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Jaime E. C. Hallak

Universidade de São Paulo, Clinics Hospital of Ribeirão Preto

95 papers in the library · 6,620 citations · publishing 0-2026

Papers

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Ibogaine as a Double-Edged Sword: Developmental Cardiotoxicity and Neurobehavioral Alterations in Zebrafish

Behavioural Brain Research August 1, 2026 Alessandra Mara de Oliveira, Flavia R. Abe, Rafael G. Dos Santos et al.

Ibogaine has attracted increasing attention as a potential treatment for substance use disorders; however, its clinical application remains limited by well-documented cardiotoxicity, and its safety during early development is poorly understood. Here, we investigated the developmental cardiotoxic and neurobehavioral effects of ibogaine using zebrafish embryos and larvae as a translational model....

Prophylactic efficacy of cannabidiol and sodium nitroprusside in a ketamine model of schizophrenia: sex-dependent effects on positive-like and cognitive impairments

Brazilian Journal of Psychiatry June 16, 2026 Daniel B.a. Prado, Matheus T. Rossignoli, Rafael N. Ruggiero et al.

Objective: Current treatments for schizophrenia (SZ) are often not effective for all symptoms, with sex-dependent effects poorly understood. Cannabidiol (CBD) and sodium nitroprusside (SNP) have emerged as potential prophylactic options. We evaluated their efficacy in preventing positive, negative, and cognitive deficits in a ketamine (KET) rodent model of SZ in both sexes. Methods: Wistar rats...

Trait mindfulness influences self-reported mental health in individuals with depression

Current Psychology June 1, 2026 Geovan Menezes de Sousa, Geissy Lainny de Lima-Araújo, Vagner Deuel de Oliveira Tavares et al.

Abstract Dispositional mindfulness, also known as trait mindfulness, refers to an individual dispositional tendency to attend the present moment experiences with openness, curiosity and awareness. It is often associated with well-being, particularly through its role with emotional regulation. Yet, it is not well understood how it may influence the expression of major depression symptoms. This...

Classic psychedelics and personality: An updated systematic review.

Journal of psychopharmacology (Oxford, England) May 31, 2026 Anna Beatriz Vicentini, Caio César De Paula, José Augusto Silva Reis et al.

The impact of classic psychedelics (5-HT2A receptor agonists) on personality traits has been studied for decades, and it has been hypothesized that the mechanisms underlying these changes are linked to agonism at cortical serotonergic 5-HT2A receptors. However, research results are contradictory. Therefore, the present paper aims to systematically evaluate the effects of psychedelics on...

Ayahuasca and Public Health III: Health Status of a Sample of Ayahuasca Ceremony Attenders in Portugal.

Journal of Psychoactive Drugs March 19, 2026 Pedro J. Teixeira, Jorge Encantado, Helena D Amaro et al.

Ayahuasca, a traditional Amazonian psychoactive brew, has gained increasing attention for its potential health benefits; however, no previous research has investigated its use in Portugal. This study aims to evaluate the health status, lifestyle behaviors, and psychosocial well-being of Portuguese ayahuasca users, comparing their self-reported health indicators with population norms. A...

Effects of ayahuasca on neuropsychological performance and social cognition: A systematic review.

Journal of psychopharmacology (Oxford, England) March 9, 2026 Caio César De Paula, Anna Beatriz Vicentini, Lorena Terene Lopes Guerra et al.

Ayahuasca has aroused increasing interest due to its therapeutic effects. However, its effects on cognition are poorly understood. Hence, a systematic review evaluating the cognitive effects of ayahuasca was conducted. This systematic review was conducted in accordance to Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. A comprehensive search was performed in...

Personality, not cognition, distinguishes chronic ayahuasca and cannabis users from non-users

European Neuropsychopharmacology February 12, 2026 José Carlos Bouso, Óscar Andión, Sabela Fondevila Estévez et al.

The increasing interest in the therapeutic potential of psychedelics and cannabis underscores the need to understand their long-term neuropsychological and personality effects. This cross-sectional study compared regular users of ayahuasca (n = 69), cannabis (n = 56), and non-substance users (n = 94) on a battery of neuropsychological tasks and psychological questionnaires. Participants were...

Ayahuasca modulation of traumatic-like fear memories requires infralimbic cortex BDNF-dependent mechanisms in rats.

European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology February 1, 2026 Isabel Werle, Francisco S Guimarães, Rafael G. Dos Santos et al.

Rodent studies have shown that psychedelic drugs can enhance fear extinction. However, investigations to date have relied on normative aversive conditioning procedures, which limit their relevance to trauma-related memories, as these tend to be overgeneralized and resistant to extinction. Fear extinction depends on activity and plasticity within the infralimbic (IL) region of the medial...

Feasibility, safety and preliminary effects of ibogaine in patients with moderate and severe alcohol use disorder: a pilot, open-label study

Trends in Psychiatry and Psychotherapy 2026 Juliana Mendes Rocha, Renan Massanobu Maekawa, José Augusto Silva Reis et al.

INTRODUCTION: Ibogaine is a natural hallucinogen with emerging evidence for treating substance use disorders. However, its cardiovascular effects are not fully known, and most clinical data focus on opioid dependence, with limited data for Alcohol Use Disorder (AUD). This study assessed the feasibility, safety, and preliminary effects of ibogaine in patients with AUD. METHOD: In this...

Psychedelic-induced behavioral and developmental effects on zebrafish: a systematic review.

Prog Neuropsychopharmacol Biol Psychiatry October 20, 2025 Arthur L. De Oliveira, Danielle P. De Oliveira, Rafael G. Dos Santos et al.

Psychedelics are mind-altering substances that have shown promising effects in the treatment of neuropsychiatric disorders owing to their antidepressant, anxiolytic and antiaddictive effects. However, data on their developmental toxicity is scarce, which might hinder its therapeutic suitability, and preclinical data on their behavioral effects is mainly restricted to rodents. In this context,...

The Ibogaine Experience Scale (IES): Development and psychometric properties of a multidimensional measure of ibogaine’s subjective effects

PLoS One October 13, 2025 Francisco González-espejito, Laura Esteban Rodríguez, Eduardo J. Pedrero Pérez et al.

Ibogaine, an indole alkaloid derived from the root bark of Tabernanthe iboga, has long been used in traditional Bwiti healing rituals and shows promise for treating opioid dependence and neurological conditions, but existing psychometric tools fail to capture its distinctive subjective/oneiric (dream-like) effects. To address this gap, we developed the 70-item Ibogaine Experience Scale (IES)...

Clinical pharmacology of ayahuasca: potential applications and future considerations

Expert Review of Clinical Pharmacology October 3, 2025 Lorena Terene Lopes Guerra, Isabella Caroline Da Silva Dias, Jaime E. C. Hallak et al. 2 citations

Similar to what happens with other psychedelics, there is an ongoing debate on subjective experience contribution to overall therapeutic mechanisms, which can depend on the targeted conditions. There are very few evidences from controlled studies, limiting the conclusions on safety and efficacy. On top of that, ayahuasca highly variable composition posits another challenge, and studies using...

Comparative effects of ayahuasca and breathwork on self-reported cognitive flexibility, emotion regulation, positive affect, and sleep quality

Journal of Psychedelic Studies September 4, 2025 Giordano Novak Rossi, Rishma S. I. Khubsing, Eline Haijen et al.

Abstract Background and aims Research on classical psychedelics like ayahuasca is increasingly focused on treating mental disorders and enhancing well-being. Ayahuasca has shown promise in improving cognitive flexibility, emotion regulation, and sleep, though findings are mixed and further research is needed. This study tracked participants over three months, assessing cognitive flexibility,...

Ayahuasca, Pain, and Inflammation: A Systematic Review of Preclinical Studies

Psychoactives July 15, 2025 Bianca Villanova, Giordano Novak Rossi, Lorena Terene Lopes Guerra et al.

Pain is a protective mechanism that can be classified into acute and chronic types. Ayahuasca is a psychoactive brew rich in dimethyltryptamine or DMT (a 5-HT2A receptor agonist), and harmine (a monoamine-oxidase (MAO) inhibitor) used for religious and therapeutic purposes. Previous preclinical and anecdotal evidence suggests that ayahuasca and its compounds have antinociceptive and...

Effects of ayahuasca on fear and anxiety: cross-talk between 5HT1A and 5HT2A receptors

Psychedelics. December 10, 2024 Lorena Terene Lopes Guerra, Rafael G. Dos Santos, Jaime E. C. Hallak 3 citations

Ayahuasca is a hallucinogenic substance currently being investigated for the treatment of mood, anxiety, and trauma-related disorders. Evidence from animal and human studies suggest that the effects of ayahuasca involve modulation of neural substrates relevant for emotional processing, especially in regions rich in serotonergic receptors. Moreover, preclinical studies also show that ayahuasca...

Genetic ablation of the isoform γ of PI3K decreases antidepressant efficacy of ketamine in male mice.

IBRO Neuroscience Reports December 1, 2024 Gabriela N Vaz, Flávia C Turcato, Isabel A V Lima et al.

About one-third of major depressive disorder (MDD) patients demonstrate unresponsiveness to classic antidepressants, and even the clinical efficacy of fast-acting drugs such as ketamine varies significantly among patients with treatment-resistant depression. Nevertheless, the lack of suitable animal models that mimic a possible ketamine-resistant phenotype challenges the understanding of...

Why N,N-dimethyltryptamine matters: unique features and therapeutic potential beyond classical psychedelics.

Front Psychiatry November 6, 2024 Cristiano Chaves, Rafael G. Dos Santos, Serdar Dursun et al. 11 citations

"Iracema comes with the pot full of the green liquor. The shaman decrees the dreams to each warrior and distributes the wine of jurema, which carries the brave Tabajara to heaven." José de Alencar, in his poetic novel “Iracema” (1865)1. IntroductionThe "wine of jurema", used in ancient Brazilian shamanic rituals, is rich in N,N-dimethyltryptamine (DMT), a naturally occurring tryptamine like...

Ketamine-induced altered states of consciousness: a systematic review of implications for therapeutic outcomes in psychiatric practices.

European Archives of Psychiatry and Clinical Neuroscience October 28, 2024 Kaike Thiê da Costa Gonçalves, Vagner Deuel O de Tavares, Maria Luiza de Morais Barros et al. 5 citations

This systematic review aims to elucidate the nexus between ketamine's psychoactive properties and its efficacy in treating a broad spectrum of psychiatric disorders. We searched three databases and used citation tracking to include 29 studies. Predominantly, mood disorders, including bipolar disorder (BD) and major depressive disorder (MDD) (MDD + BD: + n = 25 studies), a large part of them...

Ayahuasca-enhanced extinction of fear behaviour: Role of infralimbic cortex 5-HT2A and 5-HT1A receptors.

British Journal of Pharmacology June 1, 2024 Isabel Werle, Laura M M Nascimento, Aymee L A Dos Santos et al. 21 citations

Ayahuasca (AYA) is a botanical psychedelic with promising results in observational and small clinical trials for depression, trauma and drug use disorders. Its psychoactive effects primarily stem from N,N-dimethyltryptamine (DMT). However, there is a lack of research on how and where AYA acts in the brain. This study addressed these questions by examining the extinction of aversive memories in...

Guidelines for Establishing Safety in Ayahuasca and Ibogaine Administration in Clinical Settings

Psychoactives December 11, 2023 Juliana Mendes Rocha, José Augusto Silva Reis, Giordano Novak Rossi et al. 3 citations

As the research field with psychedelic substances grows, it is expected to encompass a more extensive cohort of individuals presenting a spectrum of medical conditions, comorbidities, and unique physiological traits, thereby increasing the likelihood of potential adverse events. Furthermore, it is worth noting that there is a scarcity of the specialized literature regarding procedures to ensure...

Subjective Effects of a Single Dose of Ayahuasca among College Students with Harmful Alcohol Use: Qualitative Analysis of Participant Accounts

Psychoactives November 17, 2023 Anna Beatriz Vicentini, Lucas Silva Rodrigues, Giordano Novak Rossi et al. 4 citations

Alcohol is the recreational drug most frequently consumed, and its high frequency of use can lead to worsening social, psychological, and domestic issues. The age group most susceptible to alcohol dependence is 18- to 24-year-old youths, demanding interventional tools to target early involvement risks. Ayahuasca seems to be a promising therapeutic tool since evidence suggests it presents...

Identifying setting factors associated with improved ibogaine safety: a systematic review of clinical studies.

European Archives of Psychiatry and Clinical Neuroscience October 1, 2023 Juliana Mendes Rocha, José A S Reis, José Carlos Bouso et al. 21 citations

Ibogaine is a psychoactive alkaloid derived from the west-African shrub Tabernanthe iboga. Western cultures are increasing the interest for the substance due to its claimed anti addictive properties, although the evidence supporting this effect is still preliminary. The use of ibogaine often occurs with no medical supervision in uncontrolled settings, and its use has been associated with...

Longitudinal and transcultural assessment of the relationship between hallucinogens, well-being, and post-traumatic growth during the COVID-19 pandemic

Scientific Reports September 11, 2023 José Carlos Bouso, Dóra Révész, Genís Ona et al. 9 citations

The COVID-19 pandemic has had a devastating impact on the health and wellbeing of the global population. This paper presents the results of a longitudinal transcultural study that was begun at the peak of the pandemic (in April, 2020). An online survey was used to collect data from English-, Spanish-, and Portuguese-speaking participants. The survey collected information about...

Hallucinations and Hallucinogens: Psychopathology or Wisdom?

Culture, Medicine and Psychiatry June 1, 2023 José Carlos Bouso, Genís Ona, Maja Kohek et al. 8 citations

Hallucinations are currently associated almost exclusively with psychopathological states. While it is evident that hallucinations can indicate psychopathology or neurological disorders, we should remember that hallucinations also commonly occur in people without any signs of psychopathology. A similar case occurs in the case of hallucinogenic drugs, which have been long associated with...