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T. Novák

The Antidepressant Effect of Ketamine Is Dampened by Concomitant Benzodiazepine Medication

November 26, 2021 / Depressive Disorders, Ketamine, Papers, Psychology / Leave a Comment / By / , , , , ,

Abstract

The rapid antidepressant effect of ketamine has become a breakthrough in the research and treatment of depression. Although predictive and modulating factors of the response to ketamine are broadly studied, little is known about optimal concurrent medication protocols. Concerning gamma-aminobutyric acid neurotransmission being a shared target for both ketamine and benzodiazepines (BZD), we evaluated the influence of BZD on the antidepressant effect of a single ketamine infusion in depressed patients. Data from 47 patients (27 females) with major depression (MADRS ≥ 20, ≥ 1 prior nonresponse to antidepressant treatment in current episode) who participated in two previous studies (EudraCT Number: 2009-010625-39 and 2013-000952-17) entered the analysis. All of the subjects were given an infusion of a subanesthetic dose of racemic ketamine (0.54 mg per kg) as an add-on medication to ongoing antidepressant treatment. Thirteen patients (28%) reached ≥ 50% reduction in MADRS within one week after ketamine administration. Nineteen (40%) patients took concomitant benzodiazepines on a daily basis. The doses of BZDs were significantly higher in nonresponders (p=0.007). ROC analysis distinguished responders from nonresponders by a criterion of >8mg of diazepam equivalent dose (DZ equivalent) with a sensitivity of 80% and a specificity of 85% (p<0.001). RM-ANOVA revealed a different time pattern of response to ketamine between the BZD+ (>8mg of DZ equivalent) and BZD- (≤8mg of DZ equivalent) groups, with a significantly worse outcome in BZD+ on day 3 (p=0.04) and day 7 (p=0.02). The results of the study indicate that concomitant benzodiazepine treatment in higher doses may attenuate ketamine’s antidepressant effect. The pathophysiological, clinical and methodological implications of this finding should be considered in future research and ketamine treatment.

Andrashko, V., Novak, T., Brunovsky, M., Klirova, M., Sos, P., & Horacek, J. (2020). The Antidepressant Effect of Ketamine Is Dampened by Concomitant Benzodiazepine Medication. Frontiers in psychiatry, 11, 844. https://doi.org/10.3389/fpsyt.2020.00844

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Psilocybin disrupts sensory and higher order cognitive processing but not pre-attentive cognitive processing—study on P300 and mismatch negativity in healthy volunteers

January 5, 2018 / Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , , , , , ,

Abstract

Rationale

Disruption of auditory event-related evoked potentials (ERPs) P300 and mismatch negativity (MMN), electrophysiological markers of attentive and pre-attentive cognitive processing, is repeatedly described in psychosis and schizophrenia. Similar findings were observed in a glutamatergic model of psychosis, but the role of serotonergic 5-HT2A receptors in information processing is less clear.

Objectives

We studied ERPs in a serotonergic model of psychosis, induced by psilocybin, a psychedelic with 5-HT2A/C agonistic properties, in healthy volunteers.

Methods

Twenty subjects (10M/10F) were given 0.26 mg/kg of psilocybin orally in a placebo-controlled, double-blind, cross-over design. ERPs (P300, MMN) were registered during the peak of intoxication. Correlations between measured electrophysiological variables and psilocin serum levels and neuropsychological effects were also analyzed.

Results

Psilocybin induced robust psychedelic effects and psychotic-like symptoms, decreased P300 amplitude (p = 0.009) but did not affect the MMN. Psilocybin’s disruptive effect on P300 correlated with the intensity of the psychedelic state, which was dependent on the psilocin serum levels. We also observed a decrease in N100 amplitude (p = 0.039) in the P300 paradigm and a negative correlation between P300 and MMN amplitude (p = 0.014).

Conclusions

Even though pre-attentive cognition (MMN) was not affected, processing at the early perceptual level (N100) and in higher-order cognition (P300) was significantly disrupted by psilocybin. Our results have implications for the role of 5-HT2A receptors in altered information processing in psychosis and schizophrenia.

Bravermanová, A., Viktorinová, M., Tylš, F., Novák, T., Androvičová, R., Korčák, J., … & Vlček, P. (2018). Psilocybin disrupts sensory and higher order cognitive processing but not pre-attentive cognitive processing—study on P300 and mismatch negativity in healthy volunteers. Psychopharmacology, 1-13. 10.1007/s00213-017-4807-2
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Relationship of ketamine's antidepressant and psychotomimetic effects in unipolar depression

June 25, 2013 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , ,

Abstract

OBJECTIVES:
Ketamine and other NMDA (N-methyl-D-aspartate) antagonists produce fast-acting antidepressant-like effects, although the underlying mechanism is unclear. Furthermore, high affinity NMDA antagonists such as ketamine are associated with psychotomimetic effects. To date the link between the antidepressant and psychotomimetic effects of ketamine has not been explored. We examined the relationship between the antidepressant and psychotomimetic effects of a single ketamine infusion in subjects diagnosed with major depressive disorder.
METHODS:
In a double-blind, cross-over, placebo-controlled, two weeks clinical trial we studied the effects of ketamine (0.54 mg/kg within 30 min) in a group of 27 hospitalized depressive patients.
RESULTS:
Higher intensity of psychotomimetic symptoms, measured using BPRS, during ketamine administration correlated with alleviation in mood ratings during the following week with maximum on day seven. Ketamine was superior to placebo in all visits (day 1, 4, and 7) assessed by MADRS with effect size (Cohen´s d) of 0.62, 0.57, and 0.44 respectively. There was no significant correlation between ketamine and nor-ketamine plasma levels and MADRS score change at any study time point.
CONCLUSION:
The substantial relationship between ketamine’s antidepressant and psychotomimetic effects was found. This relationship could be mediated by the initial steps of ketamine’s action, trough NMDA receptors, shared by both ketamine’s clinical effects.
Sos, P., Klirova, M., Novak, T., Kohutova, B., Horacek, J., & Palenicek, T. (2013). Relationship of ketamine’s antidepressant and psychotomimetic effects in unipolar depression. Neuroendocrinology Letters, 34(4), 287-293.
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