Magnitude of the Placebo Response Across Treatment Modalities Used for Treatment-Resistant Depression in Adults: A Systematic Review and Meta-analysis

Effect of Minocycline on Depressive Symptoms in Patients With Treatment-Resistant Depression: A Randomized Clinical Trial

IMPORTANCE

Insufficient treatment response and resulting chronicity constitute a major problem in depressive disorders. Remission rates range as low as 15% to 40% and treatment-resistant depression (TRD) is associated with low-grade inflammation, suggesting anti-inflammatory interventions as a rational treatment strategy. Minocycline, which inhibits microglial activation, represents a promising repurposing candidate in the treatment of TRD.

OBJECTIVE

To determine whether 6 weeks of minocycline as add-on to antidepressant treatment as usual can significantly reduce depressive symptoms in patients with TRD.

DESIGN, SETTING, AND PARTICIPANTS

The study was conducted in Germany and designed as a multicenter double-blind randomized clinical trial (RCT) of 200 mg/d minocycline treatment over a course of 6 weeks with a 6-month follow-up. Participants were recruited from January 2016 to August 2020 at 9 university hospitals that served as study sites. Key inclusion criteria were a diagnosis of major depressive disorder (according to Diagnostic and Statistical Manual of Mental Disorders [Fifth Edition] criteria), severity of depressive symptoms on the Hamilton Depression Rating Scale (HAMD-17) greater than or equal to 16 points, aged 18 to 75 years, body mass index 18 to 40, Clinical Global Impression Scale (CGI-S) greater than or equal to 4, failure to adequately respond to an initial antidepressant standard medication as per Massachusetts General Hospital Antidepressant Treatment History Questionnaire, and stable medication for at least 2 weeks. A total of 258 patients were screened, of whom 173 were randomized and 168 were included into the intention-to-treat population. Statistical analysis was performed from April to November 2020.

INTERVENTIONS

Participants were randomized (1:1) to receive adjunct minocycline (200 mg/d) or placebo for 6 weeks.

MAIN OUTCOMES AND MEASURES

Primary outcome measure was the change in Montgomery-Åsberg Depression Rating Scale (MADRS) score from baseline to week 6 analyzed by intention-to-treat mixed model repeated measures. Secondary outcome measures were response, remission, and various other clinical rating scales.

RESULTS

Of 173 eligible and randomized participants (84 randomized to minocycline and 89 randomized to placebo), 168 formed the intention-to-treat sample (79 [47.0%] were women, 89 [53.0%] were men, 159 [94.6%] were White, 9 [6.4%] were of other race and ethnicity, including Asian and unknown ethnicity), with 81 in the minocycline group and 87 in the placebo group. The mean (SD) age was 46.1 (13.1) years, and the mean (SD) MADRS score at baseline was 26.5 (5.0). There was no difference in rates of completion between the minocycline (83.3% [70 of 81]) and the placebo group (83.1% [74 of 87]). Minocycline treatment did not alter the course of depression severity compared with placebo as assessed by a decrease in MADRS scores over 6 weeks of treatment (1.46 [-1.04 to 3.96], P = .25). Minocycline treatment also exhibited no statistically significant effect on secondary outcomes.

CONCLUSIONS AND RELEVANCE

In this large randomized clinical trial with minocycline at a dose of 200 mg/d added to antidepressant treatment as usual for 6 weeks, minocycline was well tolerated but not superior to placebo in reducing depressive symptoms in patients with TRD. The results of this RCT emphasize the unmet need for therapeutic approaches and predictive biomarkers in TRD.

TRIAL REGISTRATION

EU Clinical Trials Register Number: EudraCT 2015-001456-29.

Placebo: a brief updated review

Our aims were to provide updated information on placebo/nocebo effect and the potential use of placebo in clinical practice. This article can only provide a rough overview on the placebo and nocebo effect and is intended to serve as a starting point for the reader to go deeper into the corresponding literature. The placebo effect has been observed in multiple medical conditions, after oral administration, with manual therapies as well as with surgery and invasive procedures. The use of placebo in clinical trials is fundamental, although the ethics of its use is under discussion. The placebo may behave like a drug from the pharmacokinetic and pharmacodynamic point of view and can also be associated with adverse events (nocebo effect). Placebo can modify treatment by increasing or decreasing the effects of drugs. The factors associated with the occurrence of placebo effect are multiple, but in addition to those that depend on the placebo itself, the doctor-patient relationship would be the most important. As a result of findings that were published in the last two decades, the psycho-neurobiological basis of placebo is becoming better understood, although further studies are needed. In conclusion, the placebo effect in the clinic exhibits weak to moderate intensity. Placebo, in addition to its use in the clinical trial, should be considered another therapeutic remedy either as stand alone or in association with treatment, and could be useful in certain circumstances. The use of placebo should be regulated by the European health authorities through a guide in clinical practice that will improve patient care.

Large multicenter randomized trials in autism: key insights gained from the balovaptan clinical development program

BACKGROUND

Autism spectrum disorder (ASD) is a common and heterogeneous neurodevelopmental condition that is characterized by the core symptoms of social communication difficulties and restricted and repetitive behaviors. At present, there is an unmet medical need for therapies to ameliorate these core symptoms in order to improve quality of life of autistic individuals. However, several challenges are currently faced by the ASD community relating to the development of pharmacotherapies, namely in the conduct of clinical trials. Balovaptan is a V1a receptor antagonist that has been investigated to improve social communication difficulties in individuals with ASD. In this viewpoint, we draw upon our recent first-hand experiences of the balovaptan clinical development program to describe current challenges of ASD trials.

DISCUSSION POINTS

The balovaptan trials were conducted in a wide age range of individuals with ASD with the added complexities associated with international trials. When summarizing all three randomized trials of balovaptan, a placebo response was observed across several outcome measures. Placebo response was predicted by greater baseline symptom severity, online recruitment of participants, and less experienced or non-academic trial sites. We also highlight challenges relating to selection of outcome measures in ASD, the impact of baseline characteristics, and the role of expectation bias in influencing trial results.

CONCLUSION

Taken together, the balovaptan clinical development program has advanced our understanding of the key challenges facing ASD treatment research. The insights gained can be used to inform and improve the design of future clinical trials with the collective aim of developing efficacious therapies to support individuals with ASD.

Great Expectations: recommendations for improving the methodological rigor of psychedelic clinical trials

RATIONALE

Psychedelic research continues to garner significant public and scientific interest with a growing number of clinical studies examining a wide range of conditions and disorders. However, expectancy effects and effective condition masking have been raised as critical limitations to the interpretability of the research.

OBJECTIVE

In this article, we review the many methodological challenges of conducting psychedelic clinical trials and provide recommendations for improving the rigor of future research.

RESULTS

Although some challenges are shared with psychotherapy and pharmacology trials more broadly, psychedelic clinical trials have to contend with several unique sources of potential bias. The subjective effects of a high-dose psychedelic are often so pronounced that it is difficult to mask participants to their treatment condition; the significant hype from positive media coverage on the clinical potential of psychedelics influences participants' expectations for treatment benefit; and participant unmasking and treatment expectations can interact in such a way that makes psychedelic therapy highly susceptible to large placebo and nocebo effects. Specific recommendations to increase the success of masking procedures and reduce the influence of participant expectancies are discussed in the context of study development, participant recruitment and selection, incomplete disclosure of the study design, choice of active placebo condition, as well as the measurement of participant expectations and masking efficacy.

CONCLUSION

Incorporating the recommended design elements is intended to reduce the risk of bias in psychedelic clinical trials and thereby increases the ability to discern treatment-specific effects of psychedelic therapy.

Dorsomedial prefrontal rTMS for depression in borderline personality disorder: A pilot randomized crossover trial

BACKGROUND

Recently, a small literature has emerged suggesting that repetitive transcranial magnetic stimulation (rTMS) may offer benefit for MDD even in BPD patients, perhaps by enhancing cognitive control, and/or disrupting excessive 'non-reward' activity in right orbitofrontal regions. This study aimed primarily to assess the therapeutic effects of dorsomedial prefrontal cortex (DMPFC)-rTMS against MDD symptoms in BPD patients, and secondarily to assess whether the therapeutic effects ensued via mechanisms of reduced impulsivity and core BPD pathology on clinical scales (BIS-11, ZAN-BPD) or of reduced alpha- and theta-band activity on EEG recordings of right orbitofrontal cortex..

METHODS

In a crossover-design trial, 20 BPD patients with MDD underwent 2 × 30 session/15 day blocks of either active-then-sham or sham-then-active bilateral 20 Hz DMPFC-rTMS.

RESULTS

Sixteen out of 20 patients completed treatment. A significant (p = 0.00764) crossover effect was detected, with overall reductions in HamD17 score from 23.1±SD3.1 to 10.75±SD5.8. Nine out of 16 (56.3%) treatment completers achieved response (>50% improvement) and 6/16 (37.5%) achieved remission (HamD≤7), maintained at 1 month followup. BIS-11 scores remained unchanged, and ZAN-BPD scores improved similarly in both groups with no significant crossover effect. Change in low-band power over right orbitofrontal regions correlated with clinical improvement.

LIMITATIONS

This was a crossover study with a small sample size. A randomized controlled trial with larger sample size will be needed to establish the efficacy more definitively.

CONCLUSIONS

The results suggest efficacy for DMPFC-rTMS in treating MDD in BPD, and provide a foundation for a larger future trial.

What is the role of placebo in neurotherapeutics?

INTRODUCTION

The widespread use of the word 'placebo' in the medical literature emphasizes the importance of this phenomenon in modern biomedical sciences. Neuroscientific research over the past thirty years shows that placebo effects are genuine psychobiological events attributable to the overall therapeutic context, and can be robust in both laboratory and clinical settings.

AREAS COVERED

Here the authors describe the biological mechanisms and the clinical implications of placebo effects with particular emphasis on neurology and psychiatry, for example in pain, movement disorders, depression. In these conditions, a number of endogenous systems have been identified, such as endogenous opioids, endocannabinoids, and dopamine, which contribute to the placebo-induced benefit.

EXPERT OPINION

Every effort should be made to maximize the placebo effect and reduce its evil twin, the nocebo effect, in medical practice. This does not require the administration of a placebo, but rather the enhancement of the effects of pharmacological and nonpharmacological treatments through a good doctor-patient interaction.