Molecular Psychiatry
August 4, 2026
Kim P. C. Kuypers, Natasha L. Mason, Aurelie Carlier et al.
Women experience a disproportionate burden of affective and stress-related disorders, with symptom variability shaped by endocrine transitions across the menstrual cycle, pregnancy, postpartum, and menopause. Although psychedelic-assisted therapies are increasingly investigated for these conditions, hormonal state represents a largely unaccounted determinant of variability in exposure,...
Journal of psychopharmacology (Oxford, England)
May 1, 2026
Otto Simonsson, Taylor Lyons, Joseph Marks et al.
Previous research suggests that psychedelics may, under certain conditions, decrease authoritarian attitudes, but larger and more rigorously designed studies are needed to confirm these findings. We aimed to examine the effects of psychedelic use on authoritarian attitudes. Using data from three separate studies with different designs and populations, we investigated the relationship between...
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,...
Psychol Med
August 26, 2025
Michael Angyus, Sarah Osborn, Eline Haijen et al.
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Current Opinion in Psychology
August 6, 2025
Iva Totomanova, Eline Haijen, Petra P M Hurks et al.
5 citations
Microdosing psychedelics, the regular use of low doses of LSD or psilocybin, have attracted growing public and scientific interest. This review synthesizes findings from 57 human studies on psychological and physiological outcomes in clinical and non-clinical populations. Reported benefits include improved mood, enhanced cognition, social functioning, and mental health, although findings are...
JAMA Psychiatry
June 1, 2025
Lorenz Mueller, Joyce Santos de Jesus, Yasmin Schmid et al.
14 citations
Microdosing psychedelics, including lysergic acid diethylamide (LSD), has gained attention for its potential benefits in several psychiatric disorders, including attention-deficit/hyperactivity disorder (ADHD). However, LSD's efficacy in reducing ADHD symptoms remains unknown. To determine the safety and efficacy of repeated low doses of LSD in reducing ADHD symptoms compared with placebo. This...
International review of neurobiology
2025
Iva Totomanova, Eline Haijen, Petra P M Hurks et al.
Clinical trials using full doses of psychedelics have provided preliminary evidence supporting their safety and efficacy in treating a variety of physical and psychological conditions. Anecdotal reports indicate that even very small amounts of these substances may provide therapeutic benefits, though robust clinical studies are still needed. This chapter reviews the current experimental studies...
Psychol Med
September 27, 2024
Michael Angyus, Sarah Osborn, Eline Haijen et al.
10 citations
Abstract Background Access to psychedelic drugs is liberalizing, yet responses are highly unpredictable. It is therefore imperative that we improve our ability to predict the nature of the acute psychedelic experience to improve safety and optimize potential therapeutic outcomes. This study sought to validate the ‘Imperial Psychedelic Predictor Scale’ (IPPS), a short, widely applicable,...
Psychoactives
March 31, 2024
Rishma S. I. Khubsing, Martin van Leerdam, Eline Haijen et al.
3 citations
Background: In recent years, there has been a growing interest in the therapeutic potential of classical psychedelics like ayahuasca for mental health improvement. Naturalistic studies at ayahuasca retreats have shown (short-term) improvements in mental well-being but understanding the psychological mechanisms is crucial. We are interested in psychological processes such as resilience,...
European Psychiatry
2024
Eline Haijen, Petra P M Hurks, Kim P. C. Kuypers
10 citations
Abstract Adults with attention-deficit hyperactivity disorder (ADHD) often struggle with emotion regulation (ER), impacting their empathic skills and relationships. ADHD medication might not be as effective for ER issues as for ADHD symptoms. Microdosing (MD) psychedelics has shown promise for ADHD treatment and previous studies reported social-emotional benefits. Two online prospective studies...
Frontiers in Psychiatry
October 16, 2023
Eline Haijen, Petra P M Hurks, Kim P. C. Kuypers
6 citations
Background Microdosing (MD), repeatedly taking psychedelics in small, non-hallucinogenic amounts, has been practiced by individuals to relieve attention deficit hyperactivity disorder (ADHD) symptoms. Generally, adults diagnosed with ADHD have lower levels of mindfulness and differ in personality structure from non-ADHD adults. How MD affects mindfulness and personality in adults with ADHD...
Neurosci Appl
October 26, 2022
Eline Haijen, Petra P M Hurks, Kim P. C. Kuypers
17 citations
ADHD in adulthood is often overlooked, which negatively affects the individual's well-being. First-line pharmacological interventions are effective in many ADHD patients, relieving symptoms rapidly. However, there seems to be a proportion of individuals who discontinue, or fail to respond to these treatments. For these individuals, alternative treatment options should be explored. A...
J Psychopharmacol
August 1, 2022
Victoria Amalie Nygart, Lis Marie Pommerencke, Eline Haijen et al.
73 citations
Background: Over the last two decades, a number of studies have highlighted the potential of psychedelic therapy. However, questions remain to what extend these results translate to naturalistic samples, and how contextual factors and the acute psychedelic experience relate to improvements in affective symptoms following psychedelic experiences outside labs/clinics. The present study sought to...
Psychopharmacology (Berl)
November 4, 2021
Joanna Kuć, Hannes Kettner, Fernando E. Rosas et al.
37 citations
RATIONALE: Classic psychedelics are currently being studied as novel treatments for a range of psychiatric disorders. However, research on how psychedelics interact with other psychoactive substances remains scarce. OBJECTIVES: The current study aimed to explore the subjective effects of psychedelics when used alongside cannabis. METHODS: Participants (n = 321) completed a set of online surveys...
Frontiers in Psychiatry
June 29, 2021
Keri Mans, Hannes Kettner, David Erritzøe et al.
65 citations
In the last 15 years, psychedelic substances, such as LSD and psilocybin, have regained legitimacy in clinical research. In the general population as well as across various psychiatric populations, mental well-being has been found to significantly improve after a psychedelic experience. Mental well-being has large socioeconomic relevance, but it is a complex, multifaceted construct. In this...
Journal of Medical Internet Research
May 4, 2021
Sebastian Hübner, Eline Haijen, Mendel Kaelen et al.
23 citations
Background The resurgence of research and public interest in the positive psychological effects of psychedelics, together with advancements in digital data collection techniques, have brought forth a new type of research design, which involves prospectively gathering large-scale naturalistic data from psychedelic users; that is, before and after the use of a psychedelic compound. A...
International Journal of Environmental Research and Public Health
December 16, 2019
Hannes Kettner, Sam Gandy, Eline Haijen et al.
159 citations
(1) Background: There appears to be a growing disconnection between humans and their natural environments which has been linked to poor mental health and ecological destruction. Previous research suggests that individual levels of nature relatedness can be increased through the use of classical psychedelic compounds, although a causal link between psychedelic use and nature relatedness has not...
J Psychopharmacol
July 11, 2019
Leor Roseman, Eline Haijen, Kelvin Idialu-Ikato et al.
415 citations
Background: Psychedelic therapy is gaining recognition and the nature of the psychedelic experience itself has been found to mediate subsequent long-term psychological changes. Much emphasis has been placed on the occurrence of mystical-type experiences in determining long-term responses to psychedelics yet here we demonstrate the importance of another component, namely: emotional breakthrough....
Frontiers in Pharmacology
November 2, 2018
Adam Hampshire, Christopher Timmermann, Christopher Timmermann et al.
422 citations
Responses to psychedelics are notoriously difficult to predict, yet significant work is currently underway to assess their therapeutic potential and the level of interest in psychedelics among the general public appears to be increasing. We aimed to collect prospective data in order to improve our ability to predict acute- and longer-term responses to psychedelics. Individuals who planned to...
J Psychopharmacol
February 15, 2018
Robin Carhart-Harris, Leor Roseman, Eline Haijen et al.
646 citations
Psychedelic drugs are making waves as modern trials support their therapeutic potential and various media continue to pique public interest. In this opinion piece, we draw attention to a long-recognised component of the psychedelic treatment model, namely ‘set’ and ‘setting’ – subsumed here under the umbrella term ‘context’. We highlight: (a) the pharmacological mechanisms of classic...
Psychopharmacology
November 16, 2017
Eline Haijen, Magı́ Farré, Rafael de la Torre et al.
9 citations
Preclinical data have suggested involvement of the endocannabinoid (eCB) system in MDMA-induced memory impairment. Clinical research has shown that blockade of the 5-HT 2 receptor nulls memory impairment during MDMA intoxication. Interestingly, studies have demonstrated that the eCB and the 5-HT system interact. It was hypothesized that MDMA would cause an increase in eCB concentrations...
Psychopharmacology
August 9, 2017
Robin Carhart-Harris, David Erritzøe, Eline Haijen et al.
268 citations
Psychedelic drugs are creating ripples in psychiatry as evidence accumulates of their therapeutic potential. An important question remains unresolved however: how are psychedelics effective? We propose that a sense of connectedness is key, provide some preliminary evidence to support this, and suggest a roadmap for testing it further.
Sebastian Hübner, Eline Haijen, Mendel Kaelen et al.
2 citations
BACKGROUND The resurgence of research and public interest in the positive psychological effects of psychedelics, together with advancements in digital data collection techniques, have brought forth a new type of research design, which involves prospectively gathering large-scale naturalistic data from psychedelic users; that is, before and after the use of a psychedelic compound. A...