Treatment-resistant depression: molecular mechanisms and management.

Due to the heterogeneous nature of depression, the underlying etiological mechanisms greatly differ among individuals, and there are no known subtype-specific biomarkers to serve as precise targets for therapeutic efficacy. The extensive research efforts over the past decades have not yielded much success, and the currently used first-line conventional antidepressants are still ineffective for close to 66% of patients. Most clinicians use trial-and-error treatment approaches, which seem beneficial to only a fraction of patients, with some eventually developing treatment resistance. Here, we review evidence from both preclinical and clinical studies on the pathogenesis of depression and antidepressant treatment response. We also discuss the efficacy of the currently used pharmacological and non-pharmacological approaches, as well as the novel emerging therapies. The review reveals that the underlying mechanisms in the pathogenesis of depression and antidepressant response, are not specific, but rather involve an interplay between various neurotransmitter systems, inflammatory mediators, stress, HPA axis dysregulation, genetics, and other psycho-neurophysiological factors. None of the current depression hypotheses sufficiently accounts for the interactional mechanisms involved in both its etiology and treatment response, which could partly explain the limited success in discovering efficacious antidepressant treatment. Effective management of treatment-resistant depression (TRD) requires targeting several interactional mechanisms, using subtype-specific and/or personalized therapeutic modalities, which could, for example, include multi-target pharmacotherapies in augmentation with psychotherapy and/or other non-pharmacological approaches. Future research guided by interaction mechanisms hypotheses could provide more insights into potential etiologies of TRD, precision biomarker targets, and efficacious therapeutic modalities.

Efficacy and Safety of Ketamine/Esketamine in Bipolar Depression in a Clinical Setting.

Background: Bipolar disorder represents a significant source of morbidity and elevated mortality risk. Ketamine has emerged as a powerful antidepressant; however, there have been few trials of ketamine in bipolar depression and no trials with esketamine in bipolar depression, and few data exist from real-world settings. Here, we report outcomes from a cohort of patients with bipolar depression treated with ketamine/ esketamine in a real-world setting.Methods: Patients with treatment refractory bipolar depression were referred to Yale Psychiatric Hospital Interventional Services for treatment from October 2014 to November 2023. Appropriate patients were treated with intravenous (IV) ketamine (0.5 mg/kg over 40 minutes) or intranasal esketamine (56 or 84 mg). Diagnosis of bipolar depression was done by clinical evaluation by an attending psychiatrist, based on DSM criteria. Clinical outcomes were tabulated from medical records.Results: Overall, 45 patients with bipolar depression were treated with IV ketamine or intranasal (IN) esketamine during the time period specified. Depression severity outcomes were available for 38 patients that completed an acute series, defined as treatment twice weekly for up to 4 weeks. Overall, 15/38 (39%) achieved clinical response (≥50% improvement on the Montgomery-Asberg Depression Rating Scale [MADRS]) and 5/38 (13.2%) achieved remission (≤10 on MADRS) following the acute series. Mean MADRS scores decreased from 31.1 to 19.2 (38.3% mean improvement). Safety data (hypomania/manic symptoms) were available for all 45 patients (518 patient-months of follow-up). No patients experienced any mania/hypomania during the acute series phase (when treatments are given twice weekly). However, 13/45 (28.9%) patients experienced symptoms consistent with a hypomanic or manic episode at some point following the acute phase while continuing to receive ketamine or esketamine during a maintenance phase. There were 16 manic/hypomanic events, indicating 1 event for every 2.7 patient-years. Only 1 event was severe and resulted in hospitalization.Conclusion: In a small sample of patients with bipolar depression treated with ketamine/esketamine, no evidence of mania/hypomania was seen during the acute phase of treatment. Further research is needed to evaluate whether ketamine or esketamine confers heightened risk of affective switch during maintenance treatment.

Ketamine and chronic treatment-resistant depression: real-world practice and after relapse.

BACKGROUND: Chronic treatment-resistant depression (TRD) poses a major challenge for clinicians. Ketamine has shown a rapid but short-lived antidepressant effect in several studies involving TRD patients with different demographic and clinical profiles. Our study aimed to assess the antidepressant effect of serial infusion sessions of ketamine in patients with chronic TRD and evaluate the severity of symptoms after relapse and the general psychiatric health of the responding patients. METHODS: In this single arm open-label study, six infusions of ketamine at 0.5 mg/kg were administered to chronic TRD patients for approximately two weeks. Response and remission rates, side effects, adverse events and after-relapse symptoms were evaluated, and patients were followed for three months. RESULTS: 23 patients underwent at least one infusion session, and 18 patients completed the six sessions. Twelve (66.67%) patients responded to the treatment at some point, and 11 (61.11%) patients maintained response after the end of the treatment protocol. One infusion was not sufficient to achieve a response (P > 0.9999, z = 1.81), and more than half of the responders met the response criteria after the third infusion. Only one patient (5.56%) achieved remission at the end of the infusion phase. All but one ketamine responders relapsed within one month after the end of the treatment. There was no statistical difference between baseline and after-relapse MADRS scores (P = 0.7886, 95% CI=-5.512-4.312, R2 = 0,008411). However, a high incidence of serious adverse events related to suicidality was evident; one of the non-responding patients attempted suicide and several attempts to sedate this patient with benzodiazepines failed. Two responding patients ended up with a suicidal attempt or severe suicidal thoughts. CONCLUSIONS: Introducing rapid-acting antidepressant to manage TRD patients in clinical practice demands further investigation, and the benefit-to-harm ratio should be assessed in the light of the increased risk of suicidality.

Effects of ketamine on metabolic parameters in depressive disorders: A systematic review.

BACKGROUND: Persons with Major Depressive Disorder (MDD), notably treatment-resistant depression (TRD), are differentially affected by type 2 diabetes mellitus and associated morbidity. Ketamine is highly efficacious in the treatment of adults living with MDD, notably TRD. Herein, we sought to determine the effect of ketamine on metabolic parameters in animal stress paradigms and human studies. METHODS: We performed a comprehensive search on PubMed, OVID, and Scopus databases for primary research articles from inception to May 5, 2024. Study screening and data extraction were performed by two reviewers (S.W. and G.H.L.). Both preclinical and clinical studies were included in this review. RESULTS: Results from the preclinical studies indicate that in experimental diabetic conditions, ketamine does not disrupt glucose-insulin homeostasis. Within adults with MDD, ketamine is associated with GLUT3 transporter upregulation and differentially affects metabolomic signatures. In adults with TRD, ketamine induces increased brain glucose uptake in the prefrontal cortex. Available evidence suggests that ketamine does not adversely affect metabolic parameters. LIMITATIONS: There are a paucity of clinical studies evaluating the effects of ketamine on glucose-insulin homeostasis in adults with MDD. CONCLUSIONS: Our results indicate that ketamine is not associated with significant and/or persistent disruptions in metabolic parameters. Available evidence indicates that ketamine does not adversely affect glucose-insulin homeostasis. These results underscore ketamine's efficacy and safety as an antidepressant treatment that is not associated with metabolic disturbances commonly reported with current augmentation therapies.

Interventional approaches to treatment resistant depression (DTR) in children and adolescents: A systematic review and meta-analysis.

BACKGROUND: Major depressive disorder (MDD) is highly prevalent in youth. Conventional treatment paradigms primarily involve selective serotonin reuptake inhibitors (SSRIs) and psychotherapy, yet a significant proportion of this population exhibits treatment-resistant depression (TRD). In adults, interventional therapies like Electroconvulsive Therapy (ECT), repetitive Transcranial Magnetic Stimulation (rTMS), and ketamine have shown promise for TRD, but their comparative efficacy remains underexplored in Adolescent and pediatric population. This systematic review and meta-analysis aims to assess the relative effectiveness of ECT, rTMS, and ketamine in treating TRD among adolescents. METHODS: Following PRISMA guidelines, we systematically searched databases for studies of ECT, rTMS, or ketamine for treatment-resistant depression in youth ages 10-24. Three reviewers independently screened for inclusion based on predefined criteria. Included observational and randomized controlled trials reported depression symptoms with measures like HDRS and MADRS in youth treated with ECT, rTMS, or ketamine. Two reviewers extracted data on interventions, patients, and depression symptom outcomes. Chance-adjusted inter-reviewer agreement was calculated. For meta-analysis, we pooled standardized mean differences (SMDs) in depression scores using random effects models and assessed heterogeneity with I2 statistics. RESULTS: Meta-analysis of 10 observational studies examined SMD in depression scores for treatment resistant depression patients treated with ECT, ketamine, or rTMS. Patients treated with ECT had a significantly lower SMD of 1.99 (95 % CI 0.92-3.05, p < 0.001) compared to baseline. Patients treated with ketamine also had a significantly lower SMD of 1.58 (95 % CI 1.04-2.12, p < 0.001). Patients treated with rTMS had the lowest SMD of 2.79 (95 % CI 0.79-4.80, p = 0.006). There was no significant difference between the three groups overall (p > 0.05). Comparative analysis between ECT and ketamine found no significant difference in SMD (p = 0.387). Comparison of ECT versus rTMS found a significant difference in SMD favoring rTMS (p = 0.004). Comparison of ketamine versus rTMS suggested a potential difference in SMD favoring rTMS (p = 0.058). In summary, rTMS resulted in significantly larger reductions in depression scores than ECT, and potentially larger reductions than ketamine. CONCLUSIONS: This meta-analysis illustrates the ability of rTMS, ECT, and ketamine to improve depression in youth. rTMS resulted in the largest improvements, highlighting its potential as a first-line treatment for pediatric treatment-resistant depression given its favorable side effect profile compared to ECT. Further research directly comparing these modalities is needed.

Exploring vortioxetine combination with intranasal esketamine: A feasible alternative to SSRI/SNRI? - Insights from the REAL-ESK study.

BACKGROUND: Treatment-Resistant Depression (TRD) affects almost 30 % of patients with Major Depressive Disorder (MDD). Esketamine Nasal Spray (ESK-NS) has recently been approved for TRD in combination with a Serotonin Specific Reuptake Inhibitor/SSRI or a Serotonin-Norepinephrine Reuptake Inhibitor/SNRI. There is a lack of studies investigating the effectiveness and safety of ESK-NS in combination with other oral antidepressants. AIM: To assess the efficacy of Vortioxetine plus ESK-NS in mitigating depressive symptoms and emotional blunting, as well as its tolerability in TRD subjects, compared to the standard-of-care of SSRI/SNRI plus ESK-NS. METHODS: We conducted a post-hoc analysis of the REAL-ESK study. The study included twenty TRD patients, ten subjects taking Vortioxetine as the main oral antidepressant with ESK-NS, and ten subjects taking SSRI or SNRI with ESK-NS. Psychometric assessments (Montgomery-Åsberg Depression Rating Scale/MADRS, Brief Psychiatric Rating Scale/BPRS) were conducted at baseline(T0), one month(T1), and three months after the treatment initiation(T2). RESULTS: The combination of Vortioxetine and ESK-NS was as effective as the standard-of-care in reducing depressive symptoms, with a higher effect size in reducing emotional blunting at T2. The safety and tolerability profile of the Vortioxetine+ESK-NS combination appeared to be better, with a lower rate of treatment-emergent adverse events. CONCLUSION: The combination of Vortioxetine and ESK-NS may be a valuable alternative to the standard-of-care SSRI/SNRI plus ESK-NS in TRD patients, particularly regarding the reduction of emotional blunting and potentially a better safety and tolerability profile. Further randomized controlled trials with larger sample sizes and prospective designs are needed to confirm these findings.

Is lack of goal-conflict-specific rhythmicity a biomarker for treatment resistance in generalised anxiety but not social anxiety or major depression?

BACKGROUND: Anxiety and depression cause major detriment to the patient, family, and society - particularly in treatment-resistant (TR) cases, which are highly prevalent. TR prevalence may be due to current diagnoses being based not on biological measures but on symptom lists that suffer from clinical subjectivity, variation in symptom presentation, and comorbidity. AIMS: Goal-conflict-specific rhythmicity (GCSR) measured using the Stop-Signal Task (SST) may provide the first neural biomarker for an anxiety process and disorder. This GCSR has been validated with selective drugs for anxiety. So, we proposed that GCSR could differ between TR and non-TR individuals and do so differently between those diagnoses normally sensitive to selective anxiolytics and those not. METHODS: We recorded electroencephalograms (EEG) from 20 TR participants (4 GAD, 5 SAD and 11 MDD) and 24 non-TR participants (4 GAD, 5 SAD and 15 Comorbid GAD/MDD (GMD)) while they performed the SST. RESULTS: There was significant positive GCSR in all groups except the GAD-TR group. GAD-TR lacked GCSR in the low-frequency range. However, TR had little effect in SAD or MDD/GMD populations with apparent increases not decreases. CONCLUSIONS: Overall, these results suggest that GAD may occur in two forms: one resulting from excessive GCSR and so being drug sensitive, and the other resulting from some other mechanism and so being TR. In SAD and MDD groups, heightened GCSR could be a consequence rather than the cause, driven by mechanisms that are normally more sensitive to non-selective panicolytic antidepressants.

Efficacy, Safety, and Tolerability of Psychedelics in Treatment-Resistant Depression (TRD).

Major depressive disorder (MDD) is a highly prevalent psychiatric disorder, associated with substantial burden and large economical costs. Notwithstanding various conventional antidepressant treatment options, a large portion of depressed people (ca. 30%) fails to respond to first-line treatment, resulting in treatment-resistant depression (TRD). Although non-response to multiple antidepressant interventions is a common outcome, a consensus definition of TRD is not yet available. In practice, TRD is applied when two or more successive treatments with different antidepressants are not working. The last decade's intense research into new medicines for TRD has led to two developments, using typical or serotonergic (psilocybin, ayahuasca) and atypical (glutamatergic) psychedelics (ketamine, esketamine). Both approaches, although via different entrance mechanism, exhibit a fast onset but also long-lasting antidepressant effect far beyond the biological presence of the drug in the body, strongly indicating that downstream mechanisms activated by signaling cascades in the brain are involved. The present chapter describes the clinical development of psilocybin and esketamine for TRD and discusses the problems involved in the use of a proper placebo because of the psychotomimetic (psilocybin) or dissociative (ketamine) effects that interfere with performing "blind" studies. Nevertheless, intranasal esketamine was developed and approved for TRD, whereas psilocybin has shown positive results. Adverse effects and tolerability of both drugs in the dose ranges used are generally acceptable. The emergence of anti-TRD medicines for treatment of a very severe disease is a breakthrough in psychiatry.

Suicidality is most centrally situated within network of depression symptom criteria in unipolar depression patients with mood stabilizer in Asia.

Lithium and mood stabilizers are considered effective augmentation agents of antidepressants for treatment-resistant depression. Thus, this study aimed to estimate the network structure of depression symptom criteria among unipolar depression patients with mood stabilizers, using data from the Research on Asian Psychotropic Prescription Patterns for mood stabilizers (REAP-MS). We estimated a network of the 9 depression symptom criteria among 411 unipolar depression patients in Asia. Each of the depression symptom criteria was considered to be a dichotomous categorical variable. Suicidality (suicidal ideation or attempt) was the most centrally situated within the network of depression symptoms, followed by depressed mood, loss of energy, anhedonia and weight loss or gain. Contrastingly, concentration problem was the least interconnected. The depression symptom criteria were organized into 4 clusters by the community detection method. The findings suggest that suicidality may be one of the significant therapeutic target symptoms in unipolar depression patients with mood stabilizers.

Efficacy of pentoxifylline for the treatment of bipolar I/II patients with treatment-resistant depression: A proof-of-concept, randomized, double-blind, placebo-controlled trial.

BACKGROUND: Immune dysregulation can play a role in depression pathophysiology, and immunological antagonists can improve depressive symptoms in treatment-resistant bipolar depression (TRD) patients according to studies. OBJECTIVE: To evaluate the anti-depressant effects of the anti-inflammatory drug, pentoxifylline (PTX) in TRD bipolar I/II adult subjects. METHODS: This 12-week, randomized, double-blind, placebo-controlled, parallel-group trial of 60 participants was conducted at Hawler Psychiatric Hospital and Private Clinic in Erbil, Iraq. Participants were confirmed as being qualified for bipolar I/II depression based on DSM-5 criteria. Data were analyzed using modified intent-to-treat analysis. RESULTS: There were no significant differences between the two groups in Hamilton Rating Scale for Depression-17 (HAM-D-17) scores (χ2=1.9, P =.48) or a significant time × treatment interaction (χ2=7.1, P=.54). Nevertheless, a significant effect of time was observed with both groups' reduction in HAM-D-17 scores from the start to the endpoint (χ2= 2.11, P=.002). Besides, a significant time × treatment × CRP interaction was found (χ2=3.1, P=0.016), where there was more reduction in HAM-D-17 score in PTX-treated subjects with CRP> 7.1 mg/L. The response rate difference between PTX and the placebo group did not reach a significance level (χ2=0.84, p=0.43). Furthermore, serum concentrations of TNF-α, CRP, and IL-6 significantly reduced at week 12 in the PTX group (P=.007,.04, and <.001, respectively). CONCLUSION: The current proof of concept study found that in terms of overall anti-depressant effectiveness in bipolar patients with TRD, PTX is not superior to placebo. However, it may improve depressive mood in a subpopulation of subjects with a higher pretreatment inflammatory profile.

Neurocognitive changes in a patient receiving esketamine for treatment-resistant depression.

ABSTRACT: Esketamine, the s(+) enantiomer of ketamine, was approved in 2019 as the first rapid-acting intranasal spray medication for treatment-resistant depression; the drug is given in combination with an antidepressant. The treatment is self-administered in a clinical setting under the supervision of a healthcare provider and usually is well tolerated. Many of its adverse reactions are mild, temporary, and dose-dependent, and they improve with subsequent treatments. Although the prescribing information lists difficulty remembering or thinking as possible adverse reactions, a neurocognitive evaluation is not part of the initial patient evaluation. This case report focuses on a patient whose neurocognitive symptoms worsened with esketamine treatment, necessitating treatment discontinuation.

Intra- and Inter-Network connectivity of the default mode network differentiates Treatment-Resistant depression from Treatment-Sensitive depression.

Understanding why some patients with depression remain resistant to antidepressant medication could be elucidated by investigating their associated neural features. Although research has consistently demonstrated abnormalities in the anterior cingulate cortex (ACC) - a region that is part of the default mode network (DMN) - in treatment-resistant depression (TRD), a considerable research gap exists in discerning how these neural networks distinguish TRD from treatment-sensitive depression (TSD). We aimed to evaluate the resting-state functional connectivity (rsFC) of the ACC with other regions of the DMN to better understand the role of this structure in the pathophysiology of TRD. 35 TRD patients, 35 TSD patients, and 38 healthy controls (HC) underwent a resting-state functional MRI protocol. Seed-based functional connectivity analyses were performed, comparing the three groups for the connectivity between two subregions of the ACC (the subgenual ACC (sgACC) and the rostral ACC (rACC)) and the DMN (p < 0.05 FWE corrected). Furthermore, inter-network connectivity of the DMN with other neural networks was explored by independent component (ICA) analyses (p < 0.01, FDR corrected). The results demonstrated hyperconnectivity between the rACC and the posterior cingulate cortex in TRD relative to TSD and HC (F(2,105) = 5.335, p < 0.05). ICA found DMN connectivity to regions of the visual network (TRDTSD), differentiating the two clinical groups. These results provide confirmatory evidence of DMN hyperconnectivity and preliminary evidence for its interactions with other neural networks as key neural mechanisms underlying treatment non-responsiveness.

rTMS as a Next Step in Antidepressant Nonresponders: A Randomized Comparison With Current Antidepressant Treatment Approaches.

OBJECTIVE: Although repetitive transcranial magnetic stimulation (rTMS) is an effective treatment for depression, little is known about the comparative effectiveness of rTMS and other treatment options, such as antidepressants. In this multicenter randomized controlled trial, rTMS was compared with the next pharmacological treatment step in patients with treatment-resistant depression. METHODS: Patients with unipolar nonpsychotic depression (N=89) with an inadequate response to at least two treatment trials were randomized to treatment with rTMS or to a switch of antidepressants, both in combination with psychotherapy. Treatment duration was 8 weeks and consisted of either 25 high-frequency rTMS sessions to the left dorsolateral prefrontal cortex or a switch of antidepressant medication following the Dutch treatment algorithm. The primary outcome was change in depression severity based on the Hamilton Depression Rating Scale (HAM-D). Secondary outcomes were response and remission rates as well as change in symptom dimensions (anhedonia, anxiety, sleep, rumination, and cognitive reactivity). Finally, expectations regarding treatment were assessed. RESULTS: rTMS resulted in a significantly larger reduction in depressive symptoms than medication, which was also reflected in higher response (37.5% vs. 14.6%) and remission (27.1% vs. 4.9%) rates. A larger decrease in symptoms of anxiety and anhedonia was observed after rTMS compared with a switch in antidepressants, and no difference from the medication group was seen for symptom reductions in rumination, cognitive reactivity, and sleep disorders. Expectations regarding treatment correlated with changes in HAM-D scores. CONCLUSIONS: In a sample of patients with moderately treatment-resistant depression, rTMS was more effective in reducing depressive symptoms than a switch of antidepressant medication. In addition, the findings suggest that the choice of treatment may be guided by specific symptom dimensions.

IN Esketamine and IV Ketamine: Results of a multi-site observational study assessing the effectiveness and tolerability of two novel therapies for treatment-resistant depression.

Intravenous (IV) ketamine and intranasal (IN) esketamine are novel therapies to manage treatment resistant depression within major depressive disorder (MDD-TRD). This is a multi-site observational study aiming to assess the real-world effectiveness and tolerability of these novel therapies in the management of MDD-TRD. 53 patients were referred to receive IV ketamine (n = 26, 69.23 % female, 52.81 ± 14.33 years old) or IN esketamine (n = 27, 51.85 % female, 43.93 ± 13.57 years old). Treatment effectiveness was assessed using the Montgomery and Åsberg Depression Rating Scale (MADRS) for depression severity and item 10 of the MADRS for suicidal ideation (SI). Tolerability was assessed by systematically tracking side effects and depersonalization using the 6-item Clinician administered dissociative symptom scale (CADSS-6). The data was analyzed using descriptive statistics, risk ratio and effect size. Both IV ketamine and IN esketamine significantly reduced depressive symptoms and suicidal ideation by treatment endpoint. Patients receiving IN esketamine, and patients receiving IV ketamine had a similar risk of developing side effects. All side effects reported were mild and transient. These results suggested that both IV ketamine and IN esketamine are effective in the management of depressive symptoms and were well tolerated. Therefore, the results of this study could serve to inform clinical practice.

Effect of Genetic Polymorphisms of ABCB1, ABCG2, and SLC22A1 on the Steady-State Plasma Concentrations of Lamotrigine in Treatment-Resistant Depressed Patients Treated With Lamotrigine Augmentation Therapy.

OBJECTIVES: The authors have demonstrated that a plasma lamotrigine concentration of 12.7 µmol/L may be a threshold for a good therapeutic response to lamotrigine augmentation therapy in treatment-resistant depressed patients. Lamotrigine is a substrate of P-glycoprotein, breast cancer resistant protein and organic cation transporter 1, which are encoded by ABCB1 , ABCG2 , and SLC22A1 , respectively. There have been several polymorphisms that affect its function. The present study investigated the relationship between these polymorphisms and the steady-state plasma concentrations (Css) of lamotrigine in treatment-resistant depressed patients receiving lamotrigine as augmentation therapy. METHODS: One hundred twenty-nine treatment-resistant depressed patients were included in this study. Treatment resistance is defined as lack of therapeutic response to at least 3 psychotropics despite adequate doses and duration. Their diagnoses were as follows: major depressive disorder (n = 58), bipolar II disorder (n = 52), and bipolar I disorder (n = 19). Lamotrigine augmentation therapy for 8 weeks was conducted. The final lamotrigine doses were 75 mg/d for 39 patients with valproate and 100 mg/d for 90 without it. Blood was sampled at 8:00 am after the 8th week of treatment. Plasma lamotrigine levels were quantified by using LC/MS/MS. The polymorphisms of ABCB1 1236C>T, 2677G>T/A, 3435C>T, ABCG2 421C>A, and SLC22A1 1222G>A were detected by polymerase chain reaction analyses. RESULTS: No significant relationships were observed between these polymorphisms and the Css of lamotrigine in the patients with or without valproate. CONCLUSIONS: The present study suggests that these genetic polymorphisms do not play a role in controlling the Css of lamotrigine in treatment-resistant depressed patients treated with lamotrigine augmentation therapy.

Raynaud's phenomenon on initiation of Lithium therapy: a case report.

Lithium Carbonate is an effective treatment for affective disorders, but has a range of side effects. This case report highlights a rare side effect of Raynaud's phenomenon following initiation of Lithium therapy in a patient with recurrent depressive disorder. He was commenced on Lithium therapy to treat severe treatment resistant depression with psychotic symptoms when alternative treatments trialled were ineffective. He had no other risk factors or known aetiological causes for development of Raynaud's phenomenon. Symptoms resolved on discontinuation of Lithium and re-emerged on recommencement. Previous case series have shown Lithium effectively treating vasospastic disorders such as cluster headache and Raynaud's phenomenon. However, a paradoxical reaction to those previously described was induced in this case.

Neural correlates of treatment response to ketamine for treatment-resistant depression: A systematic review of MRI-based studies.

Treatment-resistant depression (TRD) is defined as patients diagnosed with depression having a history of failure with different antidepressants with an adequate dosage and treatment duration. The NMDA receptor antagonist ketamine rapidly reduces depressive symptoms in TRD. We examined neural correlates of treatment response to ketamine in TRD through a systematic review of brain magnetic resonance imaging (MRI) studies. A comprehensive search in PubMed was performed using "ketamine AND depression AND magnetic resonance." The time span for the database queries was "Start date: 2018/01/01; End date: 2024/05/31." Total 41 original articles comprising 1,396 TRD and 587 healthy controls (HC) were included. Diagnosis of depression was made using the Structured Clinical Interview for DSM Disorders (SCID), the Mini-International Neuropsychiatric Interview (MINI), and/or the clinical assessment by psychiatrists. Patients with affective psychotic disorders were excluded. Most studies applied ketamine [0.5mg/kg racemic ketamine and/or 0.25mg/kg S-ketamine] diluted in 60cc of normal saline via intravenous infusion over 40 min one time, four times, or six times spaced 2-3 days apart over 2 weeks. Clinical outcome was defined as either remission, response, and/or percentage changes of depressive symptoms. Brain MRI of the T2*-weighted imaging (resting-state or task performance), arterial spin labeling, diffusion weighted imaging, and T1-weighted imaging were acquired at baseline and mainly 1-3days after the ketamine administration. Only the study results replicated by ≥ 2 studies and were included in the default-mode, salience, fronto-parietal, subcortical, and limbic networks were regarded as meaningful. Putative brain-based markers of treatment response to ketamine in TRD were found in the structural/functional features of limbic (subgenual ACC, hippocampus, cingulum bundle-hippocampal portion; anhedonia/suicidal ideation), salience (dorsal ACC, insula, cingulum bundle-cingulate gyrus portion; thought rumination/suicidal ideation), fronto-parietal (dorsolateral prefrontal cortex, superior longitudinal fasciculus; anhedonia/suicidal ideation), default-mode (posterior cingulate cortex; thought rumination), and subcortical (striatum; anhedonia/thought rumination) networks. Brain features of limbic, salience, and fronto-parietal networks could be useful in predicting the TRD with better response to ketamine in relief of anhedonia, thought rumination, and suicidal ideation.

Predicting treatment response to ketamine in treatment-resistant depression using auditory mismatch negativity: Study protocol.

BACKGROUND: Ketamine has recently attracted considerable attention for its rapid effects on patients with major depressive disorder, including treatment-resistant depression (TRD). Despite ketamine's promising results in treating depression, a significant number of patients do not respond to the treatment, and predicting who will benefit remains a challenge. Although its antidepressant effects are known to be linked to its action as an antagonist of the N-methyl-D-aspartate (NMDA) receptor, the precise mechanisms that determine why some patients respond and others do not are still unclear. OBJECTIVE: This study aims to understand the computational mechanisms underlying changes in the auditory mismatch negativity (MMN) response following treatment with intravenous ketamine. Moreover, we aim to link the computational mechanisms to their underlying neural causes and use the parameters of the neurocomputational model to make individual treatment predictions. METHODS: This is a prospective study of 30 patients with TRD who are undergoing intravenous ketamine therapy. Prior to 3 out of 4 ketamine infusions, EEG will be recorded while patients complete the auditory MMN task. Depression, suicidality, and anxiety will be assessed throughout the study and a week after the last ketamine infusion. To translate the effects of ketamine on the MMN to computational mechanisms, we will model changes in the auditory MMN using the hierarchical Gaussian filter, a hierarchical Bayesian model. Furthermore, we will employ a conductance-based neural mass model of the electrophysiological data to link these computational mechanisms to their neural causes. CONCLUSION: The findings of this study may improve understanding of the mechanisms underlying response and resistance to ketamine treatment in patients with TRD. The parameters obtained from fitting computational models to EEG recordings may facilitate single-patient treatment predictions, which could provide clinically useful prognostic information. TRIAL REGISTRATION: Clinicaltrials.gov NCT05464264. Registered June 24, 2022.

Entactogen Effects of Ketamine: A Reverse-Translational Study.

OBJECTIVE: The authors sought to assess the prosocial, entactogen effects of ketamine. METHODS: Pleasure from social situations was assessed in a sample of participants with treatment-resistant depression from randomized, double-blind, placebo-controlled studies, using four items of the Snaith-Hamilton Pleasure Scale (SHAPS) at five time points over 1 week following treatment with ketamine (0.5 mg/kg intravenously) or placebo. The primary endpoint was postinfusion self-reported pleasure on the four SHAPS items pertaining to social situations, including the item on helping others, between the ketamine and placebo groups. In a rodent experiment, the impact of ketamine on helping behavior in rats was assessed using the harm aversion task. The primary endpoint was a reduction in lever response rate relative to baseline, which indicated the willingness of rats to forgo obtaining sucrose to help protect their cage mate from electric shock. RESULTS: Relative to placebo, ketamine increased ratings of feeling pleasure from being with family or close friends, seeing other people's smiling faces, helping others, and receiving praise, for 1 week following treatment. In the rodent experiment, during the harm aversion task, ketamine-treated rats maintained lower response rates relative to baseline to a greater extent than what was observed in vehicle-treated rats for 6 days posttreatment and delivered fewer shocks overall. CONCLUSIONS: In patients with treatment-resistant depression, ketamine treatment was associated with increased pleasure from social situations, such as feeling pleasure from helping others. Ketamine-treated rats were more likely to protect their cage mate from harm, at the cost of obtaining sucrose. These findings suggest that ketamine has entactogen effects.

Treatment-emergent symptoms during short-term ketamine administration in treatment-resistant bipolar depression: A retrospective cross-sectional descriptive study.

Symptoms that emerge during pharmacological treatment of bipolar depression are frequently observed, underscoring the necessity for comprehensive treatment monitoring. This observational study sought to observe the correlation of eight intravenous ketamine infusions with treatment-emergent depressive symptoms in treatment-resistant bipolar depression patients who maintained their baseline psychotropic and chronic somatic treatments. Depressive symptoms were evaluated using the Inventory of Depressive Symptomatology Self-Report 30 (IDS-SR30). Treatment-emergent symptoms TES were defined as symptoms absent at baseline but present at the conclusion of the study. The most common TES included decreased appetite, increased weight, hypersomnia, and diurnal mood variation. Conversely, feelings of sadness, altered perceptions of the future, decreased interest in sex, and physical discomfort were absent in all patients. Notably, 13.6 % of patients reported thoughts of death or suicide. Larger-scale studies, integrating clinician-rated and patient-reported outcome measures, are essential to deepen our understanding of treatment-emergent symptoms. Establishing regulatory or professional definitions for treatment-emergent symptoms is warranted to improve the robustness of future research endeavors.