Universidade de São Paulo, Clinics Hospital of Ribeirão Preto
93 papers in the library · 6,629 citations · publishing 0-2026
Scientific Reports February 28, 2018 Will Lawn, Jaime E. C. Hallak, J.a.s. Crippa et al. 3 citations
A correction to this article has been published and is linked from the HTML and PDF versions. The error has not been fixed in the paper.
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
Whether subjective experience contributes to therapeutic mechanisms of ayahuasca is debated and may depend on the targeted condition. Few controlled studies exist, limiting conclusions on safety and efficacy. Ayahuasca's highly variable composition poses an additional challenge, prompting studies using isolated compounds.
Brazilian Journal of Psychiatry October 7, 2020 Rafael G. Dos Santos, Dráulio Barros de Araújo, Rafael Faria Sanches et al. 2 citations
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Brazilian Journal of Psychiatry June 16, 2026 Daniel B.a. Prado, Matheus T. Rossignoli, Rafael N. Ruggiero et al.
In a rat model of schizophrenia-like symptoms induced by ketamine, the combination of cannabidiol and sodium nitroprusside given during brain development prevented hyperactivity and memory problems in both sexes, while each drug alone had limited effects. The model produced different symptoms in males and females: females showed greater hyperactivity and long-term memory deficits, whereas males showed reduced pleasure-seeking and short-term memory impairments. The combined treatment was more effective in females, and distinct behavioral patterns were seen between sexes. This suggests that a combination of these two compounds may offer a sex-specific preventive strategy for schizophrenia symptoms.
Current Psychology June 1, 2026 Geovan Menezes de Sousa, Geissy Lainny de Lima-Araújo, Vagner Deuel de Oliveira Tavares et al.
Adults with major depressive disorder who report higher levels of dispositional mindfulness—the tendency to attend to present-moment experiences with openness and awareness—show fewer depressive and anxiety symptoms, better sleep quality, and higher self-esteem compared to those with lower trait mindfulness. In a cross-sectional study of 97 adults diagnosed with MDD, two clusters emerged: a High Trait group and a Low Trait group. The High Trait group had significantly lower depressive symptoms (d = 0.795) and anxiety symptoms (d = 0.739), and higher self-esteem (d = -0.586) and sleep quality (d = 0.460). These results suggest trait mindfulness may protect against poor mental health in depression.
Journal of psychopharmacology (Oxford, England) May 31, 2026 Anna Beatriz Vicentini, Caio César De Paula, José Augusto Silva Reis et al.
A systematic review of 48 studies (14 experimental, 34 observational) covering 2016–2024 found that classic psychedelics—such as psilocybin and ayahuasca—most consistently increase the personality trait Openness and reduce Neuroticism. Changes in Extraversion, Agreeableness, and Conscientiousness were more variable. Microdosing was linked to modest reductions in Neuroticism and higher Absorption. Most studies used the Five-Factor Model. The findings suggest psychedelics can promote lasting personality changes, but contradictory results remain, and future research should combine experimental and naturalistic designs with longer follow-ups.
Journal of Psychoactive Drugs March 19, 2026 Pedro J. Teixeira, Jorge Encantado, Helena D Amaro et al.
Portuguese adults who participate in ayahuasca ceremonies report good or very good health, with lower rates of chronic disease and obesity compared to the general population. They also report greater physical activity, lower alcohol consumption, and enhanced psychological well-being. Many attribute positive lifestyle changes, reduced substance use, and less reliance on prescription medication to their ayahuasca experiences. These findings align with prior research linking ayahuasca use to health and well-being, though causal pathways remain unclear.
Journal of psychopharmacology (Oxford, England) March 9, 2026 Caio César De Paula, Anna Beatriz Vicentini, Lorena Terene Lopes Guerra et al.
A systematic review of 16 studies found that ayahuasca has distinct short- and long-term cognitive effects. In the short term, improvements in working memory and cognitive flexibility were observed, linked to neurochemical modulation of cortical networks. Observational studies reported increased empathy and emotion recognition, while experimental studies only found reduced reaction times in social cognition tasks. Long-term studies generally found no neuropsychological deficits, with some reporting improved memory and executive function. The review notes methodological limitations including small sample sizes, varied protocols, and potential learning effects, calling for more controlled, randomized studies.
European Neuropsychopharmacology February 12, 2026 José Carlos Bouso, Óscar Andión, Sabela Fondevila Estévez et al.
Regular users of ayahuasca or cannabis show no detectable lasting impairments in executive function or working memory compared to non-users, after abstaining for 10-30 days. Personality traits, not cognition or psychopathology, best distinguish the groups: ayahuasca users score higher on self-transcendence and lower on harm avoidance and persistence, while cannabis users score higher on novelty seeking and impulsive nonconformity and lower on introvertive anhedonia. Although ayahuasca users had a higher lifetime prevalence of mood and anxiety disorders, they showed no current psychopathological symptoms. The study's cross-sectional, self-selected, non-treatment-seeking sample may limit generalizability.
European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology February 1, 2026 Isabel Werle, Francisco S Guimarães, Rafael G. Dos Santos et al.
Ayahuasca, a brew containing the psychedelic DMT, helps rodents overcome persistent and generalized fear memories by boosting brain-derived neurotrophic factor (BDNF) signaling in the infralimbic (IL) region of the medial prefrontal cortex. In rats exposed to stress or high-intensity fear conditioning, repeated ayahuasca (0.3 mg/kg DMT) enhanced extinction learning and its retention, and reduced fear generalization. These effects were blocked by infusing an anti-BDNF antibody or a TrkB receptor antagonist into the IL cortex. The reduction in fear generalization depended on BDNF in females but not males. The findings suggest psychedelics may aid in treating difficult-to-extinguish trauma memories, such as those in PTSD.
Prog Neuropsychopharmacol Biol Psychiatry October 20, 2025 Arthur L. De Oliveira, Danielle P. De Oliveira, Rafael G. Dos Santos et al.
A systematic review of 13 studies examined the developmental toxicity and behavioral effects of psychedelics in zebrafish. Substances included ayahuasca, DMT, ibogaine, LSD, MDMA, mescaline, noribogaine, psilocybin, and psilocin. Overall, psychedelics did not cause morphological abnormalities in embryo-larvae, though ayahuasca induced edemas and increased mortality at high concentrations. Ibogaine, MDMA, and LSD were linked to locomotor impairments after developmental exposure. DMT, psilocybin, and psilocin had anxiolytic effects on larvae, while LSD, MDMA, mescaline, and noribogaine reduced anxiety in adult fish. The findings suggest a safe toxicological profile at low concentrations, but whether they cause neurodevelopmental deficits in offspring remains unclear.
PLoS One October 13, 2025 Francisco González-espejito, Laura Esteban Rodríguez, Eduardo J. Pedrero Pérez et al.
Ibogaine, a compound from the iboga plant used in traditional Bwiti rituals, shows promise for treating opioid dependence and neurological conditions, but existing tools fail to capture its dream-like subjective effects. A new 70-item Ibogaine Experience Scale (IES) was developed from a prior qualitative study and tested with 499 participants in neuropsychiatric and substance use treatment settings. The final scale has seven factors—including narrative visions, visual changes, discomfort, cosmic visions, introspection, somatosensory sensitivity, and dissociation—explaining 53.9% of variance, with excellent statistical fit and high internal consistency. The IES offers a reliable way to measure ibogaine's multidimensional effects for research and clinical use.
Braz J Psychiatry September 29, 2025 José Augusto S. Reis, Giordano N. Rossi, Anna Beatriz V. Zacharias et al.
A case report describes an instance of acute suicidal behavior that occurred after a participant ingested ayahuasca in a clinical trial setting. The report details the circumstances and clinical presentation of this adverse event, highlighting a potential risk associated with ayahuasca use even within a controlled research environment. The authors suggest that such reactions, though rare, warrant careful screening and monitoring of participants in psychedelic research.
Journal of Psychedelic Studies September 4, 2025 Giordano Novak Rossi, Rishma S. I. Khubsing, Eline Haijen et al.
Both a single ayahuasca ceremony and a single breathwork session led to lasting improvements in cognitive flexibility, emotion regulation, positive affect, and sleep quality over three months. Improvements in cognitive flexibility appeared before changes in emotion regulation, partially supporting the idea that cognitive shifts may drive later emotional gains. The two treatments did not differ in their overall benefits, and the role of participants' experience and motivation remains unclear. The findings suggest that both practices can promote psychological well-being, but further research is needed to clarify the mechanisms and temporal order of these effects.
Psychoactives July 15, 2025 Bianca Villanova, Giordano Novak Rossi, Lorena Terene Lopes Guerra et al.
Ayahuasca, a psychoactive brew containing DMT and harmine, may reduce pain and inflammation. A systematic review of 29 preclinical studies found that ayahuasca and its alkaloids, especially harmine, produce antinociceptive effects and shift cytokine balance toward anti-inflammatory. More research is needed.
IBRO Neuroscience Reports December 1, 2024 Gabriela N Vaz, Flávia C Turcato, Isabel A V Lima et al.
Mice lacking the PI3Kγ gene did not respond to standard doses of ketamine or to classic antidepressants such as imipramine and fluoxetine, as measured by the forced swimming test. This unresponsiveness required a chronic deficiency of the PI3Kγ-mediated pathway, not just acute inhibition. The findings suggest PI3Kγ plays a role in antidepressant activity and may be involved in treatment resistance observed in some patients with major depressive disorder.
Psychoactives November 21, 2022 Rafael G. Dos Santos, Jaime E. C. Hallak
Ayahuasca, a traditional Amazonian brew containing the hallucinogen DMT, shows promise for treating mental health disorders. Over the past twenty years, research has increasingly explored its therapeutic potential, particularly for depression, anxiety, and addiction. The brew's active compounds interact with serotonin receptors in the brain, potentially promoting neuroplasticity and emotional processing. Clinical studies suggest that ayahuasca can produce rapid and sustained reductions in depressive symptoms, often after a single dose. However, the authors note that more rigorous randomized controlled trials are needed to confirm these effects and understand the underlying mechanisms. The cultural and spiritual context of ayahuasca use also plays a role in its therapeutic outcomes.
Advances in experimental medicine and biology January 1, 2021 Rafael G. Dos Santos, Jaime E. C. Hallak, José Alexandre S. Crippa
Cannabis contains over 400 compounds, including more than 100 phytocannabinoids, primarily THC and CBD. THC acts as a partial agonist at cannabinoid receptors, producing euphoria, relaxation, and altered perceptions, but also dysphoria, anxiety, and psychotic symptoms; it is used therapeutically for nausea, appetite stimulation, and chronic pain. CBD acts as a negative allosteric modulator of CB1 receptors, an inverse agonist of CB2, and inhibits anandamide reuptake; it also activates 5-HT1A and vanilloid receptors. CBD does not produce typical cannabis effects and has anxiolytic and antipsychotic properties; it is approved for treatment-resistant epilepsy. Common CBD adverse effects include diarrhea, somnolence, nausea, and transaminase elevations. The mechanisms underlying therapeutic and adverse effects are not fully understood and involve multiple targets beyond the endocannabinoid system.