Front Child Adolesc Psychiatry
June 7, 2024
Nadhrah Izmi, Robin Lester Carhart-Harris, Hannes Kettner
23 citations
Adolescents aged 16–24 who self-initiated a psychedelic experience showed significant improvements in psychological well-being four weeks later, with a clinically meaningful average increase of 3.3 points on the Warwick-Edinburgh Mental Wellbeing Scale—similar to changes seen in adults aged 25 and older. However, adolescents reported more challenging acute effects and ego-dissolution, and a higher prevalence of visual symptoms resembling hallucinogen persisting perceptual disorder (73.5% vs. 34.2% in adults), though only one adolescent found these distressing. These findings suggest psychedelic interventions could benefit adolescents but require special attention to risks and treatment design.
Journal of Medical Internet Research
May 4, 2021
Sebastian Hübner, Eline Haijen, Mendel Kaelen et al.
23 citations
In web-based studies that track people before and after they use psychedelics, many participants stop responding, which can bias the results. Analyzing data from 654 initial participants, younger age, lower education, higher extraversion, and lower conscientiousness predicted dropping out before the four-week endpoint. Neither positive attitudes toward psychedelics nor intense challenging experiences during the drug session predicted dropout. These attrition patterns match those seen in other long-term studies, suggesting they are not unique to psychedelic research. The absence of dropout linked to psychedelic advocacy or negative drug experiences reduces concerns about certain biases in this type of data.
Scientific reports
July 17, 2024
Sara de la Salle, Hannes Kettner, Julien Thibault Lévesque et al.
21 citations
A prospective longitudinal survey of eight Canadians with cancer who received legal psilocybin-assisted psychotherapy under Section 56 exemptions found significant improvements in anxiety, depression, pain, fear of COVID-19, quality of life, and spiritual well-being two weeks after the session. Attitudes toward death, medical assistance in dying, and desire for hastened death remained unchanged. Most participants found the sessions highly meaningful, though one reported a substantial decrease in well-being. These preliminary data suggest that real-world psilocybin-assisted psychotherapy can produce psychiatric benefits similar to those in clinical trials, but limited enrollment and negative experiences indicate a need for formal real-world evaluation programs.
Am J Geriatr Psychiatry
May 19, 2024
Hannes Kettner, Leor Roseman, Adam Gazzaley et al.
18 citations
Guided psychedelic group sessions improve well-being in older adults (age 60+) similarly to younger adults, but through different mechanisms. Acute psychedelic effects are less intense in older adults and do not predict later well-being changes, whereas relational experiences before and after the sessions do predict improvements. Among older adults, having a lifetime psychiatric diagnosis was linked to greater well-being increases at the four-week follow-up. These findings suggest that the social and relational aspects of psychedelic group therapy may be especially important for older adults, warranting further research into psychedelic interventions for this population.
Journal of Psychopharmacology
January 1, 2023
Matthias Forstmann, Christina Sagioglou, Alexander Irvine et al.
18 citations
Among people who have used psychedelics, only past use of psilocybin—not LSD, mescaline, Salvia divinorum, ketamine, ibogaine, or DMT—reliably predicted a stronger sense of connection to nature (nature relatedness). The finding held even when people who had never used psychedelics were included in the analysis. For those who had used only psilocybin, more frequent use was linked to higher nature relatedness. This suggests that psilocybin may have a unique association with nature relatedness, possibly due to its pharmacology or the contexts in which it is used.
July 7, 2022
Richard J. Zeifman, Meg J. Spriggs, Hannes Kettner et al.
13 citations
preprint
The Relaxed Beliefs Under pSychedelics (REBUS) model suggests that psychedelics reduce the strength of deeply held beliefs. In a preliminary test of this idea, 11 healthy adults received a low (1 mg) and a high (25 mg) dose of psilocybin four weeks apart. Confidence in negative self-beliefs decreased after the high dose but not after the low dose. Greater brain signal entropy and stronger subjective effects during the high dose correlated with larger decreases in negative belief confidence, both during the session and four weeks later. Reduced confidence in negative beliefs was strongly linked to improved well-being at the four-week follow-up. These findings provide initial psychological support for the REBUS model, though replication in larger and clinical samples is needed.
Journal of affective disorders
February 1, 2025
Grant Jones, Matthew X Lowe, Sandeep Nayak et al.
12 citations
Psilocybin, the psychoactive compound in magic mushrooms, is linked to improved mental wellbeing on average, but few studies examine how effects differ by race. In a large online longitudinal study of 2,833 people planning naturalistic psilocybin use, race/ethnicity moderated changes in spiritual wellbeing, cognitive flexibility, and emotion regulation (expressive suppression) at 2–3 months post-experience, but not at 2–4 weeks. Participants of Color reported minor differences in context and subjective effects, such as being more likely to set an intention before use. Both groups showed comparable reductions in anxiety and depression, with no significant moderation by race.
Psychol Med
September 27, 2024
Michael Angyus, Sarah Osborn, Eline Haijen et al.
10 citations
A 9-item scale called the Imperial Psychedelic Predictor Scale (IPPS) can predict key features of the acute psychedelic experience. The scale has three factors: set (mindset), rapport (relationship with the guide or setting), and intention. In a controlled administration dataset, set and rapport together explained 40% of the variance in mystical experiences, while set alone explained 16% of the variance in challenging experiences. In another controlled dataset, rapport explained 9% of the variance in emotional breakthrough. The scale shows good internal consistency and predicts mystical, challenging, and emotional breakthrough experiences across naturalistic and controlled settings.
PNAS nexus
April 1, 2025
Katie Zhou, David de Wied, Robin L Carhart-Harris et al.
9 citations
Delusional ideation decreased one month after a planned psychedelic experience, while magical thinking showed no change. Over 30% of participants reported hallucinogen persisting perception disorder (HPPD)-type effects at four weeks, though fewer than 1% found them distressing. Younger age, female gender, a history of psychiatric diagnosis, and baseline trait absorption predicted HPPD-like effects. Lifetime psychedelic use at baseline correlated positively with both magical thinking and delusional ideation, suggesting these traits may correlate with psychedelic use rather than being caused by it.
Frontiers in psychiatry
January 1, 2024
Matthew X Lowe, Hannes Kettner, Del R P Jolly et al.
9 citations
Ceremonial ayahuasca use is associated with significant improvements in mental health, well-being, and psychological functioning among Middle Eastern and North African (MENA) immigrants and refugees. In a longitudinal online survey of 15 primarily female participants, reductions in depression, anxiety, and shame were reported, along with increases in cognitive reappraisal and self-compassion. Most participants reported no lasting adverse effects and experienced positive behavioral changes persisting months after ingestion. The findings suggest naturalistic ayahuasca use might hold therapeutic potential for MENA populations exposed to trauma prior to and during migration, though data are preliminary.
PsyArXiv
October 17, 2023
Alessia Marrocu, Hannes Kettner, Brandon Weiss et al.
9 citations
preprint
About 16% of people who used psychedelics in naturalistic settings experienced a clinically meaningful decline in psychological well-being four weeks later. Those with a prior personality disorder diagnosis were disproportionately affected, making up 31% of negative responders and facing more than a four-fold elevated risk of adverse psychological responses. The findings suggest that personality disorders may heighten vulnerability to negative outcomes from psychedelic use, highlighting the need for careful screening and robust psychological support.
November 15, 2022
Katie Zhou, D. de Wied, Robin Carhart‐Harris et al.
8 citations
preprint
About a third (32.7%) of people reported symptoms of hallucinogen persisting perception disorder (HPPD) four weeks after a real-world psychedelic experience, but only 2.94% found those symptoms distressing. Delusional ideation was slightly higher among those with more lifetime psychedelic use at baseline, yet it decreased significantly four weeks after the experience, suggesting the baseline correlation may not be causal. Younger age, female gender, a personality trait called absorption, less non-psychedelic substance use in the prior six months, and using psychedelics outside a retreat setting predicted HPPD-like symptoms. The findings are limited by the observational design.
Journal of psychoactive drugs
June 28, 2025
Laura C Carvalho, Jorge Encantado, Hannes Kettner et al.
6 citations
A review of 103 naturalistic psychedelic studies found that most used cross-sectional surveys, ayahuasca was the most studied substance (66%), and ceremonial settings were the most common context (35.9%). Sample characteristics were widely reported but varied considerably, while specific contextual details like music were often missing. The authors call for systematic reporting standards to improve the value of real-world psychedelic research alongside clinical trials.
Frontiers in Psychology
June 6, 2025
William Roseby, Hannes Kettner, Leor Roseman et al.
6 citations
Psychedelics like psilocybin strongly increase the sense that life has meaning, based on three different studies: a clinical trial for depression, a healthy volunteer study, and naturalistic retreats. The 'presence of meaning' rose substantially after a psychedelic experience, while the 'search for meaning' dropped only slightly. These meaning enhancements were moderately linked to improvements in mental health, such as greater wellbeing and reduced depression. Mystical, ego dissolution, and emotional breakthrough experiences were associated with increased meaning, though the strength varied by context. The evidence converges to show a robust, lasting positive effect of psychedelics on meaning in life, with context influencing outcomes.
Research square
March 8, 2024
Hannes Kettner, Leor Roseman, Adam Gazzaley et al.
5 citations
Older adults (age 60+) who participated in a guided psychedelic group retreat showed significant improvements in well-being, with larger gains among those with a prior psychiatric diagnosis. Compared to younger adults, older adults experienced weaker acute psychedelic effects, and these effects did not predict well-being changes. Instead, a sense of communitas—the relational or social connection during the group session—predicted well-being improvements in older adults, suggesting that the social context of psychedelic therapy may be especially important for this age group.
Brain and Behavior
July 1, 2025
Megan Calnan, Grace Blest‐hopley, Chris Busch et al.
4 citations
Military veterans who attended psilocybin or ayahuasca retreats showed significant improvements in eight measures of mental health and community reintegration, with the largest gains in depression (29.1% reduction on the PHQ-9) and PTSD (26.1% reduction on the PCL-5). Psilocybin retreats produced greater improvements on seven of eight outcomes, while ayahuasca retreats yielded slightly larger PTSD reductions (26.4% vs. 24.8%). Male participants improved more on all outcomes except PTSD, where females showed a larger reduction (32.1% vs. 24.1%). Veterans with worse initial symptoms benefited most. The findings suggest psychedelic retreats could offer a holistic treatment framework addressing psychological well-being, community factors, and civilian reintegration.
Current Psychiatry Reports
November 1, 2024
Matthew J Reid, Hannes Kettner, Tessa F Blanken et al.
4 citations
Psilocybin is an emerging treatment for depression, but its effects on sleep are not well understood. Clinical trials show large improvements in depressive symptoms, but sleep quality or insomnia symptoms have not been directly studied. Preliminary data indicate that both depressive symptoms and sleep disturbances decreased significantly after psilocybin use, though sleep improvements were smaller than those for depression. More severe sleep disturbances at baseline were linked to a lower probability of depression remission, suggesting a potential interaction between sleep and psilocybin's efficacy. Addressing sleep disturbances could enhance therapeutic outcomes and lead to more personalized treatment strategies.
bioRxiv : the preprint server for biology
August 12, 2024
Lorenzo Pasquini, Alexander J Simon, Courtney L Gallen et al.
4 citations
preprint
The psychedelic DMT rapidly alters consciousness, producing physical transcendence, vivid auditory distortions, and visual imagery. Using simultaneous fMRI and EKG data from 14 healthy volunteers before, during, and after intravenous DMT (versus placebo), a brain substate emerged immediately after injection characterized by deactivations in the hippocampus and medial parietal cortex alongside increased superior temporal lobe activity. Hippocampal and medial parietal deactivations correlated with disruptions in the sense of time, space, and self-referential processes, reflecting a deconstruction of ordinary consciousness. Superior temporal lobe activations correlated with audio/visual hallucinations and the experience of "entities.
Frontiers in Psychiatry
August 6, 2025
Grace Blest‐hopley, Giuseppe Pasculli, Simon Ruffell et al.
3 citations
Veterans with traumatic brain injuries who participated in psilocybin retreats showed improvements in PTSD, depression, and anxiety symptoms four weeks afterward. PTSD scores decreased by 50%, depression scores by 65%, and anxiety scores by 28%. Electroencephalography measurements revealed decreased delta and theta brainwave power in frontal and temporal regions, along with enhanced coherence in alpha and beta bands, suggesting improved cognitive control, emotional processing, and neural communication. The preliminary findings provide a rationale for larger controlled studies.
Research Square
October 15, 2024
Alexandra R. Gordon, Brennan M. Carrithers, Broc A. Pagni et al.
3 citations
Among individuals who reported a personality disorder diagnosis, psychedelic use was associated with improvements in mental health outcomes. In two observational studies, participants showed reductions in anxiety and depression symptoms lasting up to 2-3 months, with moderate to large effect sizes. Suicidal ideation decreased, and no participants moved to high risk of suicidal behavior after use. A small proportion experienced clinically significant worsening of anxiety (up to 8.2%) or depression (up to 7.1%). Transient increases in cognitive flexibility and sustained increases in cognitive reappraisal were observed, with the latter linked to reduced anxiety and depression. The findings are limited by small sample sizes and self-reported data.
Research Square
August 22, 2025
Richard J. Zeifman, George Danias, Gabrielle Agin-Liebes et al.
2 citations
Psychedelics can acutely induce mystical experiences and elevated positive mood, which may contribute to the potential benefits of psychedelic therapy. However, there remains limited understanding of the occurrence and importance of specific positive emotional experiences within psychedelic therapy. Therefore, we examined the effects of psychedelics on positive emotional experiences and their association with improvements in mental health. Methods: Study 1 was an observational study of naturalistic psychedelic use. Study 2 used data from a clinical trial that compared psilocybin with escitalopram in individuals with major depressive disorder.
JMIR formative research
March 4, 2024
Grant Jones, Felipe Herrmann, Adam Bear et al.
2 citations
In a group of people who recently used psychedelics, increases in mindfulness were followed by improvements in well-being. The findings suggest that mindfulness may be a mechanism through which psychedelic experiences lead to positive mental health outcomes.
PsyArXiv
June 25, 2021
Christopher Timmermann, Hannes Kettner, Chris Letheby et al.
2 citations
preprint
Psychedelic use can shift metaphysical beliefs away from materialism and toward panpsychism and fatalism, and these changes persist for at least six months. In a large prospective online survey, participants reported significant belief changes after using psychedelics, with shifts linked to the extent of past use and improved mental health. The belief shifts were moderated by baseline impressionability and mediated by perceived emotional synchrony with others during the experience. Findings were confirmed in an independent controlled clinical trial, suggesting psychedelics causally influence metaphysical beliefs.
Sebastian Hübner, Eline Haijen, Mendel Kaelen et al.
2 citations
Younger age, lower educational levels, lower conscientiousness, and higher extraversion predict dropout in web-based prospective studies of psychedelic use. Baseline attitudes toward psychedelics and the intensity of acute challenging experiences do not predict attrition. These demographic and personality predictors align with those found in longitudinal research in other fields, suggesting that concerns about bias from psychedelic advocacy or negative drug experiences may be less problematic than previously thought.
Imaging Neuroscience
April 16, 2025
Lorenzo Pasquini, Alexander J. Simon, Courtney L. Gallen et al.
1 citation
DMT rapidly induces a short-lasting altered state of consciousness marked by physical transcendence, vivid auditory distortions, and visual imagery. Using simultaneous fMRI and EKG data from 14 healthy volunteers before, during, and after intravenous DMT or placebo, a brain substate emerged immediately after DMT injection, characterized by deactivations in the hippocampus and medial parietal cortex and increased activity in the superior temporal lobe. Hippocampal and medial parietal deactivations correlated with altered sense of time, space, and self-referential processes, reflecting a deconstruction of ordinary consciousness. Superior temporal lobe activations correlated with audio/visual hallucinations and the experience of "entities.