OPEN Foundation

Menu
Search
Close this search box.

Psychology

Glutamate and GABA Systems in the Pathophysiology of Major Depression and Antidepressant Response to Ketamine

May 12, 2016 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

In patients with major depressive disorder (MDD) or bipolar disorder (BD), abnormalities in excitatory and/or inhibitory neurotransmission and neuronal plasticity may lead to aberrant functional connectivity patterns within large brain networks. Network dysfunction in association with altered brain levels of glutamate (Glu) and gamma-aminobutyric acid (GABA) have been identified in both animal and human studies of depression. In addition, evidence of an antidepressant response to subanesthetic dose ketamine has led to a collection of studies that have examined neurochemical (e.g. glutamatergic and GABA-ergic) and functional imaging correlates associated with such an effect. Results from these studies suggest that an antidepressant response in association with ketamine occurs, in part, by reversing these neurochemical/physiological disturbances. Future studies in depression will require a combination of neuroimaging approaches from which more biologically homogeneous subgroups can be identified, particularly with respect to treatment response biomarkers of glutamatergic modulation.

Lener, M. S., Niciu, M. J., Ballard, E. D., Park, M., Park, L. T., Nugent, A., & Zarate, C. A. (2016). Glutamate and GABA Systems in the Pathophysiology of Major Depression and Antidepressant Response to Ketamine. Biological Psychiatry. http://dx.doi.org/10.1016/j.biopsych.2016.05.005
Link to full text

Treatment of heroin dependence with ibogaine

May 12, 2016 / Iboga / Ibogaine, Papers, Psychology, Publications, Substance Use Disorder / By / , , ,

Abstract

The use of the hallucinogen ibogaine as an anti-addiction agent has been described in several case reports, dating back to the eighties. The anti-addiction properties of ibogaine have been confirmed in a large body of animal work. Ibogaine has been shown to be effective in reducing withdrawal severity and substance use for a variety of substances, including cocaine and opiates. Animal studies also show some potentially dangerous adverse reactions, including cerebellar toxicity and potential cardiac effects. While pharmacological treatment options for opiate and cocaine dependence are still limited, ibogaine assisted treatment might be a promising new option. Therefore more systematic studies on its toxicity and efficacy are warranted. In our studies we address these two research questions: is ibogaine treatment for opiate dependence safe and effective for treating opiate withdrawal and relapse prevention? A secondary objective is to explore the pharmacokinetic properties of ibogaine.Animal work: first we performed a systematic review and meta-analysis of animal studies on ibogaine. Thirty studies were included in the systematic review, of which 27 could be analyzed in meta-analysis. Human studies: fifteen opiate dependent patients will be treated with ibogaine (10mg/kg), on top of treatment as usual. Ibogaine toxicity will be assessed through close monitoring with electrocardiography, with QTc prolongation as main outcome measure, repeated assessments of ataxia using the (SARA) and observation of psychotic symptoms by using the Delirium Observations Scale (DOS). Ibogaine efficacy will be measured, using repeated evaluations of opiate withdrawal severity (Subjective Opiate Withdrawal Scale: SOWS; Objective Opiate Withdrawal Scale: OOWS), craving intensity (using a Visual Analogue Scale) and substance use, with a six-month follow-up. Clinical observations in ibogaine treated individuals will be compared with a cohort of opiate dependent patients treated with a rapid detoxification procedure. Both acute and long-term effects will be linked with serum ibogaine and noribogaine levels.Animal work: overall, ibogaine reduced drug self-administration, particularly during the first 24hours after administration. Ibogaine had no effect on drug-induced conditioned place preference. Ibogaine administration resulted in motor impairment in the first 24hours after supplementation, and cerebral cell loss even weeks after administration. Data on ibogaines effect on cardiac rhythm as well as on its neuropharmacological working mechanisms are limited. Human studies: human data are still being collected. Treatment of the first patients confirmed strong effects of ibogaine on heart rhythm (QTc prolongation) and ataxia, while the opiate withdrawal symptoms were relatively mild. The first observations on the clinical effect of ibogaine on craving and substance use will also be shared.Based on our meta-analysis of animal data, there is strong evidence that ibogaine is effective in reducing drug self-administration in animals. This warrants further studies into the clinical efficacy of ibogaine in substance dependent patients in reducing craving and substance use. Our first clinical experiences in a limited number of patients confirm that ibogaine treatment may be effective in reducing opiate withdrawal, but can potentially have transient cardiac and cerebellar toxicity.

Schellekens, A., Oosteren, T., Knuijver, T., & Belgers, M. (2016). Treatment of heroin dependence with ibogaine. European Psychiatry, 33, S10-S11. http://dx.doi.org/10.1016%2Fj.eurpsy.2016.01.799
Link to full text

Ketamine: stimulating antidepressant treatment?

May 11, 2016 / Depressive Disorders, Ketamine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

The appeal of ketamine – in promptly ameliorating depressive symptoms even in those with non-response – has led to a dramatic increase in its off-label use. Initial promising results await robust corroboration and key questions remain, particularly concerning its long-term administration. It is, therefore, timely to review the opinions of mood disorder experts worldwide pertaining to ketamine’s potential as an option for treating depression and provide a synthesis of perspectives – derived from evidence and clinical experience – and to consider strategies for future investigations.

Malhi, G. S., Byrow, Y., Cassidy, F., Cipriani, A., Demyttenaere, K., Frye, M. A., … & McShane, R. (2016). Ketamine: stimulating antidepressant treatment?. British Journal of Psychiatry Open, 2(3), e5-e9. 10.1192/bjpo.bp.116.002923
Link to full text

Effects of low dose ibogaine on subjective mood state and psychological performance

May 11, 2016 / Iboga / Ibogaine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Ethnopharmacological relevance: Root bark from Tabernanthe iboga has been used traditionally in West Africa as a psychoactive substance in religious rituals. In smaller doses it is reported anecdotally to have stimulant properties.

Aim of the study: To evaluate the influence of a single 20 mg ibogaine dose on psychological variables reflecting subjective mood state and a range of cognitive functions.

Materials and methods: 21 healthy male volunteers received single 20 mg doses of ibogaine after 6 days pretreatment with double-blind paroxetine or placebo. We compared responses to a battery of psychometric tests and subjective mood ratings performed before and 2 h after ibogaine dosing, and assessed relationships between changes in test scores and concentrations of active moiety (the sum of molar noribogaine and ibogaine concentrations). Psychological tests were chosen based on responsiveness to opioid and serotonergic ligands.

Results: Ibogaine had minimal influence on psychological tests and mood ratings. The ability to selectively ignore distracting spatial information showed some evidence of modulation; however because this effect was limited to the less challenging condition calls into question the reliability of this result.

Conclusion: We were unable to identify stimulant effects after single 20 mg doses of ibogaine. Future research is needed to confirm whether active moiety concentrations impact selective attention abilities while leaving other cognitive functions and mood state unaffected.

Forsyth, B., Machado, L., Jowett, T., Jakobi, H., Garbe, K., Winter, H., & Glue, P. (2016). Effects of low dose ibogaine on subjective mood state and psychological performance. Journal of Ethnopharmacology. http://dx.doi.org/10.1016/j.jep.2016.05.022

Link to full text

LSD-induced entropic brain activity predicts subsequent personality change

May 6, 2016 / LSD, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Personality is known to be relatively stable throughout adulthood. Nevertheless, it has been shown that major life events with high personal significance, including experiences engendered by psychedelic drugs, can have an enduring impact on some core facets of personality. In the present, balanced-order, placebo-controlled study, we investigated biological predictors of post-lysergic acid diethylamide (LSD) changes in personality. Nineteen healthy adults underwent resting state functional MRI scans under LSD (75µg, I.V.) and placebo (saline I.V.). The Revised NEO Personality Inventory (NEO-PI-R) was completed at screening and 2 weeks after LSD/placebo. Scanning sessions consisted of three 7.5-min eyes-closed resting-state scans, one of which involved music listening. A standardized preprocessing pipeline was used to extract measures of sample entropy, which characterizes the predictability of an fMRI time-series. Mixed-effects models were used to evaluate drug-induced shifts in brain entropy and their relationship with the observed increases in the personality trait openness at the 2-week follow-up. Overall, LSD had a pronounced global effect on brain entropy, increasing it in both sensory and hierarchically higher networks across multiple time scales. These shifts predicted enduring increases in trait openness. Moreover, the predictive power of the entropy increases was greatest for the music-listening scans and when “ego-dissolution” was reported during the acute experience. These results shed new light on how LSD-induced shifts in brain dynamics and concomitant subjective experience can be predictive of lasting changes in personality.

Link to full text

Depression: Ketamine steps out of the darkness

May 4, 2016 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By /

Abstract

The way in which ketamine exerts its antidepressant effects has been perplexing. Evidence that a metabolite of the drug is responsible, and acts on a different target from ketamine, might be the key to an answer.

Malinow, R. (2016). Depression: Ketamine steps out of the darkness. Nature. http://dx.doi.org/10.1038/nature17897

Link to full text

NMDAR inhibition-independent antidepressant actions of ketamine metabolites

May 4, 2016 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Major depressive disorder affects around 16 per cent of the world population at some point in their lives. Despite the availability of numerous monoaminergic-based antidepressants, most patients require several weeks, if not months, to respond to these treatments, and many patients never attain sustained remission of their symptoms. The non-competitive, glutamatergic NMDAR (N-methyl-d-aspartate receptor) antagonist (R,S)-ketamine exerts rapid and sustained antidepressant effects after a single dose in patients with depression, but its use is associated with undesirable side effects. Here we show that the metabolism of (R,S)-ketamine to (2S,6S;2R,6R)-hydroxynorketamine (HNK) is essential for its antidepressant effects, and that the (2R,6R)-HNK enantiomer exerts behavioural, electroencephalographic, electrophysiological and cellular antidepressant-related actions in mice. These antidepressant actions are independent of NMDAR inhibition but involve early and sustained activation of AMPARs (α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors). We also establish that (2R,6R)-HNK lacks ketamine-related side effects. Our data implicate a novel mechanism underlying the antidepressant properties of (R,S)-ketamine and have relevance for the development of next-generation, rapid-acting antidepressants.

Zanos, P., Moaddel, R., Morris, P. J., Georgiou, P., Fischell, J., Elmer, G. I., … & Dossou, K. S. (2016). NMDAR inhibition-independent antidepressant actions of ketamine metabolites. Nature. http://dx.doi.org/10.1038/nature17998
Link to full text

Treating posttraumatic stress disorder with MDMA-assisted psychotherapy: A preliminary meta-analysis and comparison to prolonged exposure therapy

April 26, 2016 / Anxiety Disorders / PTSD, MDMA, Papers, Psychology, Publications / By / ,

Abstract

Since the wars in Iraq and Afghanistan, posttraumatic stress disorder (PTSD) has become a major area of research and development. The most widely accepted treatment for PTSD is prolonged exposure (PE) therapy, but for many patients it is intolerable or ineffective. ±3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy (MDMA-AP) has recently re-emerged as a new treatment option, with two clinical trials having been published and both producing promising results. However, these results have yet to be compared to existing treatments. The present paper seeks to bridge this gap in the literature. Often the statistical significance of clinical trials is overemphasized, while the magnitude of the treatment effects is overlooked. The current meta-analysis aims to provide a comparison of the cumulative effect size of the MDMA-AP studies with those of PE. Effect sizes were calculated for primary and secondary outcome measures in the MDMA-AP clinical trials and compared to those of a meta-analysis including several PE clinical trials. It was found that MDMA-AP had larger effect sizes in both clinician-observed outcomes than PE did (Hedges’ g=1.17 vs. g=1.08, respectively) and patient self-report outcomes (Hedges’ g=0.87 vs. g=0.77, respectively). The dropout rates of PE and MDMA-AP were also compared, revealing that MDMA-AP had a considerably lower percentage of patients dropping out than PE did. These results suggest that MDMA-AP offers a promising treatment for PTSD.

Amoroso, T., & Workman, M. (2016). Treating posttraumatic stress disorder with MDMA-assisted psychotherapy: A preliminary meta-analysis and comparison to prolonged exposure therapy. Journal of psychopharmacology (Oxford, England). http://dx.doi.org/10.1177/0269881116642542

Link to full text

Functional neurotoxicity evaluation of noribogaine using video-EEG in cynomolgus monkeys

April 25, 2016 / Iboga / Ibogaine, Papers, Psychology, Publications / By / , , , , , ,

Abstract

INTRODUCTION:
Continuous video-electroencephalographic (EEG) monitoring remains the gold standard for seizure liability assessments in preclinical drug safety assessments. EEG monitored by telemetry was used to assess the behavioral and EEG effects of noribogaine hydrochloride (noribogaine) in cynomolgus monkeys. Noribogaine is an iboga alkaloid being studied for the treatment of opioid dependence.
METHODS:
Six cynomolgus monkeys (3 per gender) were instrumented with EEG telemetry transmitters. Noribogaine was administered to each monkey at both doses (i.e., 160 and 320mg/kg, PO) with an interval between dosing of at least 6days, and the resulting behavioral and EEG effects were evaluated. IV pentylenetetrazol (PTZ), served as a positive control for induced seizures.
RESULTS:
The administration of noribogaine at either of the doses evaluated was not associated with EEG evidence of seizure or with EEG signals known to be premonitory signs of increased seizure risk (e.g., sharp waves, unusual synchrony, shifts to high-frequency patterns). Noribogaine was associated with a mild reduction in activity levels, increased scratching, licking and chewing, and some degree of poor coordination and related clinical signs. A single monkey exhibited brief myoclonic movements that increased in frequency at the high dose, but which did not appear to generalize, cluster or to be linked with EEG abnormalities. Noribogaine was also associated with emesis and partial anorexia. In contrast, PTZ was associated with substantial pre-ictal EEG patterns including large amplitude, repetitive sharp waves leading to generalized seizures and to typical post-ictal EEG frequency attenuation.
INTERPRETATION:
EEG patterns were within normal limits following administration of noribogaine at doses up to 320mg/kg with concurrent clinical signs that correlated with plasma exposures and resolved by the end of the monitoring period. PTZ was invariably associated with EEG paroxysmal activity leading to ictal EEG. In the current study, a noribogaine dose of 320mg/kg was considered to be the EEG no observed adverse effect level (NOAEL) in conscious freely moving cynomolgus monkeys.
Authier, S., Accardi, M. V., Paquette, D., Pouliot, M., Arezzo, J., Stubbs, R. J., … & Weis, H. (2016). Functional neurotoxicity evaluation of noribogaine using video-EEG in cynomolgus monkeys. Journal of pharmacological and toxicological methods, 81, 306-312. 10.1016/j.vascn.2016.04.012
Link to full text

Neuropharmacology of N,N-Dimethyltryptamine

April 25, 2016 / DMT, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

N,N-Dimethyltryptamine (DMT) is an indole alkaloid widely found in plants and animals. It is best known for producing brief and intense psychedelic effects when ingested. Increasing evidence suggests that endogenous DMT plays important roles for a number of processes in the periphery and central nervous system, and may act as a neurotransmitter. This paper reviews the current literature of both the recreational use of DMT and its potential roles as an endogenous neurotransmitter. Pharmacokinetics, mechanisms of action in the periphery and central nervous system, clinical uses and adverse effects are also reviewed. DMT appears to have limited neurotoxicity and other adverse effects except for intense cardiovascular effects when administered intravenously in large doses. Because of its role in nervous system signaling, DMT may be a useful experimental tool in exploring how brain works, and may also be a useful clinical tool for treatment of anxiety and psychosis.

Carbonaro, T. M., & Gatch, M. B. (2016). Neuropharmacology of N, N-Dimethyltryptamine. Brain Research Bulletin. http://dx.doi.org/10.1016/j.brainresbull.2016.04.016

Link to full text

interested in becoming a trained psychedelic-assisted therapist?

Online Event - Psychedelic Care in Recreational Settings - 3 October 2024

REGISTER NOW