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1.
Ketamine and Serotonergic Psychedelics: Common Mechanisms Underlying the Effects of Rapid-Acting Antidepressants.
Kadriu, B, Greenwald, M, Henter, ID, Gilbert, JR, Kraus, C, Park, LT, Zarate, CA
The international journal of neuropsychopharmacology. 2021;(1):8-21
Abstract
BACKGROUND The glutamatergic modulator ketamine has created a blueprint for studying novel pharmaceuticals in the field. Recent studies suggest that "classic" serotonergic psychedelics (SPs) may also have antidepressant efficacy. Both ketamine and SPs appear to produce rapid, sustained antidepressant effects after a transient psychoactive period. METHODS This review summarizes areas of overlap between SP and ketamine research and considers the possibility of a common, downstream mechanism of action. The therapeutic relevance of the psychoactive state, overlapping cellular and molecular effects, and overlapping electrophysiological and neuroimaging observations are all reviewed. RESULTS Taken together, the evidence suggests a potentially shared mechanism wherein both ketamine and SPs may engender rapid neuroplastic effects in a glutamatergic activity-dependent manner. It is postulated that, though distinct, both ketamine and SPs appear to produce acute alterations in cortical network activity that may initially produce psychoactive effects and later produce milder, sustained changes in network efficiency associated with therapeutic response. However, despite some commonalities between the psychoactive component of these pharmacologically distinct therapies-such as engagement of the downstream glutamatergic pathway-the connection between psychoactive impact and antidepressant efficacy remains unclear and requires more rigorous research. CONCLUSIONS Rapid-acting antidepressants currently under investigation may share some downstream pharmacological effects, suggesting that their antidepressant effects may come about via related mechanisms. Given the prototypic nature of ketamine research and recent progress in this area, this platform could be used to investigate entirely new classes of antidepressants with rapid and robust actions.
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2.
Synthesizing the Evidence for Ketamine and Esketamine in Treatment-Resistant Depression: An International Expert Opinion on the Available Evidence and Implementation.
McIntyre, RS, Rosenblat, JD, Nemeroff, CB, Sanacora, G, Murrough, JW, Berk, M, Brietzke, E, Dodd, S, Gorwood, P, Ho, R, et al
The American journal of psychiatry. 2021;(5):383-399
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Abstract
Replicated international studies have underscored the human and societal costs associated with major depressive disorder. Despite the proven efficacy of monoamine-based antidepressants in major depression, the majority of treated individuals fail to achieve full syndromal and functional recovery with the index and subsequent pharmacological treatments. Ketamine and esketamine represent pharmacologically novel treatment avenues for adults with treatment-resistant depression. In addition to providing hope to affected persons, these agents represent the first non-monoaminergic agents with proven rapid-onset efficacy in major depressive disorder. Nevertheless, concerns remain about the safety and tolerability of ketamine and esketamine in mood disorders. Moreover, there is uncertainty about the appropriate position of these agents in treatment algorithms, their comparative effectiveness, and the appropriate setting, infrastructure, and personnel required for their competent and safe implementation. In this article, an international group of mood disorder experts provides a synthesis of the literature with respect to the efficacy, safety, and tolerability of ketamine and esketamine in adults with treatment-resistant depression. The authors also provide guidance for the implementation of these agents in clinical practice, with particular attention to practice parameters at point of care. Areas of consensus and future research vistas are discussed.
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Augmentative Pharmacological Strategies in Treatment-Resistant Major Depression: A Comprehensive Review.
Caldiroli, A, Capuzzi, E, Tagliabue, I, Capellazzi, M, Marcatili, M, Mucci, F, Colmegna, F, Clerici, M, Buoli, M, Dakanalis, A
International journal of molecular sciences. 2021;(23)
Abstract
Treatment resistant depression (TRD) is associated with poor outcomes, but a consensus is lacking in the literature regarding which compound represents the best pharmacological augmentation strategy to antidepressants (AD). In the present review, we identify the available literature regarding the pharmacological augmentation to AD in TRD. Research in the main psychiatric databases was performed (PubMed, ISI Web of Knowledge, PsychInfo). Only original articles in English with the main topic being pharmacological augmentation in TRD and presenting a precise definition of TRD were included. Aripiprazole and lithium were the most investigated molecules, and aripiprazole presented the strongest evidence of efficacy. Moreover, olanzapine, quetiapine, cariprazine, risperidone, and ziprasidone showed positive results but to a lesser extent. Brexpiprazole and intranasal esketamine need further study in real-world practice. Intravenous ketamine presented an evincible AD effect in the short-term. The efficacy of adjunctive ADs, antiepileptic drugs, psychostimulants, pramipexole, ropinirole, acetyl-salicylic acid, metyrapone, reserpine, testosterone, T3/T4, naltrexone, SAMe, and zinc cannot be precisely estimated in light of the limited available data. Studies on lamotrigine and pindolol reported negative results. According to our results, aripiprazole and lithium may be considered by clinicians as potential effective augmentative strategies in TRD, although the data regarding lithium are somewhat controversial. Reliable conclusions about the other molecules cannot be drawn. Further controlled comparative studies, standardized in terms of design, doses, and duration of the augmentative treatments, are needed to formulate definitive conclusions.
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The Putative Antidepressant Mechanisms of Probiotic Bacteria: Relevant Genes and Proteins.
Poluektova, E, Yunes, R, Danilenko, V
Nutrients. 2021;(5)
Abstract
Probiotic bacteria are widely accepted as therapeutic agents against inflammatory bowel diseases for their immunostimulating effects. In the last decade, more evidence has emerged supporting the positive effects of probiotics on the course of neurodegenerative and psychiatric diseases. This brief review summarizes the data from clinical studies of probiotics possessing antidepressant properties and focuses on the potential genes and proteins underlying these mechanisms. Data from small-sample placebo-controlled pilot studies indicate that certain strains of bacteria can significantly reduce the symptoms of depression, especially in depressed patients. Despite the disparity between studies attempting to pinpoint the bacterial putative genes and proteins accounting for these mechanisms, they ultimately show that bacteria are a potential source of metabiotics-microbial metabolites or structural components. Since the constituents of cells-namely, secreted proteins, peptides and cell wall components-are most likely to be entangled in the gut-brain axis, they can serve as starting point in the search for probiotics with concrete properties.
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Perisynaptic astrocytes as a potential target for novel antidepressant drugs.
Frizzo, ME, Ohno, Y
Journal of pharmacological sciences. 2021;(1):60-68
Abstract
Emerging evidence suggests that dysfunctions in glutamatergic signaling are associated with the pathophysiology of depression. Several molecules that act on glutamate binding sites, so-called glutamatergic modulators, are rapid-acting antidepressants that stimulate synaptogenesis. Their antidepressant response involves the elevation of both extracellular glutamate and brain-derived neurotrophic factor (BDNF) levels, as well as the postsynaptic activation of the mammalian target of rapamycin complex 1. The mechanisms involved in the antidepressant outcomes of glutamatergic modulators, including ketamine, suggest that astrocytes must be considered a cellular target for developing rapid-acting antidepressants. It is well known that extracellular glutamate levels and glutamate intrasynaptic time-coursing are maintained by perisynaptic astrocytes, where inwardly rectifying potassium channels 4.1 (Kir4.1 channels) regulate both potassium and glutamate uptake. In addition, ketamine reduces membrane expression of Kir4.1 channels, which raises extracellular potassium and glutamate levels, increasing postsynaptic neural activities. Furthermore, inhibition of Kir4.1 channels stimulates BDNF expression in astrocytes, which may enhance synaptic connectivity. In this review, we discuss glutamatergic modulators' actions in regulating extracellular glutamate and BDNF levels, and reinforce the importance of perisynaptic astrocytes for the development of novel antidepressant drugs.
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Ketamine as a Treatment for Anorexia Nervosa: A Narrative Review.
Keeler, JL, Treasure, J, Juruena, MF, Kan, C, Himmerich, H
Nutrients. 2021;(11)
Abstract
Anorexia nervosa (AN) is a highly complex disorder to treat, especially in severe and enduring cases. Whilst the precise aetiology of the disorder is uncertain, malnutrition and weight loss can contribute to reductions in grey and white matter of the brain, impairments in neuroplasticity and neurogenesis and difficulties with cognitive flexibility, memory and learning. Depression is highly comorbid in AN and may be a barrier to recovery. However, traditional antidepressants are often ineffective in alleviating depressive symptoms in underweight patients with AN. There is an urgent need for new treatment approaches for AN. This review gives a conceptual overview for the treatment of AN with ketamine. Ketamine has rapid antidepressant effects, which are hypothesised to occur via increases in glutamate, with sequelae including increased neuroplasticity, neurogenesis and synaptogenesis. This article provides an overview of the use of ketamine for common psychiatric comorbidities of AN and discusses particular safety concerns and side effects. Potential avenues for future research and specific methodological considerations are explored. Overall, there appears to be ample theoretical background, via several potential mechanisms, that warrant the exploration of ketamine as a treatment for adults with AN.
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Conceptualizing Health Behaviors as Acute Mood-Altering Agents: Implications for Cancer Control.
Dunton, GF, Kaplan, JT, Monterosso, J, Pang, RD, Mason, TB, Kirkpatrick, MG, Eckel, SP, Leventhal, AM
Cancer prevention research (Philadelphia, Pa.). 2020;(4):343-350
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Abstract
A massive portion of cancer burden is accounted for by a small collection of highly prevalent cancer risk behaviors (e.g., low physical activity, unhealthy diet, and tobacco use). Why people engage in numerous types of cancer risk behaviors and fail to adopt various cancer prevention behaviors has been poorly understood. In this commentary, we propose a novel scientific framework, which argues that a common affective (i.e., emotion based) mechanism underpins a diversity of such cancer risk and prevention behaviors. The scientific premise is that cancer risk and prevention behaviors produce immediate and robust changes in affective states that are translated into motivations and drives, which promote further pursuit of risk behaviors or avoidance of prevention behaviors. After describing the conceptual and scientific basis for this framework, we then propose central research questions that can address the validity and utility of the framework. Next, we selectively review and integrate findings on the mood-altering effects of various cancer risk and prevention behaviors from the addiction science, exercise science, and behavioral nutrition literatures, focusing on the nature and phenomenology of behavior-elicited mood changes and their value for predicting future behavior change. We conclude by discussing how this framework can be applied to address critical scientific questions in cancer control.
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Nutraceutical Augmentation Strategies for Depression: A Narrative Review.
Lande, RG
The Journal of the American Osteopathic Association. 2020;(2):100-106
Abstract
CONTEXT Depression is one of the most commonly diagnosed psychiatric disorders, but antidepressant pharmacotherapy often fails to achieve remission, leading health care professionals and researchers to consider various augmentation strategies to improve clinical outcomes. OBJECTIVE To assess the safety, tolerability, and efficacy of nutraceutical augmentation for depression. METHODS Nutraceutical-focused systematic reviews and clinical practice guidelines identified the more commonly studied augmentation strategies for depression. RESULTS S-adenosylmethionine, l-methylfolate, omega-3 fatty acids, and hydroxyvitamin D have sufficient scientific evidence to support their clinical consideration in the stepped care approach to the management of depression. CONCLUSIONS Clinical remission is the goal in the management of depression, and nutraceuticals may be part of an overall treatment approach to achieve that outcome.
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Predictors of Response to Ketamine in Treatment Resistant Major Depressive Disorder and Bipolar Disorder.
Rong, C, Park, C, Rosenblat, JD, Subramaniapillai, M, Zuckerman, H, Fus, D, Lee, YL, Pan, Z, Brietzke, E, Mansur, RB, et al
International journal of environmental research and public health. 2018;(4)
Abstract
OBJECTIVES Extant evidence indicates that ketamine exerts rapid antidepressant effects in treatment-resistant depressive (TRD) symptoms as a part of major depressive disorder (MDD) and bipolar disorder (BD). The identification of depressed sub-populations that are more likely to benefit from ketamine treatment remains a priority. In keeping with this view, the present narrative review aims to identify the pretreatment predictors of response to ketamine in TRD as part of MDD and BD. METHOD Electronic search engines PubMed/MEDLINE, ClinicalTrials.gov, and Scopus were searched for relevant articles from inception to January 2018. The search term ketamine was cross-referenced with the terms depression, major depressive disorder, bipolar disorder, predictors, and response and/or remission. RESULTS Multiple baseline pretreatment predictors of response were identified, including clinical (i.e., Body Mass Index (BMI), history of suicide, family history of alcohol use disorder), peripheral biochemistry (i.e., adiponectin levels, vitamin B12 levels), polysomnography (abnormalities in delta sleep ratio), neurochemistry (i.e., glutamine/glutamate ratio), neuroimaging (i.e., anterior cingulate cortex activity), genetic variation (i.e., Val66Met BDNF allele), and cognitive functioning (i.e., processing speed). High BMI and a positive family history of alcohol use disorder were the most replicated predictors. CONCLUSIONS A pheno-biotype of depression more, or less likely, to benefit with ketamine treatment is far from complete. Notwithstanding, metabolic-inflammatory alterations are emerging as possible pretreatment response predictors of depressive symptom improvement, most notably being cognitive impairment. Sophisticated data-driven computational methods that are iterative and agnostic are more likely to provide actionable baseline pretreatment predictive information.
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Experimental medication treatment approaches for depression.
Ionescu, DF, Papakostas, GI
Translational psychiatry. 2017;(3):e1068
Abstract
Depression is one of the most common psychiatric conditions. Symptoms can lead to significant disability, which result in impairments in overall quality of life. Though there are many approved antidepressant treatments for depression-including selective serotonin reuptake inhibitors, tricyclic antidepressants and monoamine oxidase inhibitors-about a third of patients do not respond to these medications. Therefore, it is imperative for drug discovery to continue towards the development of novel and rapidly acting compounds, especially for patients with treatment-resistant depression. After a brief review of the efficacy of approved antidepressant therapies, we will discuss experimental medication treatments for depression. Specifically, we examine novel medications that are thought to primarily modulate the glutamatergic, cholinergic and opioid systems to achieve antidepressant efficacy. We also give examples of anti-inflammatories, neurokinin-1 modulators, vasopressin antagonists and neurogenesis enhancers that may have a therapeutic role in treatment-resistant depression. The current pipeline of antidepressant treatments is shifting towards medications with novel mechanisms, which may lead to important, life-changing discoveries for patients with severe disease.