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Ketamine

Psychological effects of (S)-ketamine and N,N-dimethyltryptamine (DMT): a double-blind, cross-over study in healthy volunteers

Abstract

INTRODUCTION:
Pharmacological challenges with hallucinogens are used as models for psychosis in experimental research. The state induced by glutamate antagonists such as phencyclidine (PCP) is often considered as a more appropriate model of psychosis than the state induced by serotonergic hallucinogens such as lysergic acid diethylamide (LSD), psilocybin and N,N-dimethyltryptamine (DMT). However, so far, the psychological profiles of the two types of hallucinogenic drugs have never been studied directly in an experimental within-subject design.

METHODS:
Fifteen healthy volunteers were included in a double-blind, cross-over study with two doses of the serotonin 5-HT2A agonist DMT and the glutamate N-methyl-D-aspartate (NMDA) antagonist (S)-ketamine.

RESULTS:
Data are reported for nine subjects who completed both experimental days with both doses of the two drugs. The intensity of global psychological effects was similar for DMT and (S)-ketamine. However, phenomena resembling positive symptoms of schizophrenia, particularly positive formal thought disorder and inappropriate affect, were stronger after DMT. Phenomena resembling negative symptoms of schizophrenia, attention deficits, body perception disturbances and catatonia-like motor phenomena were stronger after (S)-ketamine.

DISCUSSION:
The present study suggests that the NMDA antagonist model of psychosis is not overall superior to the serotonin 5-HT2A agonist model. Rather, the two classes of drugs tend to model different aspects or types of schizophrenia. The NMDA antagonist state may be an appropriate model for psychoses with prominent negative and possibly also catatonic features, while the 5-HT2A agonist state may be a better model for psychoses of the paranoid type.

Gouzoulis-Mayfrank, E., Heekeren, K., Neukirch, A., Stoll, M., Stock, C., Obradovic, M., & Kovar, K .A. (2005). Psychological effects of (S)-ketamine and N,N-dimethyltryptamine (DMT): a double-blind, cross-over study in healthy volunteers. Pharmacopsychiatry, 38(6), 301-311. http://dx.doi.org/10.1055/s-2005-916185
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Effects of peritraumatic ketamine medication on early and sustained posttraumatic stress symptoms in moderately injured accident victims

Abstract

Rationale: Ketamine, an N-methyl-D-aspartate receptor antagonist, produces transient dissociative and psychotic states in healthy humans that resemble symp- toms shown by subjects with acute and chronic posttrau- matic stress disorder (PTSD). Since ketamine is widely used as an analgesic and sedative in emergency care, it might be one factor triggering, modulating, or exacerbat- ing PTSD in accident victims when given in the acute trauma phase. Objectives: The purpose of the present study was to determine whether the peritraumatic administration of ketamine affects acute and sustained PTSD symptoms in accident victims. Methods: A sample of 56 moderate- ly injured accident victims was screened retrospectively for acute (Peritraumatic Dissociative Experiences Ques- tionnaire; Acute Stress Disorder Scale) and for current PTSD symptoms (Impact of Event Scale) approximately 1 year postaccident. All subjects had received a single or fractionated dose of either racemic ketamine (n=17), (S)- ketamine (n=12), or opioids (n=27) during emergency am- bulance transportation. Results: Retrospectively assessed acute symptomatology was strongly increased in (S)-keta- mine subjects in terms of dissociation, reexperiencing, and avoidance, and slightly heightened in racemic ketamines. Current PTSDsymptoms were substantially elevated in (S)- ketamine subjects, while there was no difference observed between opioids and racemic ketamines. Medication groups did not differ in regard to demographic variables, previous or postaccidental traumatic events, time between accident and investigation, and injury severity. Conclusions: The data provide first evidence for a modulating effect of a single-dose ketamine on the severity and duration of post- traumatic stress symptoms in accident victims.

Schönenberg, M., Reichwald, U., Domes, G., Badke, A., & Hautzinger, M. (2005). Effects of peritraumatic ketamine medication on early and sustained posttraumatic stress symptoms in moderately injured accident victims. Psychopharmacology, 182(3), 420-425. https://dx.doi.org/10.1007/s00213-005-0094-4
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Effects of different subanesthetic doses of (S)-ketamine on neuropsychology, psychopathology, and state of consciousness in man

Abstract

This is the first neuropsychological study using the S-enantiomer of the noncompetetive N-methyl-D-aspartate antagonist ketamine. In 2 randomized placebo-controlled trials we studied effects of two different doses of (S)-ketamine (low dose/high dose) on neuropsychological functions and psychopathology in 12 healthy male volunteers. Impairment was measured via standardized neuropsychological tests. Results indicate that both subanaesthetic doses produce only nonsignificant impair ment in most of the tasks. Tasks involving divided and sustained attention as well as scores for objective and subjective psychopathology show significant impairment in a dose-dependent manner. Implications of these findings for the neuropsychology of attention and schizophrenia are discussed.

Passie, T., Karst, M., Wiese, B., Emrich, H. M., & Schneider, U. (2005). Effects of different subanesthetic doses of (S)-ketamine on neuropsychology, psychopathology, and state of consciousness in man. Neuropsychobiology, 51(4), 226-233. http://dx.doi.org/10.1159%2F000085724
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Effects of the 5-HT2A Agonist Psilocybin on Mismatch Negativity Generation and AX-Continuous Performance Task: Implications for the Neuropharmacology of Cognitive Deficits in Schizophrenia

Abstract

Previously the NMDA (N-methyl-D-aspartate) receptor (NMDAR) antagonist ketamine was shown to disrupt generation of the auditory event-related potential (ERP) mismatch negativity (MMN) and the performance of an ‘AX’-type continuous performance test (AX-CPT)–measures of auditory and visual context-dependent information processing–in a similar manner as observed in schizophrenia. This placebo-controlled study investigated effects of the 5-HT(2A) receptor agonist psilocybin on the same measures in 18 healthy volunteers. Psilocybin administration induced significant performance deficits in the AX-CPT, but failed to reduce MMN generation significantly. These results indirectly support evidence that deficient MMN generation in schizophrenia may be a relatively distinct manifestation of deficient NMDAR functioning. In contrast, secondary pharmacological effects shared by NMDAR antagonists and the 5-HT(2A) agonist (ie disruption of glutamatergic neurotransmission) may be the mechanism underlying impairments in AX-CPT performance observed during both psilocybin and ketamine administration. Comparable deficits in schizophrenia may result from independent dysfunctions of 5-HT(2A) and NMDAR-related neurotransmission.

Umbricht, D., Vollenweider, F. X., Schmid, L., Gruebel, C., Skrabo, A., Huber, T., & Koller, R. (2003). Effects of the 5-HT2A agonist psilocybin on mismatch negativity generation and AX-continuous performance task: implications for the neuropharmacology of cognitive deficits in schizophrenia. Neuropsychopharmacology: official publication of the American College of Neuropsychopharmacology, 28(1), 170-181. http://dx.doi.org/10.1038/sj.npp.1300005
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Effects of different subanaesthetic doses of (S)-ketamine on psychopathology and binocular depth inversion in man

Abstract

The role of the N-methyl-D-aspartate (NMDA) neurotransmitter system in relation to psychoses is not completely understood, but represent a challenge in neurobiological research. The psychotic states induced by NMDA antagonists such as phencyclidine and ketamine have been described as being most similar to schizophrenia and the NMDA system has been implicated in the pathogenesis of schizophrenia. Binocular depth inversion, an illusion of visual perception, has been shown to be impaired in psychotic and psychotomimetic states in healthy and schizophrenic subjects. In this study, pictures of natural and artificial objects were presented stereoscopically to 12 healthy male volunteers and depth perception assessed using an operationalized method. The effects of the psychotomimetic S-enantiomer of the anaesthetic ketamine in two different subanaesthetic doses were compared with those of a placebo. In spite of dose dependence and grave subjective and significant objective psychopathology, no significant impairment of binocular depth perception was found with (S)-ketamine. Implications related to memory function, perceptogenesis and ‘bottom-up’ processing in ketamine model psychosis and schizophrenia are discussed.

Passie, T., Karst, M., Borsutzky, M., Wiese, B., Emrich, H. M., & Schneider, U. (2003). Effects of different subanaesthetic doses of (S)-ketamine on psychopathology and binocular depth inversion in man. Journal of Psychopharmacology, 17(1), 51-56. http://dx.doi.org/10.1177/0269881103017001698
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Ketamine psychotherapy for heroin addiction: immediate effects and two-year follow-up

Abstract

Seventy detoxified heroin-addicted patients were randomly assigned to one of two groups receiving ketamine psychotherapy (KPT) involving two different doses of ketamine. The patients of the experimental group received existentially oriented psychotherapy in combination with a hallucinogenic (“psychedelic”) dose of ketamine (2.0 mg/kg im). The patients of the control group received the same psychotherapy combined with a low, non-hallucinogenic (non-psychedelic), dose of ketamine (0.2 mg/kg im). Both the psychotherapist and patient were blind to the dose of ketamine. The therapy included preparation for the ketamine session, the ketamine session itself, and the post session psychotherapy aimed to help patients to integrate insights from their ketamine session into everyday life. The results of this double blind randomized clinical trial of KPT for heroin addiction showed that high dose (2.0 mg/kg) KPT elicits a full psychedelic experience in heroin addicts as assessed quantitatively by the Hallucinogen Rating Scale. On the other hand, low dose KPT (0.2 mg/kg) elicits “sub-psychedelic” experiences and functions as ketamine-facilitated guided imagery. High dose KPT produced a significantly greater rate of abstinence in heroin addicts within the first two years of follow-up, a greater and longer-lasting reduction in craving for heroin, as well as greater positive change in nonverbal unconscious emotional attitudes than did low dose KPT.

Krupitsky, E., Burakov, A., Romanova, T., Dunaevsky, I., Strassman, R., & Grinenko, A. (2002). Ketamine psychotherapy for heroin addiction: immediate effects and two-year follow-up. Journal of substance abuse treatment, 23(4), 273-283. http://dx.doi.org/10.1016/S0740-5472(02)00275-1
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Serotonergic Agents That Activate 5HT2A Receptors Prevent NMDA Antagonist Neurotoxicity

Abstract

Phencyclidine, ketamine, and other agents that block NMDA glutamate receptors trigger a schizophrenia-like psychosis in humans and induce pathomorphological changes in cerebrocortical neurons in rat brain. Accumulating evidence suggests that a complex network disturbance involving multiple transmitter receptor systems is responsible for the neuronal injury, and it is proposed that a similar network disturbance is responsible for the psychotomimetic effects of NMDA antagonists, and might also be involved in the pathophysiology of schizophrenia. In the present study we present evidence that serotonergic agents possessing 5HT2A agonist activity prevent NMDA antagonist neurotoxicity in rat brain. It isproposed that 5HT2A agonists may also prevent the psychotomimetic effects of NMDA antagonists. Among the 5HT2A agonists examined and found to be neuroprotective are LSD and related hallucinogens. The apparent contradiction in proposing that these agents might have antipsychotic properties is resolved by evidence linking their hallucinogenic activity to agonist action at 5HT2C receptors, whereas antipsychotic activity would be attributable to agonist action at 5HT2A receptors.

Farber, N. B., Hanslick, J., Kirby, C., McWilliams, L., & Olney, J. W. (1998). Serotonergic Agents That Activate 5HT2A Receptors Prevent NMDA Antagonist Neurotoxicity. Neuropsychopharmacology, 18(1), 57-62. http://dx.doi.org/doi:10.1016/S0893-133X(97)00127-9

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Ketamine psychedelic therapy (KPT): a review of the results of ten years of research

Abstract

Ketamine is a prescription drug used for general anesthesia. In subanesthetic doses, it induces profound psychedelic experiences and hallucinations. The subanesthetic effect of ketamine was the hypothesized therapeutic mechanism in the authors’ use of ketamine-assisted psychotherapy for alcoholism. The results of a controlled clinical trial demonstrated a considerable increase in efficacy of the authors’ standard alcoholism treatment when supplemented by ketamine psychedelic therapy (KPT). Total abstinence for more than one year was observed in 73 out of 111 (65.8%) alcoholic patients in the KPT group, compared to 24% (24 out of 100 patients) of the conventional treatment control group (p < 0.01). The authors’ studies of the underlying psychological mechanisms of KPT have indicated that ketamine-assisted psychedelic therapy of alcoholic patients induces a harmonization of the Minnesota Multiphasic Personality Inventory (MMPI) personality profile, positive transformation of nonverbalized (mostly unconscious) self-concept and emotional attitudes to various aspects of self and other people, positive changes in life values and purposes, important insights into the meaning of life and an increase in the level of spiritual development. Most importantly, these psychological changes were shown to favor a sober lifestyle. The data from biochemical investigations showed that pharmacological action of KPT affects both monoaminergic and opioidergic neurotransmitter metabolism, i.e., those neurochemical systems which are involved in the pathogenesis of alcohol dependence. The data from EEG computer-assisted analysis demonstrated that ketamine increases theta activity in cerebrocortical regions of alcoholic patients. This is evidence of the reinforcement of limbic cortex interaction during KPT session.

Krupitsky, E. M., & Grinenko, A. Y. (1997). Ketamine psychedelic therapy (KPT): a review of the results of ten years of research. Journal of psychoactive drugs, 29(2), 165-183. https://dx.doi.org/10.1080/02791072.1997.10400185

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Placeboing with Psychedelics

Letter to the editor

When we consider the so-called “placebo effect,” we should realize that it is not something mysterious that merely happens on its own. It is something we do with our minds that effects our bodies. To be more accurate: we placebo. To placebo is a verb. Our minds plus our bodies do this, and like any other human activity we can speak of placeboing. When looked at this way, we can ask: How do we placebo? and Can we learn placeboing more skillfully?

A clue comes from studies of stress and emotions in the immune system. It is widely known that negative emotions and stressful life events weaken the immune system, while positive emotions and life events strengthen it. Since positive life events strengthen our immune system, here is a clue to learning to placebo.

A common healing cluster of positive feelings and thoughts accompany many instances of spontaneous remission and spiritual healing. These include feelings of exceedingly positive mood, being cared for in the hands of a loving power, dropping stress, feelings of sacredness, feeling at home in the world, among others. Thoughts include a sense of temporarily transcending one’s identity, forgiving oneself and others, overwhelming gratitude, and increased sense of reality—this is the way things really are and ought to be.

If we can reproduce this cluster, we will be on the way to learning to placebo. Various mindbody techniques including meditation, imagery, contemplative prayer, yoga, the martial arts, breathing techniques, hypnosis, and chanting all suggest a yes answer to this question, and more research to follow these apparent leads may lead to learning how to use these mindbody methods to increase our placeboing skills by strengthening our immune systems.

Do examples of extreme positive emotional states produce extreme healing? The recent flurry of articles about current research into exploring the psychotherapeutic use of psychedelics for post traumatic stress disorder, death anxiety, and other disorders show that these substances are successful when they produce states of unitive consciousness (mystical experiences) and not successful when they do not.

Lost in this discussion is that fact that mystical experiences are the most powerful emotionally positive experiences humans can have, and if normal daily positive events boost the immune system somewhat, do these strongest positive experiences boost it a great deal?

Can this spontaneous cluster of healing thoughts and feelings be recreated in a medical setting? As a 2008 Johns Hopkins study of psilocybin induced mystical experiences showed, under the right conditions and with careful screening, preparation, and professional guidance, psychedelic sessions can produce mystical experiences and a similar cluster of emotions and experiences in normal, healthy, adult volunteers. In a 14-month following up, volunteers’ comments illustrated this healing cluster:

– The utter joy and freedom of letting go—without anxiety—without direction— beyond ego self.
– The understanding that in the eyes of God—all people—were equally important and equally loved by God.
– When I confronted my shadow and yelled “What do you want?” and it disappeared in a puff smoke.

Among the other outcomes were positive mood changes, improved sense of well-being and life satisfaction, positive attitudes about life and/or self, and altruistic social effects. About two-thirds of healthy adults rated as one of the five most important spiritual experiences of their lives, including about one-third who rated them as the single most important spiritual experience of their lives. However, the researchers did not measure possible effects on the immune system.

A question on placeboing: Do overwhelmingly powerful peak experiences stimulated by psychedelics as part of professionally guided sessions boost the immune system? A possible major advance in mindbody health awaits an answer.

Roberts, T. B. (1987). Is There a Placebo Ability? Advances: Journal of the Institute for the Advancement of Health, 4(1), 5.

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