Predictors of placebo response in randomized controlled trials of psychotropic drugs for children and adolescents with internalizing disorders

The Impact of Development on Antidepressant and Placebo Response in Anxiety Disorders: A Bayesian Hierarchical Meta-Analytic Examination of Randomized Controlled Trials in Children, Adolescents, and Adults

Background: Understanding how development influences medication and placebo responses in anxiety disorders could inform treatment decisions, including age-specific first- versus second-line psychopharmacological interventions. Objective: To meta-analytically compare the trajectory of selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), and placebo response in youth and adults with anxiety disorders. Methods: Weekly symptom severity data were extracted from prospective, randomized, parallel-group, placebo-controlled trials of SSRIs and SNRIs in children, adolescents, and adults with anxiety disorders (generalized, separation, and social anxiety disorders as well as panic disorder). Treatment response was modeled for the standardized change in continuous measures of anxiety using a Bayesian hierarchical model. Change in symptom severity was evaluated as a function of time, and post hoc analyses were conducted to determine the sensitivity of these results across sample heterogeneity and alternative functional forms. Results: Data were included from 11 trials of youth (SSRI, κ = 7; SNRI, κ = 4) and 71 studies of adults (SSRI, κ = 46; SNRI, κ = 25). In total, 1067 youth participated in SSRI trials and 1024 in SNRI trials. In total, 10,826 adults participated in SSRI trials (placebo, n = 5367; SSRI n = 5,459) and 6232 in SNRI trials (placebo, n = 3,128; SNRI n = 3,094). A logarithmic model best described the response. Placebo response was similar in youth and adults (mean difference = -1.98 ± 6.21, 95% credible interval [CrI]: -10.2 to 14.2, p = 0.750), and statistically significant improvement from baseline emerged by week 2 in both adults (mean difference: -18.34 + 1.017, 95% CrI: -20.3 to 16.3, p < 0.001) and youth (mean difference: -23.74 + 3.736, 95% CrI: -31.1 to -16.4, p < 0.001). SSRIs produced similar improvements for youth and adults (p = 0.129), but SNRIs produced slower improvement in youth than adults (p = 0.018). Conclusions: Antidepressant-related improvement occurs early in youth and adults with anxiety disorders. SSRI response is similar in adults and youth; however, SNRIs produce greater responses in adults than youth, potentially representing a developmental effect.

Placebo response in trials with patients with anxiety, obsessive-compulsive and stress disorders across the lifespan: a three-level meta-analysis

QUESTION

Randomised controlled trials assessing treatments for anxiety, obsessive-compulsive and stress-related disorders often present high placebo response rates in placebo groups. Understanding the placebo response is essential in accurately estimating the benefits of pharmacological agents; nevertheless, no studies have evaluated the placebo response across these disorders using a lifespan approach.

STUDY SELECTION AND ANALYSIS

We searched MEDLINE, PsycINFO, Embase, Cochrane, websites of regulatory agencies and international registers from inception to 9 September 2022. The primary outcome was the aggregate measure of internalising symptoms of participants in the placebo arms of randomised controlled trials designed to assess the efficacy of selective serotonin reuptake inhibitors (SSRIs) and serotonin and norepinephrine reuptake inhibitors (SNRIs) in individuals diagnosed with anxiety, obsessive-compulsive or stress-related disorders. The secondary outcomes were placebo response and remission rates. Data were analysed through a three-level meta-analysis.

FINDINGS

We analysed 366 outcome measures from 135 studies (n=12 583). We found a large overall placebo response (standardised mean difference (SMD)=-1.11, 95% CI -1.22 to -1.00). The average response and remission rates in placebo groups were 37% and 24%, respectively. Larger placebo response was associated with a diagnosis of generalised anxiety disorder and post-traumatic stress disorder, when compared with panic, social anxiety and obsessive-compulsive disorder (SMD range, 0.40-0.49), and with absence of a placebo lead-in period (SMD=0.44, 95% CI 0.10 to 0.78). No significant differences were found in placebo response across age groups. We found substantial heterogeneity and moderate risk of bias.

CONCLUSIONS

Placebo response is substantial in SSRI and SNRI trials for anxiety, obsessive-compulsive and stress-related disorders. Clinicians and researchers should accurately interpret the benefits of pharmacological agents in contrast to placebo response.

PROSPERO REGISTRATION NUMBER

CRD42017069090.

Meta-Analysis: Pediatric Placebo Response in Depression Trials Does Not Replicate in Anxiety and Obsessive-Compulsive Disorder Trials

Background: Placebo response has been identified as an important factor influencing the success of adult antidepressant trials, yet little research of placebo response has been conducted in pediatric populations. Understanding disorder-specific and transdiagnostic predictors of pediatric placebo response is important in designing successful child psychopharmacological trials. Methods: A PubMed search was conducted for all pediatric antidepressant randomized controlled trials treating depression, anxiety, or obsessive-compulsive disorder (OCD). A random-effects model was utilized to examine the magnitude of placebo symptom improvement using standardized mean difference (SMD) and placebo response rates. Stratified subgroup analysis was performed by diagnostic indication. Meta-regression was utilized to search possible correlates of placebo symptom improvement and placebo response rate. Results: Thirty antidepressant trials involving 2911 participants receiving placebo were included in this meta-analysis. Magnitude of placebo improvement and placebo response rates varied significantly across disorders; being greater in depression (SMD = 1.44, 95% confidence interval [CI]: 1.18 to 1.71) than anxiety disorders (SMD = 1.09, 95% CI: 0.77 to 1.41) and the lowest in OCD (SMD = 0.71, 95% CI: 0.32 to 1.12). Different predictors were associated with placebo response in different indications. Conclusions: Both the magnitude and predictors of placebo response in pediatric depression trials do not replicate across anxiety and OCD. Based on our results, across disorders, minimizing the number of sites might significantly reduce placebo improvement. In addition to these, we could potentially decrease the placebo response in depression trials by increasing the number of subjects enrolled per study site, minimizing the number of study visits and conducting the studies in the United States. Further research is needed into the predictors of placebo response in pediatric anxiety and OCD.

The Impact of Failed Antidepressant Trials on Outcomes in Children and Adolescents with Anxiety and Depression: A Systematic Review and Meta-Analysis

Objective: To identify predictors of medication-placebo differences in double-blind placebo-controlled antidepressant trials in children and adolescents with anxiety and depression. Methods: Clinical trials in patients <18 years of age with major depressive disorder or generalized, separation or social anxiety disorders were obtained from PubMed, the Cochrane Database and clinicaltrials.gov searches from inception through 2019. Forty-nine trials (43 published and 6 unpublished) of anxiety (κ = 13) and depression (κ = 36) evaluated 19 antidepressants in 8642 child and adolescent patients; placebo and medication response rates, trial characteristics, disorder, medication class, and funding source were extracted. Antidepressant-placebo differences were examined using Bayesian hierarchical models and estimates of response were determined for trial design, disorder, and medication class variables. Using meta-regression, correlates of antidepressant-placebo difference and placebo response were examined. Results: Funding source differentiated medication-placebo differences regardless of disorder. Industry trials had larger placebo response rates (mean difference: 0.189 ± 0.066, credible interval [CrI]: 0.067 to 0.33, p = 0.0008) and smaller medication-placebo differences (-0.235 ± 0.078, CrI: -0.397 to -0.086, p = 0.005) compared with federally funded trials. However, medication response was similar for industry- and federally-funded studies (-0.046 ± 0.042, CrI: -0.130 to 0.038, p = 0.252). Conclusions: The impact of study sponsorship on trial outcome supports the assertion that industry-funded trials with high placebo response rates and small drug-placebo differences are "failed trials" and should not be described as "negative trials" or used to determine public health estimates of antidepressant efficacy in children and adolescents with anxiety and depression. Identifying the proper role and value of industry-funded trials is critical to establishing the evidence base for antidepressants in youth.

Greater Dynamic and Lower Static Functional Brain Connectivity Prospectively Predict Placebo Response in Pediatric Generalized Anxiety Disorder

Objectives: Placebo response is one of the most significant barriers to detecting treatment effects in pediatric (and adult) clinical trials focusing on affective and anxiety disorders. We sought to identify neurofunctional predictors of placebo response in adolescents with generalized anxiety disorder (GAD) by examining dynamic and static functional brain connectivity. Methods: Before randomization to blinded placebo, adolescents, aged 12-17 years, with GAD (N = 25) underwent resting state functional magnetic resonance imaging. Whole brain voxelwise correlation analyses were used to determine the relationship between change in anxiety symptoms from baseline to week 8 and seed-based dynamic and static functional connectivity maps of regions in the salience and ventral attention networks (amygdala, dorsal anterior cingulate cortex [dACC], and ventrolateral prefrontal cortex [VLPFC]). Results: Greater dynamic functional connectivity variability in amygdala, dACC, VLPFC, and regions within salience, default mode, and frontoparietal networks was associated with greater placebo response. Lower static functional connectivity between amygdala and dorsolateral prefrontal cortex, amygdala and medial prefrontal cortex, dACC and posterior cingulate cortex and greater static functional connectivity between VLPFC and inferior parietal lobule were associated with greater placebo response. Conclusion: Placebo response is associated with a distinct dynamic and static connectivity fingerprint characterized by "variable" dynamic but "weak" static connectivity in the salience, default mode, frontoparietal, and ventral attention networks. These data provide granular evidence of how circuit-based biotypes mechanistically relate to placebo response. Finding biosignatures that predict placebo response is critically important in clinical psychopharmacology and to improve our ability to detect medication-placebo differences in clinical trials.

A Randomized, Double-Blind, Placebo-Controlled Trial of Vilazodone in Children and Adolescents with Major Depressive Disorder with Twenty-Six-Week Open-Label Follow-Up

Objective: To evaluate the efficacy and long-term safety of vilazodone in children and adolescent outpatients with major depressive disorder (MDD). Methods: Children and adolescents aged 7-17 years of age with MDD were randomized 2:2:1 to 8 weeks of double-blind placebo, vilazodone 15 or 30 mg/day or fluoxetine 20 mg/day, respectively. The primary and secondary efficacy outcomes, respectively, were change from baseline to week 8 in Children's Depression Rating Scale-Revised (CDRS-R) score total score and Clinical Global Impressions-Severity (CGI-S) score analyzed using a mixed model for repeated measurement approach. Patients who completed the 8-week randomized controlled trial (RCT), as well as new (de novo) patients, could participate in a 26-week, vilazodone-only, open-label extension (OLE) study. Results: The RCT enrolled 473 patients (60% female) with an average age of 13 years. Change in CDRS-R and CGI-S scores from baseline to week 8 did not differ between patients who received vilazodone and those randomized to placebo. The least-squares mean change from baseline in CDRS-R scores was similar for vilazodone and placebo (-20.7 vs. -20.3, p = 0.77; least-squares mean difference [LSMD] = -0.40). For fluoxetine, the LSMD versus placebo was -2.3 (p = 0.14). The OLE enrolled 330 patients (60% female) with an average age of 13-14 years. Overall, no new safety concerns were identified compared to what is known in adults. Conclusions: Similar improvements in depressive symptoms were observed in all arms. This study does not support the efficacy of vilazodone 15 or 30 mg/day for pediatric patients with MDD. No new or unexpected safety concerns were detected during the RCT or OLE studies.

Placebo response rates and potential modifiers in double-blind randomized controlled trials of second and newer generation antidepressants for major depressive disorder in children and adolescents: a systematic review and meta-regression analysis

Children and adolescents with major depressive disorder (MDD) appear to be more responsive to placebo than adults in randomized placebo-controlled trials (RCTs) of second and newer generation antidepressants (SNG-AD). Previous meta-analyses obtained conflicting results regarding modifiers. We aimed to conduct a meta-analytical evaluation of placebo response rates based on both clinician-rating and self-rating scales. Based on the most recent and comprehensive study on adult data, we tested whether the placebo response rates in children and adolescents with MDD also increase with study duration and number of study sites. We searched systematically for published RCTs of SNG-AD in children and/or adolescents (last update: September 2017) in public domain electronic databases and additionally for documented studies in clinical trial databases. The log-transformed odds of placebo response were meta-analytically analyzed. The primary and secondary outcomes were placebo response rates at the end of treatment based on clinician-rating and self-rating scales, respectively. To examine the impact of study duration and number of study sites on placebo response rates, we performed simple meta-regression analyses. We selected other potential modifiers of placebo response based on significance in at least one previous pediatric meta-analysis and on theoretical considerations to perform explorative analyses. We applied sensitivity analyses with placebo response rates closest to week 8 to compare our data with those reported for adults. We identified 24 placebo-controlled trials (2229 patients in the placebo arms). The clinician-rated placebo response rates ranged from 22 to 62% with a pooled response rate of 45% (95% CI 41-50%). The number of study sites was a significant modifier in the simple meta-regression analysis [odds ratio (OR) 1.01, 95% CI 1.01-1.02, p = 0.0003, k = 24) with more study sites linked to a higher placebo response. Study duration was not significantly associated with the placebo response rate. The explorative simple analyses revealed that publication year may be an additional modifier. However, in the explorative multivariable analysis including the number of study sites and the publication year only the number of study sites reached a p value ≤ 0.05. The self-rated placebo response rates ranged from 1 to 68% with a pooled response rate of 26% (95% CI 10-54%) (k = 6; n = 396). This meta-analysis confirms a high pooled placebo response rate in children and adolescents based on clinician ratings, which exceeds that observed in the most recent meta-analysis of placebo effects in adults (36%; 95% CI 35-37%) published in 2016. However, and similar to findings in adults, the pooled response rates based on self-ratings were substantially lower. In accordance with previous meta-analyses, we corroborated the number of study sites as significant modifier. In comparison to the recent adult meta-analysis, the substantially lower number of pediatric studies entails a reduced power to detect modifiers. Future studies should provide more precise and homogenous information to support discovery of potential modifiers and consider no-treatment-if ethically permissible-to allow differentiation between placebo and spontaneous remission rates. If these differ, practicing clinicians should facilitate placebo effects as an addition to the verum effect to maximize benefits. Further research is required to explain the discrepant response rates between clinician and self-ratings.

The Impact of Placebo Response Rates on Clinical Trial Outcome: A Systematic Review and Meta-Analysis of Antidepressants in Children and Adolescents with Major Depressive Disorder

Objective: The high placebo response rate may hamper the discovery of antidepressants in children and adolescents with major depressive disorder (MDD). The aim of the study was to clarify the relationship between the placebo response rate and clinical trial outcomes of the use of antidepressants in children and adolescents, and distinguish main factors responsible to placebo response rate. Methods: The PubMed and Cochrane Library databases were searched for double-blind randomized placebo-controlled trials of the new-generation antidepressants for the acute treatment of MDD in children and adolescents. The response rate differences (RDs) between placebo group and treatment group under different level of placebo response rate were pooled by random-effects meta-analysis. The classification thresholds for low, medium, and high placebo response rate were set at <40%, 40%-50%, and ≥50%, respectively. Predictors of placebo response rate were explored using meta-regression. Results: The analysis included 18 trials with 4365 participants. This study found that the lower the placebo response rate, the greater the efficacy differences between antidepressants and placebo. In the high, moderate, and low placebo response rate subgroups, the response RDs (95% CI) between antidepressants and placebo were 8 (1-14)%, 10 (2-17)%, and 21 (9-32)%, respectively. The meta-regression showed that the number of study sites was the factor most associated with placebo response rate, and that response rate increased 3% with every additional 10 study sites. Conclusions: The clinical outcome was related to the placebo response rates in the clinical trials of antidepressants in children and adolescents with MDD. The efficacy differences between antidepressants and placebo will be maximized when placebo response rates are reduced. The number of study sites was the factor most associated with the placebo response rates.

Does Sex/Gender Play a Role in Placebo and Nocebo Effects? Conflicting Evidence From Clinical Trials and Experimental Studies

Sex has been speculated to be a predictor of the placebo and nocebo effect for many years, but whether this holds true or not has rarely been investigated. We utilized a placebo literature database on various aspects of the genuine placebo/nocebo response. In 2015, we had extracted 75 systematic reviews, meta-analyses, and meta-regressions performed in major medical areas (neurology, psychiatry, internal medicine). These meta-analyses were screened for whether sex/gender differences had been noted to contribute to the placebo/nocebo effect: in only 3 such analyses female sex was associated with a higher placebo effect, indicating poor evidence for a contribution of sex to it in RCTs. This was updated with another set of meta-analyses for the current review, but did not change the overall conclusion. The same holds true for 18 meta-analyses investigating adverse event (nocebo) reporting in RCT in the placebo arm of trials. We also screened our database for papers referring to sex/gender and the placebo effect in experimental studies, and identified 28 papers reporting 29 experiments. Their results can be summarized as follows: (a) Despite higher sensitivity of pain in females, placebo analgesia is easier to elicit in males; (b) It appears that conditioning is effective specifically eliciting nocebo effects; (c) Conditioning works specifically well to elicit placebo and nocebo effects in females and with nausea; (d) Verbal suggestions are not sufficient to induce analgesia in women, but work in men. These results will be discussed with respect to the question why nausea and pain may be prone to be responsive to sex/gender differences, while other symptoms are less. Lastly, we will discuss the apparent discrepancy between RCT with low relevance of sex, and higher relevance of sex in specific experimental settings. We argue that the placebo response is predominantly the result of a conditioning (learning) response in females, while in males it predominantly may be generated via (verbal) manipulating of expectancies. In RCT therefore, the net outcome of the intervention may be the same despite different mechanisms generating the placebo effect between the sexes, while in experimental work when both pathways are separated and explicitly explored, such differences may surface.

Factors Associated With Response to Placebo in Patients With Irritable Bowel Syndrome and Constipation

BACKGROUND & AIMS

A high proportion of patients with irritable bowel syndrome (IBS) respond to placebo in clinical trials (estimated at about 40%). We aimed to identify factors that contribute to the high placebo response rate using data from a placebo-controlled trial of patients with IBS.

METHODS

We performed a retrospective analysis of 599 women with IBS with constipation who were in the placebo group of a 12-week, randomized, double-blind, phase 3 trial of the experimental medication renzapride. Primary analyses evaluated frequency of abdominal pain in patients who received placebo, defined as ≥30% pain improvement from baseline for ≥6 of the 12 study weeks. We performed backward elimination regression with bootstrapping to identify factors associated with response to placebo.

RESULTS

In the placebo group, 29.0% of the patients had an abdominal pain response. Factors associated with a response to placebo were baseline variation in abdominal pain (odds ratio [OR], 1.71), maximum baseline pain severity (OR, 1.34), and placebo response in study week 2 (OR, 2.23) or week 3 (OR, 3.69). Factors associated with lack of response to placebo were number of baseline complete spontaneous bowel movements (OR, 0.73; P = .019) and final baseline pain ratings (OR, 0.73; P < .001).

CONCLUSIONS

We identified factors associated with a response in abdominal pain to placebo using original data from an IBS clinical trial. Baseline factors associated with the placebo response in women with IBS and constipation included variation in baseline pain symptoms, severity of baseline symptoms, and early improvement of abdominal pain. These findings have significant implications for clinical trial design.

A Machine Learning Approach to Identifying Placebo Responders in Late-Life Depression Trials

OBJECTIVE

Despite efforts to identify characteristics associated with medication-placebo differences in antidepressant trials, few consistent findings have emerged to guide participant selection in drug development settings and differential therapeutics in clinical practice. Limitations in the methodologies used, particularly searching for a single moderator while treating all other variables as noise, may partially explain the failure to generate consistent results. The present study tested whether interactions between pretreatment patient characteristics, rather than a single-variable solution, may better predict who is most likely to benefit from placebo versus medication.

METHODS

Data were analyzed from 174 patients aged 75 years and older with unipolar depression who were randomly assigned to citalopram or placebo. Model-based recursive partitioning analysis was conducted to identify the most robust significant moderators of placebo versus citalopram response.

RESULTS

The greatest signal detection between medication and placebo in favor of medication was among patients with fewer years of education (≤12) who suffered from a longer duration of depression since their first episode (>3.47 years) (B = 2.53, t(32) = 3.01, p = 0.004). Compared with medication, placebo had the greatest response for those who were more educated (>12 years), to the point where placebo almost outperformed medication (B = -0.57, t(96) = -1.90, p = 0.06).

CONCLUSION

Machine learning approaches capable of evaluating the contributions of multiple predictor variables may be a promising methodology for identifying placebo versus medication responders. Duration of depression and education should be considered in the efforts to modulate placebo magnitude in drug development settings and in clinical practice.

The Short-Term Placebo Response in Children With Attention-Deficit Hyperactivity Disorder (ADHD)

To assess short-term placebo response in 6- to 13-year-old children with ADHD, children who were administered a double-blind placebo-methylphenidate trial, 1 week each, were included in the analysis. Conners' parents and Teacher Rating scales, the Aggregate Neurobehavioral Student Health and Educational Review inventory, and the Matching Familiar Figure Test were employed. A reduction of 30% or more in one or more of the teachers report subscales was observed in 18.8% of the participants. Attention test performance resulted in 58% of children exhibiting reduction in error rates and 36.2% exhibited longer latency period. Significant correlations between placebo response and methylphenidate response in all of the teachers report subscales were found. Base line severity, learning problem and emotional status were found associated with placebo response. Short-term placebo response should be accounted for in children with ADHD.

Factors impacting the efficacy of venlafaxine extended release 75-225 mg/day in patients with major depressive disorder: exploratory post hoc subgroup analyses of a randomized, double-blind, placebo-controlled study in Japan

PURPOSE

To explore the potential factors impacting the efficacy of venlafaxine extended release (ER) and treatment differences between 75 mg/day and 75-225 mg/day dose in patients with major depressive disorder (MDD).

METHODS

We performed exploratory post hoc subgroup analyses of a randomized, double-blind, placebo-controlled study conducted in Japan. A total of 538 outpatients aged 20 years or older with a primary diagnosis of MDD who experienced single or recurrent episodes were randomized into three groups: fixed-dose, flexible-dose, or placebo. Venlafaxine ER was initiated at 37.5 mg/day and titrated to 75 mg/day for both fixed-dose and flexible-dose group, and to 225 mg/day for flexible-dose group (if well tolerated). Efficacy endpoints were changes from baseline at Week 8 using the Hamilton Rating Scale for Depression-17 items (HAM-D₁₇) total score, Hamilton Rating Scale for Depression-6 items score, and Montgomery-Asberg Depression Rating Scale total score. The following factors were considered in the subgroup analyses: sex, age, HAM-D₁₇ total score at baseline, duration of MDD, duration of current depressive episode, history of previous depressive episodes, history of previous medications for MDD, and CYP2D6 phenotype. For each subgroup, an analysis of covariance model was fitted and the adjusted mean of the treatment effect and corresponding 95% CI were computed. Due to the exploratory nature of the investigation, no statistical hypothesis testing was used.

RESULTS

Venlafaxine ER improved symptoms of MDD compared with placebo in most subgroups. The subgroup with a long duration of MDD (>22 months) consistently showed greater treatment benefits in the flexible-dose group than in the fixed-dose group.

CONCLUSION

These results suggest that a greater treatment response to venlafaxine ER (up to 225 mg/day) can be seen in patients with a longer duration of MDD. Further investigations are needed to identify additional factors impacting the efficacy of venlafaxine ER.

Placebo Response in Pediatric Anxiety Disorders: Results from the Child/Adolescent Anxiety Multimodal Study

OBJECTIVES

The aim of this study is to identify predictors of pill placebo response and to characterize the temporal course of pill placebo response in anxious youth.

METHODS

Data from placebo-treated patients (N = 76) in the Child/Adolescent Anxiety Multimodal Study (CAMS), a multisite, randomized controlled trial that examined the efficacy of cognitive-behavioral therapy, sertraline, their combination, and placebo for the treatment of separation, generalized, and social anxiety disorders, were evaluated. Multiple linear regression models identified features associated with placebo response and models were confirmed with leave-one-out cross-validation. The likelihood of improvement in patients receiving pill placebo-over time-relative to improvement associated with active treatment was determined using probabilistic Bayesian analyses.

RESULTS

Based on a categorical definition of response (Clinical Global Impressions-Improvement Scale score ≤2), nonresponders (n = 48), and pill placebo responders (n = 18) did not differ in age (p = 0.217), sex (p = 0.980), race (p = 0.743), or primary diagnosis (all ps > 0.659). In terms of change in anxiety symptoms, separation anxiety disorder and treatment expectation were associated with the degree of pill placebo response. Greater probability of placebo-related anxiety symptom improvement was observed early in the course of treatment (baseline to week 4, p < 0.0001). No significant change in the probability of placebo-related improvement was observed after week 4 (weeks 4-8, p = 0.07; weeks 8-12, p = 0.85), whereas the probability of improvement, in general, significantly increased week over week with active treatment.

CONCLUSIONS

Pill placebo-related improvement occurs early in the course of treatment and both clinical factors and expectation predict this improvement. Additionally, probabilistic approaches may refine our understanding and prediction of pill placebo response.

The Placebo and Nocebo Phenomena: Their Clinical Management and Impact on Treatment Outcomes

PURPOSE

This overview focuses on placebo and nocebo effects in clinical trials and routine care. Our goal was to propose strategies to improve outcomes in clinical practice, maximizing placebo effects and reducing nocebo effects, as well as managing these phenomena in clinical trials.

METHODS

A narrative literature search of PubMed was conducted (January 1980-September 2016). Systematic reviews, randomized controlled trials, observational studies, and case series that had an emphasis on placebo or nocebo effects in clinical practice were included in the qualitative synthesis. Search terms included: placebo, nocebo, clinical, clinical trial, clinical setting, placebo effect, nocebo effect, adverse effects, and treatment outcomes. This search was augmented by a manual search of the references of the key articles and the related literature.

FINDINGS

Placebo and nocebo effects are psychobiological events imputable to the therapeutic context. Placebo is defined as an inert substance that provokes perceived benefits, whereas the term nocebo is used when an inert substance causes perceived harm. Their major mechanisms are expectancy and classical conditioning. Placebo is used in several fields of medicine, as a diagnostic tool or to reduce drug dosage. Placebo/nocebo effects are difficult to disentangle from the natural course of illness or the actual effects of a new drug in a clinical trial. There are known strategies to enhance clinical results by manipulating expectations and conditioning.

IMPLICATIONS

Placebo and nocebo effects occur frequently and are clinically significant but are underrecognized in clinical practice. Physicians should be able to recognize these phenomena and master tactics on how to manage these effects to enhance the quality of clinical practice.

Evidence-based treatments for youths with severely dysregulated mood: a qualitative systematic review of trials for SMD and DMDD

The aim of this literature review was to examine the evidence for psychotherapeutic and pharmacological treatments in subjects with severely dysregulated mood and to identify potential areas for improvements in research designs. A literature search was conducted using several databases for published (PubMed, PsycINFO) and ongoing (clinical trial registries) studies conducted in youths who met NIMH's criteria for Severe Mood Dysregulation (SMD) or the DSM-5 diagnosis of Disruptive Mood Dysregulation Disorder (DMDD). Eight completed studies were identified: three randomized trials, four open pilot studies and one case report. Seven ongoing studies were found in trial registries. The available evidence suggests potential efficacy of psychotherapies which have previously been developed for internalizing and externalizing disorders. The two main pharmacological strategies tested are, first, a monotherapy of psychostimulant or atypical antipsychotic such as risperidone, already used in the treatment of severe irritability in youths with developmental disorders; and second, the use of a serotonergic antidepressant as an add-on therapy in youths treated with psychostimulant. Ongoing studies will further clarify the effectiveness of psychotherapeutic interventions for DMDD individuals and whether they should be given alone or in conjunction with other treatments. The short duration of the trials for a chronic disorder, the low number of studies, the lack of placebo or active comparator arm, and restrictive inclusion criteria in most of the controlled trials dramatically limit the interpretation of the results. Finally, future research should be conducted across multiple sites, with standardized procedures to measure DMDD symptoms reduction, and include a run-in period to limit placebo effect.

Placebo Response in Pediatric Anxiety Disorders: Implications for Clinical Trial Design and Interpretation

OBJECTIVES

The characterization and prediction of placebo response in clinical trials of youth with anxiety disorders have received little attention, despite the critical effects of placebo response rate on the success or failure of clinical trials. With this in mind, we sought to examine the factors that predict or influence placebo response in randomized controlled trials of youth with anxiety disorders.

METHODS

Prospective, randomized, parallel-group controlled trials of psychopharmacologic interventions in pediatric patients with anxiety disorders were identified using a search of PubMed/Medline (1966-2015). Weighted least squares regression models and z-tests were utilized to examine the impact of continuous and categorical variables, respectively, on placebo response. These variables included demographic (e.g., age, percent white, percent female), clinical (e.g., baseline symptom severity), and trial characteristics (sample size, duration, funding). Finally, the relationship between the class of comparator medication and placebo response rate was examined using a multiple comparison for proportions test.

RESULTS

The analyses of data from 14 trials involving 2230 patients and 9 medications reveal that higher placebo response rates were associated with a greater number of study sites (p = 0.013) and fewer patients per site (p < 0.008), while placebo dropout rates increased with more recent publication (p = 0.01) and were positively associated with the number of study visits (p < 0.02). Lower placebo response rates were associated with federally funded studies (z = -4.61, p < 0.001), studies conducted in the United States (z = 1.81, p < 0.035), and with an increased likelihood of detecting a significant effect on the primary outcome (z = 4.58, p < 0.0001). Additionally, studies, in which the majority of patients (>60%) had a diagnosis of social anxiety disorder, exhibited lower placebo response rates (p < 0.001). Finally, for trials, effect size has decreased over time (p = 0.004).

CONCLUSIONS

Important trial-specific factors affect placebo response and placebo dropout in youth with anxiety disorders and have pragmatic implications for the conduct and design of clinical trials and raise the possibility that limiting the number of sites while maximizing the number of patients per site could enhance the ability to detect medication-placebo differences.

Predicting Therapeutic Effects of Psychodiagnostic Assessment Among Children and Adolescents Participating in Randomized Controlled Trials

This study explored predictors of improvement after completing a psychodiagnostic screening assessment but before randomization among youth who participated in two pilot randomized controlled trials of omega-3 supplementation and Individual-Family Psychoeducational Psychotherapy (PEP). Ninety-five youth (56.8% male, 61.1% White) ages 7-14 with mood disorders completed screening and baseline assessments (including Clinical Global Impressions-Improvement [CGI-I], Children's Depression Rating Scale-Revised, Young Mania Rating Scale), then were randomized into a 12-week trial of omega-3, PEP, their combination, or placebo. Between screening and randomization, 35.8% minimally improved (CGI-I = 3), 12.6% much improved (CGI-I < 3), totaling 48.4% improved. Caregiver postsecondary education (p = .018), absence of attention-deficit/hyperactivity disorder (p = .027), and lower screen depression severity (p = .034) were associated with CGI-I. Caregiver postsecondary education (p = .020) and absence of a disruptive behavior diagnosis (p = .038) were associated with depression severity improvement. Prerandomization improvement moderated treatment outcomes: Among youth who improved prerandomization, those who received PEP (alone or with omega-3) had more favorable placebo-controlled depression trajectories due to a lack of placebo response. This open-label trial of psychodiagnostic assessment provides suggestive evidence that psychodiagnostic assessment is beneficial, especially for those with depression and without externalizing disorders. Prerandomization improvement is associated with better placebo-controlled treatment response. Future research should test alternative hypotheses for change and determine if less intensive (shorter and/or automated) assessments would provide comparable results.

Mechanisms of the placebo effect in pain and psychiatric disorders

Placebo effect research over the past 15 years has improved our understanding of how placebo treatments reduce patient symptoms. The expectation of symptom improvement is the primary factor underlying the placebo effect. Such expectations are shaped by past experiences, contextual cues and biological traits, which ultimately modulate one's degree of response to a placebo. The body of evidence that describes the physiology of the placebo effect has been derived from mechanistic studies primarily restricted to the setting of pain. Imaging findings support the role of endogenous opioid and dopaminergic networks in placebo analgesia in both healthy patients as well as patients with painful medical conditions. In patients with psychiatric illnesses such as anxiety disorders or depression, a vast overlap in neurological changes is observed in drug responders and placebo responders supporting the role of serotonergic networks in placebo response. Molecular techniques have been relatively underutilized in understanding the placebo effect until recently. We present an overview of the placebo responder phenotypes and genetic markers that have been associated with the placebo effect in pain, schizophrenia, anxiety disorders and depression.

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

The placebo effect has often been considered a nuisance in basic and particularly clinical research. This view has gradually changed in recent years due to deeper insight into the neuro-bio-behavioral mechanisms steering both the placebo and nocebo responses, the evil twin of placebo. For the neuroscientist, placebo and nocebo responses have evolved as indispensable tools to understand brain mechanisms that link cognitive and emotional factors with symptom perception as well as peripheral physiologic systems and end organ functioning. For the clinical investigator, better understanding of the mechanisms driving placebo and nocebo responses allow the control of these responses and thereby help to more precisely define the efficacy of a specific pharmacological intervention. Finally, in the clinical context, the systematic exploitation of these mechanisms will help to maximize placebo responses and minimize nocebo responses for the patient's benefit. In this review, we summarize and critically examine the neuro-bio-behavioral mechanisms underlying placebo and nocebo responses that are currently known in terms of different diseases and physiologic systems. We subsequently elaborate on the consequences of this knowledge for pharmacological treatments of patients and the implications for pharmacological research, the training of healthcare professionals, and for the health care system and future research strategies on placebo and nocebo responses.

INFLUENCE OF STUDY DESIGN ON TREATMENT RESPONSE IN ANXIETY DISORDER CLINICAL TRIALS

OBJECTIVE

The influence of study design variables and publication year on response to medication and placebo was investigated in clinical trials for social anxiety disorder (SAD), generalized anxiety disorder (GAD), and panic disorder (PD).

METHOD

Hierarchical linear modeling determined whether publication year, treatment assignment (medication vs. placebo), study type (placebo-controlled or active comparator), study duration, and the number of study visits affected the mean change associated with medication and placebo.

RESULTS

In the 66 trials examined, the change associated with both medication and placebo increased over time (t = 4.23, df = 39, P < .001), but average drug-placebo differences decreased over time (t = -2.04, df = 46, P = .047). More severe baseline illness was associated with greater drug-placebo differences for serotonin norepinephrine reuptake inhibitors (SNRIs, t = 3.46, df = 106, P = .001) and selective serotonin reuptake inhibitors (SSRI, t = 10.37, df = 106, P < .001). Improvement with medication was significantly greater in active-comparator studies compared to placebo-controlled trials (t = 3.41, df = 39, P = .002). A greater number of study visits was associated with greater symptom improvement in PD trials relative to SAD (t = 2.83, df = 39, P = .008) and GAD (t = 2.16, df = 39, P = .037).

CONCLUSIONS

Placebo response is substantial in SAD, GAD, and PD trials, and its rise over time has been associated with diminished drug-placebo differences. Study design features that influence treatment response in anxiety disorder trials include patient expectancy, frequency of follow-up visits, and baseline illness severity.

Age and sex as moderators of the placebo response – an evaluation of systematic reviews and meta-analyses across medicine

Predictors of the placebo response (PR) in randomized controlled trials (RCT) have been searched for ever since RCT have become the standard for testing novel therapies and age and gender are routinely documented data in all trials irrespective of the drug tested, its indication, and the primary and secondary end points chosen. To evaluate whether age and gender have been found to be reliable predictors of the PR across medical subspecialties, we extracted 75 systematic reviews, meta-analyses, and meta-regressions performed in major medical areas (neurology, psychiatry, internal medicine) known for high PR rates. The literature database used contains approximately 2,500 papers on various aspects of the genuine PR. These ‘meta-analyses’ were screened for statistical predictors of the PR across multiple RCT, including age and gender, but also other patient-based and design-based predictors of higher PR rates. Retrieved papers were sorted for areas and disease categories. Only 15 of the 75 analyses noted an effect of younger age to be associated with higher PR, and this was predominantly in psychiatric conditions but not in depression, and internal medicine but not in gastroenterology. Female gender was associated with higher PR in only 3 analyses. Among the patient-based predictors, the most frequently noted factor was lower symptom severity at baseline, and among the design- based factors, it was a randomization ratio that selected more patients to drugs than to placebo, more frequent study visits, and more recent trials that were associated with higher PR rates. While younger age may contribute to the PR in some conditions, sex does not. There is currently no evidence that the PR is different in the elderly. PR are, however, markedly influenced by the symptom severity at baseline, and by the likelihood of receiving active treatment in placebo- controlled trials.

Predicting placebo response in adolescents with major depressive disorder: The Adolescent Placebo Impact Composite Score (APICS)

OBJECTIVE

The aim of this study was to construct a composite scoring system to predict the probability of placebo response in adolescents with Major Depressive Disorder (MDD).

METHOD

Participants of the current study were 151 adolescents (aged 12-17 years) who were randomized to the placebo arm (placebo transdermal patches) of a randomized controlled trial (RCT) comparing the selegiline transdermal patch with placebo (DelBello et al., 2014). The primary outcome of response was defined as a CGI-I score of 1 or 2 (very much or much improved) at week 12 (study-end) or exit. As a first step, a multiple logistic mixed model was used to estimate the odds of placebo response from each predictor in the model, including age, CDRS-R total at baseline (depressive symptom severity), history of recurrent depression (yes vs. no), sex (female vs. male), and race (non-Caucasian vs. Caucasian). On the basis of the initial logistic mixed model analysis, we then constructed an Adolescent Placebo Impact Composite Score (APICS) that became the sole predictor in a re-specified Bayesian logistic regression model to estimate the probability of placebo response. Finally, the AUC for the APICS was tested against a nominal area of 0.50 to evaluate how well the APICS discriminated placebo response status.

RESULTS

Among the 151 adolescents, with a mean age of 14.6 years (SD = 1.6) and a mean baseline CDRS-R total of 60.6 (SD = 12.1), 68.2% were females, 50.3% was Caucasian, and 39.7% had a history of recurrent depression. Placebo response rate was 58.3%. Based on the logistic mixed model, the re-specified equation with the highest discriminatory ability to estimate the probability of placebo response was APICS = age + (0.32 × CDRS-R Total at baseline) + (-2.85 × if female) + (-5.50 × if history of recurrent depression) + (-5.85 × if non-Caucasian). The AUC for this model was 0.59 (p = .049). Within a Bayesian decision-theoretic framework, in 95.5% of the time, the 10,000 posterior Monte Carlo samples suggested that as APICS decreased the probability of placebo response increased. The observed APICS and related probability of responding to placebo in this adolescent sample ranged from 14.1 = 74.1% (in placebo responders) to 39.1 = 41.8% (in placebo non-responders).

CONCLUSION

The APICS model estimates the probability of placebo response in adolescents with MDD with a modest degree of accuracy (AUC = 0.59) and with a reasonable degree of positive predictive value (74.5%), and is based on five previously identified patient characteristics of placebo response from prior meta-analytic studies (Bridge et al., 2009; Cohen et al., 2010) of randomized placebo-controlled trials of antidepressants in youth with MDD. Calculation of the APICS should be restricted to the range of the adolescent ages (12-17 years) and CDRS-R total scores (17-113); thus, the APICS can assume possible calculated values and related probability of responding to placebo ranging from about 3 (84%) to 53 (25%). The APICS Bayesian logistic model, based on a given aggregate patient profile, has a range of predicted probabilities of placebo response that is fairly wide, albeit truncated, but potentially meaningful for predicting the probability of placebo response among adolescent youth with MDD. The ability of the APICS to objectify the probability of placebo response in adolescents with MDD could be accounted for in the clinical research design of the trial itself and perhaps aid clinicians in treatment strategy for youth who are more likely to experience placebo response.

Placebo response in antipsychotic trials of patients with acute mania: Results of an individual patient data meta-analysis

We examined the role of placebo response in acute mania trials. Specifically, whether placebo response: (1) predicts treatment effect, (2) can be predicted by patient and study characteristics, and (3) can be predicted by a parsimonious model. We performed a meta-analysis of individual patient data from 10 registration studies (n=1019) for the indication acute manic episode of bipolar disorder. We assessed the effect of 14 determinants on placebo response. Primary outcome measures were mean symptom change score (MCS) on the Young Mania Rating Scale (YMRS) and response rate (RR), defined as ≥ 50% YMRS symptom improvement from baseline to endpoint. The overall placebo response was 8.5 points improvement on the YMRS (=27.9%) with a RR of 32.8%. Placebo response was significantly associated with the overall treatment response. Five determinants significantly (p<0.05) predicted the placebo response. The multivariate prediction model, which consisted of baseline severity, psychotic features at baseline, number of geographic regions, and region, explained 10.4% and 5.5% of the variance in MSC and RR, respectively. Our findings showed that the placebo response in efficacy trials of antipsychotics for acute mania is substantial and an important determinant of treatment effect. Placebo response is influenced by patient characteristics (illness severity and presence of psychotic features) and by study characteristics (study year, number of geographic regions and region). However, the prediction model could only explain the placebo response to a limited extent. Therefore, limiting trials to certain patients in certain geographic regions seems not a viable strategy to improve assay sensitivity.

Comparative efficacy and acceptability of psychotherapies for depression in children and adolescents: A systematic review and network meta-analysis

Previous meta-analyses of psychotherapies for child and adolescent depression were limited because of the small number of trials with direct comparisons between two treatments. A network meta-analysis, a novel approach that integrates direct and indirect evidence from randomized controlled studies, was undertaken to investigate the comparative efficacy and acceptability of psychotherapies for depression in children and adolescents. Systematic searches resulted in 52 studies (total N=3805) of nine psychotherapies and four control conditions. We assessed the efficacy at post-treatment and at follow-up, as well as the acceptability (all-cause discontinuation) of psychotherapies and control conditions. At post-treatment, only interpersonal therapy (IPT) and cognitive-behavioral therapy (CBT) were significantly more effective than most control conditions (standardized mean differences, SMDs ranged from -0.47 to -0.96). Also, IPT and CBT were more beneficial than play therapy. Only psychodynamic therapy and play therapy were not significantly superior to waitlist. At follow-up, IPT and CBT were significantly more effective than most control conditions (SMDs ranged from -0.26 to -1.05), although only IPT retained this superiority at both short-term and long-term follow-up. In addition, IPT and CBT were more beneficial than problem-solving therapy. Waitlist was significantly inferior to other control conditions. With regard to acceptability, IPT and problem-solving therapy had significantly fewer all-cause discontinuations than cognitive therapy and CBT (ORs ranged from 0.06 to 0.33). These data suggest that IPT and CBT should be considered as the best available psychotherapies for depression in children and adolescents. However, several alternative psychotherapies are understudied in this age group. Waitlist may inflate the effect of psychotherapies, so that psychological placebo or treatment-as-usual may be preferable as a control condition in psychotherapy trials.

Placebo eff ects in psychiatry: mediators and moderators

A strong placebo response in psychiatric disorders has been noted for the past 50 years and various attempts have been made to identify predictors of it, by use of meta-analyses of randomised controlled trials and laboratory studies. We reviewed 31 meta-analyses and systematic reviews of more than 500 randomised placebo-controlled trials across psychiatry (depression, schizophrenia, mania, attention-deficit hyperactivity disorder, autism, psychosis, binge-eating disorder, and addiction) for factors identified to be associated with increased placebo response. Of 20 factors discussed, only three were often linked to high placebo responses: low baseline severity of symptoms, more recent trials, and unbalanced randomisation (more patients randomly assigned to drug than placebo). Randomised controlled trials in non-drug therapy have not added further predictors, and laboratory studies with psychological, brain, and genetic approaches have not been successful in identifying predictors of placebo responses. This comprehensive Review suggests that predictors of the placebo response are still to be discovered, the response probably has more than one mediator, and that different and distinct moderators are probably what cause the placebo response within psychiatry and beyond.

Pain and placebo in pediatrics: a comprehensive review of laboratory and clinical findings

Pain modulation by placebo mechanisms is one of the most robust and best-studied phenomena, yet almost all research investigating the mechanisms and implications of the placebo analgesia are based on adult research. After highlighting crucial aspects that need to be considered in studying pain modulation in children, this comprehensive review examines studies related to pain modulation with an emphasis on factors such as age, neural development and pain measures. We critically discuss psychological mechanisms underlying placebo effects, including (1) verbally induced expectations, (2) conditioning and learning mechanisms, and (3) child-parent-physician interactions. Taken together, research suggests that placebo mechanisms can affect therapeutic outcomes and potentially be exploited clinically to improve clinical outcomes in pediatric population. Recommendations for further investigating the mechanistic bases and harnessing placebo effects for supportive therapeutic applications are given.

Comparison among clomipramine, fluoxetine, and placebo for the treatment of anxiety disorders in children and adolescents

OBJECTIVE

The purpose of this study was to test the efficacy of clomipramine and fluoxetine, controlled by placebo, and compare their action in children and adolescents with anxiety disorders.

METHOD

Thirty subjects (ages 7-17 years), who were diagnosed with generalized anxiety disorder and/or separation anxiety disorder and/or social phobia, were submitted to a 12 week double-blind, randomized, placebo-controlled trial of clomipramine and fluoxetine. The instruments included: the Schedule for Affective Disorders and Schizophrenia, the Multidimensional Anxiety Scale for Children, the Children's Depression Inventory, the Clinical Global Impressions, and the Children's Global Assessment Scale.

RESULTS

All groups (clomipramine [n=9], fluoxetine [n=10], placebo [n=11]) showed a significant improvement after 12 weeks of treatment. There were significant differences between the fluoxetine and placebo groups in some ratings of anxiety severity and impairment. No significant differences were observed between clomipramine and placebo groups or between fluoxetine and clomipramine groups.

CONCLUSIONS

Treatment with placebo showed an unusual high response rate. Clomipramine showed similar efficacy compared with fluoxetine, although it was not superior to placebo.

Baseline factors predicting placebo response to treatment in children and adolescents with autism spectrum disorders: a multisite randomized clinical trial

IMPORTANCE

The finding of factors that differentially predict the likelihood of response to placebo over that of an active drug could have a significant impact on study design in this population.

OBJECTIVE

To identify possible nonspecific, baseline predictors of response to intervention in a large randomized clinical trial of children and adolescents with autism spectrum disorders.

DESIGN, SETTING, AND PARTICIPANTS

Randomized clinical trial of citalopram hydrobromide for children and adolescents with autism spectrum disorders and prominent repetitive behavior. Baseline data at study entry were examined with respect to final outcome to determine if response predictors could be identified. A total of 149 children and adolescents 5 to 17 years of age (mean [SD] age, 9.4 [3.1] years) from 6 academic centers were randomly assigned to citalopram (n = 73) or placebo (n = 76). Participants had autistic disorder, Asperger syndrome, or pervasive developmental disorder, not otherwise specified; had illness severity ratings that were moderate or more than moderate on the Clinical Global Impression-Severity scale; and scored moderate or more than moderate on compulsive behaviors measured with the modified Children's Yale-Brown Obsessive-Compulsive Scale.

INTERVENTIONS

Twelve weeks of treatment with citalopram (10 mg/5 mL) or placebo. The mean (SD) maximum dose of citalopram was 16.5 (6.5) mg by mouth daily (maximum dose, 20 mg/d).

MAIN OUTCOMES AND MEASURES

A positive response was defined as having a score of at least much improved on the Clinical Global Impression-Improvement scale at week 12. Baseline measures included demographic (sex, age, weight, and pubertal status), clinical, and family measures. Clinical variables included baseline illness severity ratings (the Aberrant Behavior Checklist, the Child and Adolescent Symptom Inventory, the Vineland Adaptive Behavior Scales, the Repetitive Behavior Scale-Revised, and the Children's Yale-Brown Obsessive-Compulsive Scale). Family measures included the Caregiver Strain Questionnaire.

RESULTS

Several baseline predictors of response were identified, and a principal component analysis yielded 3 composite measures (disruptive behavior, autism/mood, and caregiver strain) that significantly predicted response at week 12. Specifically, participants in the placebo group were significantly less likely than participants in the citalopram group to respond at week 12 if they entered the study more symptomatic on each of the 3 composite measures, and they were at least 2 times less likely to be responders.

CONCLUSIONS AND RELEVANCE

This analysis suggests strategies that may be useful in anticipating and potentially mitigating the nonspecific response in randomized clinical trials of children and adolescents with autism spectrum disorders.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00086645.

Cognitive-coping therapy for obsessive-compulsive disorder: a randomized controlled trial

Pharmacotherapy and cognitive-behavioral therapy (CBT) are widely used to treat obsessive-compulsive disorder (OCD). These treatments have helped many patients with OCD, but there still is room for improvement. Recently, a promising psychotherapy for OCD, cognitive-coping therapy (CCT), has been developed. Pharmacotherapy plus CCT (PCCT) demonstrates higher efficacy in a shorter period of time and lower relapses than pharmacotherapy or pharmacotherapy plus CBT. In this randomized controlled trial, we investigated the efficacy of CCT for OCD treatment. One hundred and forty-five OCD patients were randomly assigned into two groups: pharmacotherapy (N = 72) and PCCT (N = 73). In each group, drug-resistant (DR) and non-drug-resistant (NDR) OCD were further analyzed to examine the efficacy of CCT. Some clinical features and the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) were blindly assessed pre-treatment and post-treatment at week 1, 2, 3, 4, and 12. The Y-BOCS scores were significantly lower in PCCT than in the pharmacotherapy group at any post-treatment time-point (P < 0.001). Compared with pre-treatment, the Y-BOCS scores were significantly reduced at any time-point (P < 0.001) in PCCT group, but only at week 12 (P < 0.001) in the pharmacotherapy group. In the PCCT group, there were no differences between DR and NDR groups' Y-BOCS scores at any post-treatment time-point. The response rates and remission rates were higher in PCCT than in the pharmacotherapy group. Three variables, the number of weeks of treatment, insight, and disregarding of obsessions, were significantly correlated with the Y-BOCS score. Therefore, CCT might be a potential treatment for OCD.

The role of pretreatment outcome expectancies and cognitive-behavioral skills in symptom improvement in an acute psychiatric setting

BACKGROUND

Prior research has found that pretreatment expectations of symptom improvement are positively correlated with depressive symptom change. The current investigation extends previous research by examining whether pretreatment outcome expectancies predict symptom change across several diagnostic categories within the context of an acute, naturalistic psychiatric setting.

METHODS

Analyses were conducted to examine whether pretreatment outcome expectancies (credibility/expectancy questionnaire [CEQ]) predicted symptom improvement within major depression (N=420), bipolar disorder (N=120) and psychosis (N=36). Bootstrap mediation analyses were conducted to examine whether acquisition of cognitive behavioral therapy (CBT) skills (cognitive behavior therapy skills questionnaire [CBTSQ]) may mediate expectancy-outcome relations.

RESULTS

Results indicated a differential pattern of associations across diagnoses. Patient CBT skills emerged as a significant mediator of expectancy-outcome relations, but only in the major depression group. Both behavioral and cognitive skills were significantly, and independently, associated with symptom improvement.

LIMITATIONS

Sample sizes were small in the bipolar manic subgroup and psychosis group. CBT skills and symptom measures were assessed at concurrent time points.

CONCLUSIONS

The present findings suggest that patient expectancies and CBT skills may have a differential impact on symptom change as a function of diagnostic category. The implication of these results and directions for future research are discussed.

Placebo effects in children: a review

Of more than 155,000 PubMed citations found with the search term "placebo," only ~9,000 (5.8%) included the terms "children" or "adolescents." When all these papers were screened, only ~2,000 of them investigated the placebo effect per se, and of those, only ~50 (2.5%) discussed the placebo effect in children and adolescents. In this narrative review, we explore four aspects of the placebo response in children and adolescents: (i) the legal and ethical limitations and restrictions for the inclusion of children in clinical trials as well as in experimental (placebo) research that may explain the poor knowledge base; (ii) the question of whether or not the placebo effect is larger in children and adolescents as compared with adults; (iii) whether the mechanisms underlying the placebo effect are similar between children and adults; and (iv) whether mediators and moderators of the placebo effect are comparable between children and adults. We finally discuss some of the consequences from the current placebo research in adults that may affect both experimental and clinical research in children and adolescents.

Efficacy and safety of carisbamate in patients with diabetic neuropathy or postherpetic neuralgia: results from 3 randomized, double-blind placebo-controlled trials

The results of 3 proof-of-concept studies to evaluate carisbamate's efficacy and safety in treating neuropathic pain are presented. In studies 1 (postherpetic neuralgia, n = 91) and 2 (diabetic neuropathy, n = 137), patients received carisbamate 400 mg/day or placebo for 4 weeks and then crossed over to the other treatment for 4 weeks. In study 3 (diabetic neuropathy, higher carisbamate doses), patients (n = 386) were randomized (1:1:1:1) to receive either carisbamate 800 mg/day, 1200 mg/day, pregabalin 300 mg/day or placebo for 15 weeks. Primary efficacy end point was the mean of the last 7 average daily pain scores obtained on days the study drug was taken, for all 3 studies. Least square mean (95% CI) differences between carisbamate and placebo groups on the primary end point were as follows: study 1: -0.512 (-1.32, 0.29) carisbamate 400 mg/day; study 2: -0.307 (-0.94, 0.33) carisbamate 400 mg/day; and study 3: -0.51 (-1.10, 0.08), carisbamate 800 mg/day; -0.55 (-1.13, 0.04), carisbamate 1200 mg/day; and -0.43 (-1.01, 0.15), pregabalin 300 mg/day. Neither carisbamate (all 3 studies) nor pregabalin (study 3) significantly differed from placebo, although multiple secondary end points showed significant improvement in efficacy with carisbamate in studies 1 and 2. Dizziness was the only treatment-emergent adverse event occurring at ≥10% difference in carisbamate groups versus placebo (study 1: 12% vs. 1%; study 3: 14% vs. 4%; study 2: 1% vs. 2%). Carisbamate, although well tolerated, did not demonstrate efficacy in neuropathic pain across these studies, nor did the active comparator pregabalin (study 3).

Placebo effect in child and adolescent psychiatric trials

Much literature has been written in the field of child psychiatry regarding the placebo as a tool to test drug efficacy in clinical trials, but quite little regarding the placebo effect itself or its clinical use in child psychiatry. In this article, we aim to critically review the literature regarding the placebo effect in children and adolescents with mental disorders, focusing especially on factors influencing the placebo effect and how they may influence the interpretation of clinical trials. The placebo effect seems to be more marked in children than adults, and particularly in children and adolescents with depression, although it is pervasive across ages and is present in non-psychiatric conditions as well. The use of a placebo in clinical trials as a comparator with drugs that have moderate efficacy at most makes it difficult to obtain positive results, and much effort is needed to design very high quality clinical trials that may overcome the limitations of using a placebo. In addition, the placebo effect across ages and clinical conditions must be tested directly (compared with no treatment whenever possible), in order to characterise which placebos work for what and to determine their use in clinical settings.

Design flaws in randomized, placebo controlled, double blind clinical trials

The hypothesis in drug clinical trials is that the drug is better than a placebo in patients suffering from a disease. The unstated assumption is that the drug cures the disease or is a powerful treatment for the disease. This is an incorrect assumption. Drugs do not cure or treat diseases. The body heals itself; drugs promote this ability of the body to heal itself. Placebos are assumed to be inactive; however, placebos can also promote the ability of the body to heal itself. Placebos are actually treatments that can stimulate endogenous healing mechanisms. The possible place of placebos in health management is controversial. Clinical trial design should be altered. The hypothesis of clinical trials should be that the drug speeds up or improves the healing of the patient, putting patient healing as the first objective. Placebos should not be used as controls but could be tested as drugs in their own right. The control in clinical trials should be no treatment. Alternatively, new drugs could be compared to existing drugs in clinical trials.

Placebo effect after prefrontal magnetic stimulation in the treatment of resistant obsessive-compulsive disorder: a randomized controlled trial

Many patients with obsessive-compulsive disorder (OCD) do not achieve satisfactory symptom improvement with conventional treatments. Here, we evaluate the efficacy of repetitive transcranial magnetic stimulation (rTMS) applied over the right dorsolateral prefrontal cortex (rDLPFC) in patients with treatment-resistant OCD. This was a double-blind randomized trial involving 30 treatment-resistant OCD outpatients, allocated to have either sham or active high-frequency rTMS (over the rDLPFC) added to their treatment regimens for 6 wk, with 6 wk of follow-up. Active rTMS consisted of 30 applications (figure-of-eight coil; 10 Hz at 110% of motor threshold; 1 session/d; 40 trains/session; 5 s/train; 25-s intertrain interval). At weeks 0, 2, 6, 8, and 12, we applied the Yale-Brown Obsessive-Compulsive Scale (YBOCS), Clinical Global Impression (CGI) scale, 14-item Hamilton Anxiety Rating Scale (HAMA-14), 17-item Hamilton Depression Rating Scale (HAMD-17), and 36-item Short-form Health Survey. The primary outcome measure was a positive response (≥ 30% improvement in YBOCS score, together with a 'much improved' or 'very much improved' CGI - Improvement scale rating). One patient in each group showed a positive response (p=1.00). For YBOCS score, there was significant effect of time (F=7.33, p=0.002) but no significant group effect or group×time interaction. In treatment-resistant OCD, active rTMS over the rDLPFC does not appear to be superior to sham rTMS in relieving obsessive-compulsive symptoms, reducing clinical severity, or improving treatment response, although there is evidence of a placebo effect.

Does experimental research support psychoanalysis?

The question of whether a psychodynamic view is compatible with experimental research is still a challenging issue-especially for child and adolescent psychopathology-despite the influence of psychoanalytic theory in this field until the 1980s. In this article, is explored the relationship between psychodynamic theory and experimental research using examples of evidence-based studies in the fields of (i) psychotherapeutic intervention assessment, (ii) placebo response in children and adolescents, (iii) unconscious lasting traumatic effects in children and adolescents, (iv) psychodynamic-oriented psychological testing. There are now a sufficient number of evidence-based studies to support the use of psychodynamic therapy in mental disorders, particularly in personality disorder and anxious/depressive disorder. In addition, placebo responses in children and adolescents with internalizing disorders are significantly higher in major depression compared to obsessive-compulsive disorder or other anxiety disorders, which highlights differential psychopathologies regarding the experience of loss. Also, using an experimental task, psychoanalysts are able to identify, without explicit knowledge and above the level of chance, healthy adults whose siblings had experienced cancer during childhood. This experiment suggests that implicit information regarding a participant's history is conveyed in interpersonal exchanges that can be intuitively perceived by judges experienced in listening to free associations from a psychodynamic perspective. Finally, psychodynamic-oriented psychological testing may predict the transition to schizophrenia in adolescents with a history of manic/mixed episodes. It can be concluded that there are no discrepancies between psychodynamic views and experimental data, whether one tests psychotherapeutic approaches, discusses data from other fields such as psychopharmacology, or designs experiments based on psychodynamic theory.