Seeing with the eyes shut: neural basis of enhanced imagery following Ayahuasca ingestion

Ayahuasca, dimethyltryptamine, and psychosis: a systematic review of human studies

Ayahuasca is a hallucinogen brew traditionally used for ritual and therapeutic purposes in Northwestern Amazon. It is rich in the tryptamine hallucinogens dimethyltryptamine (DMT), which acts as a serotonin 5-HT_2A agonist. This mechanism of action is similar to other compounds such as lysergic acid diethylamide (LSD) and psilocybin. The controlled use of LSD and psilocybin in experimental settings is associated with a low incidence of psychotic episodes, and population studies corroborate these findings. Both the controlled use of DMT in experimental settings and the use of ayahuasca in experimental and ritual settings are not usually associated with psychotic episodes, but little is known regarding ayahuasca or DMT use outside these controlled contexts. Thus, we performed a systematic review of the published case reports describing psychotic episodes associated with ayahuasca and DMT intake. We found three case series and two case reports describing psychotic episodes associated with ayahuasca intake, and three case reports describing psychotic episodes associated with DMT. Several reports describe subjects with a personal and possibly a family history of psychosis (including schizophrenia, schizophreniform disorders, psychotic mania, psychotic depression), nonpsychotic mania, or concomitant use of other drugs. However, some cases also described psychotic episodes in subjects without these previous characteristics. Overall, the incidence of such episodes appears to be rare in both the ritual and the recreational/noncontrolled settings. Performance of a psychiatric screening before administration of these drugs, and other hallucinogens, in controlled settings seems to significantly reduce the possibility of adverse reactions with psychotic symptomatology. Individuals with a personal or family history of any psychotic illness or nonpsychotic mania should avoid hallucinogen intake.

Antidepressive and anxiolytic effects of ayahuasca: a systematic literature review of animal and human studies

OBJECTIVE

To conduct a systematic literature review of animal and human studies reporting anxiolytic or antidepressive effects of ayahuasca or some of its isolated alkaloids (dimethyltryptamine, harmine, tetrahydroharmine, and harmaline).

METHODS

Papers published until 3 April 2015 were retrieved from the PubMed, LILACS and SciELO databases following a comprehensive search strategy and using a predetermined set of criteria for article selection.

RESULTS

Five hundred and fourteen studies were identified, of which 21 met the established criteria. Studies in animals have shown anxiolytic and antidepressive effects of ayahuasca, harmine, and harmaline, and experimental studies in humans and mental health assessments of experienced ayahuasca consumers also suggest that ayahuasca is associated with reductions in anxiety and depressive symptoms. A pilot study reported rapid antidepressive effects of a single ayahuasca dose in six patients with recurrent depression.

CONCLUSION

Considering the need for new drugs that produce fewer adverse effects and are more effective in reducing anxiety and depression symptomatology, the described effects of ayahuasca and its alkaloids should be further investigated.

Herbal Highs: Review on Psychoactive Effects and Neuropharmacology

BACKGROUND

A new trend among users of new psychoactive substances' the consumption of "herbal highs": plant parts containing psychoactive substances. Most of the substances extracted from herbs, in old centuries were at the centre of religious ceremonies of ancient civilizations. Currently, these herbal products are mainly sold by internet web sites and easily obtained since some of them have no legal restriction.

OBJECTIVE

We reviewed psychoactive effects and neuropharmacology of the most used "herbal highs" with characterized active principles, with studies reporting mechanisms of action, pharmacological and subjective effects, eventual secondary effects including intoxications and/or fatalities Method: The PubMed database was searched using the following key.words: herbal highs, Argyreia nervosa, Ipomoea violacea and Rivea corymbosa; Catha edulis; Datura stramonium; Piper methysticum; Mitragyna speciosa.

RESULTS

Psychoactive plants here reviewed have been known and used from ancient times, even if for some of them limited information still exist regarding subjective and neuropharmacological effects and consequent eventual toxicity when plants are used alone or in combination with "classical" drugs of abuse.

CONCLUSION

Some "herbal highs" should be classified as harmful drugs since chronic administration has been linked with addiction and cognitive impairment; for some others taking into consideration only the recent trends of abuse, studies investigating these aspects are lacking.

The current state of research on ayahuasca: A systematic review of human studies assessing psychiatric symptoms, neuropsychological functioning, and neuroimaging

RATIONALE

In recent decades, the use of ayahuasca (AYA) - a β-carboline- and dimethyltryptamine-rich hallucinogenic botanical preparation traditionally used by Northwestern Amazonian tribes for ritual and therapeutic purposes - has spread from South America to Europe and the USA, raising concerns about its possible toxicity and hopes of its therapeutic potential. Thus, it is important to analyze the acute, subacute, and long-term effects of AYA to assess its safety and toxicity.

OBJECTIVES

The purpose of this study was to conduct a systematic review of human studies assessing AYA effects on psychiatric symptoms, neuropsychological functioning, and neuroimaging.

METHODS

Papers published until 16 December 2015 were included from PubMed, LILACS and SciELO databases following a comprehensive search strategy and pre-determined set of criteria for article selection.

RESULTS

The review included 28 full-text articles. Acute AYA administration was well tolerated, increased introspection and positive mood, altered visual perceptions, activated frontal and paralimbic regions and decreased default mode network activity. It also improved planning and inhibitory control and impaired working memory, and showed antidepressive and antiaddictive potentials. Long-term AYA use was associated with increased cortical thickness of the anterior cingulate cortex and cortical thinning of the posterior cingulate cortex, which was inversely correlated to age of onset, intensity of prior AYA use, and spirituality. Subacute and long-term AYA use was not associated with increased psychopathology or cognitive deficits, being associated with enhanced mood and cognition, increased spirituality, and reduced impulsivity.

CONCLUSIONS

Acute, subacute, and long-term AYA use seems to have low toxicity. Preliminary studies about potential therapeutic effects of AYA need replication due to their methodological limitations.

Psychological and neuropsychological assessment of regular hoasca users

BACKGROUND

Hoasca (also called ayahuasca) is a N,N-dimethyltryptamine (DMT) - containing psychedelic brew originally used for magico-religious purposes by Amerindian populations of the Amazon Basin. Recently, Brazilian syncretic churches have helped spread the ritual use of hoasca to Western societies. The aim of this study was to evaluate substance use, and neuropsychological and psychological functioning of regular hoasca users within a religious setting.

METHODS

Assessment of socio-economic status, mood, personality traits, impulsiveness, drug use, quality of life, extrinsic and intrinsic religiosity, and neuropsychological function was performed on 30 volunteers from a U.S. branch of União do Vegetal (UDV), a Brazilian religion which uses hoasca ritually. We also assessed 27 non-hoasca-using control subjects matched by socio-demographic profile and church attendance. Mann-Whitney U, chi-squared and Fisher tests were used to analyze differences between groups. Spearman's association and simple logistic regression tests were used to analyze the impact of frequency of hoasca use on dependent variables.

RESULTS

Relative to the control group, the UDV group demonstrated lower scores for depression (p=0.043, r=.27) and confusion (p=0.032, r=.29) as assessed by the Profile of Mood States (POMS); higher scores on the instrument Big Five Inventory (BFI) for the personality traits agreeableness (p=0.028, r=.29) and openness (p=0.037, r=.28); higher scores on the quality life domain role limitations due to physical health as determined by the instrument Medical Outcomes Study Short Form-36 - SF-36 (p=0.035, r=.28); less recent use of alcohol (p<0.001, φ_c=.57), greater past use of alcohol to intoxication (p=0.007, φ_c=.36) and past use of cannabis (p=0.001, φ_c=.45) as measured by the Addiction Severity Index (ASI), 5th edition; better score on a measure of memory vulnerability to proactive interference as measured by the California Verbal Learning Test - CVLT (p=0.040, r=.27). Lifetime use of hoasca was positively correlated with role limitations due to physical health (p=0.032, r_s=.39) and negatively associated with lifetime heavy alcohol use (p=0.034, OR=0.979).

CONCLUSIONS

The findings indicate that religious use of hoasca does not adversely affect neuropsychological functioning and may have positive effects on substance abuse and mood.

Classical hallucinogens and neuroimaging: A systematic review of human studies: Hallucinogens and neuroimaging

Serotonergic hallucinogens produce alterations of perceptions, mood, and cognition, and have anxiolytic, antidepressant, and antiaddictive properties. These drugs act as agonists of frontocortical 5-HT_2A receptors, but the neural basis of their effects are not well understood. Thus, we conducted a systematic review of neuroimaging studies analyzing the effects of serotonergic hallucinogens in man. Studies published in the PubMed, Lilacs, and SciELO databases until 12 April 2016 were included using the following keywords: "ayahuasca", "DMT", "psilocybin", "LSD", "mescaline" crossed one by one with the terms "mri", "fmri", "pet", "spect", "imaging" and "neuroimaging". Of 279 studies identified, 25 were included. Acute effects included excitation of frontolateral/frontomedial cortex, medial temporal lobe, and occipital cortex, and inhibition of the default mode network. Long-term use was associated with thinning of the posterior cingulate cortex, thickening of the anterior cingulate cortex, and decreased neocortical 5-HT_2A receptor binding. Despite the high methodological heterogeneity and the small sample sizes, the results suggest that hallucinogens increase introspection and positive mood by modulating brain activity in the fronto-temporo-parieto-occipital cortex.

Measuring the subjective: revisiting the psychometric properties of three rating scales that assess the acute effects of hallucinogens

OBJECTIVE

In the present study we explored the psychometric properties of three widely used questionnaires to assess the subjective effects of hallucinogens: the Hallucinogen Rating Scale (HRS), the Mystical Experience Questionnaire (MEQ), and the Addiction Research Center Inventory (ARCI).

METHODS

These three questionnaires were administered to a sample of 158 subjects (100 men) after taking ayahuasca, a hallucinogen whose main active component is N,N-dimethyltryptamine (DMT). A confirmatory factorial study was conducted to check the adjustment of previous data obtained via theoretical proposals. When this was not possible, we used an exploratory factor analysis without restrictions, based on tetrachoric and polychoric matrices and correlations.

RESULTS

Our results sparsely match the theoretical proposals of the authors, perhaps because previous studies have not always employed psychometric methods appropriate to the data obtained. However, these data should be considered preliminary, pending larger samples to confirm or reject the proposed structures obtained.

CONCLUSIONS

It is crucial that instruments of sufficiently precise measurement are utilized to make sense of the information obtained in the study of the subjective effects of psychedelic drugs. Copyright © 2016 John Wiley & Sons, Ltd.

LSD alters eyes-closed functional connectivity within the early visual cortex in a retinotopic fashion

The question of how spatially organized activity in the visual cortex behaves during eyes-closed, lysergic acid diethylamide (LSD)-induced "psychedelic imagery" (e.g., visions of geometric patterns and more complex phenomena) has never been empirically addressed, although it has been proposed that under psychedelics, with eyes-closed, the brain may function "as if" there is visual input when there is none. In this work, resting-state functional connectivity (RSFC) data was analyzed from 10 healthy subjects under the influence of LSD and, separately, placebo. It was suspected that eyes-closed psychedelic imagery might involve transient local retinotopic activation, of the sort typically associated with visual stimulation. To test this, it was hypothesized that, under LSD, patches of the visual cortex with congruent retinotopic representations would show greater RSFC than incongruent patches. Using a retinotopic localizer performed during a nondrug baseline condition, nonadjacent patches of V1 and V3 that represent the vertical or the horizontal meridians of the visual field were identified. Subsequently, RSFC between V1 and V3 was measured with respect to these a priori identified patches. Consistent with our prior hypothesis, the difference between RSFC of patches with congruent retinotopic specificity (horizontal-horizontal and vertical-vertical) and those with incongruent specificity (horizontal-vertical and vertical-horizontal) increased significantly under LSD relative to placebo, suggesting that activity within the visual cortex becomes more dependent on its intrinsic retinotopic organization in the drug condition. This result may indicate that under LSD, with eyes-closed, the early visual system behaves as if it were seeing spatially localized visual inputs. Hum Brain Mapp 37:3031-3040, 2016. © 2016 Wiley Periodicals, Inc.

Treating Addiction: Perspectives from EEG and Imaging Studies on Psychedelics

Despite reports of apparent benefits, social and political pressure beginning in the late 1960s effectively banned scientific inquiry into psychedelic substances. Covert examination of psychedelics persisted through the 1990s; the turn of the century and especially the past 10 years, however, has seen a resurgent interest in psychedelic substances (eg, LSD, ayahuasca, psilocybin). This chapter outlines relevant EEG and brain imaging studies evaluating the effects of psychedelics on the brain. This chapter also reviews evidence of the use of psychedelics as adjunct therapy for a number of psychiatric and addictive disorders. In particular, psychedelics appear to have efficacy in treating depression and alcohol-use disorders.

Antidepressive, anxiolytic, and antiaddictive effects of ayahuasca, psilocybin and lysergic acid diethylamide (LSD): a systematic review of clinical trials published in the last 25 years

To date, pharmacological treatments for mood and anxiety disorders and for drug dependence show limited efficacy, leaving a large number of patients suffering severe and persistent symptoms. Preliminary studies in animals and humans suggest that ayahuasca, psilocybin and lysergic acid diethylamide (LSD) may have antidepressive, anxiolytic, and antiaddictive properties. Thus, we conducted a systematic review of clinical trials published from 1990 until 2015, assessing these therapeutic properties. Electronic searches were performed using the PubMed, LILACS, and SciELO databases. Only clinical trials published in peer-reviewed journals were included. Of these, 151 studies were identified, of which six met the established criteria. Reviewed studies suggest beneficial effects for treatment-resistant depression, anxiety and depression associated with life-threatening diseases, and tobacco and alcohol dependence. All drugs were well tolerated. In conclusion, ayahuasca, psilocybin and LSD may be useful pharmacological tools for the treatment of drug dependence, and anxiety and mood disorders, especially in treatment-resistant patients. These drugs may also be useful pharmacological tools to understand psychiatric disorders and to develop new therapeutic agents. However, all studies reviewed had small sample sizes, and half of them were open-label, proof-of-concept studies. Randomized, double-blind, placebo-controlled studies with more patients are needed to replicate these preliminary findings.

Lysergic acid diethylamide: a drug of 'use'?

Lysergic acid diethylamide (LSD), described as a classical hallucinogen, began its journey from the middle of the last century following an accidental discovery. Since then, it was used as a popular and notorious substance of abuse in various parts of the world. Its beneficial role as an adjunct to psychotherapy was much unknown, until some 'benevolent' experiments were carried out over time to explore some of its potential uses. But, many of its effects were unclear and seemed to be a psychedelic enigma. In this review article, we have described the receptor pharmacology, mechanism of action, effects and adverse effects of LSD on the normal body system. We have also highlighted its addictive potentials and the chances of developing tolerance. We have assimilated some of the interesting therapeutic uses of this drug, such as an antianxiety agent, a creativity enhancer, a suggestibility enhancer, and a performance enhancer. We have also described LSD to be successfully used in drug and alcohol dependence, and as a part of psychedelic peak therapy in terminally ill patients. The relevant chronological history and literature in the light of present knowledge and scenarios have been discussed. Based on available evidence, LSD could be tried therapeutically in certain specific conditions under controlled settings. But as we mention, due to all the safety concerns, the use of this nonaddictive 'entheogen' in actual practice warrants a lot of expertise, caution, cooperation and ethical considerations.

Neural correlates of the LSD experience revealed by multimodal neuroimaging

Lysergic acid diethylamide (LSD) is the prototypical psychedelic drug, but its effects on the human brain have never been studied before with modern neuroimaging. Here, three complementary neuroimaging techniques: arterial spin labeling (ASL), blood oxygen level-dependent (BOLD) measures, and magnetoencephalography (MEG), implemented during resting state conditions, revealed marked changes in brain activity after LSD that correlated strongly with its characteristic psychological effects. Increased visual cortex cerebral blood flow (CBF), decreased visual cortex alpha power, and a greatly expanded primary visual cortex (V1) functional connectivity profile correlated strongly with ratings of visual hallucinations, implying that intrinsic brain activity exerts greater influence on visual processing in the psychedelic state, thereby defining its hallucinatory quality. LSD's marked effects on the visual cortex did not significantly correlate with the drug's other characteristic effects on consciousness, however. Rather, decreased connectivity between the parahippocampus and retrosplenial cortex (RSC) correlated strongly with ratings of "ego-dissolution" and "altered meaning," implying the importance of this particular circuit for the maintenance of "self" or "ego" and its processing of "meaning." Strong relationships were also found between the different imaging metrics, enabling firmer inferences to be made about their functional significance. This uniquely comprehensive examination of the LSD state represents an important advance in scientific research with psychedelic drugs at a time of growing interest in their scientific and therapeutic value. The present results contribute important new insights into the characteristic hallucinatory and consciousness-altering properties of psychedelics that inform on how they can model certain pathological states and potentially treat others.

Psychedelics

Psychedelics (serotonergic hallucinogens) are powerful psychoactive substances that alter perception and mood and affect numerous cognitive processes. They are generally considered physiologically safe and do not lead to dependence or addiction. Their origin predates written history, and they were employed by early cultures in many sociocultural and ritual contexts. After the virtually contemporaneous discovery of (5R,8R)-(+)-lysergic acid-N,N-diethylamide (LSD)-25 and the identification of serotonin in the brain, early research focused intensively on the possibility that LSD and other psychedelics had a serotonergic basis for their action. Today there is a consensus that psychedelics are agonists or partial agonists at brain serotonin 5-hydroxytryptamine 2A receptors, with particular importance on those expressed on apical dendrites of neocortical pyramidal cells in layer V. Several useful rodent models have been developed over the years to help unravel the neurochemical correlates of serotonin 5-hydroxytryptamine 2A receptor activation in the brain, and a variety of imaging techniques have been employed to identify key brain areas that are directly affected by psychedelics. Recent and exciting developments in the field have occurred in clinical research, where several double-blind placebo-controlled phase 2 studies of psilocybin-assisted psychotherapy in patients with cancer-related psychosocial distress have demonstrated unprecedented positive relief of anxiety and depression. Two small pilot studies of psilocybin-assisted psychotherapy also have shown positive benefit in treating both alcohol and nicotine addiction. Recently, blood oxygen level-dependent functional magnetic resonance imaging and magnetoencephalography have been employed for in vivo brain imaging in humans after administration of a psychedelic, and results indicate that intravenously administered psilocybin and LSD produce decreases in oscillatory power in areas of the brain's default mode network.

The Therapeutic Potentials of Ayahuasca: Possible Effects against Various Diseases of Civilization

Ayahuasca is an Amazonian psychoactive brew of two main components. Its active agents are β-carboline and tryptamine derivatives. As a sacrament, ayahuasca is still a central element of many healing ceremonies in the Amazon Basin and its ritual consumption has become common among the mestizo populations of South America. Ayahuasca use amongst the indigenous people of the Amazon is a form of traditional medicine and cultural psychiatry. During the last two decades, the substance has become increasingly known among both scientists and laymen, and currently its use is spreading all over in the Western world. In the present paper we describe the chief characteristics of ayahuasca, discuss important questions raised about its use, and provide an overview of the scientific research supporting its potential therapeutic benefits. A growing number of studies indicate that the psychotherapeutic potential of ayahuasca is based mostly on the strong serotonergic effects, whereas the sigma-1 receptor (Sig-1R) agonist effect of its active ingredient dimethyltryptamine raises the possibility that the ethnomedical observations on the diversity of treated conditions can be scientifically verified. Moreover, in the right therapeutic or ritual setting with proper preparation and mindset of the user, followed by subsequent integration of the experience, ayahuasca has proven effective in the treatment of substance dependence. This article has two important take-home messages: (1) the therapeutic effects of ayahuasca are best understood from a bio-psycho-socio-spiritual model, and (2) on the biological level ayahuasca may act against chronic low grade inflammation and oxidative stress via the Sig-1R which can explain its widespread therapeutic indications.

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes.

Acute Biphasic Effects of Ayahuasca

Ritual use of ayahuasca, an amazonian Amerindian medicine turned sacrament in syncretic religions in Brazil, is rapidly growing around the world. Because of this internationalization, a comprehensive understanding of the pharmacological mechanisms of action of the brew and the neural correlates of the modified states of consciousness it induces is important. Employing a combination of electroencephalogram (EEG) recordings and quantification of ayahuasca's compounds and their metabolites in the systemic circulation we found ayahuasca to induce a biphasic effect in the brain. This effect was composed of reduced power in the alpha band (8-13 Hz) after 50 minutes from ingestion of the brew and increased slow- and fast-gamma power (30-50 and 50-100 Hz, respectively) between 75 and 125 minutes. Alpha power reductions were mostly located at left parieto-occipital cortex, slow-gamma power increase was observed at left centro-parieto-occipital, left fronto-temporal and right frontal cortices while fast-gamma increases were significant at left centro-parieto-occipital, left fronto-temporal, right frontal and right parieto-occipital cortices. These effects were significantly associated with circulating levels of ayahuasca's chemical compounds, mostly N,N-dimethyltryptamine (DMT), harmine, harmaline and tetrahydroharmine and some of their metabolites. An interpretation based on a cognitive and emotional framework relevant to the ritual use of ayahuasca, as well as it's potential therapeutic effects is offered.

Behavioural and neurotoxic effects of ayahuasca infusion (Banisteriopsis caapi and Psychotria viridis) in female Wistar rat

Ayahuasca, a psychoactive beverage used by indigenous and religious groups, is generally prepared by the coction of Psychotria viridis and Banisteriopsis caapi plants containing N,N-dimethyltryptamine (DMT) and β-carboline alkaloids, respectively. To investigate the acute toxicity of ayahuasca, the infusion was administered by gavage to female Wistar rats at doses of 30X and 50X the dose taken during a religious ritual, and the animals observed for 14 days. Behavioural functions were investigated one hour after dosing at 15X and 30X using the open field, elevated plus maze, and forced swimming tests. Neuronal activation (c-fos marked neurons) and toxicity (Fluoro-Jade B and Nissl/Cresyl staining) were investigated in the dorsal raphe nuclei (DRN), amygdaloid nucleus, and hippocampal formation brain areas of rats treated with a 30X ayahuasca dose. The actual lethal oral dose in female Wistar rats could not be determined in this study, but was shown to be higher than the 50X (which corresponds to 15.1mg/kg bw DMT). The ayahuasca and fluoxetine treated groups showed a significant decrease in locomotion in the open field and elevated plus-maze tests compared to controls. In the forced swimming test, ayahuasca treated animals swam more than controls, a behaviour that was not significant in the fluoxetine group. Treated animals showed higher neuronal activation in all brain areas involved in serotoninergic neurotransmission. Although this led to some brain injury, no permanent damage was detected. These results suggest that ayahuasca has antidepressant properties in Wistar female at high doses, an effect that should be further investigated.

Serotonergic psychedelics temporarily modify information transfer in humans

BACKGROUND

Psychedelics induce intense modifications in the sensorium, the sense of "self," and the experience of reality. Despite advances in our understanding of the molecular and cellular level mechanisms of these drugs, knowledge of their actions on global brain dynamics is still incomplete. Recent imaging studies have found changes in functional coupling between frontal and parietal brain structures, suggesting a modification in information flow between brain regions during acute effects.

METHODS

Here we assessed the psychedelic-induced changes in directionality of information flow during the acute effects of a psychedelic in humans. We measured modifications in connectivity of brain oscillations using transfer entropy, a nonlinear measure of directed functional connectivity based on information theory. Ten healthy male volunteers with prior experience with psychedelics participated in 2 experimental sessions. They received a placebo or a dose of ayahuasca, a psychedelic preparation containing the serotonergic 5-HT2A agonist N,N-dimethyltryptamine.

RESULTS

The analysis showed significant changes in the coupling of brain oscillations between anterior and posterior recording sites. Transfer entropy analysis showed that frontal sources decreased their influence over central, parietal, and occipital sites. Conversely, sources in posterior locations increased their influence over signals measured at anterior locations. Exploratory correlations found that anterior-to-posterior transfer entropy decreases were correlated with the intensity of subjective effects, while the imbalance between anterior-to-posterior and posterior-to-anterior transfer entropy correlated with the degree of incapacitation experienced.

CONCLUSIONS

These results suggest that psychedelics induce a temporary disruption of neural hierarchies by reducing top-down control and increasing bottom-up information transfer in the human brain.

The psychedelic state induced by ayahuasca modulates the activity and connectivity of the default mode network

The experiences induced by psychedelics share a wide variety of subjective features, related to the complex changes in perception and cognition induced by this class of drugs. A remarkable increase in introspection is at the core of these altered states of consciousness. Self-oriented mental activity has been consistently linked to the Default Mode Network (DMN), a set of brain regions more active during rest than during the execution of a goal-directed task. Here we used fMRI technique to inspect the DMN during the psychedelic state induced by Ayahuasca in ten experienced subjects. Ayahuasca is a potion traditionally used by Amazonian Amerindians composed by a mixture of compounds that increase monoaminergic transmission. In particular, we examined whether Ayahuasca changes the activity and connectivity of the DMN and the connection between the DMN and the task-positive network (TPN). Ayahuasca caused a significant decrease in activity through most parts of the DMN, including its most consistent hubs: the Posterior Cingulate Cortex (PCC)/Precuneus and the medial Prefrontal Cortex (mPFC). Functional connectivity within the PCC/Precuneus decreased after Ayahuasca intake. No significant change was observed in the DMN-TPN orthogonality. Altogether, our results support the notion that the altered state of consciousness induced by Ayahuasca, like those induced by psilocybin (another serotonergic psychedelic), meditation and sleep, is linked to the modulation of the activity and the connectivity of the DMN.

LSD enhances suggestibility in healthy volunteers

RATIONALE

Lysergic acid diethylamide (LSD) has a history of use as a psychotherapeutic aid in the treatment of mood disorders and addiction, and it was also explored as an enhancer of mind control.

OBJECTIVES

The present study sought to test the effect of LSD on suggestibility in a modern research study.

METHODS

Ten healthy volunteers were administered with intravenous (i.v.) LSD (40-80 μg) in a within-subject placebo-controlled design. Suggestibility and cued mental imagery were assessed using the Creative Imagination Scale (CIS) and a mental imagery test (MIT). CIS and MIT items were split into two versions (A and B), balanced for 'efficacy' (i.e. A ≈ B) and counterbalanced across conditions (i.e. 50 % completed version 'A' under LSD). The MIT and CIS were issued 110 and 140 min, respectively, post-infusion, corresponding with the peak drug effects.

RESULTS

Volunteers gave significantly higher ratings for the CIS (p = 0.018), but not the MIT (p = 0.11), after LSD than placebo. The magnitude of suggestibility enhancement under LSD was positively correlated with trait conscientiousness measured at baseline (p = 0.0005).

CONCLUSIONS

These results imply that the influence of suggestion is enhanced by LSD. Enhanced suggestibility under LSD may have implications for its use as an adjunct to psychotherapy, where suggestibility plays a major role. That cued imagery was unaffected by LSD implies that suggestions must be of a sufficient duration and level of detail to be enhanced by the drug. The results also imply that individuals with high trait conscientiousness are especially sensitive to the suggestibility-enhancing effects of LSD.

Brain complex network analysis by means of resting state fMRI and graph analysis: will it be helpful in clinical epilepsy?

Functional magnetic resonance imaging (fMRI) has just completed 20 years of existence. It currently serves as a research tool in a broad range of human brain studies in normal and pathological conditions, as is the case of epilepsy. To date, most fMRI studies aimed at characterizing brain activity in response to various active paradigms. More recently, a number of strategies have been used to characterize the low-frequency oscillations of the ongoing fMRI signals when individuals are at rest. These datasets have been largely analyzed in the context of functional connectivity, which inspects the covariance of fMRI signals from different areas of the brain. In addition, resting state fMRI is progressively being used to evaluate complex network features of the brain. These strategies have been applied to a number of different problems in neuroscience, which include diseases such as Alzheimer's, schizophrenia, and epilepsy. Hence, we herein aimed at introducing the subject of complex network and how to use it for the analysis of fMRI data. This appears to be a promising strategy to be used in clinical epilepsy. Therefore, we also review the recent literature that has applied these ideas to the analysis of fMRI data in patients with epilepsy.

Safety and efficacy of lysergic acid diethylamide-assisted psychotherapy for anxiety associated with life-threatening diseases

A double-blind, randomized, active placebo-controlled pilot study was conducted to examine safety and efficacy of lysergic acid diethylamide (LSD)-assisted psychotherapy in 12 patients with anxiety associated with life-threatening diseases. Treatment included drug-free psychotherapy sessions supplemented by two LSD-assisted psychotherapy sessions 2 to 3 weeks apart. The participants received either 200 μg of LSD (n = 8) or 20 μg of LSD with an open-label crossover to 200 μg of LSD after the initial blinded treatment was unmasked (n = 4). At the 2-month follow-up, positive trends were found via the State-Trait Anxiety Inventory (STAI) in reductions in trait anxiety (p = 0.033) with an effect size of 1.1, and state anxiety was significantly reduced (p = 0.021) with an effect size of 1.2, with no acute or chronic adverse effects persisting beyond 1 day after treatment or treatment-related serious adverse events. STAI reductions were sustained for 12 months. These results indicate that when administered safely in a methodologically rigorous medically supervised psychotherapeutic setting, LSD can reduce anxiety, suggesting that larger controlled studies are warranted.

The effects of psilocybin and MDMA on between-network resting state functional connectivity in healthy volunteers

Perturbing a system and observing the consequences is a classic scientific strategy for understanding a phenomenon. Psychedelic drugs perturb consciousness in a marked and novel way and thus are powerful tools for studying its mechanisms. In the present analysis, we measured changes in resting-state functional connectivity (RSFC) between a standard template of different independent components analysis (ICA)-derived resting state networks (RSNs) under the influence of two different psychoactive drugs, the stimulant/psychedelic hybrid, MDMA, and the classic psychedelic, psilocybin. Both were given in placebo-controlled designs and produced marked subjective effects, although reports of more profound changes in consciousness were given after psilocybin. Between-network RSFC was generally increased under psilocybin, implying that networks become less differentiated from each other in the psychedelic state. Decreased RSFC between visual and sensorimotor RSNs was also observed. MDMA had a notably less marked effect on between-network RSFC, implying that the extensive changes observed under psilocybin may be exclusive to classic psychedelic drugs and related to their especially profound effects on consciousness. The novel analytical approach applied here may be applied to other altered states of consciousness to improve our characterization of different conscious states and ultimately advance our understanding of the brain mechanisms underlying them.

Zkušenost s halucinogenní rostlinou ayahuasca v kontextu šamanského rituálu

Výzkum je zaměřen na osoby, které se vydaly do amazonských pralesů užívat přírodní halucinogen ayahuasku v kontextu „šamanského“ rituálu. Tento jev popisovaný antropology od 70. let. 20. stol. jako tzv. „šamanský turismus“ je stále aktuálnější především mezi obyvateli zemí Evropy a USA. Našim cílem bylo zmapovat, jakým způsobem ayahuaskový šamanský turismus probíhá – motivaci osob, které tento druh zkušenosti vyhledávají, přínosy, rizika a následnou integraci této neobvyklé zkušenosti. Sběr dat probíhal v ČR a v peruánské Amazonii na místech známých jako centra ayahuaskového šamanského turismu (města Tarapoto a Iquitos) formou polostrukturovaných rozhovorů, screeningových dotazníků a zúčastněného pozorování. Získali jsme výpovědi 77 osob, které mají zkušenost s ayahuaskou v kontextu rituálu v pralesech Jižní Ameriky, především pak v Peru.  Z rozhovorů vyplývá, že hlavní motivací pro užití ayahuasky byla zvědavost a touha po dobrodružství, léčba psychických problémů, potřeba sebepoznání, zájem o psychedelickou medicínu a terapii, spirituální rozvoj a nalezení životního směru. Přínosy byly vnímány především ve vztahu k sobě ve smyslu sebepoznání a sebepřijetí a v rovině duchovní, psychické, somatické a vztahové. Často byl zmiňován životní nadhled, spokojenost a ujasnění si životního směřování. Jako rizika byla uváděna nedůvěra v šamana či organizátora, zkreslení jimi poskytnutých informací a vystavení rizikové situaci. Většina respondentů považuje samotnou zkušenost za bezpečnou a náročné prožitky během sezení s ayahuaskou byly následně hodnoceny kladně ve smyslu zkvalitnění života. Výzkum byl hrazen ze dvou výzkumných projektů UP: IGA (SPP:432101021) a FPVČ (SPP: 452100061).

Ayahuasca and cancer treatment

OBJECTIVES

Comprehensively review the evidence regarding the use of ayahuasca, an Amerindian medicine traditionally used to treat many different illnesses and diseases, to treat some types of cancer.

METHODS

An in-depth review of the literature was conducted using PubMed, books, institutional magazines, conferences and online texts in nonprofessional sources regarding the biomedical knowledge about ayahuasca in general with a specific focus in its possible relations to the treatment of cancer.

RESULTS

At least nine case reports regarding the use of ayahuasca in the treatment of prostate, brain, ovarian, uterine, stomach, breast, and colon cancers were found. Several of these were considered improvements, one case was considered worse, and one case was rated as difficult to evaluate. A theoretical model is presented which explains these effects at the cellular, molecular, and psychosocial levels. Particular attention is given to ayahuasca's pharmacological effects through the activity of N,N-dimethyltryptamine at intracellular sigma-1 receptors. The effects of other components of ayahuasca, such as harmine, tetrahydroharmine, and harmaline, are also considered.

CONCLUSION

The proposed model, based on the molecular and cellular biology of ayahuasca's known active components and the available clinical reports, suggests that these accounts may have consistent biological underpinnings. Further study of ayahuasca's possible antitumor effects is important because cancer patients continue to seek out this traditional medicine. Consequently, based on the social and anthropological observations of the use of this brew, suggestions are provided for further research into the safety and efficacy of ayahuasca as a possible medicinal aid in the treatment of cancer.

Personality, psychopathology, life attitudes and neuropsychological performance among ritual users of Ayahuasca: a longitudinal study

Ayahuasca is an Amazonian psychoactive plant beverage containing the serotonergic 5-HT_2A agonist N,N-dimethyltryptamine (DMT) and monoamine oxidase-inhibiting alkaloids (harmine, harmaline and tetrahydroharmine) that render it orally active. Ayahuasca ingestion is a central feature in several Brazilian syncretic churches that have expanded their activities to urban Brazil, Europe and North America. Members of these groups typically ingest ayahuasca at least twice per month. Prior research has shown that acute ayahuasca increases blood flow in prefrontal and temporal brain regions and that it elicits intense modifications in thought processes, perception and emotion. However, regular ayahuasca use does not seem to induce the pattern of addiction-related problems that characterize drugs of abuse. To study the impact of repeated ayahuasca use on general psychological well-being, mental health and cognition, here we assessed personality, psychopathology, life attitudes and neuropsychological performance in regular ayahuasca users (n = 127) and controls (n = 115) at baseline and 1 year later. Controls were actively participating in non-ayahuasca religions. Users showed higher Reward Dependence and Self-Transcendence and lower Harm Avoidance and Self-Directedness. They scored significantly lower on all psychopathology measures, showed better performance on the Stroop test, the Wisconsin Card Sorting Test and the Letter-Number Sequencing task from the WAIS-III, and better scores on the Frontal Systems Behavior Scale. Analysis of life attitudes showed higher scores on the Spiritual Orientation Inventory, the Purpose in Life Test and the Psychosocial Well-Being test. Despite the lower number of participants available at follow-up, overall differences with controls were maintained one year later. In conclusion, we found no evidence of psychological maladjustment, mental health deterioration or cognitive impairment in the ayahuasca-using group.

Genuine and drug-induced synesthesia: a comparison

Despite some principal similarities, there is no systematic comparison between the different types of synesthesia (genuine, acquired and drug-induced). This comprehensive review compares the three principal types of synesthesia and focuses on their phenomenological features and their relation to different etiological models. Implications of this comparison for the validity of the different etiological models are discussed. Comparison of the three forms of synesthesia show many more differences than similarities. This is in contrast to their representation in the literature, where they are discussed in many respects as being virtually similar. Noteworthy is the much broader spectrum and intensity with the typical drug-induced synesthesias compared to genuine and acquired synesthesias. A major implication of the phenomenological comparison in regard to the etiological models is that genuine and acquired synesthesias point to morphological substrates, while drug-induced synesthesia appears to be based on functional changes of brain activity.