Skip to content

Kim van Oorsouw

16 papers in the library · 797 citations · publishing 2018-2026

Papers

Sort Most recent Most cited

Beliefs in and experiences of sorcery, black magic and brujería among psychedelic users: a quantitative and qualitative survey

June 19, 2026 Jules Evans, Christian Jurlando, David Luke et al. preprint

Sorcery, black magic, and supernatural harm are central to many Amazonian shamanic traditions, yet their role in contemporary Western psychedelic culture has received little systematic empirical attention. Ethnographic work suggests that Western participants in ayahuasca tourism often downplay indigenous sorcery frameworks in favour of psychological or therapeutic interpretations of difficult...

Brain-body integromics of the ayahuasca experience.

Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie June 1, 2026 Francisco Madrid-Gambin, Pablo Mallaroni, Noemí Haro et al.

Ayahuasca is a psychoactive brew containing N,N-dimethyltryptamine (DMT) and β-carboline alkaloids that induces marked alterations in perception, emotion and self-referential processing. However, the multiscale biological organization linking peripheral metabolism, brain network dynamics, neurochemistry, and subjective experience in humans remains poorly understood. Here, we applied an...

Ayahuasca enhances the formation of hippocampal-dependent episodic memory without impacting false memory susceptibility in experienced ayahuasca users: An observational study.

Journal of Psychopharmacology April 1, 2025 Manoj K. Doss, Lilian Kloft, Natasha L. Mason et al. 5 citations

Ayahuasca is an Amazonian brew with 5-HT2A-dependent psychedelic effects taken by religious groups globally. Recently, psychedelics have been shown to impair the formation of recollections (hippocampal-dependent episodic memory for specific details) and potentially distort memory while remembering. However, psychedelics spare or enhance the formation of familiarity-based memory...

Shared functional connectome fingerprints following ritualistic ayahuasca intake.

Neuroimage 2024 Pablo Mallaroni, Natasha L. Mason, Lilian Kloft et al. 17 citations

The knowledge that brain functional connectomes are unique and reliable has enabled behaviourally relevant inferences at a subject level. However, whether such "fingerprints" persist under altered states of consciousness is unknown. Ayahuasca is a potent serotonergic psychedelic which produces a widespread dysregulation of functional connectivity. Used communally in religious ceremonies, its...

DOI: 10.1016/j.neuroimage.2023.120480 (opens in new tab) Full text (opens in new tab) DMT Entheogens Brain connectivity connectome Neuroimaging FMRI +8

Cortical structural differences following repeated ayahuasca use hold molecular signatures

Frontiers in Neuroscience October 5, 2023 Pablo Mallaroni, Lilian Kloft, Natasha L. Mason et al. 8 citations

Introduction Serotonergic psychedelics such as ayahuasca are reported to promote both structural and functional neural plasticity via partial 5-HT 2A agonism. However, little is known about how these molecular mechanisms may extend to repeated psychedelic administration in humans, let alone neuroanatomy. While early evidence suggests localised changes to cortical thickness in long-term...

Altered State of Consciousness and Mental Imagery as a Function of N, N-dimethyltryptamine Concentration in Ritualistic Ayahuasca Users

Journal of Cognitive Neuroscience 2023 Johannes G. Ramaekers, Pablo Mallaroni, Lilian Kloft et al. 15 citations

Abstract Consumption of the psychedelic brew ayahuasca is a central ritualistic aspect of the Santo Daime religion. The current observational, baseline controlled study was designed to assess whether members (n = 24) of the Santo Daime church would show enhanced capacity for mental imagery during an ayahuasca experience. In addition, this study assessed whether the effects of ayahuasca on...

DOI: 10.1162/jocn_a_02003 (opens in new tab) Ayahuasca DMT Psychedelics Consciousness research +1

Altered States of Consciousness During Ceremonial San Pedro Use

International Journal for the Psychology of Religion December 5, 2022 Arne Bohn, Michiel H. H. Kiggen, Malin V. Uthaug et al. 10 citations

San Pedro, a mescaline containing cactus, has been used for thousands of years and is currently popular as a psychedelic substance in ceremonial retreats in Europe. The current research investigates the consciousness altering effects of San Pedro. Forty-two participants who joined ceremonial psychedelic retreats in the Netherlands were investigated with questionnaires probing 11 dimensions of...

Ritualistic use of ayahuasca enhances a shared functional connectome identity with others

bioRxiv (Cold Spring Harbor Laboratory) October 11, 2022 Pablo Mallaroni, Natasha L. Mason, Lilian Kloft et al. 4 citations preprint

Abstract The knowledge that brain functional connectomes are both unique and reliable has enabled behaviourally relevant inferences at a subject level. However, it is unknown whether such “fingerprints” persist under altered states of consciousness. Ayahuasca is a potent serotonergic psychedelic which elicits a widespread dysregulation of functional connectivity. Used communally in religious...

The influence of ceremonial settings on mystical and challenging experiences occasioned by ayahuasca: A survey among ritualistic and religious ayahuasca users

Frontiers in Psychology July 15, 2022 Alexandre Augusto de Deus Pontual, Alexandre Augusto de Deus Pontual, Luís Fernando Tófoli et al. 27 citations

Recent studies have recognized the importance of non-pharmacological factors such as setting to induce or promote mystical experiences or challenging experiences among ayahuasca users. This study aimed to evaluate the association between the setting in which ayahuasca is consumed and the intensity of mystical and challenging experiences considering three ayahuasca using traditions (União do...

DOI: 10.3389/fpsyg.2022.857372 (opens in new tab) Full text (opens in new tab) Udv Neo-shamanic Mystical experiences Ayahuasca-ceremony ayahuasca ritual +6

Metabolomics and integrated network analysis reveal roles of endocannabinoids and large neutral amino acid balance in the ayahuasca experience

Biomedicine & Pharmacotherapy March 24, 2022 Francisco Madrid-Gambin, Alex Gomez-Gomez, Arnau Busquets-García et al. 14 citations

There has been a renewed interest in the potential use of psychedelics for the treatment of psychiatric conditions. Nevertheless, little is known about the mechanism of action and molecular pathways influenced by ayahuasca use in humans. Therefore, for the first time, our study aims to investigate the human metabolomics signature after consumption of a psychedelic, ayahuasca, and its connection...

Therapeutic effect of an ayahuasca analogue in clinically depressed patients: a longitudinal observational study.

Psychopharmacology January 24, 2022 Kim van Oorsouw, S. W. Toennes, J. G. Ramaekers 71 citations

RATIONALE: Studies have suggested mental health improvements following the use of the psychotropic plant concoction ayahuasca in non-clinical and clinical samples. OBJECTIVES: The present observational study assessed depressive symptomatology in 20 clinically depressed patients (symptom score > 13 on the Beck's Depression Inventory) before attendance of an ayahuasca ceremony and 1 month and 1...

Persisting Effects of Ayahuasca on Empathy, Creative Thinking, Decentering, Personality, and Well-Being

Frontiers in Pharmacology October 1, 2021 Maggie Kiraga, Natasha L. Mason, Malin V. Uthaug et al. 83 citations

Background: Naturalistic and placebo-controlled studies have suggested that ayahuasca, a traditional Amazonian beverage, could be helpful in the treatment of psychopathologies like depression and anxiety disorders by changing otherwise disturbed cognitive and emotional processes. To better understand its full therapeutic potential, one way is to study the effects on processes like flexible...

Sub-acute and long-term effects of ayahuasca on mental health and well-being in healthy ceremony attendants: A replication study

Journal of Psychedelic Studies August 26, 2021 Kim van Oorsouw, Malin V. Uthaug, Natasha L. Mason et al. 16 citations

Abstract Background and aims There is a growing body of evidence suggesting that the psychedelic plant tea, ayahuasca, holds therapeutic potential. Uthaug et al. (2018) demonstrated that a single dose of ayahuasca improved mental health sub-acutely and 4-weeks post-ceremony in healthy participants. The present study aimed to replicate and extend these findings. A first objective was to assess...

A placebo-controlled study of the effects of ayahuasca, set and setting on mental health of participants in ayahuasca group retreats

Psychopharmacology March 10, 2021 Malin V. Uthaug, Natasha L. Mason, Stefan W. Toennes et al. 116 citations

Abstract Ayahuasca is a plant concoction containing N,N -dimethyltryptamine (DMT) and certain β-carboline alkaloids from South America. Previous research in naturalistic settings has suggested that ingestion of ayahuasca can improve mental health and well-being; however, these studies were not placebo controlled and did not control for the possibility of expectation bias. This naturalistic...

A single inhalation of vapor from dried toad secretion containing 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) in a naturalistic setting is related to sustained enhancement of satisfaction with life, mindfulness-related capacities, and a decrement of psychopathological symptoms.

Psychopharmacology April 13, 2019 Malin V. Uthaug, R. Lancelotta, Kim van Oorsouw et al. 198 citations

Background: 5-methoxy-N,N-dimethyltryptamine (hereinafter referred to as 5-MeO-DMT) is a psychedelic substance found in the secretion from the parotoid glands of the Bufo alvarius toad. Inhalation of vapor from toad secretion containing 5-MeO-DMT has become popular in naturalistic settings as a treatment of mental health problems or as a means for spiritual exploration. However, knowledge of...

DOI: 10.1007/s00213-019-05236-w (opens in new tab) Full text (opens in new tab) Mental health Psychological health Emotional well-being Mental wellness +25

Sub-acute and long-term effects of ayahuasca on affect and cognitive thinking style and their association with ego dissolution

Psychopharmacology August 13, 2018 Malin V. Uthaug, Kim van Oorsouw, Kim P. C. Kuypers et al. 213 citations

RATIONALE: Ayahuasca is a psychotropic plant tea from South America used for religious purposes by indigenous people of the Amazon. Increasing evidence indicates that ayahuasca may have therapeutic potential in the treatment of mental health disorders and can enhance mindfulness-related capacities. Most research so far has focused on acute and sub-acute effects of ayahuasca on mental...