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Neuroscience

Double-blind comparison of the two hallucinogens psilocybin and dextromethorphan: effects on cognition

July 30, 2018 / Mushrooms / Psilocybin, Neuroscience, Papers, Psychiatry & Medicine, Publications / By / , , , ,

Abstract

Objectives

Classic psychedelics (serotonin 2A receptor agonists) and dissociative hallucinogens (NMDA receptor antagonists), though differing in pharmacology, may share neuropsychological effects. These drugs, however, have undergone limited direct comparison. This report presents data from a double-blind, placebo-controlled within-subjects study comparing the neuropsychological effects of multiple doses of the classic psychedelic psilocybin with the effects of a single high dose of the dissociative hallucinogen dextromethorphan (DXM).

Methods

Twenty hallucinogen users (11 females) completed neurocognitive assessments during five blinded drug administration sessions (10, 20, and 30 mg/70 kg psilocybin; 400 mg/70 kg DXM; and placebo) in which participants and study staff were informed that a large range of possible drug conditions may have been administered.

Results

Global cognitive impairment, assessed using the Mini-Mental State Examination during peak drug effects, was not observed with psilocybin or DXM. Orderly and dose-dependent effects of psilocybin were observed on psychomotor performance, working memory, episodic memory, associative learning, and visual perception. Effects of DXM on psychomotor performance, visual perception, and associative learning were in the range of effects of a moderate to high dose (20 to 30 mg/70 kg) of psilocybin.

Conclusions

This was the first study of the dose effects of psilocybin on a large battery of neurocognitive assessments. Evidence of delirium or global cognitive impairment was not observed with either psilocybin or DXM. Psilocybin had greater effects than DXM on working memory. DXM had greater effects than all psilocybin doses on balance, episodic memory, response inhibition, and executive control.

Barrett, F. S., Carbonaro, T. M., Hurwitz, E., Johnson, M. W., & Griffiths, R. R. (2018). Double-blind comparison of the two hallucinogens psilocybin and dextromethorphan: effects on cognition. Psychopharmacology, 235(10), 2915-2927., 10.1007/s00213-018-4981-x
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Efficacy of Ketamine in the Treatment of Substance Use Disorders: A Systematic Review

July 24, 2018 / Anxiety Disorders / PTSD, Depressive Disorders, Ketamine, Neuroscience, Papers, Psychiatry & Medicine, Publications / By / , , , ,

Abstract

Background: Despite advances in behavioral and pharmacotherapy interventions, substance use disorders (SUDs) are frequently refractory to treatment. Glutamatergic dysregulation has received increasing attention as one common neuropathology across multiple substances of abuse. Ketamine is a potent N-methyl-D-aspartate (NMDA) glutamatergic receptor antagonist which has been found to be effective in the treatment of severe depression. Here we review the literature on the efficacy of ketamine in the treatment of SUDs.

Methods: A systematic review of the PubMed, Scopus, and ClinicalTrials.gov databases was undertaken to identify completed and ongoing human studies of the effectiveness of ketamine in the treatment of SUDs between January 1997 and January 2018.

Results and conclusion: Seven completed studies were identified. Two studies focused on alcohol use disorder, two focused on cocaine use disorder, and three focused on opioid use disorder. Both cocaine studies found improvements in craving, motivation, and decreased cocaine use rates, although studies were limited by small sample sizes, a homogeneous population and short follow-up. Studies of alcohol and opioid use disorders found improvement in abstinence rates in the ketamine group, with significant between-group effects noted for up to two years following a single infusion, although these were not placebo-controlled trials. These results suggest that ketamine may facilitate abstinence across multiple substances of abuse and warrants broader investigation in addiction treatment. We conclude with an overview of the six ongoing studies of ketamine in the treatment of alcohol, cocaine, cannabis, and opioid use disorders and discuss future directions in this emerging area of research.

Jones, J. L., Mateus, C. F., Malcolm, R. J., Brady, K. T., & Back, S. E. (2018). Efficacy of ketamine in the treatment of substance use disorders: a systematic review. Frontiers in Psychiatry, 9., 10.3389/fpsyt.2018.00277
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A Mixed-Method Analysis of Persisting Effects Associated with Positive Outcomes Following Ibogaine Detoxification

July 18, 2018 / Iboga / Ibogaine, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / , , , ,

Abstract

We examined persisting effects, self-perceived challenges, and potential benefits associated with positive outcomes following ibogaine detoxification using data collected as part of a larger online retrospective study of 73 patients who received treatment for chronic opioid use in Mexico between 2012 and 2015. A mixed-methods design was used comparing treatment responders versus non-responders, as well as content coding of themes from open-ended questions. Most participants reported positive persisting effects of ibogaine detoxification (e.g., enhanced personal sense of gratitude and authenticity, and meaning and appreciation for life). Compared to non-responders, treatment responders endorsed greater persisting changes in their ability to tolerate difficult/painful feelings, capacity for coping with stress, and reduced unhealthy anger. Treatment responders reported greater change in subjective levels of inner peace, joy, feelings of love/openheartedness, and experiences of sacredness in life. Qualitative analyses revealed that treatment responders reported a heightened sense of spiritual awareness and greater connection to their intra-/interpersonal relationships after ibogaine detoxification. Notable challenges of ibogaine detoxification included psychological and health-related difficulties during treatment and challenges with post-treatment integration. Findings highlight the persisting effects associated with positive response to ibogaine detoxification and possible post-treatment needs (i.e., more integration/aftercare resources). Future research using rigorous experimental designs is needed.

Davis, A. K., Renn, E., Windham-Herman, A. M., Polanco, M., & Barsuglia, J. P. (2018). A mixed-method analysis of persisting effects associated with positive outcomes following ibogaine detoxification. Journal of psychoactive drugs, 50(4), 287-297., 10.1080/02791072.2018.1487607.
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Dark Classics in Chemical Neuroscience: 3,4-Methylenedioxymethamphetamine

July 12, 2018 / Humanities & Art, MDMA, Neuroscience, Papers, Pharmacology & Chemistry, Psychiatry & Medicine, Psychology, Publications / By / , ,

Abstract

Better known as “ecstasy”, 3,4-methylenedioxymethamphetamine (MDMA) is a small molecule that has played a prominent role in defining the ethos of today’s teenagers and young adults, much like lysergic acid diethylamide (LSD) did in the 1960s. Though MDMA possesses structural similarities to compounds like amphetamine and mescaline, it produces subjective effects that are unlike any of the classical psychostimulants or hallucinogens and is one of the few compounds capable of reliably producing prosocial behavioral states. As a result, MDMA has captured the attention of recreational users, the media, artists, psychiatrists, and neuropharmacologists alike. Here, we detail the synthesis of MDMA as well as its pharmacology, metabolism, adverse effects, and potential use in medicine. Finally, we discuss its history and why it is perhaps the most important compound for the future of psychedelic science-having the potential to either facilitate new psychedelic research initiatives, or to usher in a second Dark Age for the field.

Dunlap, L. E., Andrews, A. M., & Olson, D. E. (2018). Dark classics in chemical neuroscience: 3, 4-Methylenedioxymethamphetamine. ACS chemical neuroscience, 9(10), 2408-2427., 10.1021/acschemneuro.8b00155
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Ketamine normalizes brain activity during emotionally valenced attentional processing in depression

July 5, 2018 / Depressive Disorders, Ketamine, Neuroscience, Papers, Psychiatry & Medicine, Publications / By / , , , , ,

Abstract

BACKGROUND:

An urgent need exists for faster-acting pharmacological treatments in major depressive disorder (MDD). The glutamatergic modulator ketamine has been shown to have rapid antidepressant effects, but much remains unknown about its mechanism of action. Functional MRI (fMRI) can be used to investigate how ketamine impacts brain activity during cognitive and emotional processing.

METHODS:

This double-blind, placebo-controlled, crossover study of 33 unmedicated participants with MDD and 26 healthy controls (HCs) examined how ketamine affected fMRI activation during an attentional bias dot probe task with emotional face stimuli across multiple time points. A whole brain analysis was conducted to find regions with differential activation associated with group, drug session, or dot probe task-specific factors (emotional valence and congruency of stimuli).

RESULTS:

A drug session by group interaction was observed in several brain regions, such that ketamine had opposite effects on brain activation in MDD versus HC participants. Additionally, there was a similar finding related to emotional valence (a drug session by group by emotion interaction) in a large cluster in the anterior cingulate and medial frontal cortex.

CONCLUSIONS:

The findings show a pattern of brain activity in MDD participants following ketamine infusion that is similar to activity observed in HCs after placebo. This suggests that ketamine may act as an antidepressant by normalizing brain function during emotionally valenced attentional processing.

CLINICAL TRIAL:

NCT#00088699: https://www.clinicaltrials.gov/ct2/show/NCT00088699.

Reed, J. L., Nugent, A. C., Furey, M. L., Szczepanik, J. E., Evans, J. W., & Zarate Jr, C. A. (2018). Ketamine normalizes brain activity during emotionally valenced attentional processing in depression. NeuroImage: Clinical, 20, 92-101., 10.1016/j.nicl.2018.07.006
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Oxytocin receptor gene variations and socio-emotional effects of MDMA: A pooled analysis of controlled studies in healthy subjects

June 18, 2018 / MDMA, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

Methylenedioxymethamphetamine (MDMA) increases oxytocin, empathy, and prosociality. Oxytocin plays a critical role in emotion processing and social behavior and has been shown to mediate the prosocial effects of MDMA in animals. Genetic variants, such as single-nucleotide polymorphisms (SNPs), of the oxytocin receptor (OXTR) may influence the emotional and social effects of MDMA in humans. The effects of common genetic variants of the OXTR (rs53576, rs1042778, and rs2254298 SNPs) on the emotional, empathogenic, and prosocial effects of MDMA were characterized in up to 132 healthy subjects in a pooled analysis of eight double-blind, placebo-controlled studies. In a subset of 53 subjects, MDMA produced significantly greater feelings of trust in rs1042778 TT genotypes compared with G allele carriers. The rs53576 and rs225498 SNPs did not moderate the subjective effects of MDMA in up to 132 subjects. None of the SNPs moderated MDMA-induced impairments in negative facial emotion recognition or enhancements in emotional empathy in the Multifaceted Empathy Test in 69 subjects. MDMA significantly increased plasma oxytocin concentrations. MDMA and oxytocin concentrations did not differ between OXTR gene variants. The present results provide preliminary evidence that OXTR gene variations may modulate aspects of the prosocial subjective effects of MDMA in humans. However, interpretation should be cautious due to the small sample size. Additionally, OXTR SNPs did not moderate the subjective overall effect of MDMA (any drug effect) or feelings of “closeness to others”.
Vizeli, P., & Liechti, M. E. (2018). Oxytocin receptor gene variations and socio-emotional effects of MDMA: A pooled analysis of controlled studies in healthy subjects. PloS one, 13(6), e0199384. 10.1371/journal.pone.0199384
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Psychedelics Promote Structural and Functional Neural Plasticity

June 12, 2018 / Depressive Disorders, LSD, Mushrooms / Psilocybin, Neuroscience, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Atrophy of neurons in the prefrontal cortex (PFC) plays a key role in the pathophysiology of depression and related disorders. The ability to promote both structural and functional plasticity in the PFC has been hypothesized to underlie the fast-acting antidepressant properties of the dissociative anesthetic ketamine. Here, we report that, like ketamine, serotonergic psychedelics are capable of robustly increasing neuritogenesis and/or spinogenesis both in vitro and in vivo. These changes in neuronal structure are accompanied by increased synapse number and function, as measured by fluorescence microscopy and electrophysiology. The structural changes induced by psychedelics appear to result from stimulation of the TrkB, mTOR, and 5-HT2A signaling pathways and could possibly explain the clinical effectiveness of these compounds. Our results underscore the therapeutic potential of psychedelics and, importantly, identify several lead scaffolds for medicinal chemistry efforts focused on developing plasticity-promoting compounds as safe, effective, and fast-acting treatments for depression and related disorders.
Ly, C., Greb, A. C., Cameron, L. P., Wong, J. M., Barragan, E. V., Wilson, P. C., … & Duim, W. C. (2018). Psychedelics Promote Structural and Functional Neural Plasticity. Cell reports, 23(11), 3170-3182. 10.1016/j.celrep.2018.05.022
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Dark Classics in Chemical Neuroscience: Mescaline

June 8, 2018 / Biology & Ethnobotany, Humanities & Art, Mescaline / Cacti, Neuroscience, Papers, Psychology, Publications / By / ,

Abstract

Archeological studies in the United States, Mexico, and Peru suggest that mescaline, as a cactus constituent, has been used for more than 6000 years. Although it is a widespread cactus alkaloid, it is present in high concentrations in few species, notably the North American peyote ( Lophophora williamsii) and the South American wachuma ( Trichocereus pachanoi, T. peruvianus, and T. bridgesii). Spanish 16th century chroniclers considered these cacti “diabolic”, leading to their prohibition, but their use persisted to our days and has been spreading for the last 150 years. In the late 1800s, peyote attracted scientific attention; mescaline was isolated, and its role in the psychedelic effects of peyote tops or “mescal buttons” was demonstrated. Its structure was established by synthesis in 1929, and alternative routes were developed, providing larger amounts for pharmacological and biosynthetic research. Although its effects are attributed mainly to its action as a 5-HT2Aserotonin receptor agonist, mescaline binds in a similar concentration range to 5-HT1A and α2A receptors. It is largely excreted unchanged in human urine, and its metabolic products are apparently unrelated to its psychedelic properties. Its low potency is probably responsible for its relative neglect by recreational substance users, as the successful search for structure-activity relationships in the hallucinogen field focused largely on finding more potent analogues. Renewed interest in the possible therapeutic applications of psychedelic drugs may hopefully lead to novel insights regarding the commonalities and differences between the actions of individual classic hallucinogens.
Cassels, B., & Sáez-Briones, P. (2018). Dark Classics in Chemical Neuroscience: Mescaline. ACS chemical neuroscience. 10.1021/acschemneuro.8b00215
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Pharmacological fMRI: Effects of subanesthetic ketamine on resting-state functional connectivity in the default mode network, salience network, dorsal attention network and executive control network.

June 1, 2018 / Ketamine, Neuroscience, Papers, Psychology, Psychotic Disorders, Publications / By / , , , , ,

Abstract

BACKGROUND:
Subanesthetic dosages of the NMDAR antagonist, S-Ketamine, can cause changes in behavior in healthy subjects, which are similar to the state acute psychosis and are relevant in translational schizophrenia research. Functional magnetic resonance imaging (fMRI) can be used for non-hypothesis-driven analysis of brain connectivity. The correlation between clinical behavioral scores and neuroimaging can help to characterize ketamine effects on healthy brains in resting state.
METHOD:
seventeen healthy, male subjects (mean: 27.42 years, SD: 4.42) were administered an infusion with S-Ketamine (initial bolus 1 mg/kg and continuous infusion of 0.015625 mg/kg/min with dosage reduction -10%/10 min) or saline in a randomized, double-blind, cross-over study. During infusion, resting state connectivity was measured and analyzed with a seed-to-voxel fMRI analysis approach. The seed regions were located in the posterior cingulate cortex, intraparietal sulcus, dorsolateral prefrontal cortex and fronto-insular cortex. Receiver operating characteristics (ROC) were calculated to assess the accuracy of the ketamine-induced functional connectivity changes. Bivariate Pearson correlation was used for correlation testing of functional connectivity changes with changes of clinical scores (PANSS, 5D-ASC).
RESULTS:
In the executive network (ECN), ketamine significantly increases the functional connectivity with parts of the anterior cingulum and superior frontal gyrus, but no significant correlations with clinical symptoms were found. Decreased connectivity between the salience network (SN) and the calcarine fissure was found, which is significantly correlated with negative symptoms (PANSS) (R2 > 0.4).
CONCLUSION:
Decreased ketamine-induced functional connectivity in the salience network may qualify as accurate and highly predictive biomarkers for ketamine induced negative symptoms.
Mueller, F., Musso, F., London, M., de Boer, P., Zacharias, N., & Winterer, G. (2018). Pharmacological fMRI: Effects of subanesthetic ketamine on resting-state functional connectivity in the default mode network, salience network, dorsal attention network and executive control network. NeuroImage: Clinical., 10.1016/j.nicl.2018.05.037
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Ayahuasca and Its DMT- and β-carbolines – Containing Ingredients Block the Expression of Ethanol-Induced Conditioned Place Preference in Mice: Role of the Treatment Environment

May 29, 2018 / Ayahuasca, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / , , , , , ,

Abstract

Ayahuasca is a hallucinogenic beverage produced from the decoction of Banisteriopsis caapi (Bc) and Psychotria viridis (Pv), β-carboline- and N,N-dimethyltryptamine(DMT)-containing plants, respectively. Accumulating evidence suggests that ayahuasca may have therapeutic effects on ethanol abuse. It is not known, however, whether its effects are dependent on the presence of DMT or if non-DMT-containing components would have therapeutic effects. The aim of the present study was to investigate the rewarding properties of ayahuasca (30, 100, and 300 mg/kg, orally), Bc (132, 440, and 1320 mg/kg, orally) and Pv (3.75, 12.5 and 37.5 mg/kg, i.p.) extracts and their effects on ethanol (1.8 g/kg, i.p.) reward using the conditioned place preference (CPP) paradigm in male mice. Animals were conditioned with ayahuasca, Bc or Pv extracts during 8 sessions. An intermediate, but not a high, dose of ayahuasca induced CPP in mice. Bc and Pv did not induce CPP. Subsequently, the effects of those extracts were tested on the development of ethanol-induced CPP. Ayahuasca, Bc or Pv were administered before ethanol injections during conditioning sessions. While Bc and Pv exerted no effects on ethanol-induced CPP, pretreatment with ayahuasca blocked the development of CPP to ethanol. Finally, the effects of a post-ethanol-conditioning treatment with ayahuasca, Bc or Pv on the expression of ethanol-induced CPP were tested. Animals were conditioned with ethanol, and subsequently treated with either ayahuasca, Bc or Pv in the CPP environment previously associated with saline or ethanol for 6 days. Animals were then reexposed to ethanol and ethanol-induced CPP was quantified on the following day. Treatment with all compounds in the ethanol-paired environment blocked the expression of ethanol-induced CPP. Administration of an intermediate, but not a high, dose of ayahuasca and Bc, as well as Pv administration, in the saline-paired compartment blocked the expression of ethanol-induced CPP. The present study sheds light into the components underlying the therapeutic effects of ayahuasca on ethanol abuse, indicating that ayahuasca and its plant components can decrease ethanol reward at doses that do not exert abuse liability. Importantly, the treatment environment seems to influence the therapeutic effects of ayahuasca and Bc, providing important insights into clinical practice.
Cata-Preta, E. G., Serra, Y. A., Moreira-Junior, E. D. C., Reis, H. S., Kisaki, N. D., Libarino-Santos, M., … & Costa, J. L. (2018). Ayahuasca and Its DMT-and β-carbolines–Containing Ingredients Block the Expression of Ethanol-Induced Conditioned Place Preference in Mice: Role of the Treatment Environment. Frontiers in pharmacology, 9. 10.3389/fphar.2018.00561
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