Meta-Analysis of Placebo Rates in Major Depressive Disorder Trials

Differential Outcomes of Placebo Treatment Across 9 Psychiatric Disorders: A Systematic Review and Meta-Analysis

Importance

Placebo is the only substance systematically evaluated across common psychiatric diagnoses, but comprehensive cross-diagnostic comparisons are lacking.

Objective

To compare changes in placebo groups in recent high-quality randomized clinical trials (RCTs) across a broad spectrum of psychiatric disorders in adult patients.

Data Sources

MEDLINE and the Cochrane Database of Systematic Reviews were systematically searched in March 2022 for the latest systematic reviews meeting predetermined high-quality criteria for 9 major psychiatric diagnoses.

Study Selection

Using these reviews, the top 10 highest-quality (ie, lowest risk of bias, according to the Cochrane Risk of Bias tool) and most recent placebo-controlled RCTs per diagnosis (totaling 90 RCTs) were selected, adhering to predetermined inclusion and exclusion criteria.

Data Extraction and Synthesis

Following the Cochrane Handbook, 2 authors independently carried out the study search, selection, and data extraction. Cross-diagnosis comparisons were based on standardized pre-post effect sizes (mean change divided by its SD) for each placebo group. This study is reported following the Meta-analysis of Observational Studies in Epidemiology (MOOSE) reporting guideline.

Main Outcome and Measure

The primary outcome, pooled pre-post placebo effect sizes (dav) with 95% CIs per diagnosis, was determined using random-effects meta-analyses. A Q test assessed statistical significance of differences across diagnoses. Heterogeneity and small-study effects were evaluated as appropriate.

Results

A total of 90 RCTs with 9985 placebo-treated participants were included. Symptom severity improved with placebo in all diagnoses. Pooled pre-post placebo effect sizes differed across diagnoses (Q = 88.5; df = 8; P < .001), with major depressive disorder (dav = 1.40; 95% CI, 1.24-1.56) and generalized anxiety disorder (dav = 1.23; 95% CI, 1.06-1.41) exhibiting the largest dav. Panic disorder, attention-deficit/hyperactivity disorder, posttraumatic stress disorder, social phobia, and mania showed dav between 0.68 and 0.92, followed by OCD (dav = 0.65; 95% CI, 0.51-0.78) and schizophrenia (dav = 0.59; 95% CI, 0.41-0.76).

Conclusion and Relevance

This systematic review and meta-analysis found that symptom improvement with placebo treatment was substantial in all conditions but varied across the 9 included diagnoses. These findings may help in assessing the necessity and ethical justification of placebo controls, in evaluating treatment effects in uncontrolled studies, and in guiding patients in treatment decisions. These findings likely encompass the true placebo effect, natural disease course, and nonspecific effects.

A pilot randomized sham controlled trial of bilateral iTBS for depression and executive function in older adults

INTRODUCTION

Executive function deficits (EFD) in late life depression (LLD) are associated with poor outcomes. Dysfunction of the cognitive control network (CCN) has been posited in the pathophysiology of LLD with EFD.

METHODS

Seventeen older adults with depression and EFD were randomized to iTBS or sham for 6 weeks. Intervention was delivered bilaterally using a recognized connectivity target.

RESULTS

A total of 89% (17/19) participants completed all study procedures. No serious adverse events occurred. Pre to post-intervention change in mean Montgomery-Asberg-depression scores was not different between iTBS or sham, p = 0.33. No significant group-by-time interaction for Montgomery-Asberg Depression rating scale scores (F _{3, 44}  = 0.51; p = 0.67) was found. No significant differences were seen in the effects of time between the two groups on executive measures: Flanker scores (F _{1, 14}  = 0.02, p = 0.88), Dimensional-change-card-sort scores F _{1, 14}  = 0.25, p = 0.63, and working memory scores (F _{1, 14}  = 0.98, p = 0.34). The Group-by-time interaction effect for functional connectivity (FC) within the Fronto-parietal-network was not significant (F _{1, 14}  = 0.36, p = 0.56). No significant difference in the effect-of-time between the two groups was found on FC within the Cingulo-opercular-network (F _{1, 14}  = 0, p = 0.98).

CONCLUSION

Bilateral iTBS is feasible in LLD. Preliminary results are unsupportive of efficacy on depression, executive function or target engagement of the CCN. A future Randomized clinical trial requires a larger sample size with stratification of cognitive and executive variables and refinement in the target engagement.

Different symptomatic improvement pattern revealed by factor analysis between placebo response and response to Esketamine in treatment resistant depression

AIMS

The aim of this study is to determine whether there is difference in the change in each symptom of depression and in symptomatic improvement pattern between placebo and antidepressant responses.

METHODS

Using data from a randomized, double-blind (DB), placebo-controlled trial of esketamine (ESK) in patients with treatment-resistant depression (TRD), we conducted exploratory analyses. To determine differences in the change in each depressive symptom on the MADRS subscale between placebo and antidepressant responses, a two-way factorial analysis was conducted using the amount of change on Day 2 and 28 of treatment. In addition, exploratory and confirmatory factor analyses were conducted on the MADRS subtotal variables on Day 2 and 28 of treatment to determine symptomatic improvement pattern between placebo response and antidepressant responses.

RESULTS

We found that as well as MADRS total score, each subscale of MADRS score did not significantly differ between esketamine and placebo at Day 2 and 28. On the other hand, factor analysis revealed that the factor structure of the response was different between esketamine and placebo at the 2nd day. There was no difference in the factor structure between esketamine and placebo in response on Day 28 of treatment.

CONCLUSION

Factor analysis revealed different patterns of symptom improvement in the early phase of the intervention between esketamine and placebo. This finding suggests that a data driven approach may provide detailed efficacy information in clinical trials for antidepressants.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02918318. Registered: 28 September 2016.

Psilocybin therapy increases cognitive and neural flexibility in patients with major depressive disorder

Psilocybin has shown promise for the treatment of mood disorders, which are often accompanied by cognitive dysfunction including cognitive rigidity. Recent studies have proposed neuropsychoplastogenic effects as mechanisms underlying the enduring therapeutic effects of psilocybin. In an open-label study of 24 patients with major depressive disorder, we tested the enduring effects of psilocybin therapy on cognitive flexibility (perseverative errors on a set-shifting task), neural flexibility (dynamics of functional connectivity or dFC via functional magnetic resonance imaging), and neurometabolite concentrations (via magnetic resonance spectroscopy) in brain regions supporting cognitive flexibility and implicated in acute psilocybin effects (e.g., the anterior cingulate cortex, or ACC). Psilocybin therapy increased cognitive flexibility for at least 4 weeks post-treatment, though these improvements were not correlated with the previously reported antidepressant effects. One week after psilocybin therapy, glutamate and N-acetylaspartate concentrations were decreased in the ACC, and dFC was increased between the ACC and the posterior cingulate cortex (PCC). Surprisingly, greater increases in dFC between the ACC and PCC were associated with less improvement in cognitive flexibility after psilocybin therapy. Connectome-based predictive modeling demonstrated that baseline dFC emanating from the ACC predicted improvements in cognitive flexibility. In these models, greater baseline dFC was associated with better baseline cognitive flexibility but less improvement in cognitive flexibility. These findings suggest a nuanced relationship between cognitive and neural flexibility. Whereas some enduring increases in neural dynamics may allow for shifting out of a maladaptively rigid state, larger persisting increases in neural dynamics may be of less benefit to psilocybin therapy.

Combined Cognitive-Behavioral Therapy and Placebo Treatment for Patients with Depression: A Follow-Up Assessment

Introduction

A previous study revealed that patients with depression who received a combination of cognitive-behavioral therapy (CBT) and placebo treatment (CBT+placebo) showed greater symptom reduction than a CBT group without a placebo. Moreover, the CBT+placebo group practiced relaxation training more frequently. We conducted a 3-month follow-up assessment to investigate the temporal stability of the placebo effects.

Methods

Eighty-two outpatients with a diagnosis of major depressive disorder who had participated in a 4-week CBT course (CBT: n = 40; CBT with daily placebo treatment: n = 42) returned to a 3-month follow-up assessment. The participants of the CBT+placebo group had been debriefed directly after the course.

Results

Compared to the CBT group, the CBT+placebo group had lower scores on the Beck Depression Inventory-II (BDI-II) at follow-up and more participants were below the clinical cut-off score of the BDI-II. Additionally, the CBT+placebo group continued to practice relaxation more frequently.

Discussion

This study demonstrates that placebo effects are not short-lived and continue to be present after the debriefing.

Understanding the Neurocomputational Mechanisms of Antidepressant Placebo Effects

Over the last two decades, neuroscientists have used antidepressant placebo probes to examine the biological mechanisms implicated in antidepressant placebo effects. However, findings from these studies have not yet elucidated a model-based theory that would explain the mechanism through which antidepressant expectancies evolve to induce persistent mood changes. Emerging evidence suggests that antidepressant placebo effects may be informed by models of reinforcement learning (RL). Such that an individual's expectation of improvement is updated with the arrival of new sensory evidence, by incorporating a reward prediction error (RPE), which signals the mismatch between the expected (expected value) and perceived improvement. Consistent with this framework, neuroimaging studies of antidepressant placebo effects have demonstrated placebo-induced μ-opioid activation and increased blood-oxygen-level dependent (BOLD) responses in regions tracking expected values (e.g., ventromedial prefrontal cortex (vmPFC)) and RPEs (e.g., ventral striatum (VS)). In this study, we will demonstrate the causal contribution of reward learning signals (expected values and RPEs) to antidepressant placebo effects by experimentally manipulating expected values using transcranial magnetic stimulation (TMS) targeting the vmPFC and μ-opioid striatal RPE signal using pharmacological approaches. We hypothesized that antidepressant placebo expectancies are represented in the vmPFC (expected value) and updated by means of μ-opioid-modulated striatal learning signal. In a 3 × 3 factorial double-blind design, we will randomize 120 antidepressant-free individuals with depressive symptoms to one of three between-subject opioid conditions: the μ-opioid agonist buprenorphine, the μ-opioid antagonist naltrexone, or an inert pill. Within each arm, individuals will be assigned to receive three within-subject counterbalanced forms of TMS targeting the vmPFC-intermittent Theta Burst Stimulation (TBS) expected to potentiate the vmPFC, continuous TBS expected to de-potentiate the vmPFC, or sham TBS. These experimental manipulations will be used to modulate trial-by-trial reward learning signals and related brain activity during the Antidepressant Placebo functional MRI (fMRI) Task to address the following aims: (1) investigate the relationship between reward learning signals within the vmPFC-VS circuit and antidepressant placebo effects; (2) examine the causal contribution of vmPFC expected value computations to antidepressant placebo effects; and (3) investigate the causal contribution of μ-opioid-modulated striatal RPEs to antidepressant placebo effects. The proposed study will be the first to investigate the causal contribution of μ-opioid-modulated vmPFC-VS learning signals to antidepressant placebo responses, paving the way for developing novel treatments modulating learning processes and objective means of quantifying and potentially reducing placebo effects during drug development.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT04276259.

Statistical methods in handling placebo effect

A critical issue facing the therapeutic area of neurological diseases is the large number of failed randomized clinical trials, especially when moving from promising Phase 2 trials to failed Phase 3 trials. A common cited reason for these failures is a high placebo response rate that thereby reduces the observed treatment effect. Explanations for this higher than anticipated placebo response include small sample sizes, inadequate study designs and/or analytic methods, baseline characteristics of the trial sample, possible investigator bias and a participant's own expectations and conditional learning. Several innovative study designs and new methodological approaches to statistical analyses have been proposed to handle placebo effects anticipated or observed in double blind, randomized clinical trials (RCT's). This chapter examines current study designs being used to reduce the observed placebo response and statistical analysis methods being employed for addressing this problem in neuroscience clinical trials.

Cortical Connectivity Moderators of Antidepressant vs Placebo Treatment Response in Major Depressive Disorder: Secondary Analysis of a Randomized Clinical Trial

IMPORTANCE

Despite the widespread awareness of functional magnetic resonance imaging findings suggesting a role for cortical connectivity networks in treatment selection for major depressive disorder, its clinical utility remains limited. Recent methodological advances have revealed functional magnetic resonance imaging-like connectivity networks using electroencephalography (EEG), a tool more easily implemented in clinical practice.

OBJECTIVE

To determine whether EEG connectivity could reveal neural moderators of antidepressant treatment.

DESIGN, SETTING, AND PARTICIPANTS

In this nonprespecified secondary analysis, data were analyzed from the Establishing Moderators and Biosignatures of Antidepressant Response in Clinic Care study, a placebo-controlled, double-blinded randomized clinical trial. Recruitment began July 29, 2011, and was completed December 15, 2015. A random sample of 221 outpatients with depression aged 18 to 65 years who were not taking medication for depression was recruited and assessed at 4 clinical sites. Analysis was performed on an intent-to-treat basis. Statistical analysis was performed from November 16, 2018, to May 23, 2019.

INTERVENTIONS

Patients received either the selective serotonin reuptake inhibitor sertraline hydrochloride or placebo for 8 weeks.

MAIN OUTCOMES AND MEASURES

Electroencephalographic orthogonalized power envelope connectivity analyses were applied to resting-state EEG data. Intent-to-treat prediction linear mixed models were used to determine which pretreatment connectivity patterns were associated with response to sertraline vs placebo. The primary clinical outcome was the total score on the 17-item Hamilton Rating Scale for Depression, administered at each study visit.

RESULTS

Of the participants recruited, 9 withdrew after first dose owing to reported adverse effects, and 221 participants (150 women; mean [SD] age, 37.8 [12.7] years) underwent EEG recordings and had high-quality pretreatment EEG data. After correction for multiple comparisons, connectome-wide analyses revealed moderation by connections within and between widespread cortical regions-most prominently parietal-for both the antidepressant and placebo groups. Greater alpha-band and lower gamma-band connectivity predicted better placebo outcomes and worse antidepressant outcomes. Lower connectivity levels in these moderating connections were associated with higher levels of anhedonia. Connectivity features that moderate treatment response differentially by treatment group were distinct from connectivity features that change from baseline to 1 week into treatment. The group mean (SD) score on the 17-item Hamilton Rating Scale for Depression was 18.35 (4.58) at baseline and 26.14 (30.37) across all time points.

CONCLUSIONS AND RELEVANCE

These findings establish the utility of EEG-based network functional connectivity analyses for differentiating between responses to an antidepressant vs placebo. A role emerged for parietal cortical regions in predicting placebo outcome. From a treatment perspective, capitalizing on the therapeutic components leading to placebo response differentially from antidepressant response should provide an alternative direction toward establishing a placebo signature in clinical trials, thereby enhancing the signal detection in randomized clinical trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT01407094.

Neural Predictors of the Antidepressant Placebo Response

The antidepressant placebo response remains a barrier to the development of novel therapies for depression, despite decades of efforts to identify and methodologically address its clinical correlates. This manuscript reviews recent neuroimaging studies that aim to identify the neural signature of antidepressant placebo response. Data captured in clinical trials have primarily focused on antidepressant efficacy or predicting antidepressant response and have reliably implicated the rostral anterior cingulate cortex (rACC) in antidepressant placebo response, but also in medication response. Imaging and electroencephalography (EEG) experiments specifically interrogating the mechanism of antidepressant placebo response, while few, suggest the reward network, including opiate neurotransmission, is also involved. Therefore, while the rACC is likely involved in the antidepressant placebo response, its observation in isolation is unlikely to prospectively distinguish antidepressant placebo from medication responders. Instead, future studies of antidepressant placebo response should probe the reward network as a whole and incorporate sophisticated computational analytical approaches.

Tachyphylaxis in major depressive disorder: A review of the current state of research

BACKGROUND

Patients with major depressive disorder (MDD) often experience a re-emergence or worsening of symptoms despite ongoing treatment with previously effective antidepressant pharmacotherapy. This lost or reduced antidepressant response during maintenance, referred to as tachyphylaxis, negatively impacts treatment outcomes and quality of life for patients with MDD. This review assesses the prevalence of antidepressant tachyphylaxis as well as the evidence for interventions to manage it.

METHODS

We searched PubMed/Medline for the relevant clinical trials and meta-analyses on antidepressant tachyphylaxis up to January 2017. Search terms included "depression" paired with "treatment" (n = 186,674), "tachyphylaxis" paired with "depression" (n = 112), "tachyphylaxis" paired with "major depressive disorder" (n = 21), and "antidepressant" paired with "tachyphylaxis" (n = 68). Studies were included if they reported on a clinical trial or meta-analysis exploring tachyphylaxis in MDD and were excluded if the sample population did not have a primary DSM diagnosis of MDD.

RESULTS

Rates of tachyphylaxis varied from 9% to 57% depending on the patient population and duration of follow-up. Limited evidence suggests potentially beneficial strategies for managing tachyphylaxis, including change in antidepressant dosing, switch of class of antidepressant medication, augmentation or combination pharmacotherapy, and psychotherapy.

LIMITATIONS

Studies of antidepressant tachyphylaxis are largely heterogeneous in nature and employ strict inclusion/exclusion criteria; thus, these findings may not be generalizable to all depressed populations.

CONCLUSION

Few established treatment strategies exist to manage antidepressant tachyphylaxis. Further interventional research is needed to provide symptomatic relief for patients with tachyphylaxis in MDD.

Can Matching-Adjusted Indirect Comparison Methods Mitigate Placebo Response Differences Among Patient Populations in Adjunctive Trials of Brivaracetam and Levetiracetam?

BACKGROUND AND OBJECTIVE

Patients with focal seizures recruited into adjunctive antiepileptic drug (AED) trials have become more refractory and severe over time; concurrently, placebo responses have increased. To attempt to account for heterogeneity among trials, propensity-score weighted patient-level data were used to indirectly compare placebo responses reported in brivaracetam and levetiracetam trials.

METHODS

Patient-level data from randomised, placebo-controlled brivaracetam (recruited 2007-2014) and levetiracetam (1993-1998) trials were pooled. Consistent inclusion/exclusion criteria were applied and outcomes were defined consistently. Potentially confounding baseline characteristics were adjusted for using propensity score weighting. Weighting success was assessed using placebo response.

RESULTS

In total, 707 and 473 active drug and 399 and 253 placebo patients comprised the brivaracetam and levetiracetam groups, respectively. Before weighting, several baseline variables were significantly different between groups; after weighting, prior vagal nerve stimulation, co-morbid depression and co-morbid anxiety remained different. Before weighting, median seizure frequency reduction was 21.7 and 3.9% in the brivaracetam and levetiracetam placebo arms, respectively; after weighting, median reduction was 15.0 and 6.0%. The comparison of non-randomised groups could be biased by unobserved confounding factors and region of residence. Lifetime AED history was unavailable in the brivaracetam trials and excluded from analysis.

CONCLUSIONS

Placebo responses remained different between brivaracetam and levetiracetam trials after propensity score weighting, indicating the presence of residual confounding factors associated with placebo response in these trials. It therefore remains problematic to conduct reliable indirect comparisons of brivaracetam and levetiracetam given the current evidence base, which may apply to comparisons between other AED trials.

Salience Network Functional Connectivity Predicts Placebo Effects in Major Depression

BACKGROUND

Recent neuroimaging studies have demonstrated resting-state functional connectivity (rsFC) abnormalities among intrinsic brain networks in Major Depressive Disorder (MDD); however, their role as predictors of treatment response has not yet been explored. Here, we investigate whether network-based rsFC predicts antidepressant and placebo effects in MDD.

METHODS

We performed a randomized controlled trial of two weeklong, identical placebos (described as having either "active" fast-acting, antidepressant effects or as "inactive") followed by a ten-week open-label antidepressant medication treatment. Twenty-nine participants underwent a rsFC fMRI scan at the completion of each placebo condition. Networks were isolated from resting-state blood-oxygen-level-dependent signal fluctuations using independent component analysis. Baseline and placebo-induced changes in rsFC within the default-mode, salience, and executive networks were examined for associations with placebo and antidepressant treatment response.

RESULTS

Increased baseline rsFC in the rostral anterior cingulate (rACC) within the salience network, a region classically implicated in the formation of placebo analgesia and the prediction of treatment response in MDD, was associated with greater response to one week of active placebo and ten weeks of antidepressant treatment. Machine learning further demonstrated that increased salience network rsFC, mainly within the rACC, significantly predicts individual responses to placebo administration.

CONCLUSIONS

These data demonstrate that baseline rsFC within the salience network is linked to clinical placebo responses. This information could be employed to identify patients who would benefit from lower doses of antidepressant medication or non-pharmacological approaches, or to develop biomarkers of placebo effects in clinical trials.

Association Between Placebo-Activated Neural Systems and Antidepressant Responses: Neurochemistry of Placebo Effects in Major Depression

IMPORTANCE

High placebo responses have been observed across a wide range of pathologies, severely impacting drug development.

OBJECTIVE

To examine neurochemical mechanisms underlying the formation of placebo effects in patients with major depressive disorder (MDD).

DESIGN, SETTING, AND PARTICIPANTS

In this study involving 2 placebo lead-in phases followed by an open antidepressant administration, we performed a single-blinded 2-week crossover randomized clinical trial of 2 identical oral placebos (described as having either active or inactive fast-acting antidepressant-like effects) followed by a 10-week open-label treatment with a selective serotonin reuptake inhibitor or, in some cases, another agent as clinically indicated. The volunteers (35 medication-free patients with MDD at a university health system) were studied with positron emission tomography and the µ-opioid receptor-selective radiotracer [11C]carfentanil after each 1-week inactive and active oral placebo treatment. In addition, 1 mL of isotonic saline was administered intravenously within sight of the volunteer during positron emission tomographic scanning every 4 minutes over 20 minutes only after the 1-week active placebo treatment, with instructions that the compound may be associated with the activation of brain systems involved in mood improvement. This challenge stimulus was used to test the individual capacity to acutely activate endogenous opioid neurotransmision under expectations of antidepressant effect.

MAIN OUTCOMES AND MEASURES

Changes in depressive symptoms in response to active placebo and antidepressant. Baseline and activation measures of µ-opioid receptor binding.

RESULTS

Higher baseline µ-opioid receptor binding in the nucleus accumbens was associated with better response to antidepressant treatment (r = 0.48; P = .02). Reductions in depressive symptoms after 1 week of active placebo treatment, compared with the inactive, were associated with increased placebo-induced µ-opioid neurotransmission in a network of regions implicated in emotion, stress regulation, and the pathophysiology of MDD, namely, the subgenual anterior cingulate cortex, nucleus accumbens, midline thalamus, and amygdala (nucleus accumbens: r = 0.6; P < .001). Placebo-induced endogenous opioid release in these regions was associated with better antidepressant treatment response, predicting 43% of the variance in symptom improvement at the end of the antidepressant trial.

CONCLUSIONS AND RELEVANCE

These data demonstrate that placebo-induced activation of the µ-opioid system is implicated in the formation of placebo antidepressant effects in patients with MDD and also participate in antidepressant responses, conferring illness resiliency, during open administration.

TRIAL REGISTRATION

clinicaltrials.gov Identifier:NCT02178696.

Novel Glutamatergic Treatments for Severe Mood Disorders

All currently approved antidepressant medications for major depressive disorder (MDD) and bipolar disorder act primarily on the monoaminergic system and have varying affinities for serotonergic, norepinephrine-ergic, and/or dopaminergic receptors. Unfortunately, these drugs are only effective in approximately two-thirds of patients. Glutamate is the major excitatory neurotransmitter in the central nervous system, and the glutamatergic system has been implicated in the pathophysiology of MDD. Here, we review the putative involvement of the glutamate receptor subtypes-N-methyl-D-aspartate (NMDA), α-amino-3-hydroxyl-5-methyl-4-isoxazoleproprionic acid (AMPA), kainate, and the group I, II, and III metabotropic glutamate receptors (mGluRs)-in the development of novel and more effective treatments for MDD as well as preclinical and clinical trials of drugs targeting these receptors. The rapid and robust antidepressant effects of ketamine-an NMDA receptor antagonist-have been consistently replicated in multiple trials. Other glutamatergic drugs have been investigated with varying success. Here, we highlight some of the most interesting results, including: 1) repeated oral, intramuscular, and sublingual ketamine appears to be less robustly effective than intravenous ketamine, but also causes fewer significant adverse effects; 2) the glycine partial agonist GLYX-13 appears to be effective both as monotherapy and adjunctive treatment in the treatment of MDD. An oral analogue, NRX-1074, is currently under investigation; and 3) mGluR modulators targeting mGluR5 have demonstrated convincing preclinical results.

Can effects of antidepressants in patients with mild depression be considered as clinically significant?

BACKGROUND

How to define clinical significance of antidepressants has become a matter of far-reaching clinical and regulatory consequences. A mean difference of at least 3 points on the Hamilton Depression Rating Scale (HAMD-17) between active treatment and placebo has been proposed as cut-off score for clinical significance in antidepressant trials.

OBJECTIVE

We aimed to present arguments that this, and other commonly used related approaches to establish clinical significance are likely to be misleading and risky depriving patients with mild depression of efficient treatments.

METHODS

These problems are exemplified with the data from a randomized placebo-controlled five-arm clinical trial with primary care patients with milder depressive syndromes (MIND-study).

RESULTS AND CONCLUSIONS

Designs for studying clinical significance have to be distinguished from those assessing efficacy. Moreover, evaluation of the clinical significance of psychotherapy as a possible alternative to antidepressants faces the problem of how to define a valid control group where blinding of neither therapists nor patients is possible.

Accelerating the development of improved analgesic treatments: the ACTION public-private partnership

There has been considerable progress identifying pathophysiologic mechanisms of neuropathic pain, but analgesic medications with improved efficacy, safety, and tolerability still represent an unmet public health need. Numerous treatments examined in recent randomized clinical trials (RCTs) have failed to show efficacy for neuropathic pain, including treatments that had previously demonstrated efficacy. This suggests that at least some negative results reflect limited assay sensitivity of RCTs to distinguish efficacious treatments from placebo. Patient characteristics, clinical trial research designs and methods, outcome measures, approaches to data analysis, and statistical power may all play a role in accounting for difficulties in demonstrating the benefits of efficacious analgesic treatments vs placebo. The identification of specific clinical trial characteristics associated with assay sensitivity in existing data has the potential to provide an evidence-based approach to the design of analgesic clinical trials. The US Food and Drug Administration recently launched the Analgesic Clinical Trial Innovations, Opportunities, and Networks (ACTION) public-private partnership, which is designed to facilitate the discovery and development of analgesics with improved efficacy, safety, and tolerability for acute and chronic pain conditions. ACTION will establish a collaborative effort to prioritize research objectives, develop a standardized analgesic database platform, and conduct methodologically focused studies to increase the assay sensitivity and efficiency of analgesic clinical trials. The results of these activities have the potential to inform and accelerate the development of improved pain management interventions of all types, not just pharmacologic treatments.

Factors determining response to antiepileptic drugs in randomized controlled trials. A systematic review and meta-analysis

PURPOSE

Because of the lack of head-to-head adjunctive-therapy trials of antiepileptic drugs (AEDs) in refractory partial epilepsy, meta-analyses of placebo-controlled randomized controlled trials (RCTs) represent a potentially important source of evidence to guide treatment decisions. However, such indirect comparisons raise various methodologic issues that may hamper their relevance.

METHODS

All RCTs in adult refractory partial epilepsy were analyzed to assess whether efficacy outcomes are influenced by: characteristics of patients and trials ; use of last observation carried forward (LOCF) analysis; evaluation period (entire period versus maintenance period); and year of publication. A meta-analysis of these AEDs was then performed taking these factors into consideration.

KEY FINDINGS

Sixty-three RCTs evaluating 20 AEDs were included. The following variables influenced efficacy estimates: (1) responder rates correlated positively with duration of the entire treatment period (p = 0.038); (2) response to placebo was significantly greater in the maintenance period than in the entire treatment period (p = 0.005); (3) responder rates increased over the years both for AEDs (p < 0.001) and for placebo (p = 0.001); (4) LOCF analysis overestimated responder rates for AEDs (p < 0.001) and for placebo (p = 0.001) compared with completer-based analysis, and the overestimation correlated positively with withdrawal rates (p < 0.001). A meta-analysis of available data showed large differences in efficacy ranking in relation to dose selection and type of analysis, but these were mostly nonsignificant due to statistical power limitations.

SIGNIFICANCE

Several methodologic issues hamper the relevance of indirect comparisons of AEDs in the adjunctive-therapy of refractory partial epilepsy. Some of these issues could be overcome by improved standardization in the reporting of efficacy outcomes.

Efficacy and safety of asenapine in a placebo- and haloperidol-controlled trial in patients with acute exacerbation of schizophrenia

Asenapine is approved by the Food and Drugs Administration in adults for acute treatment of schizophrenia or of manic or mixed episodes associated with bipolar I disorder with or without psychotic features. In a double-blind 6-week trial, 458 patients with acute schizophrenia were randomly assigned to fixed-dose treatment with asenapine at 5 mg twice daily (BID), asenapine at 10 mg BID, placebo, or haloperidol at 4 mg BID (to verify assay sensitivity). With last observations carried forward (LOCF), mean Positive and Negative Syndrome Scale total score reductions from baseline to endpoint were significantly greater with asenapine at 5 mg BID (-16.2) and haloperidol (-15.4) than placebo (-10.7; both P < 0.05); using mixed model for repeated measures (MMRM), changes at day 42 were significantly greater with asenapine at 5 and 10 mg BID (-21.3 and -19.4, respectively) and haloperidol (-20.0) than placebo (-14.6; all P < 0.05). On the Positive and Negative Syndrome Scale positive subscale, all treatments were superior to placebo with LOCF and MMRM; asenapine at 5 mg BID was superior to placebo on the negative subscale with MMRM and on the general psychopathology subscale with LOCF and MMRM. Treatment-related adverse events (AEs) occurred in 44% and 52%, 57%, and 41% of the asenapine at 5 and 10 mg BID, haloperidol, and placebo groups, respectively. Extrapyramidal symptoms reported as AEs occurred in 15% and 18%, 34%, and 10% of the asenapine at 5 and 10 mg BID, haloperidol, and placebo groups, respectively. Across all groups, no more than 5% of patients had clinically significant weight change. Post hoc analyses indicated that efficacy was similar with asenapine and haloperidol; greater contrasts were seen in AEs, especially extrapyramidal symptoms.

No evidence for switching the antidepressant: systematic review and meta-analysis of RCTs of a common therapeutic strategy

OBJECTIVE

Switching antidepressants is a common strategy for managing treatment-resistant depressed patients. However, no systematic reviews have been conducted to date.

METHOD

We systematically searched MEDLINE/EMBASE/Cochrane Central Register of Controlled Trials and additional sources. We included double-blind studies of patients with depressive symptomatology who were not responding to initial antidepressant monotherapy and were subsequently randomized to another antidepressant or to continue the same antidepressant. Results were pooled for meta-analysis of response + remission rates using a fixed-effects model.

RESULTS

A total of three studies were included. Switching to another antidepressant was not superior to continuing the initial antidepressant in any of these studies. Our meta-analysis showed no significant advantages to either strategy and no significant heterogeneity of results [OR for response rates: 0.85 (95% CI: 0.55-1.30) favoring continuing].

CONCLUSION

There is a discrepancy between the published evidence and the frequent decision to switch antidepressants, indicating an urgent need for more controlled studies. Pending such studies we recommend that physicians rely on more thoroughly evaluated strategies.

Placebo responses in randomized trials of antiepileptic drugs

This meta-analysis of published, randomized, controlled trials (RCTs) of antiepileptic drugs in adults with focal drug-resistant epilepsy was performed to estimate a mean placebo effect, to evaluate variability in placebo response rates, to investigate associations between placebo effect rates and study characteristics, and to determine whether there were changes in placebo response rates over recent years in RCTs (so-called "placebo drift"). One hundred ninety-eight potentially appropriate studies were identified after MEDLINE search and carefully reviewed. Twenty-seven RCTs (with 5662 randomized patients, including 1887 patients in placebo arms) were included in the meta-analysis. A random effects meta-analytic model estimated the pooled placebo response at 12.5% (95% CI: 10.03-14.94%). A statistically significant correlation between baseline median seizure frequency and placebo response rates was not observed. "Placebo drift" was not considered statistically significant.

Anti-depressants and suicide

Suicide takes the lives of around a million people each year, most of whom suffer from depression. In recent years there has been growing controversy about whether one of the best-selling anti-depressants - selective serotonin reuptake inhibitors (SSRIs) - increases or decreases the risk of completed suicide. Randomized clinical trials are not informative in this application because of small samples and other problems. We present what we believe are the most scientifically credible estimates to date on how SSRI sales affect suicide mortality using data from 26 countries for up to 25 years. We exploit just the variation in SSRI sales that can be explained by institutional differences in how drugs are regulated, priced, and distributed, as reflected by the sales growth of new drugs more generally. We find an increase in SSRI sales of 1 pill per capita (12% of 2000 sales levels) reduces suicide by 5%.

Placebo response of non-pharmacological and pharmacological trials in major depression: a systematic review and meta-analysis

BACKGROUND

Although meta-analyses have shown that placebo responses are large in Major Depressive Disorder (MDD) trials; the placebo response of devices such as repetitive transcranial magnetic stimulation (rTMS) has not been systematically assessed. We proposed to assess placebo responses in two categories of MDD trials: pharmacological (antidepressant drugs) and non-pharmacological (device- rTMS) trials.

METHODOLOGY/PRINCIPAL FINDINGS

We performed a systematic review and meta-analysis of the literature from April 2002 to April 2008, searching MEDLINE, Cochrane, Scielo and CRISP electronic databases and reference lists from retrieved studies and conference abstracts. We used the keywords placebo and depression and escitalopram for pharmacological studies; and transcranial magnetic stimulation and depression and sham for non-pharmacological studies. All randomized, double-blinded, placebo-controlled, parallel articles on major depressive disorder were included. Forty-one studies met our inclusion criteria - 29 in the rTMS arm and 12 in the escitalopram arm. We extracted the mean and standard values of depression scores in the placebo group of each study. Then, we calculated the pooled effect size for escitalopram and rTMS arm separately, using Cohen's d as the measure of effect size. We found that placebo response are large for both escitalopram (Cohen's d - random-effects model - 1.48; 95%C.I. 1.26 to 1.6) and rTMS studies (0.82; 95%C.I. 0.63 to 1). Exploratory analyses show that sham response is associated with refractoriness and with the use of rTMS as an add-on therapy, but not with age, gender and sham method utilized.

CONCLUSIONS/SIGNIFICANCE

We confirmed that placebo response in MDD is large regardless of the intervention and is associated with depression refractoriness and treatment combination (add-on rTMS studies). The magnitude of the placebo response seems to be related with study population and study design rather than the intervention itself.

Treatment of social anxiety with paroxetine: mediation of changes in anxiety and depression symptoms

Investigation of relationship patterns between co-occurring symptoms has greatly improved the efficacy of psychiatric care. Depression and anxiety often present together, and identification of primary vs secondary psychiatric symptoms has implications for treatment. Previous psychotherapy research investigating the relationship between social anxiety and depression, across social anxiety treatment, found that severity of social anxiety accounted for most of the change in depression severity across time. Conversely, severity of depression accounted for little variation in severity of social anxiety. The current investigation was conducted to extend these findings by examining this mediational relationship in a pharmacologic trial comparing paroxetine (n = 20) and placebo (n = 22). Social anxiety and depression severity were assessed weekly for 16 weeks. Consistent with the previous study, results indicated that social anxiety severity mediated most of the variance in depression severity, with little variance accounted for by a test of the reverse mediation. Surprisingly, this same pattern was also found in the placebo group. These findings suggest that this pattern of mediational relationships may be fundamental to social anxiety, rather than specific to treatment modality or secondary comorbidity.

Comparison of data analysis strategies for intent-to-treat analysis in pre-test-post-test designs with substantial dropout rates

The pre-test-post-test design (PPD) is predominant in trials of psychotherapeutic treatments. Missing data due to withdrawals present an even bigger challenge in assessing treatment effectiveness under the PPD than under designs with more observations since dropout implies an absence of information about response to treatment. When confronted with missing data, often it is reasonable to assume that the mechanism underlying missingness is related to observed but not to unobserved outcomes (missing at random, MAR). Previous simulation and theoretical studies have shown that, under MAR, modern techniques such as maximum-likelihood (ML) based methods and multiple imputation (MI) can be used to produce unbiased estimates of treatment effects. In practice, however, ad hoc methods such as last observation carried forward (LOCF) imputation and complete-case (CC) analysis continue to be used. In order to better understand the behaviour of these methods in the PPD, we compare the performance of traditional approaches (LOCF, CC) and theoretically sound techniques (MI, ML), under various MAR mechanisms. We show that the LOCF method is seriously biased and conclude that its use should be abandoned. Complete-case analysis produces unbiased estimates only when the dropout mechanism does not depend on pre-test values even when dropout is related to fixed covariates including treatment group (covariate-dependent: CD). However, CC analysis is generally biased under MAR. The magnitude of the bias is largest when the correlation of post- and pre-test is relatively low.

Escitalopram administered in the luteal phase exerts a marked and dose-dependent effect in premenstrual dysphoric disorder

This is the first placebo-controlled trial evaluating the efficacy of the selective serotonin reuptake inhibitor (SSRI), escitalopram, in the treatment of premenstrual dysphoric disorder (PMDD). Women with PMDD (intention-to-treat population, n = 151) were treated intermittently for 3 months, during luteal phases only, with 10 mg/d escitalopram, 20 mg/d escitalopram, or placebo. Escitalopram was found to exert a marked and a dose-dependent symptom-reducing effect, 20 mg/d being clearly superior to 10 mg/d. Although the primary outcome parameter, that is, the sum of the symptoms irritability, depressed mood, tension, and affective lability, was decreased by 90% with 20 mg/d escitalopram, the effect of active treatment on breast tenderness, food craving, and lack of energy was more modest and not significantly different from that of placebo; this outcome supports our previous assumption that the former symptoms are more inclined to respond to intermittent administration of an SSRI than are the latter. Although the placebo response was high, the difference between the placebo group and the 20-mg/d escitalopram group with respect to the percentage of subjects displaying 80% or greater reduction in the rating of the cardinal symptom of PMDD, that is, irritability, was considerable: 30% versus 80%. Adverse events were those normally reported in SSRI trials, such as nausea and reduced libido, and were not more common in patients given 20 mg/d of escitalopram than in patients given the lower dose. This study supports the usefulness of escitalopram for the treatment of PMDD and sheds further light on how different components of this syndrome are differently influenced by intermittent administration of an SSRI.

Lamotrigine in the acute treatment of bipolar depression: results of five double-blind, placebo-controlled clinical trials

OBJECTIVES

The efficacy of lamotrigine as maintenance treatment for bipolar disorder (BD), particularly for delaying depressive episodes, is well established, but its efficacy in the acute treatment of bipolar depression is less clear. This paper reports the results of five randomized, double-blind, placebo-controlled trials of lamotrigine monotherapy for the acute treatment of bipolar depression.

METHODS

Adult subjects with bipolar I or II disorder experiencing a depressive episode were randomized to placebo or lamotrigine monotherapy (after titration, at a fixed dose of 50 mg or 200 mg daily in Study 1; a flexible dose of 100-400 mg daily in Study 2; or a fixed dose of 200 mg daily in Studies 3, 4 and 5) for 7-10 weeks.

RESULTS

Lamotrigine did not differ significantly from placebo on primary efficacy endpoints [17-item Hamilton Depression Rating Scale in Studies 1 and 2; Montgomery-Asberg Depression Rating Scale (MADRS) in Studies 3, 4 and 5]. In Study 1, lamotrigine significantly separated from placebo on some secondary measures of efficacy, including the MADRS, the Clinical Global Impressions-Severity (CGI-S) and the CGI-Improvement (CGI-I), but seldom differed on secondary efficacy endpoints for the other studies.

CONCLUSIONS

Lamotrigine monotherapy did not demonstrate efficacy in the acute treatment of bipolar depression in four out of five placebo-controlled clinical studies. Lamotrigine was well tolerated in the acute treatment of bipolar depression.

Creatine monohydrate in resistant depression: a preliminary study

OBJECTIVES

Creatine plays a pivotal role in brain energy homeostasis, and altered cerebral energy metabolism may be involved in the pathophysiology of depression. Oral creatine supplementation may modify brain high-energy phosphate metabolism in depressed subjects.

METHODS

Eight unipolar and two bipolar patients with treatment-resistant depression were treated for four weeks with 3-5 g/day of creatine monohydrate in an open add-on design. Outcome measures were the Hamilton Depression Rating Scale, Hamilton Anxiety Scale, and Clinical Global Impression scores, recorded at baseline and at weeks 1, 2, 3 and 4.

RESULTS

One patient improved considerably after one week and withdrew. Both bipolar patients developed hypomania/mania. For the remaining seven patients, all scale scores significantly improved. Adverse reactions were mild and transitory.

CONCLUSIONS

This small, preliminary, open study of creatine monohydrate suggests a beneficial effect of creatine augmentation in unipolar depression, but possible precipitation of a manic switch in bipolar depression.

Bupropion in the treatment of pathological gambling: a randomized, double-blind, placebo-controlled, flexible-dose study

We tested the efficacy of bupropion in the treatment of persons with pathological gambling (PG). Nondepressed, healthy subjects with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition PG were randomly assigned to placebo or flexibly dosed bupropion in a 12-week double-blind trial. Outcome measures included the Yale-Brown Obsessive-Compulsive Scale modified for PG, the Gambling Severity Assessment Scale, the Clinical Global Impression Improvement and Severity Scales, the Global Assessment Scale, the Timeline Follow Back, the Attention-Deficit/Hyperactivity Disorder Rating Scale, and the Sheehan Disability Scale. Thirty-nine subjects (28 men, 11 women) were randomized to bupropion (n = 18) or placebo (n = 21). The 2 groups were similar on demographic and clinical measures. There were few differences between the treatment groups on any primary or secondary outcome measure, although subjects in each cell experienced significant improvement. Of subjects with at least 1 postrandomization visit, 35.7% of bupropion and 47.1% of placebo recipients experienced "much" or "very much" improvement on the Clinical Global Impression Improvement Scale. The trial was complicated by a high noncompletion rate (43.6%). Bupropion was well tolerated. Bupropion and placebo recipients did equally well in a short-term trial, with improvement seen as early as the first week of treatment. The high placebo response rate and the high noncompletion rate each reflect the challenge inherent in treating persons with PG.

Placebo response and antidepressant response

OBJECTIVE

Much of the response to an antidepressant is the result of placebo response. The placebo response embedded in drug response confounds studies seeking to identify brain mechanisms essential for pharmacologic response. Exclusion of patients who fail to meet entry criteria at the end of a placebo lead-in phase has been inadequate to reduce the effect of placebo during pharmacologic trials. This study focused on the placebo lead-in phase and examines whether change in severity of depression during placebo lead-in predicts change in depressive symptoms during antidepressant treatment.

METHOD

The subjects were patients aged 60-85 years with nonpsychotic unipolar major depression not attributed to dementing disorders, medical illnesses, or drugs causing depression and had a 24-item Hamilton Depression Rating Scale score of 18 or greater. After a two-week placebo lead-in, subjects with Hamilton Depression Rating Scale score of 18 or greater received 10 mg escitalopram for 12 weeks.

RESULTS

Worsening or limited change in depression during placebo treatment predicted improvement in depressive symptoms during escitalopram treatment. Limited change in anxiety, melancholia, helplessness, and paranoia during placebo treatment were the strongest predictors of improvement in depression while on escitalopram.

CONCLUSIONS

These findings, if replicated, may be used to characterize depressed older patients likely to respond to the pharmacologic action of antidepressants rather than the placebo response embedded in drug trials and thus improve the methodology of biomarker studies of antidepressant response. On a clinical level, depressed older patients who improve during a prolonged evaluation may be candidates for nonpharmacologic treatments because their drug response may be limited.

The efficacy of selective serotonin reuptake inhibitors in adult social anxiety disorder: a meta-analysis of double-blind, placebo-controlled trials

Social anxiety disorder is associated with impairment in social and occupational functioning, significant personal distress and a possible economic burden, resulting in a reduction in quality of life. To understand better the efficacy of selective serotonin reuptake inhibitors in social anxiety disorder, randomized, double-blind, placebo-controlled trials were evaluated. Pubmed and PsychINFO electronic databases were searched for social anxiety disorder, social phobia, selective serotonin reuptake inhibitors, citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine and sertraline. Fifteen published, randomized, double-blind, placebo-controlled trials of selective serotonin reuptake inhibitors in social anxiety disorder were identified. Design, subject number, drug and dose, trial length, rating instruments, and baseline and end point data were extracted and then verified independently by a second investigator. Effect sizes were calculated from mean changes in drug and placebo groups in the Liebowitz Social Anxiety Scale and the Sheehan Disability Scale, as well as from other scales where available. For the binary data of the Clinical Global Impression of Change scores, Theta log-odds ratios (the effect-size measure appropriate for binary data) were calculated from proportion changes. Effect sizes for the Liebowitz Social Anxiety Scale ranged from -0.029 to 1.214. Effect sizes for the Sheehan Disability Scale ranged from 0.203 to 0.480 for work, 0.237 to 0.786 for social function, and 0.118 to 0.445 for family function. The Theta log-odds ratios for Clinical Global Impression of Change scores ranged from 0.644 to 3.267. Consistent with previous studies, selective serotonin reuptake inhibitors appear more effective than placebo for social anxiety disorder, with improvement extending into social and occupational function.

Effect of personality type on pharmacodynamics through changing pharmacokinetics

A few studies have showed that there is an association between the genetic polymorphisms of drug-metabolizing enzyme, CYP2D6, to persons with different personality type. More and more evidences suggested that personality type is kind of behavioral or psychological factor which might influence the pharmacodynamics as well as patient's gender, age, disease, and genetic background. We hypothesized that personality affect the pharmacodynamics through changing pharmacokinetic mediated by different polymorphism of drug-metabolizing enzymes. Since many major diseases, from cancer to infectious disease, are involved with risky Type A personality, we appeal for attention to the clinical pharmacologist and psychiatrists further to study personality pharmacokinetics for individualized medicine.

Mifepristone versus placebo in the treatment of psychosis in patients with psychotic major depression

BACKGROUND

Abnormalities in the hypothalamic pituitary adrenal axis have been implicated in the pathophysiology of psychotic major depression (PMD). Recent studies have suggested that the antiglucocorticoid, mifepristone might have a role in the treatment of PMD. The current study tested the efficacy of mifepristone treatment of the psychotic symptoms of PMD.

METHODS

221 patients, aged 19 to 75 years, who met DSM-IV and SCID criteria for PMD and were not receiving antidepressants or antipsychotics, participated in a double blind, randomized, placebo controlled study. Patients were randomly assigned to either 7 days of mifepristone (n = 105) or placebo (n = 116) followed by 21 days of usual treatment.

RESULTS

Patients treated with mifepristone were significantly more likely to achieve response, defined as a 30% reduction in the Brief Psychiatric Rating Scale (BPRS). In addition, mifepristone treated patients were significantly more likely to achieve a 50% reduction in the BPRS Positive Symptom Scale (PSS). No significant differences were observed on measures of depression.

CONCLUSION

A seven day course of mifepristone followed by usual treatment appears to be effective and well tolerated in the treatment of psychosis in PMD. This study suggests that the antiglucocorticoid, mifepristone, might represent an alternative to traditional treatments of psychosis in psychotic depression.

New developments in antidepressant therapy

Depression is an overwhelmingly common problem in the United States. It is not only life threatening, but also costly, both personally and financially. Following a brief overview of depression, this article presents a variety of treatment modalities. Advantages and dis-advantages of each intervention are explored along with suggestions for evaluating current and future advances in treatment options.