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C. Zarate

Ketamine and Serotonergic Psychedelics: Common Mechanisms Underlying the Effects of Rapid-Acting Antidepressants

January 7, 2022 / Depressive Disorders, Ketamine, Neuroscience, Papers / Leave a Comment / By / , , , , , ,

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.

Kadriu, B., Greenwald, M., Henter, I. D., Gilbert, J. R., Kraus, C., Park, L. T., & Zarate, C. A. (2021). Ketamine and Serotonergic Psychedelics: Common Mechanisms Underlying the Effects of Rapid-Acting Antidepressants. The international journal of neuropsychopharmacology, 24(1), 8–21. https://doi.org/10.1093/ijnp/pyaa087

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Convergent Mechanisms Underlying Rapid Antidepressant Action

March 1, 2018 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , ,

Abstract

Traditional pharmacological treatments for depression have a delayed therapeutic onset, ranging from several weeks to months, and there is a high percentage of individuals who never respond to treatment. In contrast, ketamine produces rapid-onset antidepressant, anti-suicidal, and anti-anhedonic actions following a single administration to patients with depression. Proposed mechanisms of the antidepressant action of ketamine include N-methyl-D-aspartate receptor (NMDAR) modulation, gamma aminobutyric acid (GABA)-ergic interneuron disinhibition, and direct actions of its hydroxynorketamine (HNK) metabolites. Downstream actions include activation of the mechanistic target of rapamycin (mTOR), deactivation of glycogen synthase kinase-3 and eukaryotic elongation factor 2 (eEF2), enhanced brain-derived neurotrophic factor (BDNF) signaling, and activation of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptors (AMPARs). These putative mechanisms of ketamine action are not mutually exclusive and may complement each other to induce potentiation of excitatory synapses in affective-regulating brain circuits, which results in amelioration of depression symptoms. We review these proposed mechanisms of ketamine action in the context of how such mechanisms are informing the development of novel putative rapid-acting antidepressant drugs. Such drugs that have undergone pre-clinical, and in some cases clinical, testing include the muscarinic acetylcholine receptor antagonist scopolamine, GluN2B-NMDAR antagonists (i.e., CP-101,606, MK-0657), (2R,6R)-HNK, NMDAR glycine site modulators (i.e., 4-chlorokynurenine, pro-drug of the glycineB NMDAR antagonist 7-chlorokynurenic acid), NMDAR agonists [i.e., GLYX-13 (rapastinel)], metabotropic glutamate receptor 2/3 (mGluR2/3) antagonists, GABAA receptor modulators, and drugs acting on various serotonin receptor subtypes. These ongoing studies suggest that the future acute treatment of depression will typically occur within hours, rather than months, of treatment initiation.
Zanos, P., Thompson, S. M., Duman, R. S., Zarate, C. A., & Gould, T. D. (2018). Convergent mechanisms underlying rapid antidepressant action. CNS drugs, 1-31. 10.1007/s40263-018-0492-x
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Features of dissociation differentially predict antidepressant response to ketamine in treatment-resistant depression

February 17, 2018 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

BACKGROUND:
Ketamine induces rapid and robust antidepressant effects, and many patients also describe dissociation, which is associated with antidepressant response. This follow-up study investigated whether antidepressant efficacy is uniquely related to dissociative symptom clusters.
METHODS:
Treatment-resistant patients with major depressive disorder (MDD) or bipolar disorder (BD) (n = 126) drawn from three studies received a single subanesthetic (0.5 mg/kg) ketamine infusion. Dissociative effects were measured using the Clinician-Administered Dissociative States Scale (CADSS). Antidepressant response was measured using the 17-item Hamilton Depression Rating Scale (HAM-D). A confirmatory factor analysis established the validity of CADSS subscales (derealization, depersonalization, amnesia), and a general linear model with repeated measures was fitted to test whether subscale scores were associated with antidepressant response.
RESULTS:
Factor validity was supported, with a root mean square error of approximation of .06, a comparative fit index of .97, and a Tucker-Lewis index of .96. Across all studies and timepoints, the depersonalization subscale was positively related to HAM-D percent change. A significant effect of derealization on HAM-D percent change was observed at one timepoint (Day 7) in one study. The amnesia subscale was unrelated to HAM-D percent change.
LIMITATIONS:
Possible inadequate blinding; combined MDD/BD datasets might have underrepresented ketamine’s antidepressant efficacy; the possibility of Type I errors in secondary analyses.
CONCLUSIONS:
From a psychometric perspective, researchers may elect to administer only the CADSS depersonalization subscale, given that it was most closely related to antidepressant response. From a neurobiological perspective, mechanistic similarities may exist between ketamine-induced depersonalization and antidepressant response, although off-target effects cannot be excluded.
Niciu, M. J., Shovestul, B. J., Jaso, B. A., Farmer, C., Luckenbaugh, D. A., Brutsche, N. E., … & Zarate, C. A. (2018). Features of dissociation differentially predict antidepressant response to ketamine in treatment-resistant depression. Journal of affective disorders, 232, 310-315. 10.1016/j.jad.2018.02.049
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Associations between Specific Dissociative Symptoms and Symptom Subsets and Anti-Depressant Response to Ketamine

May 15, 2017 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , ,

Abstract

Ketamine has been shown to produce rapid antidepressant effects in major depression and bipolar disorder. Due to ketamine’s glutamatergic properties, many patients report dissociative effects, which recent studies have shown to be associated with increased anti-depressant response. Thus we investigated the connection between distinct subscales of dissociation and differing treatment response.

Shovestul, B., Jaso, B., Luckenbaugh, D., Park, L., Niciu, M., & Zarate, C. (2017). 199-Associations between Specific Dissociative Symptoms and Symptom Subsets and Anti-Depressant Response to Ketamine. Biological Psychiatry, 81(10), S82-S83. 10.1016/j.biopsych.2017.02.212
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Clinical Predictors of an Antisuicidal Response to Ketamine

May 15, 2017 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Suicide is one of the leading causes of death in the United States. Despite treatment efforts, the national suicide rate has increased in recent years. Currently, there are no pharmacological treatments for suicidal ideation (SI). For individuals experiencing a suicidal crisis, rapid acting medications may save lives. Recent studies suggest ketamine, a glutamate modulator, elicits rapid antisuicidal responses. We examined clinical factors that might predict ketamine’s antisuicidal response as a step towards understanding ketamine’s mechanism of action on suicidal thoughts.

Yarrington, J., Ballard, E., Luckenbaugh, D., Niciu, M., Lener, M., Kadriu, B., … & Zarate, C. (2017). 1004-Clinical Predictors of an Antisuicidal Response to Ketamine. Biological Psychiatry, 81(10), S406. 10.1016/j.biopsych.2017.02.731
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Mood Dependent Effects of Ketamine on REM Eye Movements in Patients with Treatment Resistant Depression (TRD)

May 15, 2017 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , ,

Abstract

Both REM and NREM sleep are dysregulated in depression. REM dysregulation in MDD is thought to be partially linked to a deficient inhibitory influence of Process-S, leading to increased REM density (RD) and short REM latency (RL). Consistent with its effects on enhanced synaptic plasticity, ketamine increases SWS and early night slow-wave activity (SWA) in patients with TRD. Here we extend the examination of ketamine effects on rapid mood improvement to RD, an important marker of REM sleep in depression.

Hejazi, N., Yu, K., Park, L., Duncan, W., & Zarate, C. (2017). 861-Mood Dependent Effects of Ketamine on REM Eye Movements in Patients with Treatment Resistant Depression (TRD). Biological Psychiatry, 81(10), S348-S349. 10.1016/j.biopsych.2017.02.586
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Ketamine Mechanism of Action: Separating the Wheat from the Chaff

January 1, 2017 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , ,

Abstract

(R,S)-ketamine (ketamine) exerts rapid (within hours) and robust (>60% response) antidepressant effects in severely ill-depressed patients who have failed conventional treatments (Zarate et al, 2006). This clinical finding has been paradigm-shifting as there is now tremendous hope that very ill-depressed patients can be treated in a matter of hours, rather than many weeks or months required for standard therapies to take effect (if they do at all).

Gould, T. D., Zanos, P., & Zarate, C. A. (2017). Ketamine Mechanism of Action: Separating the Wheat from the Chaff. Neuropsychopharmacology, 42(1), 368-369. 10.1038/npp.2016.210
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Antisuicidal Response Following Ketamine Infusion Is Associated With Decreased Nighttime Wakefulness in Major Depressive Disorder and Bipolar Disorder

December 6, 2016 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

OBJECTIVE: Insomnia and disrupted sleep are associated with increased risk of suicide. The N-methyl-D-aspartate antagonist ketamine has been associated with reduced suicidal thoughts, but the mechanism of action is unknown. This study sought to evaluate differences in nocturnal wakefulness in depressed individuals who did and did not have an antisuicidal response to ketamine.

METHODS: Thirty-four participants with baseline suicidal ideation diagnosed with either DSM-IV major depressive disorder (n = 23) or bipolar depression (n = 11) between 2006 and 2013 completed nighttime electroencephalography (EEG) the night before and the night after a single ketamine infusion (0.5 mg/kg over 40 minutes). Suicidal ideation was assessed at baseline and the morning after ketamine infusion via several measures, including the Hamilton Depression Rating Scale suicide item, the suicide item of the Montgomery-Asberg Depression Rating Scale, and the first 5 items of the Scale for Suicide Ideation. A generalized linear mixed model evaluated differences in nocturnal wakefulness, as verified by EEG, between those who had an antisuicidal response to ketamine and those who did not, controlling for baseline nocturnal wakefulness. Results were also compared to the sleep of healthy controls (n = 22).

RESULTS: After analyses adjusted for baseline sleep, participants with an antisuicidal response to ketamine showed significantly reduced nocturnal wakefulness the night after ketamine infusion compared to those without an antisuicidal response (F₁,₂₂ = 5.04, P = .04). Level of nocturnal wakefulness after antisuicidal response to ketamine did not differ significantly from nocturnal wakefulness in the control sample but did differ at a trend level (F₁,₄₀ = 3.15, P = .08).

CONCLUSIONS: Reductions in wakefulness following ketamine may point to a biological mechanism underlying the effect of ketamine on suicidal ideation.

Vande Voort, J. L., Ballard, E. D., Luckenbaugh, D. A., Bernert, R. A., Richards, E. M., Niciu, M. J., … & Zarate, C. A. (2016). Antisuicidal response following ketamine infusion is associated with decreased nighttime wakefulness in major depressive disorder and bipolar disorder. Journal of clinical psychiatry. 10.4088/JCP.15m10440
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Case series: Antidepressant effects of low-affinity and low-trapping NMDA receptor antagonists did not predict response to ketamine in seven subjects

November 21, 2016 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , ,

Abstract

Ketamine’s antidepressant effects have variously been attributed to its wide-acting N-methyl-D-aspartate (NMDA) antagonism, its high-affinity for the NMDA receptor (Sanacora et al., 2008), and its trapping mechanism of blockade (Autry et al., 2011; Duman et al., 2016; Zarate et al., 2013). Several novel agents are being developed and tested that attempt to maintain ketamine’s antidepressant efficacy while minimizing its side effects, particularly its psychotomimetic properties and abuse potential.

Lepow, L., Luckenbaugh, D. A., Park, L., Henter, I. D., & Zarate, C. A. (2017). Case series: Antidepressant effects of low-affinity and low-trapping NMDA receptor antagonists did not predict response to ketamine in seven subjects. Journal of psychiatric research, 86, 55-57. 10.1016/j.jpsychires.2016.10.023
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