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R. dos Santos

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

October 31, 2016 / Ayahuasca, DMT, LSD, Mescaline / Cacti, Mushrooms / Psilocybin, Neuroscience, Papers, Publications / By / , , ,

Abstract

Serotonergic hallucinogens produce alterations of perceptions, mood, and cognition, and have anxiolytic, antidepressant, and antiaddictive properties. These drugs act as agonists of frontocortical 5-HT2A 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-HT2A 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.

dos Santos, R. G., Osório, F. L., Crippa, J. A. S., & Hallak, J. E. (2016). Classical hallucinogens and neuroimaging: A systematic review of human studies: Hallucinogens and neuroimaging. Neuroscience & Biobehavioral Reviews, 71, 715-728. 10.1016/j.neubiorev.2016.10.026
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The current state of research on ayahuasca: A systematic review of human studies assessing psychiatric symptoms, neuropsychological functioning, and neuroimaging

June 10, 2016 / Ayahuasca, Papers, Psychology, Publications, Substance Use Disorder / By / , , ,

Abstract

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.

dos Santos, R. G., Balthazar, F. M., Bouso, J. C., & Hallak, J. E. (2016). The current state of research on ayahuasca: A systematic review of human studies assessing psychiatric symptoms, neuropsychological functioning, and neuroimaging. Journal of Psychopharmacology, 0269881116652578.

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Effects of Ayahuasca and its Alkaloids on Drug Dependence: A Systematic Literature Review of Quantitative Studies in Animals and Humans

May 26, 2016 / Ayahuasca, Neuroscience, Papers, Psychology, Publications, Substance Use Disorder / By / , , , , ,

Abstract

Recently, the anti-addictive potential of ayahuasca, a dimethyltryptamine(DMT)- and β-carboline-rich hallucinogenic beverage traditionally used by indigenous groups of the Northwest Amazon and currently by syncretic churches worldwide, has received increased attention. To better evaluate this topic, we performed a systematic literature review using the PubMed database to find quantitative studies (using statistical analysis) that assessed the effects of ayahuasca or its components in drug-related symptoms or disorders. We found five animal studies (using harmaline, harmine, or ayahuasca) and five observational studies of regular ayahuasca consumers. All animal studies showed improvement of biochemical or behavioral parameters related to drug-induced disorders. Of the five human studies, four reported significant reductions of dependence symptoms or substance use, while one did not report significant results. The mechanisms responsible for the anti-addictive properties of ayahuasca and its alkaloids are not clarified, apparently involving both peripheral MAO-A inhibition by the β-carbolines and central agonism of DMT at 5-HT2A receptors expressed in brain regions related to the regulation of mood and emotions. Although results are promising, controlled studies are needed to replicate these preliminary findings.

Nunes, A. A., dos Santos, R. G., Osório, F. L., Sanches, R. F., Crippa, J. A. S., & Hallak, J. E. (2016). Effects of Ayahuasca and its Alkaloids on Drug Dependence: A Systematic Literature Review of Quantitative Studies in Animals and Humans. Journal of psychoactive drugs, 1-11. http://dx.doi.org/10.1080/02791072.2016.1188225

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

March 24, 2016 / Anxiety Disorders / PTSD, Ayahuasca, Depressive Disorders, Papers, Psychology, Publications / By / , , ,

Abstract

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.

dos Santos, R. G., Osório, F. L., Crippa, J. A. S., & Hallak, J. E. (2016). Antidepressive and anxiolytic effects of ayahuasca: a systematic literature review of animal and human studies. Revista Brasileira de Psiquiatria, 38(1), 65-72. http://dx.doi.org/10.1590/1516-4446-2015-1701
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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

March 18, 2016 / Anxiety Disorders / PTSD, Ayahuasca, Depressive Disorders, LSD, Mushrooms / Psilocybin, Papers, Psychology, Publications, Substance Use Disorder / By / , , , , ,

Abstract

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.

dos Santos, R. G., Osório, F. L., Crippa, J. A. S., Riba, J., Zuardi, A. W., & Hallak, J. E. (2016). 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. Therapeutic Advances in Psychopharmacology, 2045125316638008.

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Antidepressant Effects of a Single Dose of Ayahuasca in Patients With Recurrent Depression: A SPECT Study

December 8, 2015 / Ayahuasca, Depressive Disorders, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Ayahuasca is an Amazonian botanical hallucinogenic brew which contains dimethyltryptamine, a 5-HT2A receptor agonist, and harmine, a monoamine-oxidase A inhibitor. Our group recently reported that ayahuasca administration was associated with fast-acting antidepressive effects in 6 depressive patients. The objective of the present work was to assess the antidepressive potentials of ayahuasca in a bigger sample and to investigate its effects on regional cerebral blood flow. In an open-label trial conducted in an inpatient psychiatric unit, 17 patients with recurrent depression received an oral dose of ayahuasca (2.2 mL/kg) and were evaluated with the Hamilton Rating Scale for Depression, the Montgomery-Asberg Depression Rating Scale, the Brief Psychiatric Rating Scale, the Young Mania Rating Scale, and the Clinician Administered Dissociative States Scale during acute ayahuasca effects and 1, 7, 14, and 21 days after drug intake. Blood perfusion was assessed eight hours after drug administration by means of single photon emission tomography. Ayahuasca administration was associated with increased psychoactivity (Clinician Administered Dissociative States Scale) and significant score decreases in depression-related scales (Hamilton Rating Scale for Depression, Montgomery-Asberg Depression Rating Scale, Brief Psychiatric Rating Scale) from 80 minutes to day 21. Increased blood perfusion in the left nucleus accumbens, right insula and left subgenual area, brain regions implicated in the regulation of mood and emotions, were observed after ayahuasca intake. Ayahuasca was well tolerated. Vomiting was the only adverse effect recorded, being reported by 47% of the volunteers. Our results suggest that ayahuasca may have fast-acting and sustained antidepressive properties. These results should be replicated in randomized, double-blind, placebo-controlled trials.
Sanches, R. F., de Lima, O. F., Dos Santos, R. G., Macedo, L. R., Maia-de-Oliveira, J. P., Wichert-Ana, L., … & Hallak, J. E. (2015). Antidepressant Effects of a Single Dose of Ayahuasca in Patients With Recurrent Depression: A SPECT Study. Journal of clinical psychopharmacology. http://dx.doi.org/10.1097/JCP.0000000000000436
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Ayahuasca Alters Structural Parameters of the Rat Aorta

July 1, 2015 / Ayahuasca, Papers, Psychiatry & Medicine, Publications / By / , , , , , ,

Abstract

Ayahuasca is a hallucinogenic brew traditionally used by Northwestern Amazonian indigenous groups for therapeutic purposes. It is prepared by the decoction of Banisteriopsis caapi with the leaves of Psychotria viridis. Banisteriopsis caapi contains β-carbolines that are inhibitors of monoamine oxidase and P. viris is rich in dimethyltryptamine, a 5-HT1A/2A/2C agonist. Acute ayahuasca administration produces moderate cardiovascular effects in healthy volunteers, but information regarding long-term use is lacking. This study investigated the effects of ayahuasca (2–4 mL/kg) in the rat aorta after acute and chronic (14 days) administration. Ayahuasca caused flattening and stretching of vascular smooth muscle cells and changes in the arrangement and distribution of collagen and elastic fibers. Chronic treatment with the higher dose significantly increased media thickness and the ratio of media thickness to lumen diameter. More research is needed on the cardiovascular function of long-term ayahuasca consumers.

Pitol, D. L., Siéssere, S., Dos Santos, R. G., Nunes, M. R. M., Cecilio, H. J., Scalize, P. H., … & Hallak, R. S. (2015). Ayahuasca alters structural parameters of the rat aorta. Journal of cardiovascular pharmacology. http://dx.doi.org/10.1097/FJC.0000000000000243
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Antidepressant effects of a single dose of ayahuasca in patients with recurrent depression: a preliminary report

March 20, 2015 / Anxiety Disorders / PTSD, Ayahuasca, Depressive Disorders, Papers, Psychology, Publications / By / , , , , , ,

Abstract

Objectives

Ayahuasca (AYA), a natural psychedelic brew prepared from Amazonian plants and rich in dimethyltryptamine (DMT) and harmine, causes effects of subjective well-being and may therefore have antidepressant actions. This study sought to evaluate the effects of a single dose of AYA in six volunteers with a current depressive episode.

Methods:

Open-label trial conducted in an inpatient psychiatric unit.

Results:

Statistically significant reductions of up to 82% in depressive scores were observed between baseline and 1, 7, and 21 days after AYA administration, as measured on the Hamilton Rating Scale for Depression (HAM-D), the Montgomery-Åsberg Depression Rating Scale (MADRS), and the Anxious-Depression subscale of the Brief Psychiatric Rating Scale (BPRS). AYA administration resulted in nonsignificant changes in Young Mania Rating Scale (YMRS) scores and in the thinking disorder subscale of the BPRS, suggesting that AYA does not induce episodes of mania and/or hypomania in patients with mood disorders and that modifications in thought content, which could indicate psychedelic effects, are not essential for mood improvement.<

Conclusions:

These results suggest that AYA has fast-acting anxiolytic and antidepressant effects in patients with a depressive disorder.

Osório, F. D. L., Sanches, R. F., Macedo, L. R., Dos Santos, R. G., Maia-de-Oliveira, J. P., Wichert-Ana, L., … & Hallak, J. E. (2015). Antidepressant effects of a single dose of ayahuasca in patients with recurrent depression: a preliminary report. Revista Brasileira de Psiquiatria, 37(1), 13-20. http://dx.doi.org/10.1590/1516-4446-2014-1496
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Salvinorin A and Related Compounds as Therapeutic Drugs for Psychostimulant-Related Disorders

January 28, 2015 / Papers, Psychology, Publications, Salvia / Salvinorin A, Substance Use Disorder / By / , , ,

Abstract

Pharmacological treatments are available for alcohol, nicotine, and opioid dependence, and several drugs for cannabis-related disorders are currently under investigation. On the other hand, psychostimulant abuse and dependence lacks pharmacological treatment. Mesolimbic dopaminergic neurons mediate the motivation to use drugs and drug-induced euphoria, and psychostimulants (cocaine, amphetamine, and methamphetamine) produce their effects in these neurons, which may be modulated by the opioid system. Salvinorin A is a κ-opioid receptor agonist extracted from Salvia divinorum, a hallucinogenic plant used in magico-ritual contexts by Mazateca Indians in México. Salvinorin A and its analogues have demonstrated anti-addiction effects in animal models using psychostimulants by attenuating dopamine release, sensitization, and other neurochemical and behavioral alterations associated with acute and prolonged administration of these drugs. The objective of the present article is to present an overview of the preclinical evidence suggesting anti-addictive effects of salvinorin A and its analogues.

dos Santos, R. G., Crippa, J. A., Machado-de-Sousa, J. P., & Hallak, J. E. (2015). Salvinorin A and Related Compounds as Therapeutic Drugs for Psychostimulant-Related Disorders. Current Drug Abuse Reviews, 7(2), 128-132. https://dx.doi.org/10.2174/1874473708666150107122741

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Immunological Effects of Ayahuasca in Humans

November 3, 2014 / Ayahuasca, DMT, Papers, Psychiatry & Medicine, Publications / By /

Abstract

Ayahuasca is a botanical hallucinogen traditionally used by indigenous groups of the northwest Amazon. In the last decade, the use of ayahuasca has spread from Brazil, Colombia, Ecuador, and Peru to the U.S., Europe, Asia, and Africa. Despite acute and long-term evidence of good tolerability and safety for ayahuasca administered in the laboratory or ritually consumed in religious contexts, little is known about the immunological impact of ayahuasca on humans. Since ayahuasca is used by an increasing number of consumers, and considering its therapeutic potential, more information is needed regarding ayahuasca potential risks. This article presents a brief overview of the available data regarding the immunological impact of ayahuasca in humans.

dos Santos, R. G. (2014). Immunological Effects of Ayahuasca in Humans. Journal of psychoactive drugs, 46(5), 383-388. https://dx.doi.org/10.1080/02791072.2014.960113

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