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Ketamine

Ketamine for the treatment of addiction: Evidence and potential mechanisms

January 12, 2018 / Ketamine, Papers, Psychology, Publications, Substance Use Disorder / By / , , ,

Abstract

Ketamine is a dissociative anaesthetic drug which acts on the central nervous system chiefly through antagonism of the n-methyl-d-aspartate (NMDA) receptor. Recently, ketamine has attracted attention as a rapid-acting anti-depressant but other studies have also reported its efficacy in reducing problematic alcohol and drug use. This review explores the preclinical and clinical research into ketamine’s ability to treat addiction. Despite methodological limitations and the relative infancy of the field, results thus far are promising. Ketamine has been shown to effectively prolong abstinence from alcohol and heroin in detoxified alcoholics and heroin dependent individuals, respectively. Moreover, ketamine reduced craving for and self-administration of cocaine in non-treatment seeking cocaine users. However, further randomised controlled trials are urgently needed to confirm ketamine’s efficacy. Possible mechanisms by which ketamine may work within addiction include: enhancement of neuroplasticity and neurogenesis, disruption of relevant functional neural networks, treating depressive symptoms, blocking reconsolidation of drug-related memories, provoking mystical experiences and enhancing psychological therapy efficacy. Identifying the mechanisms by which ketamine exerts its therapeutic effects in addiction, from the many possible candidates, is crucial for advancing this treatment and may have broader implications understanding other psychedelic therapies. In conclusion, ketamine shows great promise as a treatment for various addictions, but well-controlled research is urgently needed.
Ezquerra-Romano, I. I., Lawn, W., Krupitsky, E., & Morgan, C. J. A. (2018). Ketamine for the treatment of addiction: Evidence and potential mechanisms. Neuropharmacology. 10.1016/j.neuropharm.2018.01.017
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A sub-set of psychoactive effects may be critical to the behavioral impact of ketamine on cocaine use disorder: Results from a randomized, controlled laboratory study

January 5, 2018 / Ketamine, Papers, Psychology, Publications, Substance Use Disorder / By / , , , , ,

Abstract

Efforts to translate sub-anesthetic ketamine infusions into widespread clinical use have centered around developing medications with comparable neurobiological activity, but with attenuated psychoactive effects so as to minimize the risk of behavioral toxicity and abuse liability. Converging lines of research, however, suggest that some of the psychoactive effects of sub-anesthetic ketamine may have therapeutic potential. Here, we assess whether a subset of these effects – the so-called mystical-type experience – mediates the effect of ketamine on craving and cocaine use in cocaine dependent research volunteers. We found that ketamine leads to significantly greater acute mystical-type effects (by Hood Mysticism Scale: HMS), dissociation (by Clinician Administered Dissociative States Scale: CADSS), and near-death experience phenomena (by the Near-Death Experience Scale: NDES), relative to the active control midazolam. HMS score, but not the CADSS or NDES score, was found to mediate the effect of ketamine on global improvement (decreased cocaine use and craving) over the post-infusion period. This is the first controlled study to show that mystical-type phenomena, long considered to have therapeutic potential, may work to impact decision-making and behavior in a sustained manner. These data suggest that an important direction for medication development is the identification of ketamine-like pharmacotherapy that is selectively psychoactive (as opposed to free of experiential effects entirely), so that mystical-type perspectival shifts are more reliably produced and factors lending to abuse or behavioral impairment are minimized. Future research can further clarify the relationship between medication-occasioned mystical-type effects and clinical benefit for different disorders.
Dakwar, E., Nunes, E. V., Hart, C. L., Hu, M. C., Foltin, R. W., & Levin, F. R. (2018). A sub-set of psychoactive effects may be critical to the behavioral impact of ketamine on cocaine use disorder: Results from a randomized, controlled laboratory study. Neuropharmacology. 10.1016/j.neuropharm.2018.01.005
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Can we confidently use ketamine as a clinical treatment for depression?

January 1, 2018 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By /

Abstract

Findings from several proof-of-concept, double-blinded, placebo-controlled studies have shown rapid and large antidepressant effects in patients with major depression after a single dose of ketamine.1 These data are remarkable in the rapidity of therapeutic effects, with remission within 24 h (though relapse often occurs within days), the high degree of antidepressant potency in cohorts with moderate-to-high treatment resistance, and the consistency of findings between studies. Given that ketamine is readily available in many countries as an approved anaesthetic drug, it is not surprising that there has been enthusiasm for the use of ketamine to treat depression.
Loo, C. (2018). Can we confidently use ketamine as a clinical treatment for depression?. The Lancet Psychiatry, 5(1), 11-12. 10.1016/S2215-0366(17)30480-7
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Ketamine and pharmacological imaging: use of functional magnetic resonance imaging to evaluate mechanisms of action

November 30, 2017 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , ,

Abstract

Ketamine has been used as a pharmacological model for schizophrenia as subanesthetic infusions have been shown to produce temporary schizophrenia-like symptoms in healthy humans. More recently, ketamine has emerged as a potential treatment for multiple psychiatric disorders, including treatment-resistant depression and suicidal ideation. However, the mechanisms underlying both the psychotomimetic and the therapeutic effects of ketamine remain poorly understood. This review provides an overview of what is known of the neural mechanisms underlying the effects of ketamine and details what functional MRI studies have yielded at a systems level focused on brain circuitry. Multiple analytic approaches show that ketamine exerts robust and consistent effects at the whole-brain level. These effects are highly conserved across human and nonhuman primates, validating the use of nonhuman primate models for further investigations with ketamine. Regional analysis of brain functional connectivity suggests that the therapeutic potential of ketamine may be derived from a strengthening of executive control circuitry, making it an intriguing candidate for the treatment of drug abuse. There are still important questions about the mechanism of action and the therapeutic potential of ketamine that can be addressed using appropriate functional neuroimaging techniques.
Maltbie, E. A., Kaundinya, G. S., & Howell, L. L. (2017). Ketamine and pharmacological imaging: use of functional magnetic resonance imaging to evaluate mechanisms of action. Behavioural Pharmacology, 28(8), 610-622. 10.1097/FBP.0000000000000354
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Psychedelics and reconsolidation of traumatic and appetitive maladaptive memories: focus on cannabinoids and ketamine

November 25, 2017 / Depressive Disorders, Ketamine, MDMA, Papers, Psychology, Publications, Substance Use Disorder / By / , , , ,

Abstract

Rationale

Clinical data with 3,4-methylenedioxymethamphetamine (MDMA) in post-traumatic stress disorder (PTSD) patients recently stimulated interest on the potential therapeutic use of psychedelics in disorders characterized by maladaptive memories, including substance use disorders (SUD). The rationale for the use of MDMA in PTSD and SUD is being extended to a broader beneficial “psychedelic effect,” which is supporting further clinical investigations, in spite of the lack of mechanistic hypothesis. Considering that the retrieval of emotional memories reactivates specific brain mechanisms vulnerable to inhibition, interference, or strengthening (i.e., the reconsolidation process), it was proposed that the ability to retrieve and change these maladaptive memories might be a novel intervention for PTSD and SUD. The mechanisms underlying MDMA effects indicate memory reconsolidation modulation as a hypothetical process underlying its efficacy.

Objective

Mechanistic and clinical studies with other two classes of psychedelic substances, namely cannabinoids and ketamine, are providing data in support of a potential use in PTSD and SUD based on the modulation of traumatic and appetitive memory reconsolidation, respectively. Here, we review preclinical and clinical data on cannabinoids and ketamine effects on biobehavioral processes related to the reconsolidation of maladaptive memories.

Results

We report the findings supporting (or not) the working hypothesis linking the potential therapeutic effect of these substances to the underlying reconsolidation process. We also proposed possible approaches for testing the use of these two classes of drugs within the current paradigm of reconsolidation memory inhibition.

Conclusions

Metaplasticity may be the process in common between cannabinoids and ketamine/ketamine-like substance effects on the mediation and potential manipulation of maladaptive memories.

Fattore, L., Piva, A., Zanda, M. T., Fumagalli, G., & Chiamulera, C. (2017). Psychedelics and reconsolidation of traumatic and appetitive maladaptive memories: focus on cannabinoids and ketamine. Psychopharmacology, 1-13. 10.1007/s00213-017-4793-4
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TrkB dependent adult hippocampal progenitor differentiation mediates sustained ketamine antidepressant response

November 21, 2017 / Depressive Disorders, Ketamine, Neuroscience, Papers, Publications / By / , , , , , ,

Abstract

Adult neurogenesis persists in the rodent dentate gyrus and is stimulated by chronic treatment with conventional antidepressants through BDNF/TrkB signaling. Ketamine in low doses produces both rapid and sustained antidepressant effects in patients. Previous studies have shed light on post-transcriptional synaptic NMDAR mediated mechanisms underlying the acute effect, but how ketamine acts at the cellular level to sustain this anti-depressive function for prolonged periods remains unclear. Here we report that ketamine accelerates differentiation of doublecortin-positive adult hippocampal neural progenitors into functionally mature neurons. This process requires TrkB-dependent ERK pathway activation. Genetic ablation of TrkB in neural stem/progenitor cells, or pharmacologic disruption of ERK signaling, or inhibition of adult neurogenesis, each blocks the ketamine-induced behavioral responses. Conversely, enhanced ERK activity via Nf1 gene deletion extends the response and rescues both neurogenic and behavioral deficits in mice lacking TrkB. Thus, TrkB-dependent neuronal differentiation is involved in the sustained antidepressant effects of ketamine.
Ma, Z., Zang, T., Birnbaum, S. G., Wang, Z., Johnson, J. E., Zhang, C. L., & Parada, L. F. (2017). TrkB dependent adult hippocampal progenitor differentiation mediates sustained ketamine antidepressant response. Nature communications, 8(1), 1668. 10.1038/s41467-017-01709-8
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Studies with psychedelic drugs in human volunteers

November 18, 2017 / DMT, Ketamine, MDMA, Papers, Psychology, Publications / By / , ,

Abstract

Scientific curiosity and fascination have played a key role in human research with psychedelics along with the hope that perceptual alterations and heightened insight could benefit well-being and play a role in the treatment of various neuropsychiatric disorders. These motivations need to be tempered by a realistic assessment of the hurdles to be cleared for therapeutic use. Development of a psychedelic drug for treatment of a serious psychiatric disorder presents substantial although not insurmountable challenges. While the varied psychedelic agents described in this chapter share some properties, they have a range of pharmacologic effects that are reflected in the gradation in intensity of hallucinogenic effects from the classical agents to DMT, MDMA, ketamine, dextromethorphan and new drugs with activity in the serotonergic system. The common link seems to be serotonergic effects modulated by NMDA and other neurotransmitter effects. The range of hallucinogens suggest that they are distinct pharmacologic agents and will not be equally safe or effective in therapeutic targets. Newly synthesized specific and selective agents modeled on the legacy agents may be worth considering. Defining therapeutic targets that represent unmet medical need, addressing market and commercial issues, and finding treatment settings to safely test and use such drugs make the human testing of psychedelics not only interesting but also very challenging.
Sellers, E. M., Romach, M. K., & Leiderman, D. B. (2017). Studies with psychedelic drugs in human volunteers. Neuropharmacology. 10.1016/j.neuropharm.2017.11.029
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Ketamine’s antidepressant effect is mediated by energy metabolism and antioxidant defense system

November 17, 2017 / Depressive Disorders, Ketamine, Neuroscience, Papers, Publications / By / , , , , , ,

Abstract

Fewer than 50% of all patients with major depressive disorder (MDD) treated with currently available antidepressants (ADs) show full remission. Moreover, about one third of the patients suffering from MDD does not respond to conventional ADs and develop treatment-resistant depression (TRD). Ketamine, a non-competitive, voltage-dependent N-Methyl-D-aspartate receptor (NMDAR) antagonist, has been shown to have a rapid antidepressant effect, especially in patients suffering from TRD. Hippocampi of ketamine-treated mice were analysed by metabolome and proteome profiling to delineate ketamine treatment-affected molecular pathways and biosignatures. Our data implicate mitochondrial energy metabolism and the antioxidant defense system as downstream effectors of the ketamine response. Specifically, ketamine tended to downregulate the adenosine triphosphate (ATP)/adenosine diphosphate (ADP) metabolite ratio which strongly correlated with forced swim test (FST) floating time. Furthermore, we found increased levels of enzymes that are part of the ‘oxidative phosphorylation’ (OXPHOS) pathway. Our study also suggests that ketamine causes less protein damage by rapidly decreasing reactive oxygen species (ROS) production and lend further support to the hypothesis that mitochondria have a critical role for mediating antidepressant action including the rapid ketamine response.
Weckmann, K., Deery, M. J., Howard, J. A., Feret, R., Asara, J. M., Dethloff, F., … & Webhofer, C. (2017). Ketamine’s antidepressant effect is mediated by energy metabolism and antioxidant defense system. Scientific reports, 7(1), 15788. 10.1038/s41598-017-16183-x
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Ketamine's antidepressant effect is mediated by energy metabolism and antioxidant defense system

November 17, 2017 / Depressive Disorders, Ketamine, Neuroscience, Papers, Publications / By / , , , , , ,

Abstract

Fewer than 50% of all patients with major depressive disorder (MDD) treated with currently available antidepressants (ADs) show full remission. Moreover, about one third of the patients suffering from MDD does not respond to conventional ADs and develop treatment-resistant depression (TRD). Ketamine, a non-competitive, voltage-dependent N-Methyl-D-aspartate receptor (NMDAR) antagonist, has been shown to have a rapid antidepressant effect, especially in patients suffering from TRD. Hippocampi of ketamine-treated mice were analysed by metabolome and proteome profiling to delineate ketamine treatment-affected molecular pathways and biosignatures. Our data implicate mitochondrial energy metabolism and the antioxidant defense system as downstream effectors of the ketamine response. Specifically, ketamine tended to downregulate the adenosine triphosphate (ATP)/adenosine diphosphate (ADP) metabolite ratio which strongly correlated with forced swim test (FST) floating time. Furthermore, we found increased levels of enzymes that are part of the ‘oxidative phosphorylation’ (OXPHOS) pathway. Our study also suggests that ketamine causes less protein damage by rapidly decreasing reactive oxygen species (ROS) production and lend further support to the hypothesis that mitochondria have a critical role for mediating antidepressant action including the rapid ketamine response.
Weckmann, K., Deery, M. J., Howard, J. A., Feret, R., Asara, J. M., Dethloff, F., … & Webhofer, C. (2017). Ketamine’s antidepressant effect is mediated by energy metabolism and antioxidant defense system. Scientific reports, 7(1), 15788. 10.1038/s41598-017-16183-x
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Antidepressant Response and Dissociative Effects After Ketamine Treatment: Two Sides of the Same Coin?

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

Abstract

In recent years, there has been growing interest in research on N-methyl-d-aspartate (NMDA) antagonists as rapid-acting agents for treating depression1 and related suicidal ideation.2 Ketamine has shown preliminary efficacy for the rapid treatment of both unipolar and bipolar depression, although it has been also associated with high rates of dissociative and psychotomimetic symptoms, especially within 60 minutes after the infusion.3 For this reason, we read with great interest the update recently published in JCP4 that synthesized issues related to efficacy, adverse effects, and mechanism of action of ketamine for treating depression. In particular, in analyzing ketamine-related adverse effects, this overview highlighted that subanesthetic doses of ketamine may induce dissociative and psychotomimetic symptoms, although these effects are often mild and short-lasting.4 In addition, the authors of a recent review5 suggest that intranasal route of administration and lower doses of ketamine, as well as alternative NMDA-modulating agents, all might mitigate dissociative and psychotomimetic effects.

However, ketamine-induced dissociative symptoms, whether therapeutic or side effects, may deserve additional insight. Findings from a randomized controlled trial6 showed that significant, though transient, dissociative effects can occur after ketamine infusion in about 1 out of 5 subjects with treatment-resistant depression. However, a significant correlation between dissociative symptoms 40 minutes after ketamine infusion and improvement in depressive symptoms (230 minutes and 7 days after infusion) has been reported in subjects with treatment-resistant major depressive or bipolar disorder.7 Among the potential mediators tested, only dissociative effects predicted a robust and sustained antidepressant response attributable to ketamine. This issue may well be supported by a biological rationale, since dissociative symptoms may be the consequence of the enhancement of glutamate release induced by ketamine.7 In addition, a recent study based on a retrospective chart review8 evaluating efficacy and safety of intravenous subanesthetic doses of esketamine in 27 subjects with treatment-resistant or bipolar depression found that mild to severe dissociative symptoms occurred in about one tenth of subjects. Nevertheless, 2 out of 3 subjects with dissociative symptoms remitted from depression within 3 weeks after esketamine infusion. Thus, also in this case, it seems that ketamine-related dissociation and therapeutic efficacy might be linked, possibly as “two sides of the same coin.” Nonetheless, available evidence is limited and not conclusive, since other studies, although based on small sample sizes, showed that dissociative symptoms were not correlated with changes in depression scores9 or could be even associated with suicidal ideation.10 Although a number of different factors involved in the efficacy of ketamine can be hypothesized,11 including induced psychotomimetic effects,12 the mechanisms of its antidepressant activity are far from being fully understood. In particular, it should be elucidated if transient dissociative effects induced by ketamine should be considered physiological conditions linked to antidepressant response, rather than intrinsic side effects that could decrease clinical confidence in terms of tolerability. Research should clarify strategies that can decrease ketamine-induced dissociative effects5 while not challenging its promising antidepressant properties.

Bartoli, F., Clerici, M., & Carrà, G. (2017). Antidepressant Response and Dissociative Effects After Ketamine Treatment: Two Sides of the Same Coin?. The Journal of clinical psychiatry, 78(9), e1318. 10.4088/JCP.17lr11789
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