A Novel, Brief, Fully Automated Intervention to Extend the Antidepressant Effect of a Single Ketamine Infusion: A Randomized Clinical Trial

Effects of ketamine on individual symptoms and symptom networks of depression in a randomised controlled trial of ketamine for treatment-resistant depression

BACKGROUND

Understanding the effects of ketamine on depressive symptoms could help identify which patients might benefit and clarify its mechanism of action in both the early (≤1 day post-infusion) and late (e.g. 2-30 days post-infusion) post-infusion periods. Symptom network analyses could provide complementary information regarding relationships between symptoms.

AIMS

To identify the effects of ketamine on symptom-level changes in depression across both the early and late post-infusion periods and on depressive symptom network changes.

METHODS

In this secondary analysis of 152 adults with treatment-resistant depression (with 38.8% reporting suicidal ideation at baseline), we compared symptom changes in the early and late post-infusion periods between individuals randomised to a single 40 min infusion of intravenous ketamine 0.5 mg/kg (n = 103) or saline (n = 49) and identified changes in symptom networks between pre- and post-ketamine treatment using network analyses.

RESULTS

In the early post-infusion period, the greatest improvement (comparing ketamine with saline) was in depressive symptoms related to sadness. In network analyses, symptom network connectivity increased following ketamine infusion. Symptoms of sadness and lassitude showed persistent improvement in the first week post-infusion, whereas improvements in suicidal thoughts first emerged 3-4 weeks post-infusion.

CONCLUSION

Ketamine improved all symptoms but showed the greatest effect on symptoms of sadness, both immediately and in the initial week after treatment. Ketamine also rapidly altered the topology of symptom networks, strengthening interrelationships between residual symptoms. The efficacy of ketamine (compared with saline) regarding suicidal symptoms emerged later. Our findings suggest potentially divergent efficacy, time courses and mechanisms for different symptoms of depression.

Embracing Internal States: A Review of Optimization of Repetitive Transcranial Magnetic Stimulation for Treating Depression

Repetitive transcranial magnetic stimulation (rTMS) is a rapid and effective therapy for major depressive disorder; however, there is significant variability in therapeutic outcomes both within and across individuals, with approximately 50% of patients showing no response to rTMS treatment. Many studies have personalized the stimulation parameters of rTMS (e.g., location and intensity of stimulation) according to the anatomical and functional structure of the brain. In addition to these parameters, the internal states of the individual, such as circadian rhythm, behavior/cognition, neural oscillation, and neuroplasticity, also contribute to the variation in rTMS effects. In this review, we summarize the current literature on the interaction between rTMS and internal states. We propose two possible methods, multimodal treatment, and adaptive closed-loop treatment, to integrate patients' internal states to achieve better rTMS treatment for depression.

Repeated administration of esketamine ameliorates mechanical allodynia in mice with chemotherapy-induced peripheral neuropathy: A role of gut microbiota and metabolites

Chemotherapy-induced peripheral neuropathy (CIPN) severely diminishes the quality of life for cancer survivors, yet effective treatments remain scarce. Esketamine, a commonly used anesthetic, has demonstrated neuroprotective effects by restoring gut microbiome dysbiosis. In this study, we investigated the impact of esketamine on nociceptive sensitivity in a mouse model of CIPN and explored the potential involvement of the gut microbiome. In mice treated with oxaliplatin, repeated esketamine doses (in contrast to a single dose) significantly improved the paw withdrawal threshold (PWT). Western blot and qPCR analyses further revealed that repeated esketamine administration markedly reduced microglial activation and neuroinflammation in the dorsal root ganglion (DRG), underscoring its potent anti-inflammatory properties. Moreover, fecal 16S rRNA analysis indicated that esketamine partially restored the abnormal gut microbiota composition (β-diversity). Plasma metabolome analysis showed that repeated esketamine treatment significantly lowered the elevated levels of 6H-indolo[2,3-b]quinoline and restored the reduced levels of (3-exo)-3-[3-methyl-5-(1-methylethyl)-4H-1,2,4-triazol-4-yl]-8-azabicyclo[3.2.1]octane observed in oxaliplatin-treated mice. In addition, fecal microbiota transplantation from esketamine-treated CIPN mice notably improved both the diminished PWT and DRG neuroinflammation in oxaliplatin-treated mice. Collectively, these findings suggest that repeated esketamine administration may alleviate mechanical allodynia in CIPN mice by modulating neuroinflammation, gut microbiota, and associated metabolites.

Royal Australian and New Zealand College of Psychiatrists professional practice guidelines for the use of ketamine in psychiatric practice

Professional practice guidelines for the use of ketamine in psychiatric practice have been developed by the Royal Australian and New Zealand College of Psychiatrists to provide guidance on the use of ketamine in clinical practice in Australia and Aotearoa New Zealand, based on scientific evidence and supplemented by expert clinical consensus. Articles and information were sourced from existing guidelines and published literature. The findings were then formulated into consensus-based recommendations and guidance by the authors. The guidelines were subjected to rigorous successive consultation within the Royal Australian and New Zealand College of Psychiatrists, involving the Section of Electroconvulsive Therapy and Neurostimulation Committee, its broader membership and expert committees. The guidelines are intended for psychiatrists and clinicians engaged in the use of ketamine therapy to facilitate best practice to optimise outcomes for patients. They strive to find the appropriate balance between promoting best evidence-based practice and acknowledging that evidence for ketamine use is continually evolving.

The Impact of Intravenous Ketamine on Attentional Bias: Probing Mechanisms of Rapid-Acting Antidepressant Effects in Two Clinical Studies

BACKGROUND

Ketamine is known for its rapid antidepressant effect, but its impact on affective information processing (including attentional bias [AB], a putative cognitive mechanism of depression) remains largely unexplored. We leveraged a novel measurement of AB and sought to 1) establish adequate test-retest reliability and validity among participants with depression prior to ketamine treatment and 2) harness a single dose of ketamine to assess mechanistic shifts in AB and their relationship to antidepressant efficacy.

METHODS

A novel dual probe video task was used to index AB toward sad film clips. In study 1, treatment-seeking adults with moderate-to-severe depression (N = 40) completed the task at baseline, 1-week retest, and 1-month retest; a subset of participants (n = 15) also performed the task at 24 hours postketamine infusion (0.5 mg/kg over 40 minutes). In study 2, participants (N = 43) completed the task pre- and 24 hours postketamine.

RESULTS

Indices from the novel AB task were stable prior to ketamine, demonstrating good 1-week and 1-month test-retest reliability. Participants in both studies exhibited a robust reduction in AB from pre- to 24 hours postketamine infusion. In study 1, cross-sectional correlations were observed between AB and clinician-rated depressive symptoms at each pretreatment assessment. In study 2, changes in AB were correlated with improved symptoms from pre- to postinfusion.

CONCLUSIONS

Results provide evidence for the validity of a novel, psychometrically robust measure of AB among individuals with depression. Findings indicate that ketamine reliably and rapidly reduces AB, offering insight into a replicable, potential cognitive mechanism involved in its antidepressant action.

Lack of relationships between ketamine treatment and peripheral neurotrophic and inflammatory factors in a randomized controlled ketamine trial of major depressive disorder

BACKGROUND

Ketamine is a rapid-acting treatment for treatment-resistant depression (TRD), though mechanisms related to ketamine's effects remain unclear. Blood-based neurotrophic and inflammatory factors (NIFs; e.g., brain-derived neurotrophic factor, interleukin-6) have emerged as markers potentially linked to ketamine and ketamine treatment response.

METHODS

In this secondary analysis of a randomized controlled trial (RCT), 133 adults with TRD received a single-dose infusion of ketamine (n = 89; 0.5 mg/kg) or saline (n = 44) and provided measures of peripheral blood NIF levels and depression severity across a five-day post-infusion period. Differences between ketamine and saline groups were examined for (1) NIF levels, (2) associations between NIF trajectories and depression score trajectories, and (3) associations between baseline NIF levels and depression score trajectories. Subgroup sensitivity analyses examined identical relationships within many (n = 28) discrete subgroups of individuals.

RESULTS

No differences were found between ketamine and saline cohorts for NIF trajectories, associations of NIF and depression trajectories, or associations of baseline NIF levels and depression trajectories. On subgroup analyses, in participants with lower BMI (BMI < 25; n = 66), increasing interleukin-1 receptor antagonist (IL-1RA) trajectories post-ketamine were associated with less improvement in depression in the first day post-infusion.

DISCUSSION

Associations between ketamine treatment and peripheral neurotrophic/inflammatory factors were not detected in our RCT of 133 adults with TRD. The sole exception across exhaustive sensitivity analyses was that, in individuals with low BMI, increases in IL-1RA levels may be linked to worse immediate treatment response. Future research investigating CNS-specific NIF activity is needed to more definitively test the posited role of NIFs in ketamine's antidepressant mechanisms.

Functional connectivity subtypes during a positive mood induction: Predicting clinical response in a randomized controlled trial of ketamine for treatment-resistant depression

Ketamine has shown promise in rapidly improving symptoms of depression and most notably treatment-resistant depression (TRD). However, given the heterogeneity of TRD, biobehavioral markers of treatment response are necessary for the personalized prescription of intravenous ketamine. Heterogeneity in depression can be manifested in discrete patterns of functional connectivity (FC) in default mode, ventral affective, and cognitive control networks. This study employed a data-driven approach to parse FC during positive mood processing to characterize subgroups of patients with TRD prior to infusion and determine whether these connectivity-based subgroups could predict subsequent antidepressant response to ketamine compared to saline infusion. 152 adult patients with TRD completed a baseline assessment of FC during positive mood processing and were randomly assigned to either ketamine or saline infusion. The assessment utilized Subgroup-Group Iterative Multiple Model Estimation to recover directed connectivity maps and applied Walktrap algorithm to determine data-driven subgroups. Depression severity was assessed pre- and 24-hr postinfusion. Two connectivity-based subgroups were identified: Subgroup A (n = 110) and Subgroup B (n = 42). We observed that treatment response was moderated by an infusion type by subgroup interaction (p = .040). For patients receiving ketamine, subgroup did not predict treatment response (β = -.326, p = .499). However, subgroup predicted response for saline patients. Subgroup B individuals, relative to A, were more likely to be saline responders at 24-hr postinfusion (β = -2.146, p = .007). Thus, while ketamine improved depressive symptoms uniformly across both subgroups, this heterogeneity was a predictor of placebo response. (PsycInfo Database Record (c) 2025 APA, all rights reserved).

Intermittent theta-burst stimulation with adjunctive D-cycloserine rapidly resolves suicidal ideation and decreases implicit association with death/suicide

BACKGROUND

Depressive disorders are the most common diagnosis among individuals who die by suicide, and intermittent theta-burst stimulation (iTBS) is a noninvasive treatment for those with difficult-to-treat depression who are at higher risk for suicide. Previous data suggests that pairing iTBS with D-cycloserine, a partial N-methyl-D-aspartate (NMDA) receptor agonist, improves antidepressant outcomes. However, its impact on suicide risk is not known.

METHODS

We examine suicidal ideation and implicit suicide risk after iTBS+D-cycloserine in two clinical trials (open-label trial [n = 12] and randomized placebo-controlled trial [RCT, n = 50]) involving adults with major depressive disorder and the acute effects of D-cycloserine on implicit suicide risk in a crossover trial (n = 18). Implicit suicide risk was assessed using the computerized death/suicide implicit association test (IAT), and depressive symptoms and suicidal ideation were assessed using the clinician-rated Montgomery-Asberg Depression Rating Scale (MADRS).

RESULTS

Open-label iTBS+D-cycloserine was associated with a rapid reduction in suicidal ideation, and iTBS+D-cycloserine was superior to iTBS+placebo in reducing suicidal ideation. Similarly, open-label iTBS+D-cycloserine was associated with decreased implicit suicide risk as measured by the death/suicide IAT, and iTBS+D-cycloserine was associated with greater decreases in death/suicide IAT scores compared to iTBS+placebo. A single acute dose of D-cycloserine in the absence of iTBS had no effect on implicit suicide risk.

CONCLUSIONS

Adjunctive D-cycloserine with iTBS is a promising strategy to reduce suicidal ideation and implicit suicide risk in depression.

Compassionate use of esketamine intranasal in patients with severe major depressive disorder resistant to the treatment

BACKGROUND

Treatment-resistant depression (TRD) is defined as the failure of at least two antidepressants in adequate doses and timing during a major depressive episode. Esketamine intranasal (ESK-IN) has been approved by the Food and Drug Administration and the European Medicines Agency for the treatment of TRD in combination with other antidepressants.

AIMS

To assess the effectiveness and tolerability of a sample of TRD patients who received treatment with ESK-IN as part of the compassionate use program.

METHODS

A retrospective, observational study was carried out on patients with a diagnosis of TRD enrolled in the early access program of ESK-IN in nine centers. Effectiveness was assessed with the Montgomery-Asberg depression rating scale (MADRS) at four time points: baseline, 28, 90, and 180 days of treatment.

RESULTS

The sample included 71 patients (70% women) with a mean baseline MADRS score of 38.27 ± 5.9 and total or partial work disability rates of 85%. ESK-IN treatment was associated with a statistically and clinically significant reduction in the severity of depressive symptoms at all time points assessed. The presence of side effects was common but the majority were mild in severity and resolved after the observation period. Those patients who received psychotherapy in combination with ESK-IN showed a significantly lower MADRS score at 90 and 180 days than those patients who did not undergo psychotherapy.

CONCLUSION

ESK-IN has proven to be effective and safe in a clinical sample of patients with severe TRD. To optimize clinical outcomes, the pharmacological treatment for TRD should always be integrated into a comprehensive therapeutic plan that encompasses strategies such as psychotherapy, social support, and family interventions.

Psilocybin: From Psychiatric Pariah to Perceived Panacea

OBJECTIVE

The authors critically examine the evidence base for psilocybin administered with psychological support/therapy (PST) in the treatment of psychiatric disorders and offer practical recommendations to guide future research endeavors.

METHODS

PubMed was searched for English-language articles from January 1998 to November 2023, using the search term "psilocybin." A total of 1,449 articles were identified and screened through titles and abstracts. Of these, 21 unique open-label or randomized controlled trials (RCTs) were identified that examine psilocybin for the treatment of obsessive-compulsive and related disorders (N=2), anxiety/depression associated with a cancer diagnosis (N=5), major depressive disorder (MDD; N=8), substance use disorders (N=4), anorexia (N=1), and demoralization (i.e., hopelessness, helplessness, and poor coping) in AIDS survivors (N=1).

RESULTS

The most developed evidence base is for the treatment of MDD (three double-blind RCTs with positive signals spanning a range of severities). However, the evidence is tempered by threats to internal and external validity, including unsuccessful blinding, small samples, large variability in dosing and PST procedures, limited sample diversity, and possibly large expectancy effects. Knowledge of mechanisms of action and predictors of response is currently limited.

CONCLUSIONS

The evidence is currently insufficient to recommend psilocybin with PST as a psychiatric treatment. Additional rigorously designed clinical trials are needed to definitively establish efficacy in larger and more diverse samples, address dosing considerations, improve blinding, and provide information on mechanisms of action and moderators of clinical response. Head-to-head comparisons with other evidence-based treatments will better inform the potential future role of psilocybin with PST in the treatment of major psychiatric disorders.

Improved implicit self-esteem is associated with extended antidepressant effects following a novel synergistic intervention

INTRODUCTION

In a previously published randomized controlled trial, automated self-association training (ASAT), a novel digital intervention, was found to extend the rapid antidepressant effect of a single infusion of ketamine for at least 30 days. In this secondary analysis, we aimed to understand the potential role of implicit self-esteem in the combined antidepressant effect of ketamine and ASAT training, by investigating the novel synergistic treatment's effects on implicit self-associations and their relation to symptom improvement.

METHODS

A total of 154 adults (ages 18-60) with treatment-resistant unipolar depression and lower-than-normative explicit self-esteem were randomized in a double-blind, parallel-arm design to receive one of three treatment allocations: an active/active treatment combination consisting of one infusion of ketamine (0.5 mg/kg) followed by four days of ASAT ( ~ 30-40 min/day), or one of two control arms that lacked either the active drug or the active behavioral component. The Implicit Association Test (IAT) was used to behaviorally assess the strength of association between self-related stimuli and negative concepts. Linear regression models were used to test the relationship between group assignment, IAT scores acquired immediately post-treatment, and both acute and extended clinical outcomes (% change in Montgomery-Asberg Depression Rating Scale scores, relative to pre-treatment baseline) in the trial.

RESULTS

The group assigned to ketamine + ASAT intervention, compared to the other groups, had a pattern of IAT scores indicating more positive self-associations immediately after treatment relative to the control arms (F(1, 131) = 3.979; p = 0.048). In regression models, IAT scores tracked with concurrent (acute post-treatment) % change in MADRS scores across all treatment arms (p = 0.001), and mediated more extended (Day 30) depression improvements specifically for the ketamine+ASAT arm (group * IAT interaction term: β = -0.201; p = 0.049).

DISCUSSION

Our findings suggest that changing implicit self-worth during a post-ketamine 'plasticity window' is one key mechanism whereby the novel ketamine+ASAT treatment combination exerts its antidepressant benefit, confirming the intended treatment target at the level of implicit cognition. Future studies should seek to further enhance the reliability of the biobehavioral intervention's impact on implicit cognition, as this mechanism appears linked to the intervention's enduring clinical benefits.

The Psychotherapy in MDMA-Assisted Psychotherapy

This Viewpoint discusses the critical yet overlooked role of the psychotherapy component in assessing the validity of the trials of midomafetamine/3,4-methylenedioxymethamphetamine (MDMA)–assisted psychotherapy for posttraumatic stress disorder.

Therapeutic Protocols Using Ketamine and Esketamine for Depressive Disorders: A Systematic Review

Depression is one of the most prevalent mental health disorders globally, causing severe emotional suffering, reducing life expectancy and increasing the risk of suicide. Recently, the use of dissociative psychedelic substances such as ketamine and esketamine for depressive disorders has expanded treatment options. We sought to analyze, through a systematic review, the existing protocols for the treatment of depression with ketamine and esketamine. The search adopted PRISMA criteria and was performed using PubMed and Web of Science databases. Procedures in each study were compared, focusing on the sample recruited, therapeutic approaches, including the clinical team and professionals engaged in treatment, medical procedures, description of the setting (including music) and factors such as specific medication (ketamine or esketamine), route of administration and dosage employed. Results indicated the predominance of a medical approach, with a limited number of studies on ketamine assisted psychotherapy (KAP) and other modalities of psychedelic assisted therapy. Additionally, there is limited information on psychosocial elements such as preparation, psychological support during session and integration of experience. Altogether these findings suggest that treatment of depression with ketamine or esketamine diverges in relation to the practices employed with psychedelic substances. This is discussed considering future research directions in the field.

Uncovering the determinants of brain functioning, behavior and their interplay in the light of context

Notwithstanding the huge progress in molecular and cellular neuroscience, our ability to understand the brain and develop effective treatments promoting mental health is still limited. This can be partially ascribed to the reductionist, deterministic and mechanistic approaches in neuroscience that struggle with the complexity of the central nervous system. Here, I introduce the Context theory of constrained systems proposing a novel role of contextual factors and genetic, molecular and neural substrates in determining brain functioning and behavior. This theory entails key conceptual implications. First, context is the main driver of behavior and mental states. Second, substrates, from genes to brain areas, have no direct causal link to complex behavioral responses as they can be combined in multiple ways to produce the same response and different responses can impinge on the same substrates. Third, context and biological substrates play distinct roles in determining behavior: context drives behavior, substrates constrain the behavioral repertoire that can be implemented. Fourth, since behavior is the interface between the central nervous system and the environment, it is a privileged level of control and orchestration of brain functioning. Such implications are illustrated through the Kitchen metaphor of the brain. This theoretical framework calls for the revision of key concepts in neuroscience and psychiatry, including causality, specificity and individuality. Moreover, at the clinical level, it proposes treatments inducing behavioral changes through contextual interventions as having the highest impact to reorganize the complexity of the human mind and to achieve a long-lasting improvement in mental health.

Implementation of a ketamine programme for treatment-resistant depression in the public health system: Lessons from the first Australian public hospital clinic

One could argue that we are living through a period of innovation and change in psychiatry unlike that seen before, with repurposed medications emerging as novel treatments. However, despite evidence of enhanced clinical outcomes and potential medium-term savings, delivering these promising interventions is resource-intensive and perceived as difficult in the public sector. Consequently, they are generally only available in the private sector, often at great cost, effectively making them inaccessible to the 'Have Nots'. The arrival of these paradigm-shifting treatments has inadvertently highlighted a growing mental health inequity. The Royal Prince Alfred Hospital's Ketamine Treatment Clinic was the first public-sector ketamine treatment clinic for complex mood disorders in Australia. Based on 3 years' experience establishing, developing and running a public-sector ketamine treatment service, we review the progress, perils and pitfalls for clinicians and health services contemplating establishing a public-sector ketamine treatment service of their own.

Experiences of Awe Mediate Ketamine's Antidepressant Effects: Findings From a Randomized Controlled Trial in Treatment-Resistant Depression

Background

Ketamine, an NMDA receptor antagonist, provides rapid antidepressant effects. Although much research has focused on neural and molecular mechanisms of action, it is critical to also consider psychological mechanisms that may contribute to its therapeutic efficacy. The construct of an awe-inducing experience, which is a well-validated psychological phenomenon tied to emotional well-being, had not been applied previously in ketamine research.

Methods

One hundred sixteen participants with depression, 77 of whom received a ketamine infusion (0.5 mg/kg over 40 minutes) and 39 patients who received saline placebo, completed a validated measure of awe (the Awe Experience Scale [AWE-S]) at 40 minutes postinfusion. AWE-S scores were examined as potential mediators of depression outcomes (% improvement in Montgomery-Åsberg Depression Rating Scale score) at 5 postinfusion time points (24 hours and 5, 12, 21, and 30 days). Dissociative effects, measured by Clinician-Administered Dissociative States Scale scores, were tested in parallel mediation models for comparison.

Results

We found that the psychological experience of awe was strongly reported by participants during ketamine infusion, but not saline infusion, and there were significant associations between total AWE-S scores and Montgomery-Åsberg Depression Rating Scale score improvement (% change) in the ketamine arm at all 5 time points. Furthermore, at all 5 time points, total AWE-S scores statistically mediated the relationship between ketamine and Montgomery-Åsberg Depression Rating Scale scores. By contrast, Clinician-Administered Dissociative States Scale scores did not mediate outcomes at any time point.

Conclusions

Ketamine infusion strongly induced heightened feelings of awe, and these experiences consistently mediated depression outcomes over a 1- to 30-day period, unlike general dissociative side effects. The specific awe-inspiring properties of ketamine may contribute to its antidepressant effects.

Psychedelics and Evidence-based Psychotherapy: A Systematic Review with Recommendations for Advancing Psychedelic Therapy Research

Administration of psychedelics for mental health treatment, typically referred to as "psychedelic-assisted therapy," is a broad term with a very heterogeneous implementation. Despite increasing interest in the clinical application of psychedelic compounds for psychiatric disorders, there is no consensus on how to best integrate the psychedelic experience with evidence-based psychotherapeutic treatment. This systematic review provides a timely appraisal of existing approaches to combining psychotherapy with psychedelics and provides clear recommendations to best develop, optimize, and integrate evidence-based psychotherapy with psychedelic administration for straightforward scientific inference and maximal therapeutic benefit.

Subjective experience of the environment determines serotoninergic antidepressant treatment outcome in male mice

BACKGROUND

The effects of the selective serotonin reuptake inhibitors (SSRIs), the first-line antidepressant treatment, have been proposed to be affected, at least in part, by the living environment. Since the quality of the environment depends not only on its objective features, but also on the subjective experience, we hypothesized that the latter plays a key role in determining SSRI treatment outcome.

METHODS

We chronically administered the SSRI fluoxetine to two groups of adult CD-1 male mice that reportedly show distinct subjective experiences of the environment measured as consistent and significantly different responses to the same emotional and social stimuli. These distinct socioemotional profiles were generated by rearing mice either in standard laboratory conditions (SN) or in a communal nest (CN) where three dams breed together their offspring, sharing caregiving behavior.

RESULTS

At adulthood, CN mice displayed higher levels of agonistic and anxiety-like behaviors than SN mice, indicating that they experience the environment as more socially challenging and potentially dangerous. We then administered fluoxetine, which increased offensive and anxious response in SN, while producing opposite effects in CN mice. BDNF regulation was modified by the treatment accordingly.

LIMITATIONS

Subjective experience in mice was assessed as behavioral response to the environment.

CONCLUSIONS

These results show that the subjective experience of the environment determines fluoxetine outcome. In a translational perspective, our findings suggest considering not only the objective quality, but also the subjective appraisal, of the patient's living environment for developing effective personalized therapeutic approaches in psychiatry.

The why, when, where, how, and so what of so-called rapidly acting antidepressants

Developing antidepressants that are not only more effective but are rapidly acting is the Holy Grail for psychiatry. We review multiple issues that arise in determining rapid responses in antidepressant trials. The current status of purportedly rapid acting agents is first reviewed. Then, a number of key questions/issues are addressed: Is there a unifying definition for rapid response across studies? Should rapid response criteria be based on required measurable effects on overall improvement? On specific symptoms such as psychomotor retardation, depressed mood, or anhedonia? In associated symptoms such as anxiety or insomnia? When should onset be considered rapid-by Day 3? Day7? Day 14? If there is a rapid response, for how long should the effects be maintained? Is maintenance of effect dependent on continuing the medication? Is rapid response associated with specific mechanisms of action? Do the mechanisms of action suggest possible risk for drug abuse? How important is rapid response really in an often chronic or recurrent depressive disorder? In which types of patients could rapid response be particularly important? What are the study design issues that need to be considered for assessing rapid response, including: selection of specific types of depressed patients, multiple doses of drug studied, designation of primary and secondary outcome measures, specific time points at which to determine efficacy, requirements for demonstrating durability, etc. A framework for approaching this complex area is developed for both researchers and clinicians.

Ketamine in neuropsychiatric disorders: an update

The discovery of ketamine as a rapid-acting antidepressant led to a new era in the development of neuropsychiatric therapeutics, one characterized by an antidepressant response that occurred within hours or days rather than weeks or months. Considerable clinical research supports the use of-or further research with-subanesthetic-dose ketamine and its (S)-enantiomer esketamine in multiple neuropsychiatric disorders including depression, bipolar disorder, anxiety spectrum disorders, substance use disorders, and eating disorders, as well as for the management of chronic pain. In addition, ketamine often effectively targets symptom domains associated with multiple disorders, such as anxiety, anhedonia, and suicidal ideation. This manuscript: 1) reviews the literature on the pharmacology and hypothesized mechanisms of subanesthetic-dose ketamine in clinical research; 2) describes similarities and differences in the mechanism of action and antidepressant efficacy between racemic ketamine, its (S) and (R) enantiomers, and its hydroxynorketamine (HNK) metabolite; 3) discusses the day-to-day use of ketamine in the clinical setting; 4) provides an overview of ketamine use in other psychiatric disorders and depression-related comorbidities (e.g., suicidal ideation); and 5) provides insights into the mechanisms of ketamine and therapeutic response gleaned from the study of other novel therapeutics and neuroimaging modalities.

Neural connectivity moderators and mechanisms of ketamine treatment among treatment-resistant depressed patients: a randomized controlled trial

BACKGROUND

Intravenous (IV) ketamine has emerged as a rapid and effective treatment for TRD. However, the specific neural mechanisms of ketamine's effects in humans remains unclear. Although neuroplasticity is implicated as a mechanism of action in animal models, relatively few randomized controlled trials (RCTs) in TRD patients have examined ketamine's impact on functional connectivity, a posited functional marker of neuroplasticity-particularly in the context of a mood-induction paradigm (termed miFC).

METHODS

152 adults with TRD (63% female; 37% male) were randomly allocated to receive a single infusion of ketamine or saline in a 2:1 ratio. We examined changes in connectivity (from baseline to 24-h post-infusion) that differed by treatment, and whether clinical treatment response at 24-h post-infusion was uniquely related (among patients allocated to ketamine relative to saline) to (1) pre-treatment connectivity and (2) changes in connectivity. We examined both miFC and rsFC, using prefrontal cortex and limbic seed regions. We also conducted a multiverse analysis to examine findings most robust against analytic decisions.

FINDINGS

Across both miFC and rsFC, ketamine was associated with greater in prefrontal/limbic connectivity compared to saline, and lower baseline connectivity of limbic and prefrontal regions predicted greater treatment response in patients receiving ketamine. Greater connectivity increases in participants receiving ketamine was uniquely related to greater treatment response. In addition, certain findings were identified as being reproducible against different analytic decisions in multiverse analyses.

INTERPRETATION

Our findings identify specific neural connectivity patterns impacted by ketamine and were uniquely related to outcomes following ketamine (relative to saline). These findings generally support prominent neuroplasticity models of ketamine's therapeutic efficacy. These findings lay new groundwork for understanding how to enhance and optimize ketamine treatments and develop novel rapid-acting treatments for depression.

FUNDING

This research was supported by NIH grant R01MH113857 and by the Clinical and Translational Sciences Institute at the University of Pittsburgh (UL1-TR-001857).

Psychedelic therapies reconsidered: compounds, clinical indications, and cautious optimism

The clinical investigation of psychedelic medicines has blossomed over the last 5 years. Data from a Phase 3 industry trial and a multicenter Phase 2 industry trial, in addition to multiple early phase investigator-initiated and industry trials, have now been published in peer-reviewed journals. This narrative review summarizes both the recent data and the current clinical trials that are being conducted with various classes of "psyche-manifesting" substances, which may prove beneficial in the treatment of a broad range of conditions. Methodological considerations, unique challenges, and next steps for research are discussed in keeping with the uniquely "experiential" nature of these therapies.

Repeated (S)-ketamine administration ameliorates the spatial working memory impairment in mice with chronic pain: role of the gut microbiota-brain axis

Chronic pain is commonly linked with diminished working memory. This study explores the impact of the anesthetic (S)-ketamine on spatial working memory in a chronic constriction injury (CCI) mouse model, focusing on gut microbiome. We found that multiple doses of (S)-ketamine, unlike a single dose, counteracted the reduced spontaneous alteration percentage (%SA) in the Y-maze spatial working memory test, without affecting mechanical or thermal pain sensitivity. Additionally, repeated (S)-ketamine treatments improved the abnormal composition of the gut microbiome (β-diversity), as indicated by fecal 16S rRNA analysis, and increased levels of butyrate, a key gut - brain axis mediator. Protein analysis showed that these treatments also corrected the upregulated histone deacetylase 2 (HDAC2) and downregulated brain-derived neurotrophic factor (BDNF) in the hippocampi of CCI mice. Remarkably, fecal microbiota transplantation from mice treated repeatedly with (S)-ketamine to CCI mice restored %SA and hippocampal BDNF levels in CCI mice. Butyrate supplementation alone also improved %SA, BDNF, and HDAC2 levels in CCI mice. Furthermore, the TrkB receptor antagonist ANA-12 negated the beneficial effects of repeated (S)-ketamine on spatial working memory impairment in CCI mice. These results indicate that repeated (S)-ketamine administration ameliorates spatial working memory impairment in CCI mice, mediated by a gut microbiota - brain axis, primarily through the enhancement of hippocampal BDNF - TrkB signaling by butyrate.

The Psychedelic Future of Post-Traumatic Stress Disorder Treatment

Post-traumatic stress disorder (PTSD) is a mental health condition that can occur following exposure to a traumatic experience. An estimated 12 million U.S. adults are presently affected by this disorder. Current treatments include psychological therapies (e.g., exposure-based interventions) and pharmacological treatments (e.g., selective serotonin reuptake inhibitors (SSRIs)). However, a significant proportion of patients receiving standard-of-care therapies for PTSD remain symptomatic, and new approaches for this and other trauma-related mental health conditions are greatly needed. Psychedelic compounds that alter cognition, perception, and mood are currently being examined for their efficacy in treating PTSD despite their current status as Drug Enforcement Administration (DEA)- scheduled substances. Initial clinical trials have demonstrated the potential value of psychedelicassisted therapy to treat PTSD and other psychiatric disorders. In this comprehensive review, we summarize the state of the science of PTSD clinical care, including current treatments and their shortcomings. We review clinical studies of psychedelic interventions to treat PTSD, trauma-related disorders, and common comorbidities. The classic psychedelics psilocybin, lysergic acid diethylamide (LSD), and N,N-dimethyltryptamine (DMT) and DMT-containing ayahuasca, as well as the entactogen 3,4-methylenedioxymethamphetamine (MDMA) and the dissociative anesthetic ketamine, are reviewed. For each drug, we present the history of use, psychological and somatic effects, pharmacology, and safety profile. The rationale and proposed mechanisms for use in treating PTSD and traumarelated disorders are discussed. This review concludes with an in-depth consideration of future directions for the psychiatric applications of psychedelics to maximize therapeutic benefit and minimize risk in individuals and communities impacted by trauma-related conditions.

Choosing Between Ketamine and Electroconvulsive Therapy for Outpatients With Treatment-Resistant Depression-Advantage Ketamine?

This Viewpoint examines key issues stemming from several recent reports of electroconvulsive therapy (ECT) vs ketamine for improving depressive symptoms in treatment-resistant depression (TRD).

Cognitive behavioral therapy following esketamine for major depression and suicidal ideation for relapse prevention: The CBT-ENDURE randomized clinical trial study protocol

In 2020, esketamine received a supplemental indication as a therapy for major depression with suicidal ideation (MDSI), based on protocols enrolling hospitalized patients. Given the high risk of suicide following hospital discharge and the high relapse rates following discontinuation of esketamine, the optimal long-term treatment approach remains unclear. Cognitive behavioral therapy (CBT) is highly effective in relapse prevention and has been shown to prevent suicide attempts in high-risk populations. Here we describe the study protocol for the CBT-ENDURE trial: Cognitive Behavioral Therapy Following Esketamine for Major Depression and SUicidal Ideation for RElapse Prevention. Patients with depression (N = 100) who are admitted to hospital or are outpatients with clinically significant suicidal ideation will be enrolled in the study. All patients will receive esketamine (twice weekly for four weeks) and will be randomly assigned (1:1 ratio) to receive a 16-week course of CBT plus treatment as usual (CBT group) or treatment as usual only (TAU only group). Patients are followed for a total of 6 months. Supported under a funding announcement from NIMH to conduct safety and feasibility trials for patients at high risk for suicide, the primary outcome of the CBT-ENDURE study is feasibility (as measured by recruitment and retention), with a key secondary outcome being relapse among those who experience substantial benefit following two weeks of esketamine.

Randomized trial of ketamine masked by surgical anesthesia in patients with depression

Ketamine may have antidepressant properties, but its acute psychoactive effects complicate successful masking in placebo-controlled trials. We present a single-center, parallel-arm, triple-masked, randomized, placebo-controlled trial assessing the antidepressant efficacy of intravenous ketamine masked by surgical anesthesia (ClinicalTrials.gov, NCT03861988). Forty adult patients with major depressive disorder who were scheduled for routine surgery were randomized to a single infusion of ketamine (0.5 mg/kg) or placebo (saline) during usual anesthesia. All participants, investigators, and direct patient care staff were masked to treatment allocation. The primary outcome was depression severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) at 1, 2, and 3 days post-infusion. After all follow-up visits, participants were asked to guess which intervention they received. A mixed-effects model showed no evidence of effect of treatment assignment on the primary outcome (-5.82, 95% CI -13.3 to 1.64, p=0.13). 36.8% of participants guessed their treatment assignment correctly; both groups allocated their guesses in similar proportions. In conclusion, a single dose of intravenous ketamine delivered during surgical anesthesia had no greater effect than placebo in acutely reducing the severity of depressive symptoms in adults with major depressive disorder. This trial successfully masked treatment allocation in moderate-to-severely depressed patients using surgical anesthesia. Although this masking strategy is impractical for most placebo-controlled trials, future studies of novel antidepressants with acute psychoactive effects should make efforts to fully mask treatment assignment in order to minimize subject-expectancy bias.

A synopsis of multitarget therapeutic effects of anesthetics on depression

Depression is a profound mental disorder that dampens the mood and undermines volition, which exhibited an increased incidence over the years. Although drug-based interventions remain the primary approach for depression treatment, the available medications still can't satisfy the patients. In recent years, the newly discovered therapeutic targets such as N-methyl-D-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor, and tyrosine kinase B (TrkB) have brought new breakthroughs in the development of antidepressant drugs. Moreover, it has come to light that certain anesthetics possess pharmacological mechanisms intricately linked to the aforementioned therapeutic targets for depression. At present, numerous preclinical and clinical studies have explored the therapeutic effects of anesthetic drugs such as ketamine, isoflurane, N2O, and propofol, on depression. These investigations suggested that these drugs can swiftly ameliorate patients' depression symptoms and engender long-term effects. In this paper, we provide a comprehensive review of the research progress and potential molecular mechanisms of various anesthetic drugs for depression treatment. By shedding light on this subject, we aim to facilitate the development and clinical implementation of new antidepressant drugs based on anesthetic medications.

History repeating: guidelines to address common problems in psychedelic science

Research in the last decade has expressed considerable optimism about the clinical potential of psychedelics for the treatment of mental disorders. This optimism is reflected in an increase in research papers, investments by pharmaceutical companies, patents, media coverage, as well as political and legislative changes. However, psychedelic science is facing serious challenges that threaten the validity of core findings and raise doubt regarding clinical efficacy and safety. In this paper, we introduce the 10 most pressing challenges, grouped into easy, moderate, and hard problems. We show how these problems threaten internal validity (treatment effects are due to factors unrelated to the treatment), external validity (lack of generalizability), construct validity (unclear working mechanism), or statistical conclusion validity (conclusions do not follow from the data and methods). These problems tend to co-occur in psychedelic studies, limiting conclusions that can be drawn about the safety and efficacy of psychedelic therapy. We provide a roadmap for tackling these challenges and share a checklist that researchers, journalists, funders, policymakers, and other stakeholders can use to assess the quality of psychedelic science. Addressing today's problems is necessary to find out whether the optimism regarding the therapeutic potential of psychedelics has been warranted and to avoid history repeating itself.

Suicide prevention and ketamine: insights from computational modeling

Suicide is a pressing public health issue, with over 700,000 individuals dying each year. Ketamine has emerged as a promising treatment for suicidal thoughts and behaviors (STBs), yet the complex mechanisms underlying ketamine's anti-suicidal effect are not fully understood. Computational psychiatry provides a promising framework for exploring the dynamic interactions underlying suicidality and ketamine's therapeutic action, offering insight into potential biomarkers, treatment targets, and the underlying mechanisms of both. This paper provides an overview of current computational theories of suicidality and ketamine's mechanism of action, and discusses various computational modeling approaches that attempt to explain ketamine's anti-suicidal effect. More specifically, the therapeutic potential of ketamine is explored in the context of the mismatch negativity and the predictive coding framework, by considering neurocircuits involved in learning and decision-making, and investigating altered connectivity strengths and receptor densities targeted by ketamine. Theory-driven computational models offer a promising approach to integrate existing knowledge of suicidality and ketamine, and for the extraction of model-derived mechanistic parameters that can be used to identify patient subgroups and personalized treatment approaches. Future computational studies on ketamine's mechanism of action should optimize task design and modeling approaches to ensure parameter reliability, and external factors such as set and setting, as well as psychedelic-assisted therapy should be evaluated for their additional therapeutic value.

Randomized Trial of Ketamine Masked by Surgical Anesthesia in Depressed Patients

BACKGROUND

Ketamine may have antidepressant properties, but its acute psychoactive effects complicate successful masking in placebo-controlled trials.

METHODS

In a triple-masked, randomized, placebo-controlled trial, 40 adult patients with major depressive disorder were randomized to a single infusion of ketamine (0.5 mg/kg) or placebo (saline) during anesthesia as usual for routine surgery. The primary outcome was depression severity measured by the Montgomery-Åsberg Depression Rating Scale (MADRS) at 1, 2, and 3 days post-infusion. The secondary outcome was the proportion of participants with clinical response (≥50% reduction in MADRS scores) at 1, 2, and 3 days post-infusion. After all follow-up visits, participants were asked to guess which intervention they received.

RESULTS

Mean MADRS scores did not differ between groups at screening or pre-infusion baseline. The mixed-effects model showed no evidence of effect of group assignment on post-infusion MADRS scores at 1 to 3 days post-infusion (-5.82, 95% CI -13.3 to 1.64, p=0.13). Clinical response rates were similar between groups (60% versus 50% on day 1) and comparable to previous studies of ketamine in depressed populations. Secondary and exploratory outcomes did not find statistical separation of ketamine from placebo. 36.8% of participants guessed their treatment assignment correctly; both groups allocated their guesses in similar proportions. One serious adverse event occurred in each group, unrelated to ketamine administration.

CONCLUSION

In adults with major depressive disorder, a single dose of intravenous ketamine delivered during surgical anesthesia had no greater effect than placebo in acutely reducing the severity of depressive symptoms. This trial successfully masked treatment allocation in moderate-to-severely depressed patients using surgical anesthesia. While it is impractical to use surgical anesthesia for most placebo-controlled trials, future studies of novel antidepressants with acute psychoactive effects should make efforts to fully mask treatment assignment in order to minimize subject-expectancy bias. (ClinicalTrials.gov number, NCT03861988).

The Role of Psychotherapy in the Management of Treatment-Resistant Depression

This article reviews the role of psychotherapy in management of treatment-resistant depression (TRD). Meta-analyses of randomized trials show that psychotherapy has a positive therapeutic benefit in TRD. There is less evidence that one type of psychotherapy approach is superior to another. However, more trials have examined cognitive-based therapies than other forms of psychotherapy. Also reviewed is the potential combination of psychotherapy modalities and medication/somatic therapies as an approach to TRD. There is significant interest in ways that psychotherapy modalities could be combined with medication/somatic therapies to harness a state of enhanced neural plasticity and improve longer-term outcomes in mood disorders.

Rapid neuroplasticity changes and response to intravenous ketamine: a randomized controlled trial in treatment-resistant depression

Intravenous ketamine is posited to rapidly reverse depression by rapidly enhancing neuroplasticity. In human patients, we quantified gray matter microstructural changes on a rapid (24-h) timescale within key regions where neuroplasticity enhancements post-ketamine have been implicated in animal models. In this study, 98 unipolar depressed adults who failed at least one antidepressant medication were randomized 2:1 to a single infusion of intravenous ketamine (0.5 mg/kg) or vehicle (saline) and completed diffusion tensor imaging (DTI) assessments at pre-infusion baseline and 24-h post-infusion. DTI mean diffusivity (DTI-MD), a putative marker of microstructural neuroplasticity in gray matter, was calculated for 7 regions of interest (left and right BA10, amygdala, and hippocampus; and ventral Anterior Cingulate Cortex) and compared to clinical response measured with the Montgomery-Asberg Depression Rating Scale (MADRS) and the Quick Inventory of Depressive Symptoms-Self-Report (QIDS-SR). Individual differences in DTI-MD change (greater decrease from baseline to 24-h post-infusion, indicative of more neuroplasticity enhancement) were associated with larger improvements in depression scores across several regions. In the left BA10 and left amygdala, these relationships were driven primarily by the ketamine group (group * DTI-MD interaction effects: p = 0.016-0.082). In the right BA10, these associations generalized to both infusion arms (p = 0.007). In the left and right hippocampus, on the MADRS only, interaction effects were observed in the opposite direction, such that DTI-MD change was inversely associated with depression change in the ketamine arm specifically (group * DTI-MD interaction effects: p = 0.032-0.06). The acute effects of ketamine on depression may be mediated, in part, by acute changes in neuroplasticity quantifiable with DTI.

Ketamine and psychotherapy for the treatment of psychiatric disorders: systematic review

BACKGROUND

Ketamine is an effective short-term treatment for a range of psychiatric disorders. A key question is whether the addition of psychotherapy to ketamine treatment improves outcomes or delays relapse.

AIM

To identify all studies combining psychotherapy with ketamine for the treatment of psychiatric disorders to summarise their effects and make recommendations for future research.

METHOD

The review protocol was prospectively registered with PROSPERO (registration number CRD42022318120). Potential studies were searched for in MEDLINE, Embase, PsycINFO, SCOPUS, the Cochrane library and Google Scholar. Eligible studies combined ketamine and psychotherapy for the treatment of psychiatric disorders and did not use case reports or qualitative designs. Key findings relating to psychotherapy type, diagnosis, ketamine protocol, sequencing of psychotherapy and study design are reported. Risk of bias was assessed using modified Joanna Briggs critical appraisal tools.

RESULTS

Nineteen studies evaluating 1006 patients were included in the systematic review. A variety of supportive individual and group, manualised and non-manualised psychotherapies were used. The majority of studies evaluated substance use disorders, post-traumatic stress disorder and treatment-resistant depression. Ketamine protocols and sequencing of ketamine/psychotherapy treatment varied substantially between studies. Outcomes were largely positive for the addition of psychotherapy to ketamine treatment.

CONCLUSION

The combination of psychotherapy and ketamine offers promise for the treatment of psychiatric disorders, but study heterogeneity prevents definitive recommendations for their integration. Larger randomised controlled trials using manualised psychotherapies and standardised ketamine protocols are recommended to clarify the extent to which the addition of psychotherapy to ketamine improves outcomes over ketamine treatment alone.

One-Year Outcomes Following Intravenous Ketamine Plus Digital Training Among Patients with Treatment-Resistant Depression: A Secondary Analysis of a Randomized Clinical Trial

This secondary analysis of a randomized clinical trial examines whether automated self-association training can prolong the antidepressant effect of a single infusion of ketamine beyond 1 month in patients with treatment-resistant depression.

Intravenous ketamine for treatment-resistant depression patients who have failed to respond to transcranial magnetic stimulation: A case series

BACKGROUND

For individuals with treatment-resistant depression (TRD), transcranial magnetic stimulation (TMS) has become a well-established approach. In the past decade, intravenous (IV) racemic ketamine has also emerged as a potential treatment for TRD. Currently, little data is available on the clinical effects of IV racemic ketamine in TRD patients who experienced TMS-failure.

METHODS

Twenty-one (21) TRD patients who had failed to respond to a standard course of high-frequency left-dorsolateral prefrontal cortex TMS were subsequently scheduled to received IV racemic ketamine infusions. The IV racemic ketamine protocol consisted of 0,5 mg/kg infusions over 60 min, 3 times a week over 2 weeks.

RESULTS

Treatment was safe with minimal side-effects. Mean baseline MADRS score was 27.6 ± 6.4 (moderate depression), decreasing down to 18.6 ± 8.9 (mild depression) post-treatment. Mean percent improvement was 34.5 % ± 21.1 from baseline to post-treatment. Paired sample t-test showed significant MADRS score decrease pre- to post-treatment [t(20) = 7.212, p < .001]. Overall, four (4) patients (19.0 %) responded and two (2) of those achieved remission (9.5 %).

LIMITATIONS

Limitations of this case series include its retrospective and uncontrolled open-label nature, the lack of self-rating and standardized adverse events questionnaires, as well as follow-ups beyond the immediate treatment period.

CONCLUSIONS

Novel ways to increase the clinical effects of ketamine are being explored. We discuss potential combination approaches of ketamine with other modalities to augment its effects. Given the global burden of TRD, novel approaches are needed to curb the current mental health epidemic around the world.

Pharmacotherapies for Treatment-Resistant Depression: How Antipsychotics Fit in the Rapidly Evolving Therapeutic Landscape

One in three adults with major depressive disorder (MDD) do not experience clinically significant improvement after multiple sequential courses of antidepressants and have treatment-resistant depression (TRD). The presence of TRD contributes to the morbidity and excess mortality associated with MDD and has been linked to significantly increased health care expenses. In the absence of a consensus definition of TRD, this report takes a broad approach by considering inadequate response to one or more courses of antidepressants and focuses on atypical antipsychotics that are approved by the U.S. Food and Drug Administration for treatment of depression (aripiprazole, brexpiprazole, cariprazine, extended-release quetiapine, and olanzapine-fluoxetine combination). While multiple acute-phase studies have demonstrated the efficacy of these medications in improving depressive symptoms, clinically meaningful improvement (i.e., remission) remains limited, with significant concerns about side effects (including weight gain, metabolic dysfunction, extrapyramidal symptoms, and tardive dyskinesia), especially with long-term use. With the rapidly evolving landscape of antidepressant treatments over the past few years, which has witnessed approval of rapid-acting antidepressants (e.g., esketamine nasal spray and dextromethorphan-bupropion combination) and several more in the late-stage pipeline (e.g., zuranolone and psilocybin), it remains to be seen whether the use of atypical antipsychotics will go the way of the older and rarely prescribed antidepressants (such as tricyclics and monoamine oxidase inhibitors). Pragmatic clinical trials are needed to compare the effectiveness of atypical antipsychotics with TRD-specific pharmacotherapies and neuromodulation treatments and to identify the optimal sequencing of these varied approaches for patients with MDD. When using atypical antipsychotics, clinicians and patients are encouraged to use a shared decision-making approach by personalizing treatment selection based on anticipated side effects, tolerability, cost, and feasibility.

The update of self-identity: Importance of assessing autobiographical memory in major depressive disorder

Major depressive disorder is a leading global cause of disability. There is a growing interest for memory in mood disorders since it might constitute an original tool for prevention, diagnosis, and treatment. MDD is associated with impaired autobiographical memory characterized by a tendency to overgeneral memory, rather than vivid episodic self-defining memory, which is mandatory for problem-solving and projection in the future. This memory bias is maintained by three mechanisms: ruminations, avoidance, and impaired executive control. If we adopt a broader and comprehensive perspective, we can hypothesize that all those alterations have the potential to impair self-identity updating. We posit that this update requires a double referencing process: (1) to internalized self-representation and (2) to an externalized framework dealing with the representation of the consequence of actions. Diagnostic and therapeutic implications are discussed in the light of this model and the importance of assessing autobiographical memory in MDD is highlighted. This article is categorized under: Psychology > Memory Psychology > Brain Function and Dysfunction Neuroscience > Clinical.