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Rafael G. Dos Santos

Rafael G. Dos Santos
Ribeirão Preto Medical School, University of São Paulo, Brazil · Department of Neuroscience and Behavior

PhD

About

133
Publications
107,310
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3,222
Citations
Introduction
He holds a bachelor's degree in Biology from the Centro Universitário de Brasília (2005), a master's degree in Psychology from the Universidade de Brasília (2006), a Ph.D. in Pharmacology from the Universitat Autònoma de Barcelona, Spain (2012), and a Postdoctoral training in the University of São Paulo (2018). He currently performs postdoctoral studies in the Postgraduate Program in Mental Health of the Ribeirão Preto Medical School (FMRP-USP), where he also acts as accredited advisor.
Additional affiliations
October 2006 - February 2012
Autonomous University of Barcelona
Position
  • PhD Student
January 2005 - October 2006
University of Brasília
Position
  • Master's Student
Education
October 2006 - February 2012
Autonomous University of Barcelona
Field of study
  • Psychopharmacology
January 2005 - October 2006
University of Brasília
Field of study
  • Psychopharmacology

Publications

Publications (133)
Article
Full-text available
Ayahuasca is a hallucinogenic/psychedelic traditionally used for ritual and therapeutic purposes. One such therapeutic use is related to Substance Use Disorders (SUDs). A previous systematic review of preclinical and human studies published until 2016 suggested that ayahuasca and its alkaloids have therapeutic effects in the treatment of SUDs. To c...
Article
Full-text available
Context Ibogaine is the main alkaloid of the African shrub Tabernanthe iboga. It produces hallucinogenic and psychostimulant effects, but it is currently known for the anti-addictive properties. Despite the potential therapeutic effects, several cases of fatalities and serious adverse events related to ibogaine/noribogaine use can be found in the l...
Article
Ayahuasca is a plant decoction in traditional Amazonian medicine. Its ritual use has been internationalized, leading to policy challenges that countries should address. This study evaluates the impact of regular ayahuasca ceremony participation on health by assessing the health status of 377 participants in ayahuasca ceremonies in the Netherlands u...
Article
Introduction: A limited number of preliminary open-label (n = 3) and placebo-controlled clinical trials (n = 5) have suggested psilocybin and LSD as potential rapid antidepressants. In this context, there is a growing need to verify and document their safety and tolerability as therapeutic agents, discuss the challenges associated with their admin...
Article
Introduction: Ayahuasca is a psychedelic brew originally used by indigenous tribes from the Amazon Rainforest and in religious rituals. Pre-clinical and observational studies have demonstrated its possible potential as an antidepressant, and open and placebo-controlled clinical trials corroborated these results. For it to become an approved treatm...
Article
Objective: To assess endocannabinoid (anandamide, AEA; 2-arachidonoylglycerol, 2-AG) plasma levels in healthy volunteers and in volunteers with social anxiety disorder (SAD) after a single oral dose of ayahuasca or placebo. Methods: Post hoc analysis of endocannabinoid plasma levels (baseline, 90 and 240 min after drug intake) from two parallel-...
Article
Importance: Owing to its anti-inflammatory properties and antiviral "in vitro" effect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), cannabidiol (CBD) has been proposed as a potential treatment for coronavirus disease 2019 (COVID-19). Objective: To investigate the safety and efficacy of CBD for treating patients with mild to...
Article
Full-text available
Rationale: Previous studies with the serotonergic hallucinogens LSD and psilocybin showed that these drugs induced changes in personality traits, such as increases in Openness. However, results are inconsistent, and the effects of ayahuasca on personality were never investigated in a controlled trial. Objectives: To assess the effects of ayahuasca...
Article
Background: Ayahuasca is a classic hallucinogen with anxiolytic and antidepressive properties. Anecdotal evidence also suggests that it improves performance (eg, singing, speech). This controlled trial assessed the effects of ayahuasca on speech performance and anxiety in individuals with social anxiety disorder. Methods: Seventeen volunteers wi...
Article
Full-text available
Background: One of the main public health strategies adopted at the beginning of the COVID-19 pandemic consisted of implementing strict lockdowns to stop the transmission of the virus. Despite being an effective measure, the confinement and the associated social isolation create a stressful, potentially lengthy situations that has been proven to ha...
Chapter
The volume of research on the therapeutic use of psychedelic drugs has been increasing during the last decades. Partly because of the need of innovative treatments in psychiatry, several studies have assessed the safety and efficacy of drugs like psilocybin or ayahuasca for a wide range of mental disorders, including major depression. The first sec...
Article
Background: The recognition of emotions in facial expressions (REFE) is a core aspect of social cognition. Previous studies with the serotonergic hallucinogens lysergic acid diethylamide and psilocybin showed that these drugs reduced the recognition of negative (fear) faces in healthy volunteers. This trial assessed the acute and prolonged effects...
Article
Major depressive disorder (MDD) is among the most prevalent mental health disorders worldwide, and it is associated with a reduced quality of life and enormous costs to health care systems. Available drug treatments show low-to-moderate response in most patients, with almost a third of patients being non-responders (treatment-resistant). Furthermor...
Article
Full-text available
Psychedelics or serotonergic hallucinogens are a group of substances that share the agonism of serotonergic 5-HT 2A receptors as their main mechanism of action. Its main effects include changes in perception, cognitive process, and mood. Despite being used for centuries by different cultures in ritual contexts, these substances have currently arous...
Article
Background: In recent decades, ritualistic use of ayahuasca has spread throughout the world. Retrospective studies have suggested a good psychological safety profile, but prospective studies involving ceremony ayahuasca-naive participants are lacking. Methods: We conducted the study using a subsample from a previous study, for which first-time c...
Article
Full-text available
Rationale Suicidality is a major public health concern with limited treatment options. Accordingly, there is a need for innovative interventions for suicidality. Preliminary evidence indicates that treatment with the psychedelic ayahuasca may lead to decreases in depressive symptoms among individuals with major depressive disorder (MDD). However, t...
Chapter
Cannabis can synthetize more than 400 compounds, including terpenes, flavonoids, and more than 100 phytocannabinoids. The main phytocannabinoids are Δ-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Cannabis-based products are used as medicines in several countries. In this text, we present an overview of the main neurochemical mechanisms of ac...
Article
The present study describes the development of a novel solvent-free vortex-assisted dispersive liquid-liquid microextraction alternative based on a natural essential oil as extracting solvent (VA-EO-DLLME) for the determination of N,N-dimethyltryptamine (DMT), harmine (HRM), harmaline (HRL) and tetrahydroarmine (THH) (compounds found in the ayahuas...
Article
Full-text available
Objective: Whether for spiritual, recreational, or potential therapeutic use, interest in ayahuasca has grown remarkably. Ayahuasca’s main active substances are N,N‐dimethyltryptamine and certain monoamine oxidase inhibitor β-carbolines. Possible drug interactions are a major concern, and research is lacking in this area. The objective of this stud...
Article
Research with psychedelic drugs has mainly focused on isolated compounds. However, this approach is challenged by the "polypharmacology" paradigm. In this Viewpoint, we suggest that we may be missing something if we do not use the whole product in the case of ayahuasca or Psilocybe mushrooms. After describing how research on psychedelic drugs can b...
Article
Full-text available
Background Posttraumatic stress disorder consists of a set of symptoms that occurs in response to one or more traumatic events and can occur in postpartum, from traumatic situations related to the birth or to the baby’s health in the first days of life. It is important tracking the presence of birth trauma, but there is not available instruments in...
Article
Full-text available
Introduction The Internet Gaming Disorder Scale – Short Form (IGDS9-SF) assesses the severity, harmful effects and/or consequences of excessive online and offline gaming. Its conciseness and theoretical foundations on current diagnostic criteria of gaming disorders make it a useful resource for clinical and screening settings. Objective To describ...
Article
Tetrahydrocannabinol (THC) and cannabidiol (CBD) are phytocannabinoids being linked with modulation of anxiety and depression. The recognition of emotions in facial expressions (REFE) is impaired in these disorders. Both drugs could modulate anxiety and mood by interfering with REFE. Thus, a systematic review of controlled trials assessing the effe...
Article
Full-text available
Ayahuasca tea is a hallucinogenic beverage used for religious purposes in Brazil and many other countries that has therapeutic potential in the treatment of some mental health disorders. In the context of psychedelic research, quantification of the tea's main alkaloids prior to its administration in animal or human studies is essential. For this re...
Article
Full-text available
Background: Therapeutic properties of ibogaine in the treatment of addiction are attracting both clinicians and patients to its use. Since ibogaine is not an authorized medicine, the quality of these products is not always known, increasing the probability of adverse reactions. Objective: This study collects different types of iboga-derived samples...
Article
Introduction: Recent trials using cannabidiol (CBD) have shown that most acute and prolonged adverse effects of CBD are mild to moderate, with rare serious adverse effects (SAEs). This review focused on analyzing SAEs of CBD and their possible relation to drug-drug interactions. Areas covered: We systematically analyzed the SAEs reported in random...
Article
Full-text available
Ayahuasca is a hallucinogenic decoction used as a traditional medicine in several Amazonian regions. The ritualistic use of ayahuasca has spread throughout many countries, making it necessary to study its risks and benefits. Two sub-studies were designed for this investigation. In sub-study 1, a psychiatric interview and a battery of questionnaires...
Article
The number of patients using cannabis for therapeutic purposes is growing worldwide. While research regarding the treatment of certain diseases/disorders with cannabis and cannabinoids is also expanding, only a few longitudinal studies have assessed the mid-term impacts of medical cannabis use on psychological variables and quality of life (QoL). T...
Article
Serotoninergic hallucinogens include drugs such as lysergic acid diethylamide (LSD), dimethyltryptamine (DMT) and psilocybin. Recent trials with single/few doses of these compounds show that they induce rapid and sustained antidepressive, anxiolytic, and antiaddictive effects. These effects are also observed in religious groups using the DMT-contai...
Article
Full-text available
In a recent issue of the BMC Psychiatry, the evidence of effectiveness of treatments for psychiatric conditions in end-stage cancer patients was reviewed (Johnson, 2018). The review was comprehensive, and included traditional and non-traditional/alternative treatments, including herbal medicines and spirituality. However, evidence showing that clas...
Article
Social anxiety disorder (SAD), or social phobia, is one of the most common types of anxiety disorder, with a lifetime prevalence that can reach 15%. Pharmacological treatments for SAD have moderate efficacy and are associated with significant adverse reactions. Therefore, recent studies have focused on searching for new treatments for this disorder...
Article
Aim: The Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders is one of the most used diagnostic instruments in clinical research worldwide. The current version of the instrument (SCID-5-CV) has not yet been assessed in respect to its psychometric qualities. We aim to assess the clinical validity and differen...
Article
Ayahuasca is a botanical hallucinogenic preparation traditionally used for ritual and therapeutic purposes by native populations of the Northwestern Amazon. In the last decades, ayahuasca use has spread to Europe, the United States, Asia, and Africa, and interest in the possible therapeutic uses of ayahuasca for treating anxiety and mood disorder a...
Article
Full-text available
Objective: To describe the process of cross-cultural adaptation of the Personality Inventory for DSM-5 (PID-5) to the Brazilian context. Methods: Cross-cultural adaptation involved the steps of independent translation of the instrument, synthesis version, and back-translation. Analysis of content validity was conducted by a multidisciplinary exp...
Article
Full-text available
Background Recognition of emotions in facial expressions (REFE) is a key aspect of social cognition. Anxiety and mood disorders are associated with deficits in REFE, and anxiolytics and antidepressants reverse these deficits. Recent studies have shown that serotonergic hallucinogens (i.e. ayahuasca, dimethyltryptamine, psilocybin, lysergic acid die...
Article
Fundamento: A doença de Parkinson (DP) é um transtorno neurodegenerativo crônico caracterizado por sintomas motores (bradicinesia, tremores, rigidez) e não motores (transtornos psicóticos, do humor e do sono). Os tratamentos farmacológicos disponíveis não são eficazes para uma parcela significativa dos pacientes. Pesquisas recentes sugerem que o fi...
Article
Full-text available
Fundamento: A doença de Parkinson (DP) é um transtorno neurodegenerativo crônico caracterizado por sintomas motores (bradicinesia, tremores, rigidez) e não motores (transtornos psicóticos, do humor e do sono). Os tratamentos farmacológicos disponíveis não são eficazes para uma parcela significativa dos pacientes. Pesquisas recentes sugerem que o fi...
Article
Full-text available
Background and aims: The psychoactive capacity of the alkaloid N,N-dimethyltryptamine (DMT) has been known for decades, and its presence in beverages used in religious contexts around the world – such as ayahuasca – has attracted growing attention from the scientific community due to its possible anxiolytic and antidepressant effects. Mimosa hostil...
Article
Assessing the health status of ayahuasca users has been challenging due to the limitations involved in randomized clinical trials and psychometric approaches. The main objective of this study is the implementation of an approach based on public health indicators. We developed a self-administered questionnaire that was administered to long-term ayah...
Article
Full-text available
Parkinson’s disease (PD) is a chronic neurodegenerative disorder characterized by motor symptoms such as bradykinesia, rest tremor, postural disturbances, and rigidity. PD is also characterized by non-motor symptoms such as sleep disturbances, cognitive deficits, and psychiatric disorders such as psychosis, depression, and anxiety. The pharmacologi...
Chapter
The history of the use of cannabis for the treatment of substance-related disorders and harm reduction is relatively recent. Although evidence of the use of cannabis for the treatment of multiple disorders, including such varied conditions as pain and malaria, has been documented across time and cultures (Landa, Jurica, Sliva, Pechackova, & Demlova...
Article
Full-text available
Introduction: Mood, anxiety, and substance use disorders are among the most prevalent psychiatric disorders in the population. Although several pharmacological treatments are available, they are not effective for a significant proportion of patients and are associated with several adverse reactions. Therefore, new treatments should be explored. Rec...
Article
Full-text available
Background and aims: Aphantasia (“blind imagination”) is a poorly described condition with an uncertain etiology, characterized by reduced or lack of voluntary visual imagery. Preliminary evidence in humans suggests that hallucinogenic or psychedelic drugs that act as agonists of cortical 5-HT2A receptors [lysergic acid diethylamide, psilocybin, an...
Article
Full-text available
Background: Recent open-label trials show that psychedelics, such as ayahuasca, hold promise as fast-onset antidepressants in treatment-resistant depression. Methods: To test the antidepressant effects of ayahuasca, we conducted a parallel-arm, double-blind randomized placebo-controlled trial in 29 patients with treatment-resistant depression. P...
Article
Full-text available
In the past decade, an increasing number of clinical trials are reporting evidence that psychedelics or serotonergic hallucinogens (such as lysergic acid diethylamide, psilocybin, and ayahuasca/dimethyltryptamine) could be effective in the treatment of mood, anxiety, and substance use disorders. The mechanisms responsible for these effects are not...
Article
Full-text available
Background Ayahuasca is a botanical hallucinogenic preparation traditionally used by indigenous populations of Northwestern Amazonian countries for ritual and therapeutic purposes. It is rich in β-carboline alkaloids and N,N-dimethyltryptamine (DMT). Preclinical, observational, and experimental studies suggest that ayahuasca and its alkaloids have...
Chapter
Anxiety disorders are among the most prevalent psychiatric disorders, having a lifetime prevalence of around 17%. Social anxiety disorder (SAD), or social phobia, is the most common type of anxiety disorder, being the third most frequent psychiatric disorder, with a lifetime prevalence that can reach 15%. Pharmacological treatments have limited eff...
Article
Serotonergic psychedelics act as agonists at cortical 5-HT2Areceptors and seem to induce personality changes. We conducted a systematic review of studies assessing the effects of these drugs on personality. Papers published from 1985 to 2016 were included from PubMed, LILACS, and SciELO databases. Three hundred and sixty-nine studies were identifie...
Article
Full-text available
Ayahuasca is a natural psychedelic brew, which contains dimethyltryptamine (DMT). Its potential as a psychiatric medicine has recently been demonstrated and its non-medical use around the world appears to be growing. We aimed to investigate well-being and problematic alcohol use in ayahuasca users, and ayahuasca’s subjective effects. An online, sel...
Article
Full-text available
Background Ayahuasca is a psychoactive ethnobotanical concoction that has been used for decades by indigenous groups of the Northwestern Amazon and by syncretic religious organizations for ritual and therapeutic purposes. In the last two decades, it is being used worldwide in evolving practices. Ayahuasca seem to therapeutic effects, but controlled...
Preprint
Recent open label trials show that psychedelics, such as ayahuasca, hold promise as fast-onset antidepressants in treatment-resistant depression. In order to further test the antidepressant effects of ayahuasca, we conducted a parallel-arm, double-blind randomized placebo-controlled trial in 29 patients with treatment-resistant depression. Patients...
Article
Full-text available
Background and aims: Ibogaine is a natural alkaloid that has been used in the last decades as an adjuvant for the treatment of opiate withdrawal. Despite the beneficial results suggested by animal studies and case series, there is a lack of clinical trials to assess the safety and efficacy of ibogaine. Moreover, the majority of reports described ca...
Article
Background and aims: Ayahuasca is a dimethyltryptamine- and β-carboline-rich hallucinogenic beverage traditionally used by indigenous groups of Northwest Amazonian for ritual and therapeutic purposes. Animal and human studies suggest that ayahuasca has antidepressant and anxiolytic potentials and has a good safety profile. However, anxiety-like rea...
Article
Full-text available
Background DSM-5 introduced some modifications on Posttraumatic Stress Disorder (PTSD) criteria. The instruments developed for the assessment of aspects related to PTSD needed a reformulation, as was the case of the Posttraumatic Stress Disorder Checklist (PCL). Objectives To present the process of transcultural adaptation of the three forms of th...
Article
Full-text available
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-HT2A agonist. This mechanism of action is similar to other compounds such as lysergic acid diethylamide (LSD) and psilocybin. The controlled...
Chapter
Epilepsy is a neurological pathology characterized by the occurrence of seizures. There are several types of epilepsy, treated by means of several medical procedures, including antiepileptic drugs, steroids, and surgery. Antiepileptic drugs currently available do not benefit all patients, and many produce several side effects, limiting their clinic...