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Ketamine

Salvinorin A fails to substitute for the discriminative stimulus effects of LSD or ketamine in Sprague–Dawley rats

September 28, 2010 / Ketamine, LSD, Other subjects, Papers, Psychopharmacology, Publications, Salvia / Salvinorin A / By / , ,

Abstract

Salvia divinorum is a small perennial shrub that has gained recent popularity among the drug-using subculture as a legal alternative to hallucinogens. Salvinorin A, the main active compound found in the S. divinorum plant, is an atypical hallucinogen with pharmacological selectivity at kappa opioid (KOP) receptor sites and is a unique non-nitrogenous neoclerodane diterpene which is structurally distinct from other opioid compounds. The novel structure of salvinorin A and its specific binding affinity to KOP receptors provide a unique opportunity to investigate neurochemical mechanisms of hallucination and hallucinogenic compounds. The current investigation assessed the substitution of salvinorin A in 16 male Sprague–Dawley rats trained to discriminate either the prototypical serotonergic hallucinogen, LSD (0.08 mg/kg, S.C., n = 8) or the dissociative anesthetic and glutamatergic hallucinogen, ketamine (8.0 mg/kg, I.P., n = 8) from vehicle under a FR 20 schedule of food-reinforced responding. Results indicated that neither LSD nor ketamine discrimination generalized to salvinorin A. These findings are consistent with the growing body of evidence that salvinorin A is pharmacologically distinct from other traditional hallucinogenic compounds.

Killingera, B. A., Peeta, M. M., & Baker, L. E. (2010). Salvinorin A fails to substitute for the discriminative stimulus effects of LSD or ketamine in Sprague–Dawley rats. Pharmacology Biochemistry and Behavior, 96(3), 260-265. http://dx.doi.org/10.1016/j.pbb.2010.05.014
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Glutamatergic Model Psychoses: Prediction Error, Learning, and Inference

September 22, 2010 / Ketamine, Neuroscience, Papers, Psychiatry, Psychology, Psychopharmacology, Psychosis, Publications / By / , , ,

Abstract

Modulating glutamatergic neurotransmission induces alterations in conscious experience that mimic the symptoms of early psychotic illness. We review studies that use intravenous administration of ketamine, focusing on interindividual variability in the profundity of the ketamine experience. We will consider this individual variability within a hypothetical model of brain and cognitive function centered upon learning and inference. Within this model, the brains, neural systems, and even single neurons specify expectations about their inputs and responding to violations of those expectations with new learning that renders future inputs more predictable. We argue that ketamine temporarily deranges this ability by perturbing both the ways in which prior expectations are specified and the ways in which expectancy violations are signaled. We suggest that the former effect is predominantly mediated by NMDA blockade and the latter by augmented and inappropriate feedforward glutamatergic signaling. We suggest that the observed interindividual variability emerges from individual differences in neural circuits that normally underpin the learning and inference processes described. The exact source for that variability is uncertain, although it is likely to arise not only from genetic variation but also from subjects’ previous experiences and prior learning. Furthermore, we argue that chronic, unlike acute, NMDA blockade alters the specification of expectancies more profoundly and permanently. Scrutinizing individual differences in the effects of acute and chronic ketamine administration in the context of the Bayesian brain model may generate new insights about the symptoms of psychosis; their underlying cognitive processes and neurocircuitry.

Corlett, P. R., Honey, G. D., Krystal, J. H., & Fletcher, P. C. (2011). Glutamatergic Model Psychoses: Prediction Error, Learning, and Inference. Neuropsychopharmacology Reviews, 36, 294–315. http://dx.doi.org/10.1038/npp.2010.163
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The neurobiology of psychedelic drugs: implications for the treatment of mood disorders

September 10, 2010 / Cacti / Mescaline, Depression, DMT, Ketamine, LSD, Mushrooms / Psilocybin, Papers, Psychiatry, Psychology, Psychopharmacology, Publications / By / ,

Abstract

After a pause of nearly 40 years in research into the effects of psychedelic drugs, recent advances in our understanding of the neurobiology of psychedelics, such as lysergic acid diethylamide (LSD), psilocybin and ketamine have led to renewed interest in the clinical potential of psychedelics in the treatment of various psychiatric disorders. Recent behavioural and neuroimaging data show that psychedelics modulate neural circuits that have been implicated in mood and affective disorders, and can reduce the clinical symptoms of these disorders. These findings raise the possibility that research into psychedelics might identify novel therapeutic mechanisms and approaches that are based on glutamate-driven neuroplasticity.

Vollenweider, F. X., & Kometer, M. (2010). The neurobiology of psychedelic drugs: implications for the treatment of mood disorders. Nature Reviews Neuroscience, 11, 642-651. http://dx.doi.org/10.1038/nrn2884
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Psychometric Evaluation of the Altered States of Consciousness Rating Scale (OAV)

August 31, 2010 / Ketamine, MDMA, Mushrooms / Psilocybin, Other subjects, Papers, Psychology, Publications / By / , ,

Abstract

This paper describes a refinement of Dittrich’s Altered States of Consciousness questionnaire. This questionnaire is among the most widely used self-report questionnaires for retrospectively assessing subjective experiences induced by psychedelics and other psychoactive drugs. Using data collected over many years from 591 human volunteers, they factored the original four subscales developed by Dittrich into 11 new subscales. This new improved instrument will play an important role in more precisely defining the qualitative subjective experiences in research with psychedelics.

Background: The OAV questionnaire has been developed to integrate research on altered states of consciousness (ASC). It measures three primary and one secondary dimensions of ASC that are hypothesized to be invariant across ASC induction methods. The OAV rating scale has been in use for more than 20 years and applied internationally in a broad range of research fields, yet its factorial structure has never been tested by structural equation modeling techniques and its psychometric properties have never been examined in large samples of experimentally induced ASC.

Methodology/Principal Findings: The present study conducted a psychometric evaluation of the OAV in a sample of psilocybin (n = 327), ketamine (n = 162), and MDMA (n = 102) induced ASC that was obtained by pooling data from 43 experimental studies. The factorial structure was examined by confirmatory factor analysis, exploratory structural equation modeling, hierarchical item clustering (ICLUST), and multiple indicators multiple causes (MIMIC) modeling. The originally proposed model did not fit the data well even if zero-constraints on non-target factor loadings and residual correlations were relaxed. Furthermore, ICLUST suggested that the ‘‘oceanic boundlessness’’ and ‘‘visionary restructuralization’’ factors could be combined on a high level of the construct hierarchy. However, because these factors were multidimensional, we extracted and examined 11 new lower order factors. MIMIC modeling indicated that these factors were highly measurement invariant across drugs, settings, questionnaire versions, and sexes. The new factors were also demonstrated to have improved homogeneities, satisfactory reliabilities, discriminant and convergent validities, and to differentiate well among the three drug groups.

Conclusions/Significance: The original scales of the OAV were shown to be multidimensional constructs. Eleven new lower order scales were constructed and demonstrated to have desirable psychometric properties. The new lower order scales are most likely better suited to assess drug induced ASC.

Studerus, E., Gamma, A., & Vollenweider, F. X. (2010). Psychometric Evaluation of the Altered States of Consciousness Rating Scale (OAV). PLoS ONE, 5(8). http://dx.doi.org/10.1371/journal.pone.0012412
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A Randomized Add-on Trial of an N-methyl-D-aspartate Antagonist in Treatment-Resistant Bipolar Depression

August 9, 2010 / Depression, Ketamine, Papers, Psychiatry, Psychology, Psychopharmacology, Publications / By / , , , , , ,

Abstract

Context: Existing therapies for bipolar depression have a considerable lag of onset of action. Pharmacological strategies that produce rapid antidepressant effects—for instance, within a few hours or days—would have an enormous impact on patient care and public health.

Objective: To determine whether an N-methyl-Daspartate–receptor antagonist produces rapid antidepressant effects in subjects with bipolar depression.

Design: A randomized, placebo-controlled, doubleblind, crossover, add-on study conducted from October 2006 to June 2009.

Setting: Mood Disorders Research Unit at the National Institute of Mental Health, Bethesda, Maryland.

Patients: Eighteen subjects with DSM-IV bipolar depression (treatment-resistant).

Interventions: Subjects maintained at therapeutic levels of lithium or valproate received an intravenous infusion of either ketamine hydrochloride (0.5 mg/kg) or placebo on 2 test days 2 weeks apart. The Montgomery- Asberg Depression Rating Scale was used to rate subjects at baseline and at 40, 80, 110, and 230 minutes and on days 1, 2, 3, 7, 10, and 14 postinfusion.

Results: Within 40 minutes, depressive symptoms significantly improved in subjects receiving ketamine compared with placebo (d=0.52, 95% confidence interval [CI], 0.28-0.76); this improvement remained significant through day 3. The drug difference effect size was largest at day 2 (d=0.80, 95% CI, 0.55-1.04). Seventy-one percent of subjects responded to ketamine and 6% responded to placebo at some point during the trial. One subject receiving ketamine and 1 receiving placebo developed manic symptoms. Ketamine was generally well tolerated; the most common adverse effect was dissociative symptoms, only at the 40-minute point.

Diazgranados, N.,  Ibrahim, L. Brutsche, N. E., Newberg, A., Kronstein, P.,  Khalife, S., … Zarate Jr., Z. A. (2010). A Randomized Add-on Trial of an N-methyl-D-aspartate Antagonist in Treatment-Resistant Bipolar Depression. Archives of General Psychiatry, 67(8). http://dx.doi.org/10.1001/archgenpsychiatry.2010.90
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The persistence of the subjective in neuropsychopharmacology: observations of contemporary hallucinogen research

February 26, 2010 / Ayahuasca, Cacti / Mescaline, DMT, Iboga / Ibogaine, Ketamine, LSD, MDMA, Mushrooms / Psilocybin, Neuroscience, Other disciplines, Other subjects, Other substances, Papers, Psychology, Psychopharmacology, Publications, Salvia / Salvinorin A / By /

Abstract

The elimination of subjectivity through brain research and the replacement of so-called ‘folk psychology’ by a neuroscientifically enlightened worldview and self-conception has been both hoped for and feared. But this cultural revolution is still pending. Based on nine months of fieldwork on the revival of hallucinogen research since the ‘Decade of the Brain,’ this paper examines how subjective experience appears as epistemic object and practical problem in a psychopharmacological laboratory. In the quest for neural correlates of (drug-induced altered states of) consciousness, introspective accounts of test subjects play a crucial role in neuroimaging studies. Firsthand knowledge of the drugs’ flamboyant effects provides researchers with a personal knowledge not communicated in scientific publications, but key to the conduct of their experiments. In many cases, the ‘psychedelic experience’ draws scientists into the field and continues to inspire their self-image and way of life. By exploring these domains the paper points to a persistence of the subjective in contemporary neuropsychopharmacology.

Langlitz, N. (2010). The persistence of the subjective in neuropsychopharmacology: observations of contemporary hallucinogen research. History of Human Sciences, 23(1), 37-57. http://dx.doi.org/10.1177/0952695109352413
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Human hallucinogen research: guidelines for safety

July 1, 2008 / Ayahuasca, Cacti / Mescaline, DMT, Iboga / Ibogaine, Ketamine, LSD, MDMA, Medicine, Mushrooms / Psilocybin, Neuroscience, Other substances, Papers, Psychiatry, Psychology, Psychopharmacology, Publications, Safety, Salvia / Salvinorin A / By / , ,

Abstract

There has recently been a renewal of human research with classical hallucinogens (psychedelics). This paper first briefly discusses the unique history of human hallucinogen research, and then reviews the risks of hallucinogen administration and safeguards for minimizing these risks. Although hallucinogens are relatively safe physiologically and are not considered drugs of dependence, their administration involves unique psychological risks. The most likely risk is overwhelming distress during drug action (‘bad trip’), which could lead to potentially dangerous behaviour such as leaving the study site. Less common are prolonged psychoses triggered by hallucinogens. Safeguards against these risks include the exclusion of volunteers with personal or family history of psychotic disorders or other severe psychiatric disorders, establishing trust and rapport between session monitors and volunteer before the session, careful volunteer preparation, a safe physical session environment and interpersonal support from at least two study monitors during the session. Investigators should probe for the relatively rare hallucinogen persisting perception disorder in follow-up contact. Persisting adverse reactions are rare when research is conducted along these guidelines. Incautious research may jeopardize participant safety and future research. However, carefully conducted research may inform the treatment of psychiatric disorders, and may lead to advances in basic science.

Johnson, M. W., Richards, W. A., & Griffiths, R. R. (2008). Human hallucinogen research: guidelines for safety.  Journal of Psychopharmacology, 22(6), 603–620. http://dx.doi.org/10.1177/0269881108093587
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The correlation between ketamine and posttraumatic stress disorder in burned service members

February 22, 2008 / Anxiety disorders / PTSD, Ketamine, Papers, Psychiatry, Psychology, Psychopharmacology, Publications, Safety / By / , , , ,

Abstract

BACKGROUND:

Predisposing factors for posttraumatic stress disorder (PTSD) include experiencing a traumatic event, threat of injury or death, and untreated pain. Ketamine, an anesthetic, is used at low doses as part of a multimodal anesthetic regimen. However, since ketamine is associated with psychosomatic effects, there is a concern that ketamine may increase the risk of developing PTSD. This study investigated the prevalence of PTSD in Operation Iraqi Freedom/Operation Enduring Freedom (OIF/OEF) service members who were treated for burns in a military treatment center.

METHODS:

The PTSD Checklist-Military (PCL-M) is a 17-question screening tool for PTSD used by the military. A score of 44 or higher is a positive screen for PTSD. The charts of all OIF/OEF soldiers with burns who completed the PCL-M screening tool (2002-2007) were reviewed to determine the number of surgeries received, the anesthetic regime used, including amounts given, the total body surface area burned, and injury severity score. Morphine equivalent units were calculated using standard dosage conversion factors.

RESULTS:

The prevalence of PTSD in patients receiving ketamine during their operation(s) was compared with patients not receiving ketamine. Of the 25,000 soldiers injured in OIF/OEF, United States Army Institute of Surgical Research received 603 burned casualties, of which 241 completed the PCL-M. Of those, 147 soldiers underwent at least one operation. Among 119 patients who received ketamine during surgery and 28 who did not; the prevalence of PTSD was 27% (32 of 119) versus 46% (13 of 28), respectively (p = 0.044).

CONCLUSIONS:

Contrary to expectations, patients receiving perioperative ketamine had a lower prevalence of PTSD than soldiers receiving no ketamine during their surgeries despite having larger burns, higher injury severity score, undergoing more operations, and spending more time in the ICU.

McGhee, L. L., Maani, C. V., Garza, T. H., Gaylord, K. M., & Black, I. H. (2008). The correlation between ketamine and posttraumatic stress disorder in burned service members. Journal of Trauma and Acute Care Surgery, 64(2), S195-S199. https://dx.doi.org/10.1097/TA.0b013e318160ba1d
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Psychological effects of (S)-ketamine and N,N-dimethyltryptamine (DMT): a double-blind, cross-over study in healthy volunteers

October 1, 2005 / DMT, Ketamine, Papers, Psychiatry, Psychology, Psychopharmacology, Psychosis, Publications / By / , , , , , ,

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

July 13, 2005 / Anxiety disorders / PTSD, Ketamine, Papers, Psychiatry, Psychology, Psychopharmacology, Publications / By / , , , ,

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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14 May - Psychedelics & Psychosis with Phoebe Friesen and Dirk Corstens

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