Treatment-resistant depression: therapeutic trends, challenges, and future directions

Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological, pre-clinical and clinical activities

ETHNOPHARMACOLOGICAL RELEVANCE

Sceletium tortuosum (L.) N.E.Br., the most sought after and widely researched species in the genus Sceletium is a succulent forb endemic to South Africa. Traditionally, this medicinal plant is mainly masticated or smoked and used for the relief of toothache, abdominal pain, as a mood-elevator, analgesic, hypnotic, anxiolytic, thirst and hunger suppressant, and for its intoxicating/euphoric effects. Sceletium tortuosum is currently of widespread scientific interest due to its clinical potential in treating anxiety and depression, relieving stress in healthy individuals, and enhancing cognitive functions. These pharmacological actions are attributed to its phytochemical constituents referred to as mesembrine-type alkaloids.

AIM OF THE REVIEW

The aim of this review was to comprehensively summarize and critically evaluate recent research advances on the phytochemistry, pharmacokinetics, biological, pre-clinical and clinical activities of the medicinal plant S. tortuosum. Additionally, current ongoing research and future perspectives are also discussed.

METHODS

All relevant scientific articles, books, MSc and Ph.D. dissertations on botany, behavioral pharmacology, traditional uses, and phytochemistry of S. tortuosum were retrieved from different databases (including Science Direct, PubMed, Google Scholar, Scopus and Web of Science). For pharmacokinetics and pharmacological effects of S. tortuosum, the focus fell on relevant publications published between 2009 and 2021.

RESULTS

Twenty-five alkaloids belonging to four structural classes viz: mesembrine, Sceletium A4, joubertiamine, and tortuosamine, have been identified from S. tortuosum, of which the mesembrine class is predominant. The crude extracts and commercially available standardized extracts of S. tortuosum have displayed a wide spectrum of biological activities (e.g. antimalarial, anti-oxidant, neuromodulatory, immunomodulatory, anti-HIV, neuroprotection) in in vitro or in vivo studies. While the plant has been studied in clinical populations, this has only been in healthy subjects, so that further study in pathological states remains to be done. Nevertheless, the aforementioned studies have demonstrated that S. tortuosum has potential for enhancing cognitive function and managing anxiety and depression.

CONCLUSION

As an important South African medicinal plant, S. tortuosum has garnered many research advances on its phytochemistry and biological activities over the last decade. These scientific studies have shown that S. tortuosum has various bioactivities. The findings have further established the link between the phytochemistry and pharmacological application, and support the traditional use of S. tortuosum in the indigenous medicine of South Africa.

Recent advances in the psychopharmacology of major depressive disorder

This review highlights some of the recent advances in the psychopharmacology of major depressive disorder (MDD). We synthesise evidence on emerging pharmacological therapies targeting the serotonergic system, before exploring several novel treatment targets: the glutamatergic system, the GABAergic system and inflammation. When describing new treatment avenues, we examine the evidence base and how far these new treatments are from routine practice.

Addressing depressive disorders among people with HIV

Depressive disorders are the most common psychiatric disorders among people with HIV. Depressive disorders cause great suffering and disability and, among people with HIV, are associated with numerous negative HIV outcomes, including nonadherence to antiretroviral medication and increased morbidity and mortality. This article is focused on the detection, differential diagnosis, and management of depressive disorders among adults in HIV primary care settings in the United States. Because of the siloed nature of HIV primary health care and behavioral health care in the United States, this paper is geared toward clinicians who are not behavioral health specialists and who are working in HIV care settings that have limited access to behavioral health services and still seek to treat depressive disorders. In clinical settings that are fortunate enough to have well-integrated behavioral health services, HIV primary care clinicians may be able to depend on this specialist workforce, but these settings tend to be the exception and not the rule.

Serum Cortisol, Nesfatin-1, and IL-1β: Potential Diagnostic Biomarkers in Elderly Patients with Treatment-Resistant Depression

Aim

Treatment-resistant depression (TRD) affects approximately 30% of patients with major depressive disorder (MDD), especially elderly patients. As individuals with TRD are at an increased risk of committing suicide and pose a higher risk of relapse, early diagnostic biomarkers of TRD and a better understanding of the resistance mechanism are highly needed. This study aimed to determine whether serum cortisol, nesfatin-1, and pro-inflammatory cytokines can be used as biomarkers for the diagnosis of elderly patients with TRD.

Methods

Thirty elderly patients with TRD were selected as the TRD group. Thirty elderly patients with MDD who were effectively treated with conventional antidepressants were selected as the non-TRD group. The baseline levels of serum cortisol, nesfatin-1, and pro-inflammatory cytokines were measured and compared, and their diagnostic values were evaluated using the receiver operating characteristic (ROC) curve method for discriminating patients with TRD from those without TRD.

Results

Serum cortisol, C-reactive protein (CRP), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) levels were significantly higher in the non-TRD and TRD groups than in the control group. Moreover, serum cortisol, CRP, TNF-α, and IL-6 levels in the TRD group were significantly lower than those in the non-TRD group. Furthermore, serum nesfatin-1 levels in the non-TRD group were significantly lower than those in the control and TRD groups, while the serum IL-1β levels in the non-TRD group were significantly higher than those in the control and TRD groups. Additionally, an ROC analysis revealed an area under the curve (AUC) of 0.929 for the combination of nesfatin-1 and IL-1β and an AUC of 0.956 for the combination of cortisol, nesfatin-1, and IL-1β in discriminating elderly patients with TRD from those without non-TRD.

Conclusion

Serum cortisol, nesfatin-1, and IL-1β may be potential diagnostic biomarkers for discriminating elderly patients with TRD from those without TRD.

Perspective-Electrochemical Sensors for Neurotransmitters and Psychiatrics: Steps toward Physiological Mental Health Monitoring

Therapeutic monitoring of neurotransmitters (NTs) and psychiatric medications is essential for the diagnosis and treatment of mental illness. However, in-vivo monitoring of NTs in humans as well as continuous physiological monitoring of psychiatrics have yet to be realized. In pursuit of this goal, there has been a plethora of work to develop electrochemical sensors for both in-vivo NT monitoring as well as in-vitro detection of psychiatric medications. We review these sensors here while discussing next steps needed to achieve concurrent, continuous physiological monitoring of NTs and psychiatric medications as part of a closed-loop feedback system that guides medication administration.

The Influence of Research Follow-Up during COVID-19 Pandemic on Mental Distress and Resilience: A Multicenter Cohort Study of Treatment-Resistant Depression

Background: During the COVID-19 outbreak, patients with mental disorders have faced more negative psychological consequences than the public. For people with treatment-resistant depression (TRD), it is unclear whether research engagement would protect them from the deterioration of their symptoms. The study aimed to examine if chronic depressive patients would have improved resilience and mental distress levels after follow-up interviews during an observation period under COVID-19. Methods: The study was nested within a three-year prospective cohort study. A two-group comparison design was conducted, i.e., the follow-up group with regular research interviews every three months after baseline assessment and the control group with one assessment-only interview. The two groups were compared with demographics, psychosocial, and suicide information. Results: Baseline assessments were not significantly different in sociodemographic variables, suicide risks, mental distress, and resilience between groups. Significant differences were detected in resilient coping and mental distress levels (p < 0.05). The follow-up group (n = 46) experienced a higher level of resilient coping (37% vs. 25%) and lower level of mental distress (47.8% vs. 64.7%) than the control group (n = 68). Conclusions: Findings highlight under universal government strategy against COVID-19, TRD patients receiving regular research follow-ups exhibited better resilience and less mental distress than those without regular support from healthcare providers.

Mycotherapy: Potential of Fungal Bioactives for the Treatment of Mental Health Disorders and Morbidities of Chronic Pain

Mushrooms have been used as traditional medicine for millennia, fungi are the main natural source of psychedelic compounds. There is now increasing interest in using fungal active compounds such as psychedelics for alleviating symptoms of mental health disorders including major depressive disorder, anxiety, and addiction. The anxiolytic, antidepressant and anti-addictive effect of these compounds has raised awareness stimulating neuropharmacological investigations. Micro-dosing or acute dosing with psychedelics including Lysergic acid diethylamide (LSD) and psilocybin may offer patients treatment options which are unmet by current therapeutic options. Studies suggest that either dosing regimen produces a rapid and long-lasting effect on the patient post administration with a good safety profile. Psychedelics can also modulate immune systems including pro-inflammatory cytokines suggesting a potential in the treatment of auto-immune and other chronic pain conditions. This literature review aims to explore recent evidence relating to the application of fungal bioactives in treating chronic mental health and chronic pain morbidities.

Real-World Treatment Patterns, Outcomes, Resource Utilization and Costs in Treatment-Resistant Major Depressive Disorder: PATTERN, a Retrospective Cohort Study in Belgium

OBJECTIVE

Treatment-resistant depression (TRD), a subgroup of major depressive disorder (MDD) that does not adequately respond to treatment, has a substantial impact on the quality of life of patients and is associated with higher medical and mental health care costs. This study aimed to report real-world treatment patterns, outcomes, resource utilization, and costs in the management of TRD by psychiatrists in Belgium.

METHODS

We conducted a retrospective, non-interventional cohort study of patients ≥ 18 years, with diagnosed MDD who are treatment-resistant, defined as not responding to two different antidepressant treatments in the current moderate to severe major depressive episode (MDE). Data obtained from medical records of patients included patient health state (MDE, response, remission, and recovery) and resource use (number of consultations and emergency room visits, non-drug and drug interventions, and hospitalizations).

RESULTS

One hundred and twenty-five patients were enrolled in nine sites, with an average observation period of 34 months. During the MDE, 89.7% of patients were treated with selective serotonin reuptake inhibitors, 63.2% with serotonin-norepinephrine reuptake inhibitors, and 60.8% with anti-psychotics. Twenty-four percent of patients did not respond to any treatment; 76% responded, of whom 61% experienced a relapse; 28% of patients reached recovery, of whom 31.4% experienced recurrence. The average yearly direct cost of a TRD patient is €9012, mainly driven by hospitalization in the MDE. The observed absenteeism relates to a high indirect cost, representing 70% of the total MDE cost.

CONCLUSION

TRD is associated with a high unmet need and economic burden for patients and society, with highest costs in the MDE health state driven by absenteeism.

Electroencephalographic Signature of Negative Self Perceptions in Medical Students

Frontal alpha asymmetry (fAA) is purported to be a neurophysiological marker for anxiety and depression. Higher left frontal alpha EEG voltage is associated with lower left and higher right frontal cerebral cortical activation, indicative of right-sided fAA. This pilot study tests the hypothesis that greater left-sided frontal alpha voltage is associated with negative thoughts about oneself. A group of eight healthy 28-41-year-old right-handed male medical students were subjected to an extensive interactive self-report inventory (ISI) evaluating perceptions of their psychosocial interactions. Quantitative EEG (qEEG) was performed with eyes closed. Computations of fAA and related parameters were based on measurements in the alpha bandwidth (8-13 Hz) at the left frontal F7 and right frontal F8 scalp electrodes. fAA was the percent difference between mean voltages at F8 minus that at F7. Significance of associations between fAA and the ISI scores was determined by Pearson’s product-moment correlation coefficient, at P≤0.05. “Depressed” scores were positively correlated with right-sided fAA (P=0.01). “Relaxed” (P=0.05), “regulated” (P=0.02), “cooperative” (P=0.05) and “dependent scores” (P=0.004) were negatively correlated with right-sided fAA. These findings imply that right-sided fAA may be associated with more perceptions of “depressed” psychosocial interactions involving negative thoughts about oneself, as well as, more reliance on others (“dependence” score), less sharing (“cooperative” ISI score), less trust (“regulated” ISI score) and less initiative (“relaxed” ISI score). These results support the hypothesis that right-sided fAA may identify individuals with a predilection for negative thoughts about themselves and other negatively-valenced perceptions of their psychosocial interactions.

Serotonin Receptor and Transporter Endocytosis Is an Important Factor in the Cellular Basis of Depression and Anxiety

Depression and anxiety are common, debilitating psychiatric conditions affecting millions of people throughout the world. Current treatments revolve around selective serotonin reuptake inhibitors (SSRIs), yet these drugs are only moderately effective at relieving depression. Moreover, up to 30% of sufferers are SSRI non-responders. Endocytosis, the process by which plasma membrane and extracellular constituents are internalized into the cell, plays a central role in the regulation of serotonin (5-hydroxytryptophan, 5-HT) signaling, SSRI function and depression and anxiety pathogenesis. Despite their therapeutic potential, surprisingly little is known about the endocytosis of the serotonin receptors (5-HT receptors) or the serotonin transporter (SERT). A subset of 5-HT receptors are endocytosed by clathrin-mediated endocytosis following serotonin binding, while for the majority of 5-HT receptors the endocytic regulation is not known. SERT internalizes serotonin from the extracellular space into the cell to limit the availability of serotonin for receptor binding and signaling. Endocytosis of SERT reduces serotonin uptake, facilitating serotonin signaling. SSRIs predominantly inhibit SERT, preventing serotonin uptake to enhance 5-HT receptor signaling, while hallucinogenic compounds directly activate specific 5-HT receptors, altering their interaction with endocytic adaptor proteins to induce alternate signaling outcomes. Further, multiple polymorphisms and transcriptional/proteomic alterations have been linked to depression, anxiety, and SSRI non-response. In this review, we detail the endocytic regulation of 5-HT receptors and SERT and outline how SSRIs and hallucinogenic compounds modulate serotonin signaling through endocytosis. Finally, we will examine the deregulated proteomes in depression and anxiety and link these with 5-HT receptor and SERT endocytosis. Ultimately, in attempting to integrate the current studies on the cellular biology of depression and anxiety, we propose that endocytosis is an important factor in the cellular basis of depression and anxiety. We will highlight how a thorough understanding 5-HT receptor and SERT endocytosis is integral to understanding the biological basis of depression and anxiety, and to facilitate the development of a next generation of specific, efficacious antidepressant treatments.

Is (R)-ketamine a Potential Therapeutic Agent for Treatment-Resistant Depression with Less Detrimental Side Effects? A Review of Molecular Mechanisms Underlying Ketamine and its Enantiomers

Approximately one-third of individuals with major depressive disorder are resistant to conventional antidepressants (i.e., monoamine-based therapies), and, even among respondents, a proper therapeutic effect may require weeks of treatment. Ketamine, a racemic mixture of the two enantiomers, (R)-ketamine and (S)-ketamine, is an N-methyl-d-aspartate receptor (NMDAR) antagonist and has been shown to have rapid-acting antidepressant properties in patients with treatment-resistant depression (TRD). Although (R)-ketamine has a lower affinity for NMDAR, it presents greater potency and longer-lasting antidepressant properties, with no major side effects, than racemic ketamine or (S)-ketamine in preclinical findings. Thereby, ketamine and its enantiomers have not only an antagonistic effect on NMDAR but also a strong synaptogenic-modulatory effect, which is impaired in TRD pathophysiology. In this review, we summarize the current evidence regarding the modulation of neurotransmission, neuroplasticity, and neural network activity as putative mechanisms of these rapid-acting antidepressants, highlighting differences on intracellular signaling pathways of synaptic proteins such as mammalian target of rapamycin (mTOR), extracellular signal-regulated kinase (ERK) and brain-derived neurotrophic factor (BDNF). In addition, we discuss probable mechanisms involved in the side effects of ketamine and its enantiomers.

Salmon Calcitonin Exerts an Antidepressant Effect by Activating Amylin Receptors

Depressive disorder is defined as a psychiatric disease characterized by the core symptoms of anhedonia and learned helplessness. Currently, the treatment of depression still calls for medications with high effectiveness, rapid action, and few side effects, although many drugs, including fluoxetine and ketamine, have been approved for clinical usage by the Food and Drug Administration (FDA). In this study, we focused on calcitonin as an amylin receptor polypeptide, of which the antidepressant effect has not been reported, even if calcitonin gene-related peptides have been previously demonstrated to improve depressive-like behaviors in rodents. Here, the antidepressant potential of salmon calcitonin (sCT) was first evaluated in a chronic restraint stress (CRS) mouse model of depression. We observed that the immobility duration in CRS mice was significantly increased during the tail suspension test and forced swimming test. Furthermore, a single administration of sCT was found to successfully rescue depressive-like behaviors in CRS mice. Lastly, AC187 as a potent amylin receptor antagonist was applied to investigate the roles of amylin receptors in depression. We found that AC187 significantly eliminated the antidepressant effects of sCT. Taken together, our data revealed that sCT could ameliorate a depressive-like phenotype probably via the amylin signaling pathway. sCT should be considered as a potential therapeutic candidate for depressive disorder in the future.

Modulation of Emotion Perception via Amygdala Stimulation in Humans

Background

Multiple lines of evidence show that the human amygdala is part of a neural network important for perception of emotion from environmental stimuli, including for processing of intrinsic attractiveness/“goodness” or averseness/“badness,” i.e., affective valence.

Objective/Hypothesis

With this in mind, we investigated the effect of electrical brain stimulation of the human amygdala on perception of affective valence of images taken from the International Affective Picture Set (IAPS).

Methods

Using intracranial electrodes in patients with epilepsy, we first obtained event-related potentials (ERPs) in eight patients as they viewed IAPS images of varying affective valence. Next, in a further cohort of 10 patients (five female and five male), we measured the effect of 50 Hz electrical stimulation of the left amygdala on perception of affective valence from IAPS images.

Results

We recorded distinct ERPs from the left amygdala and found significant differences in the responses between positively and negatively valenced stimuli (p = 0.002), and between neutral and negatively valenced stimuli (p = 0.017) 300–500 ms after stimulus onset. Next, we found that amygdala stimulation did not significantly affect how patients perceived valence for neutral images (p = 0.58), whereas stimulation induced patients to report both positively (p = 0.05) and negatively (< 0.01) valenced images as more neutral.

Conclusion

These results render further evidence that the left amygdala participates in a neural network for perception of emotion from environmental stimuli. These findings support the idea that electrical stimulation disrupts this network and leads to partial disruption of perception of emotion. Harnessing this effect may have clinical implications in treatment of certain neuropsychiatric disorders using deep brain stimulation (DBS) and neuromodulation.

Real-world evidence from a European cohort study of patients with treatment resistant depression: Healthcare resource utilization

BACKGROUND

Treatment resistant depression (TRD) is diagnosed when patients experiencing a major depressive episode fail to respond to ≥2 treatments. Along with substantial indirect costs, patients with TRD have higher healthcare resource utilization (HCRU) than other patients with depression. However, research on the economic impact of this HCRU, and differences according to response to treatment, is lacking.

METHODS

This multicenter, observational study documented HCRU among patients with TRD in European clinical practice initiating new antidepressant treatments. Data regarding access to outpatient consultations and other healthcare resources for the first 6 months, collected using a questionnaire, were analyzed qualitatively according to response and remission status. The economic impact of HCRU, estimated using European costing data, was analyzed quantitatively.

RESULTS

Among 411 patients, average HCRU was higher in non-responders, attending five times more general practitioner (GP) consultations and spending longer in hospital (1.7 versus 1.1 days) than responders. Greater differences were observed according to remission status, with non-remitters attending seven times more GP consultations and spending approximately three times longer in hospital (1.7 versus 0.6 days) than remitters. Consequently, the estimated economic impacts of non-responders and non-remitters were significantly greater than those of responders and remitters, respectively.

LIMITATIONS

Key limitations are small cohort size, absence of control groups and generalizability to different healthcare systems.

CONCLUSION

Patients with TRD, particularly those not achieving remission, have considerable HCRU, with associated economic impact. The costs of unmet TRD treatment needs are thus substantial, and treatment success is fundamental to reduce individual needs and societal costs.

Biomarkers for Deep Brain Stimulation in Animal Models of Depression

OBJECTIVES

Despite recent advances in depression treatment, many patients still do not respond to serial conventional therapies and are considered "treatment resistant." Deep brain stimulation (DBS) has therapeutic potential in this context. This comprehensive review of recent studies of DBS for depression in animal models identifies potential biomarkers for improving therapeutic efficacy and predictability of conventional DBS to aid future development of closed-loop control of DBS systems.

MATERIALS AND METHODS

A systematic search was performed in Pubmed, EMBASE, and Cochrane Review using relevant keywords. Overall, 56 animal studies satisfied the inclusion criteria.

RESULTS

Outcomes were divided into biochemical/physiological, electrophysiological, and behavioral categories. Promising biomarkers include biochemical assays (in particular, microdialysis and electrochemical measurements), which provide real-time results in awake animals. Electrophysiological tests, showing changes at both the target site and downstream structures, also revealed characteristic changes at several anatomic targets (such as the medial prefrontal cortex and locus coeruleus). However, the substantial range of models and DBS targets limits the ability to draw generalizable conclusions in animal behavioral models.

CONCLUSIONS

Overall, DBS is a promising therapeutic modality for treatment-resistant depression. Different outcomes have been used to assess its efficacy in animal studies. From the review, electrophysiological and biochemical markers appear to offer the greatest potential as biomarkers for depression. However, to develop closed-loop DBS for depression, additional preclinical and clinical studies with a focus on identifying reliable, safe, and effective biomarkers are warranted.

Differences in Cerebral Distribution between Imipramine and Paroxetine via Membrane Transporters at the Rat Blood-Brain Barrier

PURPOSE

The present study aimed to elucidate the transport properties of imipramine and paroxetine, which are the antidepressants, across the blood-brain barrier (BBB) in rats.

METHODS

In vivo influx and efflux transport of imipramine and paroxetine across the BBB were tested using integration plot analysis and a combination of brain efflux index and brain slice uptake studies, respectively. Conditionally immortalized rat brain capillary endothelial cells, TR-BBB13 cells, were utilized to characterize imipramine and paroxetine transport at the BBB in vitro.

RESULTS

The in vivo influx clearance of [3H]imipramine and [3H]paroxetine in rats was determined to be 0.322 mL/(min·g brain) and 0.313 mL/(min·g brain), respectively. The efflux clearance of [3H]imipramine and [3H]paroxetine was 0.380 mL/(min·g brain) and 0.126 mL/(min·g brain), respectively. These results suggest that the net flux of paroxetine, but not imipramine, at the BBB in vivo was dominated by transport to the brain from the circulating blood. The uptake of imipramine and paroxetine by TR-BBB13 cells exhibited time- and temperature-dependence and one-saturable kinetics with a Km of 37.6 μM and 89.2 μM, respectively. In vitro uptake analyses of extracellular ion dependency and the effect of substrates/inhibitors for organic cation transporters and transport systems revealed minor contributions to known transporters and transport systems and the difference in transport properties in the BBB between imipramine and paroxetine.

CONCLUSIONS

Our study showed the comprehensive outcomes of imipramine and paroxetine transport at the BBB, implying that molecular mechanism(s) distinct from previously reported transporters and transport systems are involved in the transport.

Treatment-Resistant Depression in Poland—Epidemiology and Treatment

(1) Background: Major depressive disorder (MDD) is one of the most prevalent psychiatric disorders worldwide. Although several antidepressant drugs have been developed, up to 30% of patients fail to achieve remission, and acute remission rates decrease with the number of treatment steps required. The aim of the current project was to estimate and describe the population of treatment-resistant depression (TRD) patients in outpatient clinics in Poland. (2) Methods: The project involved a representative sample of psychiatrists working in outpatient clinics, chosen through a process of quota random sampling. The doctors completed two questionnaires on a consecutive series of patients with MDD, which captured the patients’ demographics, comorbidities, and medical histories. TRD was defined as no improvement seen after a minimum of two different antidepressant drug therapies applied in sufficient doses for a minimum of 4 weeks each. The data were weighted and extrapolated to the population of TRD outpatients in Poland. (3) Results: A total of 76 psychiatrists described 1781 MDD patients, out of which 396 fulfilled the criteria of TRD. The TRD patients constituted 25.2% of all MDD patients, which led to the number of TRD outpatients in Poland being estimated at 34,800. The demographics, comorbidities, medical histories, and histories of treatment of Polish TRD patients were described. In our sample of the TRD population (mean age: 45.6 ± 13.1 years; female: 64%), the patients had experienced 2.1 ± 1.6 depressive episodes (including the current one), and the mean duration of the current episode was 4.8 ± 4.4 months. In terms of treatment strategies, most patients (around 70%) received monotherapy during the first three therapies, while combination antidepressant drugs (ADs) were applied more often from the fourth line of treatment. The use of additional medications and augmentation was reported in only up to one third of the TRD patients. During all of the treatment steps, patients most often received a selective serotonin reuptake inhibitor (SSRI) and a serotonin norepinephrine reuptake inhibitor (SNRI). (4) Conclusions: TRD is a serious problem, affecting approximately one fourth of all depressive patients and nearly 35,000 Poles.

Serum Mature BDNF Level Is Associated with Remission Following ECT in Treatment-Resistant Depression

The search for a biological marker predicting the future failure or success of electroconvulsive therapy (ECT) remains highly challenging for patients with treatment-resistant depression. Evidence suggests that Brain-Derived Neurotrophic Factor (BDNF), a protein known to be involved in brain plasticity mechanisms, can play a key role in both the clinical efficacy of ECT and the pathophysiology of depressive disorders. We hypothesized that mature BDNF (mBDNF), an isoform of BDNF involved in the neural plasticity and survival of neural networks, might be a good candidate for predicting the efficacy of ECT. Total BDNF (tBDNF) and mBDNF levels were measured in 23 patients with severe treatment-resistant depression before (baseline) they received a course of ECT. More precisely, tBDNF and mBDNF measured before ECT were compared between patients who achieved the criteria of remission after the ECT course (remitters, n = 7) and those who did not (non-remitters, n = 16). We found that at baseline, future remitters displayed significantly higher mBDNF levels than future non-remitters (p = 0.04). No differences were observed regarding tBDNF levels at baseline. The multiple logistic regression model controlled for age and sex revealed that having a higher baseline mBDNF level was significantly associated with future remission after ECT sessions (odd ratio = 1.38; 95% confidence interval = 1.07–2.02, p = 0.04). Despite the limitations of the study, current findings provide additional elements regarding the major role of BDNF and especially the mBDNF isoform in the clinical response to ECT in major depression.

The bidirectional association between depression and lower urinary tract symptoms (LUTS) in men: A systematic review and meta-analysis of observational studies

BACKGROUND

Recent evidence from observational studies suggests a bidirectional association between lower urinary tract symptoms (LUTS) and depression in men. We sought to systematically quantify the effect of the presence of LUTS on depression symptoms, compared to those without LUTS, in adult males, and vice versa.

METHODS

Electronic databases (MEDLINE, PsycINFO, SCOPUS, Embase) were examined for articles in English before March 2021. Observational studies of men aged over 18 years; reporting an association between LUTS and depression; including a validated scale for LUTS and depression symptoms were eligible for study inclusion.

RESULTS

Seventeen studies out of 1787 records identified 163 466 men with reported depression symptoms by LUTS status, while 10 studies reported 72 363 men with LUTS by depression symptoms. Pooled estimates showed a strong effect of LUTS presence on depression risk (OR: 2.89, 95% CI: 2.50-3.33), with a high degree of heterogeneity among the examined studies (I²  = 83%; τ²  = 0,06; p < 0.001). Subgroup analyses demonstrated differences by study region (Q value:13.7, df:4, p = 0.003), setting (7.8(2), p = 0.020), design (7.2(1), p = 0.003), quality (6.2(1), p = 0.013), and LUTS measure (40.9(3), p < 0.001). Pooled estimates also showed a strong effect of depression presence on LUTS risk in men (OR: 3.13, 95% CI: 2.72-3.60), with only moderate heterogeneity between studies (I²  = 58%; τ²  = 0,02; p = 0.001).

CONCLUSIONS

The strong relationship observed between LUTS and depression implies shared risk factors that cannot be solely attributed to the prostate. This has immediate implications for future studies and the assessment and management of patients with either condition.

Evaluation of Individual Items of the Patient Health Questionnaire (PHQ-9) and Montgomery-Asberg Depression Rating Scale (MADRS) in Adults with Treatment-Resistant Depression Treated with Esketamine Nasal Spray Combined with a New Oral Antidepressant

OBJECTIVE

The objective of this study was to determine which symptoms measured by the Patient Health Questionnaire (PHQ-9) and Montgomery-Asberg Depression Rating Scale (MADRS) improve in those treated with esketamine nasal spray in combination with oral antidepressant (AD) compared with those treated with placebo plus AD for adult patients with treatment-resistant depression (TRD). These results complement the interpretation of PHQ-9 and MADRS total scores.

METHODS

The TRANSFORM 2 study evaluated the efficacy and safety of esketamine nasal spray in combination with AD. This post-hoc analysis used PHQ-9 and MADRS data to evaluate symptom changes. The total scores change and proportions of individual item change scores on the PHQ-9 and MADRS were evaluated at days 15 and 28; analysis of variance was used to test differences on total scores. Generalized estimation equations of logistic regression models were used to estimate the likelihood of improvement on instrument items.

RESULTS

The mean total score reduction of the PHQ-9, indicating improvement, was greater in the esketamine plus AD arm compared with placebo plus AD at day 15 (- 1.8; p = 0.045) and day 28 (- 2.8; p = 0.006). Proportions of those who improved (≥ 1 point on a 4-point scale and ≥ 2 points on a 7-point scale for the PHQ-9 and MADRS, respectively) was greater in the esketamine plus AD group compared with the placebo plus AD group across all items. The odds of improving for those in the esketamine plus AD group compared with the placebo plus AD group were over two times greater on the PHQ-9 items: "Little interest/pleasure in things" (OR 2.252, 95% CI 1.165-4.355); "Feeling down, depressed, or hopeless" (OR 2.767, 95% CI 1.400-5.470); and "Feeling tired or having little energy" (OR 2.171, 95% CI 1.153-4.087). The mean reduction in total scores on the MADRS, indicating improvement, was numerically greater at day 15 (- 2.0; p = 0.189) and statistically significantly greater at day 28 (- 4.4; p = 0.017) in the esketamine plus AD arm compared with placebo plus AD. The odds of improving for those in the esketamine plus AD group compared with the placebo plus AD group were over two times greater on the MADRS items measuring "Apparent sadness" (OR 2.007, 95% CI 1.096-3.674); and "Inability to feel" (OR 2.099, 95% CI 1.180-3.735).

CONCLUSION

Improvement in mean total scores in those treated with esketamine plus AD compared with placebo plus AD are important results to confirm efficacy. The odds of improving in those treated with esketamine plus AD was at least two times greater than with placebo plus AD on three patient- and two clinician-reported individual symptoms of TRD. These findings provide patient-relevant quantification of the esketamine plus AD treatment benefit, adding understanding as to which symptoms are most improved with treatment.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02418585; first posted 16 April 2015.

Neuroinflammation and Mitochondrial Dysfunction Link Social Stress to Depression

Major depressive disorder is a debilitating mental illness and a leading cause of global disease burden. While many etiological factors have been identified, social stress is a highly prevalent causative factor for the onset of depression. Unfortunately, rates of depression continue to increase around the world, and the recent COVID-19 pandemic has further exacerbated this mental health crisis. Though several therapeutic strategies are available, nearly 50% of patients who receive treatment never reach remission. The exact mechanisms by which social stress exposure promotes the development of depression are unclear, making it challenging to develop novel and more effective therapeutics. However, accumulating evidence points to a role for stress-induced neuroinflammation, particularly in treatment-resistant patients. Moreover, recent evidence has expanded the concept of the pathogenesis of depression to mitochondrial dysfunction, suggesting that the combined effects of social stress on mitochondria and inflammation may synergize to facilitate stress-related depression. In this chapter, we review evidence for neuroinflammation and mitochondrial dysfunction in the pathogenesis of social stress-induced depression and discuss these in the context of novel therapeutic targets for the treatment of depression.

The economics of psychedelic-assisted therapies: A research agenda

After a long hiatus, psychiatry is undergoing a resurgence of interest in psychedelic drugs as therapy for a wide range of mental health disorders Accumulating clinical evidence suggests substantial potential for psychedelics used in a therapeutic context, as treatment for, among other disorders, depression, post-traumatic stress disorder (PTSD), and addictions to tobacco, opioids and alcohol. As soon as 2024, powerful new therapeutic modalities could become available for individuals with mental health problems refractory to traditional therapies. Yet research has lagged on economic considerations, such as costs and cost-effectiveness, the economic effects of widespread implementation, pricing, and economic appraisal's methodological considerations relevant to psychedelic therapies. These issues are critical if psychedelic therapies are to become widely accessible. We describe six types of economic analyses and their rationale for decisions and planning including the needs of health care payers. We also outline desirable features of this research, including scientific rigor, long horizons, equity, and a global view.

Association between the consumption of omega-3-rich fish and depressive symptoms in older adults living in a middle-income country: EpiFloripa Aging cohort study

This study aimed to verify the association between the consumption of omega-3-rich (n-3) fish and depressive symptoms in older adults living in Southern Brazil. This is a cross-sectional analysis with data from the second wave of the EpiFloripa Aging cohort study (2013/2014) including 1,130 individuals aged 60 years or older. The presence of depressive symptoms was measured by the 15-items Geriatric Depression Scale (GDS-15), and the consumption of n-3-rich fish by a question of weekly frequency. The minimum set of variables for adjustment was defined using directed acyclic graph (DAG). Poisson regression with robust error variance was applied (adjusted by Model 1: demographic and socioeconomic variables, Model 2: added behavioral variables, Model 3: added health variables). We identified the prevalence of depressive symptoms in 19% of older adults and 51.8% reported eating n-3-rich fish once a week. Models 1 and 3 showed an inverse association between n-3-rich fish and depressive symptoms. However, the association was reduced when behavioral factors (leisure-time physical activity) were included in Model 2. These findings suggest that n-3-rich fish intake tends to be associated with depressive symptoms in older adults. However, other factors, such as physical exercise, are as pivotal as n-3 fatty acids in preventing the development of depressive symptoms.

Zinc in depression: From development to treatment: A comparative/ dose response meta-analysis of observational studies and randomized controlled trials

BACKGROUND

A previous meta-analysis suggested that zinc status may be linked to depression status. However, it remains unclear whether zinc status can predict the risk of depression development, or whether the monotherapy of zinc is superior to the combination of zinc supplementation and antidepressant medications in the treatment of depression. Therefore, this meta-analysis aimed to clarify the impact of zinc status and supplementation on depression development and status across all available evidence.

METHODS

PubMed, EMBASE, Scopus, and ISI web of science were searched, up to 14 May 2020, for relevant publications. Pooled relative risks (RRs) with 95% confidence intervals (CI) in observational studies, and mean and standard deviation (SD) for the change in depression score in RCTs were calculated using a random-effects model.

RESULTS

The meta-analysis of RCTs indicated that zinc supplementation significantly lowered depressive symptom scores of depressed patients [weighted mean difference (WMD = -4.15 point; 95% CI: -6.56, -1.75 point; P < 0.01)], and the improvement in depression status occurred only when zinc supplementation was prescribed as a monotherapy. The cohort studies showed that the highest level of zinc intake was associated with a 28% reduced risk of depression (RR: 0.66; 95% CI: 0.50, 0.82; I² = 13.90). Dose-response analyses revealed a significant non-linear effect of baseline mood status on depression score.

CONCLUSION

Current evidence from observational studies and RCT's supports the potential benefits zinc to reduce the risk of, and alleviate, depression. However, further trials are needed to confirm the beneficial effect of zinc as a monotherapy versus adjunctive therapies.

A comparative study of the effect of electroconvulsive therapy and transcranial direct current stimulation in the treatment of persons suffering from treatment-resistant depression

BACKGROUND

About 20%-30% of persons with major depression are said to have treatment-resistant depression (TRD) when they do not respond to antidepressants. These people continue to suffer in life and have poor quality of life. Although electroconvulsive therapy (ECT) is the most successful option in treating TRD, many people refuse ECT due to various reasons (stigma, the cost involved, and medical complications). Various studies combine treatment options such as psychotherapy, repetitive trans magnetic stimulation, ketamine, and transcranial direct current stimulation (tDCS) in an attempt to reduce symptoms for those people suffering from TRD. This study aims to compare the effectiveness of ECT and tDCS in TRD.

SUBJECTS AND METHODS

A total of 90 persons suffering from TRD were selected for the study. 46 persons received 6 ECTs and 44 persons received 10 sessions of tDCS. Treatment response was measured using baseline and postassessment scores of Hamilton depression rating scale and clinical global impression. The scores were used to determine the effectiveness of ECT in comparison to tDCS in TRD.

STATISTICAL ANALYSIS

The mean ± standard deviation was analyzed and paired t-test was used to find the significance of treatment outcome in a group at a 95% confidence interval.

RESULTS

ECT was found to be more effective than tDCS in the reduction of depressive symptoms. tDCS showed a significant reduction in depressive symptoms (P < 0.001). ECT has yet again been proven to be effective in the treatment of TRD.

CONCLUSION AND DISCUSSION

tDCS is effective in reducing depressive symptoms in persons suffering from TRD. However, ECT is superior in decreasing depressive symptoms in TRD when compared to tDCS.

Frequency analysis of symptomatic worsening following ketamine infusions for treatment resistant depression in a real-world sample: Results from the canadian rapid treatment center of excellence

Antidepressants are associated with symptomatic worsening in a subgroup of patients. Replicated evidence has demonstrated rapid and robust antidepressant effects with intravenous (IV) ketamine in treatment resistant depression (TRD); however, the risk of ketamine worsening depressive symptoms in a subgroup of patients remains unknown. Herein we report a retrospective analysis on the rates of symptomatic worsening during an acute course of IV ketamine in individuals with unipolar (n = 142) and bipolar (n = 22) TRD. Adults (N = 164; mean age = 45.97) with TRD underwent four sub-anesthetic infusions (0.5-0.75 mg/kg over 40 min) of IV ketamine over two weeks, and were assessed with the Quick Inventory for Depression Symptomatology-Self Report-16 (QIDS-SR₁₆) at baseline and after each infusion. The primary outcome was the proportion of patients experiencing clinically significant worsening of depressive symptoms (≥20% increase on the QIDS-SR₁₆) at each time point relative to baseline. Secondary analyses explored trends in the results. The frequency of clinically significant worsening fluctuated between 1.83% to 5.49%, with no identifiable trend across time. Zero individuals with bipolar TRD reported symptomatic worsening. Limitations include the single-centered, uncontrolled, retrospective nature of this study. Rates of symptomatic worsening associated with IV ketamine therapy for TRD appear to be very low and similar to conventional antidepressants.

Efficacy and Safety of Esketamine Combined with Antidepressants for Treatment-Resistant Depression: A Meta-Analysis

OBJECTIVE

To evaluate the efficacy and safety of esketamine + antidepressant in treatment-resistant depression.

METHODS

We searched PubMed, Web of Science, Embase, CNKI, and Wanfang databases to obtain published information on esketamine + antidepressant from inception to July 2022. We searched for randomized controlled studies on the treatment of depression with a double-blind induction phase. Outcome indicators included changes in Montgomery-Asberg Depression Rating Scale (MADRS) scores before and after treatment, effective response rate, remission rate, and changes in self-rating depression scale (SDS). We analyzed data using Review Manager 5.4 and assessed the quality of evidence using Grading of Recommendations Assessment, Development, and Evaluation (GRADE) analysis.

RESULTS

A total of seven articles were included, including 701 patients in the esketamine + antidepressant group and 551 in the placebo group. Meta-analysis results showed that esketamine + antidepressant could improve the MADRS score in patients with treatment-resistant depression (MD = -2.68, 95% CI -3.98 to -1.37, P < 0.0001), SDS (MD = -2.9, 95% CI -4.01 to -1.79, P < 0.00001), response rate at the end of the double-blind induction period (RR = 1.28, 95% CI 1.12 to 1.46, P = 0.0002), remission rate at the end of the double-blind induction period (RR = 1.39, 95% CI 1.18 to 1.63, P < 0.0001), Five-Dimensional Health Scale (EQ-5D-5L) (MD = 0.05, 95% CI 0.02 to 0.08, P = 0.00009), Visual Analogue Scale of Health Status (EQ-VAS) (MD = 5.54, 95% CI 2.37 to 8.71, P = 0.0006).

CONCLUSION

Esketamine + antidepressant has an obvious curative effect in treatment-resistant depression and can rapidly improve depression in patients, quality of life and satisfaction, but minor adverse reactions can occur.

High-resolution Virtual Brain Modeling Personalizes Deep Brain Stimulation for Treatment-Resistant Depression: Spatiotemporal Response Characteristics Following Stimulation of Neural Fiber Pathways

Over the past 15 years, deep brain stimulation (DBS) has been actively investigated as a groundbreaking therapy for patients with treatment-resistant depression (TRD); nevertheless, outcomes have varied from patient to patient, with an average response rate of ∼50%. The engagement of specific fiber tracts at the stimulation site has been hypothesized to be an important factor in determining outcomes, however, the resulting individual network effects at the whole-brain scale remain largely unknown. Here we provide a computational framework that can explore each individual's brain response characteristics elicited by selective stimulation of fiber tracts. We use a novel personalized in-silico approach, the Virtual Big Brain, which makes use of high-resolution virtual brain models at a mm-scale and explicitly reconstructs more than 100 000 fiber tracts for each individual. Each fiber tract is active and can be selectively stimulated. Simulation results demonstrate distinct stimulus-induced event-related potentials as a function of stimulation location, parametrized by the contact positions of the electrodes implanted in each patient, even though validation against empirical patient data reveals some limitations (i.e., the need for individual parameter adjustment, and differential accuracy across stimulation locations). This study provides evidence for the capacity of personalized high-resolution virtual brain models to investigate individual network effects in DBS for patients with TRD and opens up novel avenues in the personalized optimization of brain stimulation.

[The decrease in procoagulant activity of blood during combined therapy with antidepressants and antipsychotics in patients with endogenous mental disorders]

OBJECTIVE

To compare the changes in thrombodynamics indices in two groups of patients with endogenous mental disorders before and after combined treatment with antipsychotics and antidepressants (AD + group) and those who did not receive antidepressants (AD-group).

MATERIAL AND METHODS

The study included 110 patients, aged from 16 to 60 years (median age [Q1; Q3] 29 years [22; 35]), admitted for inpatient treatment at the clinic of Mental Health Research Center with the following mental disorders: schizophrenia with attack-like/attack-progressive/continuous type of course (F20.00-2), schizotypal disorder with affective fluctuations (F21.3-4), affective disorder (F 31.1-5; F 32.0-3; F 33.0-3). The thrombodynamics test (TD) was carried out on a T-2 thrombodynamics device according to the manufacturer's instructions (Hemacore LLC, Moscow, Russia).

RESULTS

In patients with endogenous mental disorders after combined therapy with antidepressants and antipsychotics, a statistically significant decrease in the procoagulant activity of plasma and procoagulant spontaneous clots is observed, which indicates a decrease in the severity of systemic, immune inflammation. In patients with endogenous mental disorders after antipsychotic therapy without the addition of antidepressants, for most thrombodynamic parameters, there is no statistically significant decrease in procoagulant plasma activity and spontaneous clots formation. It indicates the persistence of acute systemic, immune inflammation in this group.

CONCLUSION

The statistically significant positive change in plasma and platelet hemostasis may testify that combined treatment with antipsychotics and antidepressants in patients with endogenous mental disorders may be a biological, pathogenetic link that promotes augmentation (extended action) of antipsychotic therapy.

Mechanisms underlying antidepressant effect of transcutaneous auricular vagus nerve stimulation on CUMS model rats based on hippocampal α7nAchR/NF-κB signal pathway

Background

Stress-induced neuroinflammation was considered to play a critical role in the pathogenesis of depression. Transcutaneous auricular vagus nerve stimulation (taVNS) is a relatively non-invasive alternative treatment for patients suffering from major depressive disorder. The anti-inflammatory signal of vagus nerve is mediated by α7 nicotinic acetylcholine receptor (α7nAchR), and the hippocampus, the region with the most distribution of α7nAchR, regulates emotions. Here, we investigated the role of α7nAchR mediating hippocampal neuroinflammation in taVNS antidepressant effect though homozygous α7nAChR (−/−) gene knockout and α7nAchR antagonist (methyllycaconitine, MLA).

Methods

There were control, model, taVNS, α7nAChR(−/−) + taVNS, hippocampus (Hi) MLA + taVNS and Hi saline + taVNS groups. We used the chronic unpredicted mild stress (CUMS) method to establish depressive model rats for 42 days, excepting control group. After the successful modeling, except the control and model, the rats in the other groups were given taVNS, which was applied through an electroacupuncture apparatus at the auricular concha (2/15 Hz, 2 mA, 30 min/days) for 21 days. Behavioral tests were conducted at baseline, after modeling and after taVNS intervention, including sucrose preference test (SPT), open field test (OFT) and forced swimming test (FST). These tests are widely used to evaluate depression-like behavior in rats. The samples were taken after experiment, the expressions of α7nAchR, NF-κB p65, IL-1β and the morphology of microglia were detected.

Results

Depression-like behavior and hippocampal neuroinflammation in CUMS model rats were manifested by down-regulated expression of α7nAchR, up-regulated expression of NF-κB p65 and IL-1β, and the morphology of microglia was in amoebic-like activated state. TaVNS could significantly reverse the above-mentioned phenomena, but had rare improvement effect for α7nAChR(−/−) rats and Hi MLA rats.

Conclusion

The antidepressant effect of taVNS is related to hippocampal α7nAchR/NF-κB signal pathway.

A Brief, Individualized Exercise Program at Intensities Below the Ventilatory Threshold Exerts Therapeutic Effects for Depression: A Pilot Study

Due to the fact that existing pharmacological treatments for depression are not ideal, effort has been devoted to the development of complementary, alternative therapies such as physical exercise. The antidepressant effect of exercise is well documented. However, current recommendations and prescriptions of exercise may be too demanding for depressed patients, as some complain about the design of exercise programs and depression is associated with reduced motivation and capacity to exercise. Therefore, appropriately designed, patient-friendly exercise programs may prove critical for the long-term maintenance and therapeutic effects of exercise. In this pilot study, we developed an exercise program based on patients’ individual level of ventilatory threshold (VT), a submaximal index of aerobic capacity measured by Cardiopulmonary Exercise Testing (CPX). Compared to traditional measures, CPX provides more trustable indices of aerobic capacity and more homogenous exercise prescriptions. The main episode of the program consisted of 15–25 min of cycling twice a week at an intensity that approached but never went higher than subjects’ VT (considered low to moderate in intensity). We found that in patients diagnosed with major depressive disorder or persistent depressive disorder (n = 8), the program resulted in a significant reduction in depressive symptoms at week 8, which was maintained at week 16. Meanwhile, patients’ social functioning, quality of life, and cognitive functions improved. Although we used a single arm, non-randomized design, our results suggest that even a brief, low to moderate intensity exercise program may exert therapeutic effects for depression and CPX may be a useful tool for exercise prescriptions.

Cost-utility analysis of esketamine and electroconvulsive therapy in adults with treatment-resistant depression

BACKGROUND

Electroconvulsive therapy (ECT) has long been used for treating individuals with treatment-resistant depression (TRD). Esketamine has recently emerged as a new treatment for TRD due to its rapid antidepressant effects. To further inform the decision regarding choice of treatment, this paper aims to evaluate whether ECT or esketamine is the more cost-effective option.

METHODS

The cost-effectiveness was derived as cost per quality-adjusted life-year (QALY) using a Markov model from a societal and life-time perspective. The incremental cost-effectiveness ratio (ICER) was calculated. Health states included different depression and remission states and death. Data to populate the model was derived from randomised controlled trials and other research. Various sensitivity analyses were carried out to test the robustness of the model.

RESULTS

The base case scenario shows that ECT is cost-effective compared to esketamine and yields more QALYs at a lower cost. The sensitivity analysis shows that ECT is cost-effective in all scenarios and ECT dominates esketamine in 12 scenarios.

CONCLUSIONS

This study found that, from a cost-effectiveness point of view, ECT should be the first-hand option for individuals with TRD, when other first line treatments have failed. Considering the lack of economic evaluation of ECT and esketamine, this study is of great value to decision makers.

Is one or two infusions better in the first week of low-dose ketamine treatment for medication-resistant depression? A post hoc pooled analysis of randomized placebo-controlled and open-label trials

BACKGROUND

Whether a second ketamine infusion in the first week improves the antidepressant, antisuicidal, and anti-inflammatory effects of the first low-dose ketamine infusion remains unclear.

METHODS

A total of 78 patients with medication-resistant depression were allocated to receive two ketamine infusions (n = 30; days 1 and 4), a single ketamine infusion (n = 24; only day 1), or normal saline placebo infusion (n = 24; only day 1). The Montgomery-Asberg Depression Scale (MADRS) and 17-item Hamilton Rating Scale for Depression (HDRS) were administered before and at 40 min, 240 min, day 2, day 4, day 5, and day 7 after infusion. Serum concentrations of interleukin (IL)-2 and tumor necrosis factor (TNF)-α were assessed.

RESULTS

Two ketamine infusions improved the overall depressive symptoms (p < 0.001) and melancholic symptoms (p < 0.001) than a single ketamine or placebo infusion. The antisuicidal effect did not differ between the ketamine treatment groups. Two ketamine infusions increased TNF-α levels compared with a single ketamine or placebo infusion (p = 0.015). A single ketamine infusion improved the TNF-α-to-IL-2 ratio, an index of average anti-inflammatory effect, than two ketamine infusions or a single placebo infusion (p = 0.027).

DISCUSSION

Repeated low-dose ketamine infusions improved the antidepressant effect, but not the antisuicidal effect, compared with a single infusion. However, repeated ketamine infusions may exert a lesser anti-inflammatory effect than a single infusion.

Machine learning in the prediction of depression treatment outcomes: a systematic review and meta-analysis

BACKGROUND

Multiple treatments are effective for major depressive disorder (MDD), but the outcomes of each treatment vary broadly among individuals. Accurate prediction of outcomes is needed to help select a treatment that is likely to work for a given person. We aim to examine the performance of machine learning methods in delivering replicable predictions of treatment outcomes.

METHODS

Of 7732 non-duplicate records identified through literature search, we retained 59 eligible reports and extracted data on sample, treatment, predictors, machine learning method, and treatment outcome prediction. A minimum sample size of 100 and an adequate validation method were used to identify adequate-quality studies. The effects of study features on prediction accuracy were tested with mixed-effects models. Fifty-four of the studies provided accuracy estimates or other estimates that allowed calculation of balanced accuracy of predicting outcomes of treatment.

RESULTS

Eight adequate-quality studies reported a mean accuracy of 0.63 [95% confidence interval (CI) 0.56-0.71], which was significantly lower than a mean accuracy of 0.75 (95% CI 0.72-0.78) in the other 46 studies. Among the adequate-quality studies, accuracies were higher when predicting treatment resistance (0.69) and lower when predicting remission (0.60) or response (0.56). The choice of machine learning method, feature selection, and the ratio of features to individuals were not associated with reported accuracy.

CONCLUSIONS

The negative relationship between study quality and prediction accuracy, combined with a lack of independent replication, invites caution when evaluating the potential of machine learning applications for personalizing the treatment of depression.

Molecular Mechanisms Associated with Antidepressant Treatment on Major Depression

Major depressive disorder (MDD) is a complex and multifactorial psychiatric disorder that causes serious health, social, and economic concerns worldwide. The main treatment of the symptoms is through antidepressant (AD) drugs. However, not all patients respond properly to these drugs. Omic sciences are widely used to analyze not only biomarkers for the AD response but also their molecular mechanism. In this review, we aimed to focus on omics data to better understand the molecular mechanisms involving AD effects on MDD. We consistently found, from preclinical to clinical data, that glutamatergic transmission, immune/inflammatory processes, energy metabolism, oxidative stress, and lipid metabolism were associated with traditional and potential new ADs. Despite efforts of studies investigating biomarkers of response to ADs, which could contribute to personalized treatment, there is no biomarker panel available for clinical application. From clinical genomic studies, we found that the main findings contribute to the development of pharmacogenomic tests for AD efficacy for each patient. Several studies pointed at DRD2, PXDNL, CACNA1E, and CACNA2D1 genes as potential targets for MDD treatment and the efficacy and rapid-antidepressant effect of ketamine. Finally, more in-depth studies of the molecular targets pointed here are needed to determine the clinical relevance and provide further evidence for precision MDD treatment.

Nanotherapeutics for Nose-to-Brain Drug Delivery: An Approach to Bypass the Blood Brain Barrier

Treatment of neurodegenerative diseases or other central nervous system (CNS) disorders has always been a significant challenge. The nature of the blood-brain barrier (BBB) limits the penetration of therapeutic molecules to the brain after oral or parenteral administration, which, in combination with hepatic metabolism and drug elimination and inactivation during its journey in the systemic circulation, decreases the efficacy of the treatment, requires high drug doses and often induces adverse side effects. Nose-to-brain drug delivery allows the direct transport of therapeutic molecules by bypassing the BBB and increases drug concentration in the brain. The present review describes mechanisms of nose-to-brain drug delivery and discusses recent advances in this area with especial emphasis on nanotechnology-based approaches.

Associations Between Antidepressant Use and Advanced Diabetes Outcomes in Patients with Depression and Diabetes Mellitus

CONTEXT

Comorbid depression in patients with diabetes deteriorates the prognosis. Antidepressants might attenuate the adverse effects of depression; however, they are associated with cardiometabolic adverse effects.

OBJECTIVE

This study aimed to explore the association between antidepressant treatment and advanced diabetic complications and mortality among patients with depression and diabetes mellitus.

METHODS

We conducted a nationwide retrospective cohort study of 36 276 patients with depression and newly treated diabetes mellitus using Taiwan's universal health insurance database. Antidepressant treatment patterns within a 6-month window were classified into none, poor, partial, and regular use, and we accounted for time-dependent variables in the Cox proportional hazards regression analysis with adjustment for time-dependent comorbidity and concomitant use of medications. Different classes of antidepressants were compared. Macro- and microvascular complications, as well as all-cause mortality, were the main outcomes. Benzodiazepines were chosen as negative control exposure.

RESULTS

Compared with poor use of antidepressants, regular use was associated with a 0.92-fold decreased risk of macrovascular complications and a 0.86-fold decreased risk of all-cause mortality but not associated with microvascular complications. Regular use of selective serotonin reuptake inhibitors was associated with a 0.83- and 0.75-fold decreased risk of macrovascular complications and all-cause mortality, respectively. Regular use of tricyclic or tetracyclic antidepressants was associated with a 0.78-fold decreased risk of all-cause mortality. Regular use of benzodiazepine showed no association with diabetic outcomes.

CONCLUSION

Regular antidepressant use was associated with lower risk of advanced diabetic complications compared with poor adherence. Clinicians should emphasize antidepressant treatment adherence among patients with depression and diabetes mellitus.

Sex Differences in the Behavioral, Molecular, and Structural Effects of Ketamine Treatment in Depression

Major depressive disorder (MDD) is a common psychiatric illness that manifests in sex-influenced ways. Men and women may experience depression differently and also respond to various antidepressant treatments in sex-influenced ways. Ketamine, which is now being used as a rapid-acting antidepressant, is likely the same. To date, the majority of studies investigating treatment outcomes in MDD do not disaggregate the findings in males and females, and this is also true for ketamine. This review aims to highlight that gap by exploring pre-clinical data-at a behavioral, molecular, and structural level-and recent clinical trials. Sex hormones, particularly estrogen and progesterone, influence the response at all levels examined, and sex is therefore a critical factor to examine when looking at ketamine response. Taken together, the data show females are more sensitive to ketamine than males, and it might be possible to monitor the phase of the menstrual cycle to mitigate some risks associated with the use of ketamine for females with MDD. Based on the studies reviewed in this article, we suggest that ketamine should be administered adhering to sex-specific considerations.

The role of ventral tegmental area orexinergic afferents in depressive-like behavior in a chronic unpredictable mild stress (CUMS) mouse model

Orexin has been implicated in comorbid diseases of depression, making it a promising target for anti-depression treatment. Although orexin neurons exhibit abnormal activity in depression, the neurocircuit mechanism of orexin remains unclear. As one of the important downstream factors of orexin neurons, the ventral tegmental area (VTA) is considered crucial to the mechanism of depression. However, the role of VTA orexinergic afferents in depression remains unclear. In this study, we applied a combination of opto/chemogenetic and neuropharmacology methods to investigate whether the VTA orexinergic afferents participate in the pathogenesis of depression in a chronic unpredictable mild stress (CUMS) mouse model. We found that c-Fos expression in these VTA-projecting orexin neurons specifically decreased in CUMS-treated mice. Optogenetic and chemogenetic activation of orexin terminals in the VTA significantly reversed depressive behavior. Microinjection of orexin-A, but not orexin-B, into the VTA significantly improved depressive-like behavior. Our study provided direct evidence that the VTA orexinergic afferents participate in the mechanism of depression, and the orexin-1 receptor plays a major role.

Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological and clinical activities

ETHNOPHARMACOLOGICAL RELEVANCE

Sceletium tortuosum (L.) N.E.Br, the most sought after and widely researched species in the genus Sceletium is a succulent forb endemic to South Africa. Traditionally, this medicinal plant is mainly masticated or smoked and used for the relief of toothache, abdominal pain, and as a mood-elevator, analgesic, hypnotic, anxiolytic, thirst and hunger suppressant, and for its intoxicating/euphoric effects. Sceletium tortuosum is currently of widespread scientific interest due to its clinical potential in treating anxiety and depression, relieving stress in healthy individuals, and enhancing cognitive functions. These pharmacological actions are attributed to its phytochemical constituents referred to as mesembrine-type alkaloids.

AIM OF THE REVIEW

The aim of this review was to comprehensively summarize and critically evaluate recent research advances on the phytochemistry, pharmacokinetics, biological and clinical activities of the medicinal plant S. tortuosum. Additionally, current ongoing research and future perspectives are also discussed.

METHODS

All relevant scientific articles, books, MSc and Ph.D. dissertations on botany, behavioral pharmacology, traditional uses, and phytochemistry of S. tortuosum were retrieved from different databases (including Science Direct, PubMed, Google Scholar, Scopus and Web of Science). For pharmacokinetics and pharmacological effects of S. tortuosum, the focus fell on relevant publications published between 2009 and 2021.

RESULTS

Twenty-five alkaloids belonging to four structural classes viz: mesembrine, Sceletium A4, joubertiamine, and tortuosamine, have been identified from S. tortuosum, of which the mesembrine class is predominant. The crude extracts and commercially available standardized extracts of S. tortuosum have displayed a wide spectrum of biological activities (e.g. antimalarial, anti-oxidant, immunomodulatory, anti-HIV, neuroprotection, enhancement of cognitive function) in in vitro or in vivo studies. This plant has not yet been studied in a clinical population, but has potential for enhancing cognitive function, and managing anxiety and depression.

CONCLUSION

As an important South African medicinal plant, S. tortuosum has garnered many research advances on its phytochemistry and biological activities over the last decade. These scientific studies have shown that S. tortuosum has various bioactivities. The findings have further established the link between the phytochemistry and pharmacological application, and support the traditional use of S. tortuosum in the indigenous medicine of South Africa.

Efficacy of amisulpride for depressive symptoms in individuals with mental disorders: A systematic review and meta-analysis

BACKGROUND

Depressive symptoms occur in several psychiatric disorders, often in the absence of a formal diagnosis of depression. We aimed to evaluate the efficacy and the tolerability of amisulpride, both alone and as augmentation therapy, in the treatment of depressive symptoms in individuals with any major psychiatric disorder.

METHODS

We searched PubMed, Embase, PsycINFO, GreyLit, OpenGrey and ProQuest up to March 2020 for randomised controlled trials focussing on the treatment of an acute depressive episode in any major psychiatric disorder. A random-effect meta-analysis was performed to synthesize the findings on depressive symptoms (primary outcome), response rate and tolerability.

RESULTS

We retrieved 11 studies including 2065 patients with a diagnosis of dysthymia (eight studies), major depression (one study) or schizophrenia (two studies). Amisulpride 50 mg/day was associated with a larger reduction of depressive symptoms compared to placebo (standardised mean difference [SMD] = -0.70, CI 95% -0.92, -0.49; I²  = 0.0%), and was found to be comparable to selective serotonin reuptake inhibitors (SSRIs; SMD = -0.08, CI 95% -0.23, 0.06, I²  = 0.0%), amineptine, imipramine and amitriptyline in the treatment of dysthymia (three studies, not pooled). In individuals with schizophrenia, amisulpride administered at higher doses (>400 mg/day) was comparable to olanzapine and risperidone (two studies, not pooled). In terms of tolerability, amisulpride was superior to placebo for dysthymia (odds ratio [OR] = 3.94, CI 95% 1.07, 14.48; I²  = 0.0) and comparable with SSRIs (OR = 0.94, CI 95% 0.55, 1.62; I²  = 0.0%).

CONCLUSION

Treatment with amisulpride could be a valid choice for selected individuals with dysthymia or depressive symptoms in the context of schizophrenia. More studies on the efficacy and tolerability of amisulpride are needed to draw firm conclusions on its potential benefits in other psychiatric disorders.

Investigating the Role of Leukocyte Telomere Length in Treatment-Resistant Depression and in Response to Electroconvulsive Therapy

Psychiatric disorders seem to be characterized by premature cell senescence. However, controversial results have also been reported. In addition, the relationship between accelerated aging and treatment-resistance has scarcely been investigated. In the current study, we measured leukocyte telomere length (LTL) in 148 patients with treatment-resistant depression (TRD, 125 with major depressive disorder, MDD, and 23 with bipolar disorder, BD) treated with electroconvulsive therapy (ECT) and analyzed whether LTL was associated with different response profiles. We also compared LTL between patients with TRD and 335 non-psychiatric controls. For 107 patients for which genome-wide association data were available, we evaluated whether a significant overlap among genetic variants or genes associated with LTL and with response to ECT could be observed. LTL was negatively correlated with age (Spearman’s correlation coefficient = −0.25, p < 0.0001) and significantly shorter in patients with treatment-resistant MDD (Quade’s F = 35.18, p < 0.0001) or BD (Quade’s F = 20.84, p < 0.0001) compared to controls. Conversely, baseline LTL was not associated with response to ECT or remission. We did not detect any significant overlap between genetic variants or genes associated with LTL and response to ECT. Our results support previous findings suggesting premature cell senescence in patients with severe psychiatric disorders and suggest that LTL could not be a predictive biomarker of response to ECT.

Plant-based dietary quality and depressive symptoms in Australian vegans and vegetarians: a cross-sectional study

Plant-based dietary patterns (vegan and vegetarian) are often considered 'healthy' and have been associated with broad health benefits, including decreased risk of obesity and ill health (cardiovascular disease, blood glucose and type II diabetes). However, the association between plant-based diets and mood disorders such as depression remains largely equivocal. This cross-sectional study of 219 adults aged 18-44 (M=31.22, SD=7.40) explored the associations between an estimate of overall plant-based diet quality and depression in vegans (n=165) and vegetarians (n=54). Overall plant-based diet quality was associated with depressive symptoms in vegans and vegetarians F(1, 215)=13.71, p<0.001 accounting for 6% of the variation in depressive symptoms. For those without depression, higher diet quality was protective against depressive symptoms F(1, 125)=6.49, p=0.012. Conversely, for those with depression no association with diet quality was found F(1, 89)=0.01, p=0.963. These findings suggest that a high-quality plant-based diet may be protective against depressive symptoms in vegans and vegetarians. In line with emerging research between food and mental health, higher-quality dietary patterns are associated with a reduced risk of depressive symptoms. Given the rapidly increasing rate of vegan and vegetarian food products within Australia, understanding the potential mechanisms of effects through which a plant-based diet may influence depressive symptoms is required.

Kir4.1 Dysfunction in the Pathophysiology of Depression: A Systematic Review

A serotonergic dysfunction has been largely postulated as the main cause of depression, mainly due to its effective response to drugs that increase the serotonergic tone, still currently the first therapeutic line in this mood disorder. However, other dysfunctional pathomechanisms are likely involved in the disorder, and this may in part explain why some individuals with depression are resistant to serotonergic therapies. Among these, emerging evidence suggests a role for the astrocytic inward rectifier potassium channel 4.1 (Kir4.1) as an important modulator of neuronal excitability and glutamate metabolism. To discuss the relationship between Kir4.1 dysfunction and depression, a systematic review was performed according to the PRISMA statement. Searches were conducted across PubMed, Scopus, and Web of Science by two independent reviewers. Twelve studies met the inclusion criteria, analyzing Kir4.1 relationships with depression, through in vitro, in vivo, and post-mortem investigations. Increasing, yet not conclusive, evidence suggests a potential pathogenic role for Kir4.1 upregulation in depression. However, the actual contribution in the diverse subtypes of the disorder and in the comorbid conditions, for example, the epilepsy-depression comorbidity, remain elusive. Further studies are needed to better define the clinical phenotype associated with Kir4.1 dysfunction in humans and the molecular mechanisms by which it contributes to depression and implications for future treatments.

Sex-based changes in rat brain serotonin and behavior in a model of altitude-related vulnerability to treatment-resistant depression

RATIONALE

Rates of depression and suicide increase with altitude. In our animal model, rats housed at moderate altitude vs. at sea level exhibit increased depressive symptoms in the forced swim test (FST) and lack of response to selective serotonin reuptake inhibitors (SSRIs). Depression and SSRI resistance are linked to disrupted serotonergic function, and hypobaric hypoxia may reduce the oxygen-dependent synthesis of serotonin. We therefore tested brain serotonin in rats housed at altitude.

METHODS

Sprague-Dawley rats were housed at altitude (4,500 ft, 10,000 ft) vs. sea level for 7-36 days. Brain serotonin was measured by ELISA, or behavior evaluated in the FST, sucrose preference (SPT), or open-field tests (OFT).

RESULTS

After 2 weeks at 4,500 ft or 10,000ft vs. sea level, serotonin levels decreased significantly at altitude in the female prefrontal cortex, striatum, hippocampus, and brainstem, but increased with altitude in the male hippocampus and brainstem. Female brain serotonin decreased from 7 to 36 days at 4,500 ft, but males did not vary. At 2 weeks and 24 days, females at altitude exhibit lower brain serotonin and increased depressive symptoms in the FST and SPT, with motor behavior unaltered. In males, serotonin, passive coping in the FST and OFT immobility increased with altitude at 2 weeks, but not at 24 days. Male SPT behavior did not change with altitude.

CONCLUSIONS

Females may be more vulnerable to depressive symptoms at altitude, while males may be resilient. Chronic hypoxic stress at altitudes as low as 4,500 ft may cause a brain serotonin imbalance to worsen vulnerability to depression and SSRI resistance, and potentially worsen suicide risk.

A partial least squares and artificial neural network study for a series of arylpiperazines as antidepressant agents

Depression affects more than 300 million people around the world and can lead to suicide. About 30% of patients on treatment for depression drop out of therapy due to side effects or to latency time associated to therapeutic effects. 5-HT receptor, known as serotonin, is considered the key in depression treatment. Arylpiperazine compounds are responsible for several pharmacological effects and are considered as ligands in serotonin receptors, such as the subtype 5-HT_2a. Here, in silico studies were developed using partial least squares (PLSs) and artificial neural networks (ANNs) to design new arylpiperazine compounds that could interact with the 5-HT_2a receptor. First, molecular and electronic descriptors were calculated and posteriorly selected from correlation matrixes and genetic algorithm (GA). Then, the selected descriptors were used to construct PLS and ANN models that showed to be robust and predictive. Lastly, new arylpiperazine compounds were designed and their biological activity values were predicted by both PLS and ANN models. It is worth to highlight compounds G5 and G7 (predicted by the PLS model) and G3 and G15 (predicted by the ANN model), whose predicted pIC₅₀ values were as high as the three highest values from the arylpiperazine original set studied here. Therefore, it can be asserted that the two models (PLS and ANN) proposed in this work are promising for the prediction of the biological activity of new arylpiperazine compounds and may significantly contribute to the design of new drugs for the treatment of depression.

Neuroprotective Effects and Therapeutic Potential of Transcorneal Electrical Stimulation for Depression

Transcorneal electrical stimulation (TES) has emerged as a non-invasive neuromodulation approach that exerts neuroprotection via diverse mechanisms, including neurotrophic, neuroplastic, anti-inflammatory, anti-apoptotic, anti-glutamatergic, and vasodilation mechanisms. Although current studies of TES have mainly focused on its applications in ophthalmology, several lines of evidence point towards its putative use in treating depression. Apart from stimulating visual-related structures and promoting visual restoration, TES has also been shown to activate brain regions that are involved in mood alterations and can induce antidepressant-like behaviour in animals. The beneficial effects of TES in depression were further supported by its shared mechanisms with FDA-approved antidepressant treatments, including its neuroprotective properties against apoptosis and inflammation, and its ability to enhance the neurotrophic expression. This article critically reviews the current findings on the neuroprotective effects of TES and provides evidence to support our hypothesis that TES possesses antidepressant effects.

The role of meningeal populations of type II innate lymphoid cells in modulating neuroinflammation in neurodegenerative diseases

Recent research into meningeal lymphatics has revealed a never-before appreciated role of type II innate lymphoid cells (ILC2s) in modulating neuroinflammation in the central nervous system (CNS). To date, the role of ILC2-mediated inflammation in the periphery has been well studied. However, the exact distribution of ILC2s in the CNS and therefore their putative role in modulating neuroinflammation in neurodegenerative diseases such as Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD), and major depressive disorder (MDD) remain highly elusive. Here, we review the current evidence of ILC2-mediated modulation of neuroinflammatory cues (i.e., IL-33, IL-25, IL-5, IL-13, IL-10, TNFα, and CXCL16-CXCR6) within the CNS, highlight the distribution of ILC2s in both the periphery and CNS, and discuss some challenges associated with cell type-specific targeting that are important for therapeutics. A comprehensive understanding of the roles of ILC2s in mediating and responding to inflammatory cues may provide valuable insight into potential therapeutic strategies for many dementia-related disorders.

Prevalence of Pre-existing Conditions Relevant for Adverse Events and Potential Drug-Drug Interactions Associated with Augmentation Therapies Among Patients with Treatment-Resistant Depression

INTRODUCTION

Pre-existing conditions relevant for adverse events (AE) and the potential for drug-drug interactions (DDIs) may limit safe pharmacotherapeutic augmentation options for patients with major depressive disorder (MDD). This concern may be heightened among patients with treatment-resistant depression (TRD), who often have comorbid medical disorders.

METHODS

Adults with MDD and ≥ 1 antidepressant claim within the first observed major depressive episode were identified in the MarketScan® Databases. Those initiating a new regimen after two regimens at adequate dose and duration were considered to have TRD. The index date was defined at TRD onset or on a random antidepressant claim among patients with non-TRD MDD. Pre-existing conditions 12 months pre-index and potential DDIs 3 months pre/post-index associated with specific non-antidepressant augmentation therapies, including atypical antipsychotics (APs), buspirone, psychostimulants, anticonvulsants, thyroid hormone, and lithium were compared between 1:1 matched TRD and non-TRD MDD cohorts.

RESULTS

Overall, 3414 patients with TRD and non-TRD MDD (mean age 39.7 years, 69% female) were matched. Relative to non-TRD MDD, patients with TRD had 33% higher likelihood of ≥ 1 pre-existing condition relevant for AEs listed in product labels of non-antidepressant augmentation therapies (p < 0.001). Patients with TRD vs. non-TRD MDD had 12.9 and 6.4 times higher likelihood of ≥ 2 and ≥ 3 DDIs, respectively, based on their medication regimen (all p < 0.001).

CONCLUSION

Pre-existing conditions relevant for listed AEs and potential DDIs limit safe augmentation options in MDD, particularly among patients with TRD. Payer prior authorization policies requiring several augmentation therapy trials to access novel treatments may complicate clinical management of this population.