Effect of next-step antidepressant treatment on suicidal ideation: findings from the VAST-D trial.

BACKGROUND: Major depressive disorder (MDD) contributes to suicide risk. Treating MDD effectively is considered a key suicide prevention intervention. Yet many patients with MDD do not respond to their initial medication and require a 'next-step'. The relationship between next-step treatments and suicidal thoughts and behaviors is uncharted. METHOD: The VA Augmentation and Switching Treatments for Depression trial randomized 1522 participants to one of three next-step treatments: Switching to Bupropion, combining with Bupropion, and augmenting with Aripiprazole. In this secondary analysis, features associated with lifetime suicidal ideation (SI) and attempts (SA) at baseline and current SI during treatment were explored. RESULTS: Compared to those with SI only, those with lifetime SI + SA were more likely to be female, divorced, or separated, unemployed; and to have experienced more childhood adversity. They had a more severe depressive episode and were more likely to respond to 'next-step' treatment. The prevalence of SI decreased from 46.5% (694/1492) at baseline to 21.1% (315/1492) at end-of-treatment. SI during treatment was associated with baseline SI; low positive mental health, more anxiety, greater severity and longer duration of current MDD episode; being male and White; and treatment with S-BUP or C-BUP as compared to A-ARI. CONCLUSION: SI declines for most patients during next-step medication treatments. But about 1 in 5 experienced emergent or worsening SI during treatment, so vigilance for suicide risk through the entire 12-week acute treatment period is necessary. Treatment selection may affect the risk of SI.

A revisionist model for treatment-resistant and difficult-to-treat depression.

OBJECTIVE: The aim of this study is to consider limitations to the heuristics 'treatment-resistant depression' (TRD) and 'difficult-to-treat' depression (DTD) and to offer a revisionist model. METHODS: A number of limitations to the two constructs are noted, particularly the risk of each positioning clinical depression as an entity and then applying a linear sequencing management model. RESULTS: Arguing that clinical depression is heterogenous in nature (with categorical and 'fuzzy set conditions), in cause and in response to treatment, allows an alternate model for addressing depressive conditions that are not readily responsive to treatment. A skeletal model for proceeding is offered for consideration and development. CONCLUSION: If such a model is accepted, then differing criteria for defining treatment resistance and treatment failure might be generated for differing depressive conditions, and condition-specific sequencing algorithms (embracing drug and non-drug strategies) developed for their management.

Alternative metrics for characterizing longer-term clinical outcomes in difficult-to-treat depression: II. Sensitivity to treatment effects.

OBJECTIVE: Characteristics of difficult-to-treat depression (DTD), including infrequent symptom remission and poor durability of benefit, compel reconsideration of the outcome metrics historically used to gauge the effectiveness of antidepressant interventions. METHODS: Self-report and clinician assessments of depression symptom severity were obtained regularly over a 2-year period in a difficult-to-treat depression registry sample receiving treatment as usual (TAU), with or without vagus nerve stimulation (VNS). Alternative outcome metrics for characterizing symptom change were compared in effect size and discriminating power in distinguishing the vagus nerve stimulation + treatment as usual and treatment as usual treatment groups. We expected metrics based on remission status to produce weaker between-group separation than those based on the classifications of partial response or response and metrics that integrate information over time to produce greater separation than those based on single endpoint assessment. RESULTS: Metrics based on remission status had smaller effect size and poorer discrimination in separating the treatment groups than metrics based on partial response or response classifications. Metrics that integrated information over the 2-year observation period had stronger performance characteristics than those based on symptom scores at single endpoint assessment. For both the clinician-rated and self-report depression ratings, the metrics with the strongest performance characteristics were the median percentage change in symptom scores over the observation period and the proportion of the observation period in partial response or better. CONCLUSION: In difficult-to-treat depression, integrative symptom severity-based and time-based measures are sensitive and informative outcomes for assessing between-group treatment effects, while metrics based on remission status are not.

Combination of Acute and Maintenance Esketamine Treatment With Adjunctive Long-Term Vagus Nerve Stimulation in Difficult-to-Treat Depression.

INTRODUCTION: The antidepressant effect of N-methyl-D-aspartate antagonists is often short lasting, raising the question of the best maintenance strategy, which has remained unanswered. Vagus nerve stimulation (VNS) as a treatment option for refractory and chronic major depression was shown to reduce the need for maintenance treatment sessions in patients receiving electroconvulsive therapy. To our knowledge, there are no published data on the combination of VNS and esketamine in the literature. MATERIALS AND METHODS: This is a naturalistic prospective and retrospective observational study in patients treated with long-term VNS owing to difficult-to-treat depression. These patients also have received esketamine maintenance sessions in addition to short-term treatment. We have investigated the need for maintenance esketamine sessions per month after VNS implantation (number of sessions/number of months between visits), the change in depression severity (mean Montgomery-Asberg Depression Rating Scale [MADRS] score), and the number of hospitalizations per month (number of hospitalizations/number of postoperative observation months). Follow-up visits have been scheduled every three months after VNS implantation (follow-up period 12-24 months, mean 17). RESULTS: All patients (n = 8, mean age 53.1 years) had severe difficult-to-treat depression (DTD) (mean MADRS at baseline 30.9). Mean number of hospitalizations per month decreased from 0.17 to 0.11 after VNS implantation (p = 0.041, T = 2.030, df = 7). Mean MADRS at 12 months was 18.3 (40.8% MADRS reduction, p = 0.008, T = 3.146, df = 7). Six of eight patients were offered maintenance esketamine treatment. Mean number of esketamine treatment sessions per month and case decreased from 2.3 at the six-month visit to 0.8 at 12 months (p = 0.076, T = 1,690, df = 5) after VNS implantation. Termination of maintenance esketamine was possible in four cases after a mean of 11.5 months. CONCLUSIONS: Combination of esketamine and VNS was effective in patients with DTD to relieve disease severity and reduce hospitalizations. The need for esketamine treatment sessions decreased after 6 months of VNS. No safety concerns arose in this study regarding the combination treatment. CLINICAL TRIAL REGISTRATION: The Clinicaltrials.gov registration number for the study is NCT03320304.

Long-Term Immunomodulatory Impact of VNS on Peripheral Cytokine Profiles and Its Relationship with Clinical Response in Difficult-to-Treat Depression (DTD).

Vagus nerve stimulation (VNS) represents a long-term adjunctive treatment option in patients with difficult-to-treat depression (DTD). Anti-inflammatory effects have been discussed as a key mechanism of action of VNS. However, long-term investigations in real-world patients are sparse. In this naturalistic observational study, we collected data on cytokines in peripheral blood in n = 6 patients (mean age 47.8) with DTD and VNS treatment at baseline and at 6 months follow-up. We have identified clusters of peripheral cytokines with a similar dynamic over the course of these 6 months using hierarchical clustering. We have investigated cytokine changes from baseline to 6 months as well as the relationship between the cytokine profile at 6 months and long-term response at 12 months. After 6 months of VNS, we observed significant correlations between cytokines (p < 0.05) within the identified three cytokine-pairs which were not present at baseline: IL(interleukin)-6 and IL-8; IL-1ß and TNF-α; IFN-α2 and IL-33. At 6 months, the levels of all the cytokines of interest had decreased (increased in non-responders) and were lower (5-534 fold) in responders to VNS than in non-responders: however, these results were not statistically significant. VNS-associated immunomodulation might play a role in long-term clinical response to VNS.

Alternative metrics for characterizing longer-term clinical outcomes in difficult-to-treat depression: I. Association with change in quality of life.

BACKGROUND: In difficult-to-treat depression (DTD) the outcome metrics historically used to evaluate treatment effectiveness may be suboptimal. Metrics based on remission status and on single end-point (SEP) assessment may be problematic given infrequent symptom remission, temporal instability, and poor durability of benefit in DTD. METHODS: Self-report and clinician assessment of depression symptom severity were regularly obtained over a 2-year period in a chronic and highly treatment-resistant registry sample (N = 406) receiving treatment as usual, with or without vagus nerve stimulation. Twenty alternative metrics for characterizing symptomatic improvement were evaluated, contrasting SEP metrics with integrative (INT) metrics that aggregated information over time. Metrics were compared in effect size and discriminating power when contrasting groups that did (N = 153) and did not (N = 253) achieve a threshold level of improvement in end-point quality-of-life (QoL) scores, and in their association with continuous QoL scores. RESULTS: Metrics based on remission status had smaller effect size and poorer discrimination of the binary QoL outcome and weaker associations with the continuous end-point QoL scores than metrics based on partial response or response. The metrics with the strongest performance characteristics were the SEP measure of percentage change in symptom severity and the INT metric quantifying the proportion of the observation period in partial response or better. Both metrics contributed independent variance when predicting end-point QoL scores. CONCLUSIONS: Revision is needed in the metrics used to quantify symptomatic change in DTD with consideration of INT time-based measures as primary or secondary outcomes. Metrics based on remission status may not be useful.

Clinical research challenges posed by difficult-to-treat depression.

Approximately one-third of individuals in a major depressive episode will not achieve sustained remission despite multiple, well-delivered treatments. These patients experience prolonged suffering and disproportionately utilize mental and general health care resources. The recently proposed clinical heuristic of 'difficult-to-treat depression' (DTD) aims to broaden our understanding and focus attention on the identification, clinical management, treatment selection, and outcomes of such individuals. Clinical trial methodologies developed to detect short-term therapeutic effects in treatment-responsive populations may not be appropriate in DTD. This report reviews three essential challenges for clinical intervention research in DTD: (1) how to define and subtype this heterogeneous group of patients; (2) how, when, and by what methods to select, acquire, compile, and interpret clinically meaningful outcome metrics; and (3) how to choose among alternative clinical trial design options to promote causal inference and generalizability. The boundaries of DTD are uncertain, and an evidence-based taxonomy and reliable assessment tools are preconditions for clinical research and subtyping. Traditional outcome metrics in treatment-responsive depression may not apply to DTD, as they largely reflect the only short-term symptomatic change and do not incorporate durability of benefit, side effect burden, or sustained impact on quality of life or daily function. The trial methodology will also require modification as trials will likely be of longer duration to examine the sustained impact, raising complex issues regarding control group selection, blinding and its integrity, and concomitant treatments.

Setting Up a Successful Vagus Nerve Stimulation Service for Patients With Difficult-to-Treat Depression.

BACKGROUND: A substantial number of patients with major depressive disorder (MDD) do not sufficiently remit after the first lines of antidepressant treatments, making them vulnerable to poor clinical outcomes. Patients who have not had adequate resolution of their depressive symptoms after four antidepressant treatments and/or have been experiencing their current episode of MDD for two years or more (with insufficient responses to adequate antidepressant treatments) should be evaluated for antidepressant vagus nerve stimulation (VNS Therapy). Adjunctive VNS Therapy is a promising long-term treatment option for patients with difficult-to-treat depression (DTD), offering significantly improved remission rates in comparison with usual treatments. However, VNS Therapy requires specialized treatment centers to support patients. MATERIALS AND METHODS: In this narrative review, we aim to outline the necessary steps for setting up an antidepressant VNS Therapy service in an efficient manner. RESULTS: Establishing a VNS Therapy service requires several high-level considerations: initiation of a collaborative multidisciplinary team of health care professionals; developing a surgical pathway for implantation; consideration of reimbursement and health care coverage; setting up a specialist clinic to identify optimal candidates for VNS Therapy; educating patients and their families about VNS Therapy; and training health care providers on patient-specific VNS Therapy treatment and long-term treatment management. CONCLUSIONS: Antidepressant VNS Therapy is a promising treatment option for the long-term treatment of patients with DTD. We have successfully initiated four VNS Therapy service centers for DTD in the United States, Austria, and Germany. Based on our experiences and lessons learned, herein, we have provided advice to psychiatric centers planning to set up a VNS Therapy service for their patients with DTD.

The Downstaging Concept in Treatment-Resistant Depression: Spotlight on Ketamine.

Treatment-resistant depression is a pleomorphic phenomenon occurring in 30% of patients with depression. The chance to achieve remission decreases with every subsequent episode. It constitutes a significant part of the global disease burden, causes increased morbidity and mortality, and is associated with poor quality of life. It involves multiple difficult-to-treat episodes, with increasing resistance over time. The concept of staging captures the process of changes causing increasing treatment resistance and global worsening of functioning in all areas of life. Ketamine is a novel rapid-acting antidepressant with neuroplastic potential. Here, we argue that ketamine use as an add-on treatment of resistant major depressive disorder, based on its unique pharmacological properties, can reverse this process, give hope to patients, and prevent therapeutic nihilism.

Vagus nerve stimulation as adjunctive therapy in patients with difficult-to-treat depression (RESTORE-LIFE): study protocol design and rationale of a real-world post-market study.

BACKGROUND: Depressive illness is associated with significant adverse consequences for patients and their families, and for society. Clinical challenges are encountered in the management of patients suffering from depression whether they are designated difficult-to-treat or treatment-resistant. Prospective serial depression treatment trials have shown that less than 40% of patients with major depressive disorder remit with an initial pharmacotherapy trial, and a progressively smaller proportion of patients remit with each subsequent trial. For patients who suffer from difficult-to-treat depression (DTD), treatments should focus on patient-centred symptom control, patient functioning, and improving patient quality of life. Among the treatment options for patients with DTD is Vagus Nerve Stimulation (VNS) Therapy. VNS Therapy involves intermittent electrical stimulation of the left cervical vagus nerve and has been shown to be efficacious for long-term management of patients with DTD. METHODS: RESTORE-LIFE is a prospective, observational, multi-site, global post-market study intended to assess short-, mid-, and long-term effectiveness and efficiency outcomes in a 'real-world' setting among patients with DTD treated with adjunctive VNS Therapy. A minimum of 500 patients will be implanted with a VNS Therapy System at up to 80 global sites. Eligible patients will participate in a baseline visit between 1 and 6 weeks before device implant and will be followed for a minimum of 36 months and a maximum of 60 months. The diagnosis of depression and comorbid disorders will be determined using the Mini-International Neuropsychiatric Interview (MINI). The primary endpoint is response rate, defined as a decrease of ≥50% in Montgomery Åsberg Depression Rating Scale (MADRS) total score from baseline to 12 months post-implant. DISCUSSION: A standardized approach in the management of DTD may not be appropriate for the treatment of such a complex heterogenous patient population. This study has been designed to evaluate whether VNS Therapy meaningfully improves and sustains clinical and depressive symptom outcomes in patients with DTD. This study will investigate the durability of VNS response in DTD and utility of VNS for long-term disease management of DTD. In addition, the study results will potentially clarify clinical, functional, and health economic questions in a real-world patient population with DTD. TRIAL REGISTRATION: ClinicalTrials.gov NCT03320304. Registered 25 October 2017.

Difficult-to-treat depression: A clinical and research roadmap for when remission is elusive.

OBJECTIVES: The report considers the pros and cons of the most commonly used conceptual model that forms the basis for most clinical practice guidelines for depression. This model promotes the attainment of sustained symptom remission as the treatment goal based on its well-established prognostic and functional importance. Sustained remission is very unlikely, however, after multiple treatment attempts. Our current model propels many clinicians to continue to change or add treatments despite little chance for remission or full functional restoration and despite the increasing risk of more adverse events from polypharmacy. An alternative 'difficult-to-treat depression' model is presented and considered. It accepts that the treatment aims for some depressed patients may shift to optimal symptom control rather than remission. When difficult-to-treat depression is suspected, the many treatable causes of persistent depression must be assessed and addressed (given the importance of remission when attainable) before difficult-to-treat depression can be ascribed. The clinical and research implications of the difficult-to-treat depression model are discussed. CONCLUSION: Suspected difficult-to-treat depression provides a practical basis for considering when to conduct a comprehensive evaluation. Once difficult-to-treat depression is confirmed, treatment may better focus on optimal disease management (symptom control and functional improvement).

Impact of Adjunctive VNS on Drug Load, Depression Severity, and Number of Neuromodulatory Maintenance Treatments.

Vagus nerve stimulation (VNS) is a long-term adjunctive treatment option in patients with difficult-to-treat depression (DTD). A total of n = 20 patients (mean age 52.6 years) were included in the multicenter, prospective, observational, naturalistic RESTORE-LIFE study and were treated with adjunctive VNS as an add-on to treatment as usual. Exploratory and secondary outcome parameters from a single center were investigated for this present analysis. The overall mean drug load slightly decreased from 4.5 at baseline to 4.4 at 12 months (Z = -0.534, p = 0.594). The drug load was lower in previous electroconvulsive therapy (ECT) responders than in non-responders. There was a reduction in the mean number of hospitalizations per month after VNS implantation (Z = 1.975, p = 0.048) and a significant decrease in the mean Montgomery Åsberg Depression Rating Scale (MADRS) score from 27.3 at baseline to 15.3 at 12 months (T = 4.230, degree of freedom (df) = 19, p = 0.001). A history of ECT response at baseline was associated with greater improvement in the MADRS score after 12 months of VNS (F = 8.171, p = 0.013). The number of neuromodulatory maintenance treatments decreased during the follow-up period. In summary, there was an alleviation in the burden of illness among DTD patients treated with VNS.

Schema therapy versus treatment as usual for outpatients with difficult-to-treat depression: study protocol for a parallel group randomized clinical trial (DEPRE-ST).

BACKGROUND: About one third of patients with depression are in a condition that can be termed as "difficult-to-treat". Some evidence suggests that difficult-to-treat depression is associated with a higher frequency of childhood trauma and comorbid personality disorders or accentuated features. However, the condition is understudied, and the effects of psychotherapy for difficult-to-treat depression are currently uncertain. The aim of this trial is to investigate the beneficial and harmful effects of 30 sessions of individual schema therapy versus treatment as usual for difficult-to-treat depression in the Danish secondary, public mental health sector. METHODS: In this randomized, multi-centre, parallel-group, superiority clinical trial, 129 outpatients with difficult-to-treat depression will be randomized (1:1) to 30 sessions of individual schema therapy or treatment as usual; in this context mainly group-based, short-term cognitive behaviour or psychodynamic therapy. The primary outcome is the change from baseline in depressive symptoms 12 months after randomization, measured on the observer-rated 6-item Hamilton Rating Scale for Depression. The secondary outcomes are health-related quality of life assessed with the European Quality of Life 5 Dimensions 5 Level Version, functional impairment assessed with the Work and Social Adjustment Scale, psychological wellbeing assessed with the WHO-5 Well-being Index, and negative effects of treatment assessed with the Negative Effects Questionnaire. Exploratory outcomes are improvement on patient self-defined outcomes, personal recovery, anxiety symptoms, anger reactions, metacognitive beliefs about anger, and perseverative negative thinking. Outcomes will be assessed at 6, 12, and 24 months after randomization; the 12-month time-point being the primary time-point of interest. Outcome assessors performing the depression-rating, data managers, statisticians, the data safety and monitoring committee, and conclusion makers for the outcome article will be blinded to treatment allocation and results. To assess cost-effectiveness of the intervention, a health economic analysis will be performed. DISCUSSION: This trial will provide evidence on the beneficial and harmful effects, as well as the cost-effectiveness of schema therapy versus treatment as usual for outpatients with difficult-to-treat depression. The results can potentially improve treatment for a large and understudied patient group. TRIAL REGISTRATION: ClinicalTrials.gov NCT05833087. Registered on 15th April 2023 (approved without prompts for revision on 27th April 2023).

Number needed to treat (NNT) for ketamine and esketamine in adults with treatment-resistant depression: A systematic review and meta-analysis.

BACKGROUND: Ketamine has been established as efficacious in adults living with Treatment-resistant Depression (TRD). Toward providing a quantifiable estimate of the clinical meaningfulness of the therapeutic benefit of ketamine, herein, we conduct a systematic review that aims to report the Number Needed to Treat (NNT) and the Number Needed to Harm (NNH). METHODS: This systematic review searched Embase, Medline/Pubmed, PsycINFO and ClinicalTrials.gov from inception up to October 15th 2023, for placebo-controlled, Randomized Controlled Trials (RCTs) assessing racemic ketamine or esketamine therapy for unipolar TRD. We calculated NNT and NNH for ketamine treatments over various time points. RESULTS: A total of 21 studies with 2042 participants were included. Racemic ketamine treatments had pooled NNTs for response of 7 at 4 h, 3 from one day to one week and 9 for studies at four weeks. Esketamine treatment was found to have a similar efficacy with an NNT of 2 at one day and 11 at four weeks. NNH values indicated low risk for ketamine treatments. LIMITATIONS: Limitations in the data used include the possibility of functional unblinding and selective reporting bias. Moreover, the meta-analysis may have been limited in its precision by including low threshold definitions of treatment resistance (≥ 1 failed antidepressant) and low-dose ketamine treatments. CONCLUSION: Herein, we determined that the NNT for ketamine treatment in adults living with TRD across different intervals of observation was <10. We conclude that the NNTs observed herein are highly clinically meaningful in this difficult to treat disorder.

Personalized Approach in the Management of Difficult-to-Treat and Treatment-Resistant Depression With Second-Generation Antipsychotics: A Delphi Statement.

Background Major depressive disorder (MDD) has many facets including mixed or atypical depression that requires personalized care to improve treatment-related outcomes. Second-generation antipsychotics (SGAs) offer complementary mechanisms for clinical roles in difficult-to-treat depression and treatment-resistant depression cases. Aim/objective To further delineate a consensus on the clinical positioning of SGAs for MDD, mixed, or atypical depression, a Knowledge Attitude Perception (KAP)-mediated Delphi Statement was planned. Material/methods A literature review for the definition, diagnosis, and management of MDD, mixed, and atypical depression as treatment-resistant depression (TRD) or difficult-to-treat depression (DTD) was conducted by a steering committee of academic and clinical experts (n=6) while developing a validated KAP questionnaire. Scientific statements as clinical recommendations were evolved using the Delphi methodology before building a clinical expert consensus with an online survey (n=24). Results Twenty-four psychiatrists highlighted DTD to offer a multidimensional approach to assess treatment strategies involving selective serotonin reuptake inhibitors (SSRIs) or SGAs, while ensuring symptom, functional, and quality of life (QoL) domain improvement for improved outcomes and remission rates. MDD cases with anxiety, anhedonia, comorbidities, and risk traits require personalized care with early induction of SGAs for severe cases or symptom persisters with functional impairment. Early augmentation with SGAs including aripiprazole or cariprazine can provide a favorable risk-benefit profile for clinical cases of MDD with or without the antecedent of mixed depression or personality disorder.  Conclusion The literature review and KAP responses emphasize the importance of early identification for personalized care strategies with SGAs for DTD. Large-scale real-world evidence needs to evolve with due recognition of different phenotypes as TRD or DTD with partial or functional impairment to understand the impact of appropriate treatment pathways with SGAs.

Difficult-To-Treat Depression. Scoping Review.

Objective: Recently, several academics have recommended that the concept of difficult-to-treat depression (DTD) should be considered in some of the cases where achieving or maintaining remission of depressive symptoms is not possible. In 2020, a consensus statement, not based on a formal process and systematic review defined difficult-to-treat depression as "depression that continues to cause significant burden despite normal treatment efforts". In addition to addressing symptom control, interventions for DTD should also target other factors, including the management of psychiatric and medical comorbidities, psychosocial functioning, self-esteem, and self-management strategies. The purpose of this scoping review is to explore the scientific literature, which is still unclear and vague, regarding the pathophysiology and treatment of difficult-to-treat depression, providing a summary of its current conceptualization. This represents a cultural and scientific shift that offers clinicians and researchers valid and up-to-date study criteria, thus expanding upon the model of treatment-resistant depression (TRD). Consequently contributions, concepts, theories and gaps of the state of the art in the description of difficult-to-treat depression have been summarized here. Method: A research study was conducted using PubMed, Scopus, PsycINFO, Cochrane Library, and Open Grey databases to identify and examine articles reporting key features related to the recent concept of difficult-to-treat depression. The research covered a period of time between January 1, 2013, and March 1, 2023. Based on a formal checklist, two researchers independently assessed the eligibility criteria to determine which studies to include or exclude in this search. Further data evaluations were conducted for the articles that were deemed to have the most comprehensive descriptions. Results: The results of the research yielded a body of literature that provides a clear definition of difficult-to-treat depression and insights into its clinical application and research perspective. Conclusions: DTD represents a cultural and scientific shift that provides clinicians and researchers with valid and up-to-date study criteria that allow the extension of the treatment-resistant depression (TRD) model. The main difference lies in the operational process of assessment and intervention in the depressive syndrome in relation to the search for a therapeutic response. The results of this review show that DTD is a theoretically and clinically useful conceptualization for depressive syndromes that are not just simply resistant to treatment. This clinical condition entails a novel clinical therapeutic approach for specific patients and may be used throughout the world to help recognize this clinical condition while optimizing overall care for these patients. However, as we have highlighted, in the absence of RCTs and further observational studies, it is desirable that DTD be further investigated and defined..

Rethinking treatment-resistant depression to quasi-tenacious depression.

With almost one-third of patients with major depression not adequately responsive to treatments, the management of treatment-resistant depression (TRD) has continued to be challenging. Recently, an essential step was taken to replace TRD with difficult-to-treat depression (DTD), pointing to some drawbacks associated with this terminology and identifying addressable barriers. In line with the DTD concept, we discuss why terming this population of patients as TRD could be semantically and clinically misleading. We then suggest replacing TRD with quasi-tenacious depression (QTD), a model and terminology that are derived from a potentially measurable outcome, the tenacity index (TI). QTD predicts that in theory remission is achievable by providing suitable treatments at hand. QTD states that every patient with major depression (even those who respond well) has some degree of tenacity that needs to be overcome by the use of proper treatment modalities. Ergo, in patients with a higher TI, due to the dearth of available armamentaria, one might suffice to achieve a partial resolution of symptoms balanced with an optimal quality of life. However, QTD calls for an incessant pursuit of novel treatments and the identification of contributing factors leading to high TI. On a track toward personalized psychiatry, and in harmony with DTD, QTD embraces all key barriers leading to a failure to treatment response and tries to provide a measurable entity for a better clinical decision while conveying a dynamic positive outlook of the disorder for both patients and health care providers.

Viewpoint: Difficult-to-treat depression versus treatment-resistant depression: A new integrative perspective for managing depression.

In the STAR*D study, the efficacy of treatments for major depression was examined. It was found that, while many responded to the initial antidepressant treatment, only 30% of participants achieved complete remission. Concerning treatment resistance in depression, there is a recent distinction emerging between treatment-resistant depression (TRD) and difficult-to-treat depression (DTD). Historically, TRD and DTD have been conflated, but it is essential to recognize them as separate entities. While TRD is characterized by a patient's inadequate response to two or more consecutive antidepressant treatments given for an adequate duration and dosage without achieving acceptable therapeutic effects, DTD describes a clinical category where patients do not achieve full symptom control despite various therapeutic approaches. The recent shift in perspective proposes a more integrated approach for DTD, encompassing psychosocial, biological, and interactive factors. This multifactorial model calls for a multidisciplinary therapeutic intervention, not restricted to pharmacological treatments but also including psychotherapy, neurostimulation, and social interventions. Informing professionals and the general public about the significance of this new approach could mitigate the stigma associated with depression and enhance the quality of care. The future challenge will involve a deeper clinical understanding of DTD and its optimal management by refining available treatments.

Overview of treatment-resistant depression.

Patients with major depressive disorder (MDD) often exhibit an inadequate treatment response or failure to achieve remission following treatment with antidepressant drugs. Treatment-resistant depression (TRD) is proposed to identify this clinical scenario. Compared to those without TRD, patients with TRD have significantly lower health-related quality of life in mental and physical dimensions, more functional impairment and productivity loss, and higher healthcare costs. TRD imposes a massive burden on the individual, family, and society. However, a lack of consensus on the TRD definition limits the comparison and interpretation of TRD treatment efficacy across trials. Furthermore, because of the various TRD definitions, there is scarce treatment guideline specifically for TRD, in contrast to the rich treatment guidelines for MDD. In this chapter, common issues related to TRD, such as proper definitions of an adequate antidepressant trial and TRD, were carefully reviewed. Prevalence of and clinical outcomes related to TRD were summarized. We also summarized the staging models ever proposed for the diagnosis of TRD. Furthermore, we highlighted variations in the definition regarding the lack of or an inadequate response in treatment guidelines for depression. Up-to-date treatment options for TRD, including pharmacological strategies, psychotherapeutic interventions, neurostimulation techniques, glutamatergic compounds, and even experimental agents were reviewed.

Treatment-resistant depression: definition, prevalence, detection, management, and investigational interventions.

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.