effectiveness of a take-home placebo treatment in the short-term alleviation of stress, anxiety and symptoms of depression in a non-patient population.

METHOD

A sample of 77 participants was randomized to either the 'oxytocin' treatment group (n = 22), the 'serotonin' treatment group (n = 22) or the wait-list control group (n = 33). The two treatment groups were given an 'anti-stress treatment spray' (placebo) to self-administer for 3 days, and completed online measures of perceived stress (Perceived Stress Scale-10), anxiety (Cognitive Somatic Anxiety Questionnaire) and symptoms of depression (Centre for Epidemiological Studies - Depression) before and after the 3-day protocol.

RESULTS

Both the 'serotonin' and 'oxytocin' treatment sprays were effective in reducing symptoms of depression; however, only those in the 'oxytocin' group reported less stress and anxiety as compared with controls. Overall, the 'oxytocin' was perceived as more effective.

CONCLUSION

Placebo effects can be translated to a real-life setting in the short-term reduction of stress, anxiety and symptoms of depression in a non-patient population. In treating psychological distress, placebos may be useful addition to the treatment repertoire. The information given with treatment may also be an important consideration for practitioners.

Relieving pain using dose-extending placebos: a scoping review

Placebos are often used by clinicians, usually deceptively and with little rationale or evidence of benefit, making their use ethically problematic. In contrast with their typical current use, a provocative line of research suggests that placebos can be intentionally exploited to extend analgesic therapeutic effects. Is it possible to extend the effects of drug treatments by interspersing placebos? We reviewed a database of placebo studies, searching for studies that indicate that placebos given after repeated administration of active treatments acquire medication-like effects. We found a total of 22 studies in both animals and humans hinting of evidence that placebos may work as a sort of dose extender of active painkillers. Wherever effective in relieving clinical pain, such placebo use would offer several advantages. First, extending the effects of a painkiller through the use of placebos may reduce total drug intake and side effects. Second, dose-extending placebos may decrease patient dependence. Third, using placebos along with active medication, for part of the course of treatment, should limit dose escalation and lower costs. Provided that nondisclosure is preauthorized in the informed consent process and that robust evidence indicates therapeutic benefit comparable to that of standard full-dose therapeutic regimens, introducing dose-extending placebos into the clinical arsenal should be considered. This novel prospect of placebo use has the potential to change our general thinking about painkiller treatments, the typical regimens of painkiller applications, and the ways in which treatments are evaluated.

Acquisition of heroin conditioned immunosuppression requires IL-1 signaling in the dorsal hippocampus

Opioid users experience increased incidence of infection, which may be partially attributable to both direct opiate-immune interactions and conditioned immune responses. Previous studies have investigated the neural circuitry governing opioid conditioned immune responses, but work remains to elucidate the mechanisms mediating this effect. Our laboratory has previously shown that hippocampal IL-1 signaling, specifically, is required for the expression of heroin conditioned immunosuppression following learning. The current studies were designed to further characterize the role of hippocampal IL-1 in this phenomenon by manipulating IL-1 during learning. Experiment 1 tested whether hippocampal IL-1 is also required for the acquisition of heroin conditioned immunosuppression, while Experiment 2 tested whether hippocampal IL-1 is required for the expression of unconditioned heroin immunosuppression. We found that blocking IL-1 signaling in the dorsal hippocampus with IL-1RA during each conditioning session, but not on interspersed non-conditioning days, significantly attenuated the acquisition of heroin conditioned immunosuppression. Strikingly, we found that the same IL-1RA treatment did not alter unconditioned immunosuppression to a single dose of heroin. Thus, IL-1 signaling is not a critical component of the response to heroin but rather may play a role in the formation of the association between heroin and the context. Collectively, these studies suggest that IL-1 signaling, in addition to being involved in the expression of a heroin conditioned immune response, is also involved in the acquisition of this effect. Importantly, this effect is likely not due to blocking the response to the unconditioned stimulus since IL-1RA did not affect heroin's immunosuppressive effects.

A virtual experimenter to increase standardization for the investigation of placebo effects

Background

Placebo effects are mediated by expectancy, which is highly influenced by psychosocial factors of a treatment context. These factors are difficult to standardize. Furthermore, dedicated placebo research often necessitates single-blind deceptive designs where biases are easily introduced. We propose a study protocol employing a virtual experimenter – a computer program designed to deliver treatment and instructions – for the purpose of standardization and reduction of biases when investigating placebo effects.

Methods

To evaluate the virtual experimenter’s efficacy in inducing placebo effects via expectancy manipulation, we suggest a partially blinded, deceptive design with a baseline/retest pain protocol (hand immersions in hot water bath). Between immersions, participants will receive an (actually inert) medication. Instructions pertaining to the medication will be delivered by one of three metaphors: The virtual experimenter, a human experimenter, and an audio/text presentation (predictor “Metaphor”). The second predictor includes falsely informing participants that the medication is an effective pain killer, or correctly informing them that it is, in fact, inert (predictor “Instruction”). Analysis will be performed with hierarchical linear modelling, with a sample size of N = 50. Results from two pilot studies are presented that indicate the viability of the pain protocol (N = 33), and of the virtual experimenter software and placebo manipulation (N = 48).

Discussion

It will be challenging to establish full comparability between all metaphors used for instruction delivery, and to account for participant differences in acceptance of their virtual interaction partner. Once established, the presence of placebo effects would suggest that the virtual experimenter exhibits sufficient cues to be perceived as a social agent. He could consequently provide a convenient platform to investigate effects of experimenter behavior, or other experimenter characteristics, e.g., sex, age, race/ethnicity or professional status. More general applications are possible, for example in psychological research such as bias research, or virtual reality research. Potential applications also exist for standardizing clinical research by documenting and communicating instructions used in clinical trials.

Conditioning of amitriptyline-induced REM sleep suppression in healthy participants: A randomized controlled trial

Clinical trials in sleep disorders report substantial improvement in symptoms in their placebo groups. Behavioral conditioning is one of the underlying mechanisms of the placebo response. However, we do not know whether, and if so, the extent to which sleep architecture is influenced by behavioral conditioning, similarly to other physiological responses (i.e., those in the immune system). We therefore applied a conditioning paradigm to 39 healthy adults pairing a novel-tasting drink (conditioned stimulus, CS) with the REM sleep suppressing tricyclic antidepressant amitriptyline as unconditioned stimulus during the acquisition phase. Subsequent sole presentation of the CS (together with a placebo pill) in an evocation night led to significantly more REM sleep in the amitriptyline group. Instead of the expected REM sleep suppression in the evocation night, we observed more REM sleep, indicating a rebound that interferes with the conditioned response.

Individualized Homeopathy: A Consideration of Its Relationship to Psychotherapy

OBJECTIVES

The benefit and potential mechanisms of action of homeopathy have long been debated. Almost entirely neglected has been the study of individualized homeopathy (IH) as a form of psychotherapy, which incorporates factors that are common to most therapies while using processes that are specific to IH.

METHODS

Recent research into the therapeutic components of IH is reviewed; similarities and differences between IH and other forms of psychotherapy are also described.

RESULTS

IH includes elements found in humanistic therapy and narrative medicine and additionally incorporates idiographic material in treatment selection. It is structured in a manner that takes maximum advantage of the components of the placebo effect, which could further expand its effectiveness beyond those conditions thought usually amenable to psychotherapy.

CONCLUSIONS

It is possible that IH entails specific psychotherapeutic processes in addition to possible therapeutic action of the homeopathic remedy, but the relative contributions of each remain to be determined. Suggestions are given for future research.

Enhance placebo, avoid nocebo: How contextual factors affect physiotherapy outcomes

INTRODUCTION

Placebo and nocebo represent complex and distinct psychoneurobiological phenomena in which behavioural and neurophysiological modifications occur together with the application of a treatment. Despite a better understanding of this topic in the medical field, little is known about their role in physiotherapy.

PURPOSE

The aim of this review is: a) to elucidate the neurobiology behind placebo and nocebo effects, b) to describe the role of the contextual factors as modulators of the clinical outcomes in rehabilitation and c) to provide clinical and research guidelines on their uses.

IMPLICATIONS

The physiotherapist's features, the patient's features, the patient-physiotherapist relationship, the characteristics of the treatment and the overall healthcare setting are all contextual factors influencing clinical outcomes. Since every physiotherapy treatment determines a specific and a contextual effect, physiotherapists should manage the contextual factors as a boosting element of any manual therapy to improve placebo effects and avoid detrimental nocebo effects.

Memory-updating abrogates extinction of learned immunosuppression

When memories are recalled, they enter a transient labile phase in which they can be impaired or enhanced followed by a new stabilization process termed reconsolidation. It is unknown, however, whether reconsolidation is restricted to neurocognitive processes such as fear memories or can be extended to peripheral physiological functions as well. Here, we show in a paradigm of behaviorally conditioned taste aversion in rats memory-updating in learned immunosuppression. The administration of sub-therapeutic doses of the immunosuppressant cyclosporin A together with the conditioned stimulus (CS/saccharin) during retrieval blocked extinction of conditioned taste aversion and learned suppression of T cell cytokine (interleukin-2; interferon-γ) production. This conditioned immunosuppression is of clinical relevance since it significantly prolonged the survival time of heterotopically transplanted heart allografts in rats. Collectively, these findings demonstrate that memories can be updated on both neural and behavioral levels as well as on the level of peripheral physiological systems such as immune functioning.

The Neurobiology Shaping Affective Touch: Expectation, Motivation, and Meaning in the Multisensory Context

Inter-individual touch can be a desirable reward that can both relieve negative affect and evoke strong feelings of pleasure. However, if other sensory cues indicate it is undesirable to interact with the toucher, the affective experience of the same touch may be flipped to disgust. While a broad literature has addressed, on one hand the neurophysiological basis of ascending touch pathways, and on the other hand the central neurochemistry involved in touch behaviors, investigations of how external context and internal state shapes the hedonic value of touch have only recently emerged. Here, we review the psychological and neurobiological mechanisms responsible for the integration of tactile “bottom–up” stimuli and “top–down” information into affective touch experiences. We highlight the reciprocal influences between gentle touch and contextual information, and consider how, and at which levels of neural processing, top-down influences may modulate ascending touch signals. Finally, we discuss the central neurochemistry, specifically the μ-opioids and oxytocin systems, involved in affective touch processing, and how the functions of these neurotransmitters largely depend on the context and motivational state of the individual.

Pre-exposure to the unconditioned or conditioned stimulus does not affect learned immunosuppression in rats

In order to analyze the effects of pre-exposure to either the unconditioned (US) or conditioned stimulus (CS) on learned immunosuppression, we employed an established conditioned taste aversion (CTA) paradigm in rats. In our model, a sweet-tasting drinking solution (saccharin) serves as CS and injection of the immunosuppressive drug cyclosporine A (CsA) is used as US. The conditioned response is reflected by a pronounced CTA and diminished cytokine production by anti-CD3 stimulated splenic T cells. In the present study, experimental animals were exposed either to the US or the CS three times prior to the acquisition phase. On the behavioral level, we found a significantly diminished CTA when animals were pre-exposed to the US or the CS before acquisition. In contrast, US or CS pre-exposure did not affect the behaviorally conditioned suppression of interleukin (IL)-2 production. From the clinical perspective, our data may suggest that conditioning paradigms could be systemically integrated as supportive therapeutic interventions in patients that are already on immunosuppressive therapy or have had previous contact to the gustatory stimulus. Such supportive therapies to pharmacological regimens could not only help to reduce the amount of medication needed and, thus, unwanted toxic side effects, but may also maximize the therapeutic outcome.

Rethinking psychopharmacotherapy: The role of treatment context and brain plasticity in antidepressant and antipsychotic interventions

Emerging evidence indicates that treatment context profoundly affects psychopharmacological interventions. We review the evidence for the interaction between drug application and the context in which the drug is given both in human and animal research. We found evidence for this interaction in the placebo response in clinical trials, in our evolving knowledge of pharmacological and environmental effects on neural plasticity, and in animal studies analyzing environmental influences on psychotropic drug effects. Experimental placebo research has revealed neurobiological trajectories of mechanisms such as patients' treatment expectations and prior treatment experiences. Animal research confirmed that "enriched environments" support positive drug effects, while unfavorable environments (low sensory stimulation, low rates of social contacts) can even reverse the intended treatment outcome. Finally we provide recommendations for context conditions under which psychotropic drugs should be applied. Drug action should be steered by positive expectations, physical activity, and helpful social and physical environmental stimulation. Future drug trials should focus on fully controlling and optimizing such drug×environment interactions to improve trial sensitivity and treatment outcome.