Journal of affective disorders
April 1, 2023
Otto Simonsson, Peter S Hendricks, Richard Chambers et al.
124 citations
Using nationally representative US adult data (N = 2822), most people who have used classic psychedelics (59.1%) never had a challenging, difficult, or distressing experience. However, 8.9% reported functional impairment lasting more than one day from such an experience, and 2.6% sought medical, psychiatric, or psychological help afterward. Co-use of lithium or other mood stabilizers, and certain set and setting factors—including no preparation, disagreeable physical environment, negative mindset, no psychological support, a dose perceived as too large, and a major life event prior—were associated with greater difficulty. Negative mindset, no psychological support, and a major life event prior were also linked to overall risk of harm.
Journal of Psychopharmacology
March 9, 2021
Otto Simonsson, James Sexton, Peter S. Hendricks
75 citations
People who have used a classic psychedelic at least once in their lifetime report better overall health and are less likely to be overweight or obese, based on data from over 171,000 U.S. adults. The study also found a trend toward lower odds of having a heart condition or cancer in the past year among those who had used a classic psychedelic. The findings suggest that classic psychedelics may be linked to better physical health, but the authors note that further research is needed to determine whether the relationship is causal and to explore possible mechanisms.
Scientific Reports
July 13, 2021
Otto Simonsson, Walter Osika, Robin Carhart‐Harris et al.
54 citations
Lifetime use of classic psychedelics is associated with lower odds of heart disease and diabetes. Analyzing data from the National Survey on Drug Use and Health (2005–2014), people who had ever tried a classic psychedelic had 23% lower odds of past-year heart disease and 12% lower odds of past-year diabetes. The associations persisted after adjusting for other factors. The authors suggest classic psychedelic use might benefit cardiometabolic health but call for more research on causal pathways.
JAMA Psychiatry
March 13, 2024
Otto Simonsson, Miriam A. Mosing, Walter Osika et al.
41 citations
Among 16,255 Swedish adolescents, 541 reported past psychedelic use, and 99% of those also used other drugs. After adjusting for other drug use, psychedelic use was associated with fewer psychotic symptoms. However, the link between psychedelic use and manic symptoms depended on genetic vulnerability: adolescents with higher genetic risk for schizophrenia or bipolar I disorder showed more manic symptoms after psychedelic use. The authors urge caution due to study limitations.
Journal of Affective Disorders
January 26, 2024
Ludwig Honk, Cecilia U.D. Stenfors, Simon B. Goldberg et al.
41 citations
Using data from nearly 10,000 adults in the US and UK, psychedelic use over a two-month period was not linked to changes in psychotic symptoms overall. However, among people with a personal or family history of bipolar disorder, psychedelic use was associated with an increase in symptoms. Conversely, those with a personal history of psychotic disorders experienced a decrease in symptoms. These findings suggest that the effects of psychedelics on psychotic symptoms depend on an individual's psychiatric history.
Journal of psychoactive drugs
January 1, 2023
Otto Simonsson, Simon B Goldberg
37 citations
In a representative sample of 953 American adults, those who had used classic psychedelics in their lifetime or reported greater ego dissolution during their most intense psychedelic experience were more likely to also have experience with meditation. Among meditators, higher ego dissolution was linked to more frequent meditation practice. Both lifetime psychedelic use and ego dissolution were associated with enlightenment as a motivation to meditate and with fewer perceived barriers to meditation. Ego dissolution was also tied to finding meditation more effective. Neither psychedelic use nor ego dissolution was associated with a higher likelihood of meditation-related adverse effects. These findings suggest a potential synergy between psychedelics and meditation, but randomized controlled trials are needed to confirm causality.
Hypertension
March 8, 2021
Otto Simonsson, Peter S. Hendricks, Robin Carhart‐Harris et al.
36 citations
Adults who had used a classic psychedelic at least once in their lifetime had 14% lower odds of hypertension in the past year, after adjusting for confounders. The association was strongest for tryptamine psychedelics (DMT, ayahuasca, psilocybin), which were linked to 20% lower odds of hypertension. No significant association was found for LSD or mescaline. The authors note these findings are correlational and call for randomized controlled trials to test causal effects.
Psychopharmacology
July 1, 2025
Otto Simonsson, Simon B Goldberg, Richard Chambers et al.
33 citations
In a US-representative sample of 2,822 adults, lifetime naturalistic psychedelic use was associated with more unusual visual experiences but not with psychotic symptoms in the past two weeks. Among those who had used psychedelics, 1.3% reported a diagnosis of hallucinogen persisting perception disorder. An interaction emerged: individuals with a family history of psychotic or bipolar disorders who used psychedelics reported more psychotic symptoms, while those without such a family history reported fewer. The findings suggest that family history may modify the association between psychedelic use and psychotic symptoms.
Therapeutic advances in psychopharmacology
January 1, 2022
Otto Simonsson, Peter S Hendricks, Richard Chambers et al.
26 citations
In a US-representative sample of 2822 adults, lifetime use of classic psychedelics was linked to healthier tobacco-related and diet-related behaviors. Among the 613 who had used psychedelics, greater psychological insight during their most insightful experience was associated with healthier exercise habits, a healthy body mass index, and diet improvements. Psychological insight was also tied to self-reported health behavior improvements attributed to the psychedelic experience, including alcohol-related changes. The findings suggest that psychological insight during a classic psychedelic experience may promote positive health behavior change and better physical health, especially in weight management, though causality cannot be established.
Int J Neuropsychopharmacol
April 1, 2025
Jacob S Aday, Otto Simonsson, Emmanuelle A D Schindler et al.
25 citations
Classic psychedelics show promise for treating neuropsychiatric disorders, but weak blinding integrity in clinical trials limits the interpretability of therapeutic effects, making alternative active placebos necessary. This review describes drawbacks of current placebos, proposes criteria for suitable active placebos—including acute psychoactive and physiological effects, matched onset and duration, safety, and lack of therapeutic effects for the target disease—and identifies several pharmacological agents that may serve as active placebos for moderate-to-high doses of short- and long-acting psychedelics, as well as low-dose and microdosing regimens. Future research should apply a thoughtful selection process and ancillary strategies to improve blinding.
Psychiatry Research
July 23, 2023
Otto Simonsson, Per Carlbring, Robin Carhart-Harris et al.
24 citations
In a meta-analysis of three psilocybin trials for depression involving 102 participants, clinically significant symptom worsening occurred for a minority of those receiving psilocybin or escitalopram (about 10%) and for a majority of those in the waitlist condition (63.6%). The psilocybin arm showed a lower likelihood of symptom worsening compared to waitlist and no difference compared to escitalopram. The authors note the limitation of a relatively small sample size.
Psychopharmacology
December 11, 2023
Haley Maria Dourron, Charles D Nichols, Otto Simonsson et al.
23 citations
5-MeO-DMT, a tryptamine being developed as an antidepressant, may work through a mechanism distinct from typical psychedelics. This review compares the acute and post-acute effects of 5-MeO-DMT to epileptiform activity, particularly in temporal lobe epileptogenic zones. The authors note that 5-MeO-DMT has notable 5-HT1A receptor agonist properties and that aberrant 5-HT1A receptor functioning occurs in epilepsy. They suggest that 5-MeO-DMT's therapeutic mechanism might be partly mediated by evoking temporary epileptiform activity, similar to electroconvulsive therapy. The phenomenon of 'reactivations'—sudden re-experiencing of drug effects common after 5-MeO-DMT but not typical psychedelics—may indicate recurrent epileptiform activity. The review concludes that further evaluation of 5-MeO-DMT's unique mechanisms is warranted.
Psychiatr Res Clin Pract
February 11, 2025
Jules Evans, Marc Aixalà, Brian T. Anderson et al.
18 citations
Thirty psychedelic researchers identified critical gaps in knowledge about harms from psychedelic use, including how to define those harms, predict them, and treat them effectively. They recommend better online information, peer support groups, affordable therapy, and psychiatric consultation for people experiencing post-psychedelic difficulties. The researchers also call for improved funding for a psychedelic safety net, suggesting that psychedelic philanthropists, investors, and companies commit 1% of their investment to support safety measures such as research and support services. The article outlines practical steps to make the field of psychedelic medicine safer.
International Journal of Environmental Research and Public Health
September 9, 2022
Christin Mellner, Micael Dahlen, Otto Simonsson
18 citations
People who have ever used classic psychedelics (such as LSD or psilocybin) report slightly fewer sick days in the past month than those who have never used them, after accounting for demographics, risky behavior, and other substance use. The analysis of a large, nationally representative US sample (over 400,000 adults) found a small but statistically significant negative association. The authors caution that the finding is correlational and that more research is needed to determine whether psychedelics actually cause reduced sick leave and to understand possible mechanisms.
Psychol Med
March 31, 2025
Otto Simonsson, Simon B. Goldberg, Walter Osika et al.
16 citations
In a large online survey of over 12,000 participants followed for two months, people who used psychedelics outside of medical supervision reported increases in psychotic and manic symptoms. These increases occurred only among those who used psychedelics in an illegal context. The severity of psychotic symptoms rose with more frequent use and more intense challenging experiences, while manic symptoms increased more in individuals with a history of schizophrenia or bipolar I disorder and those who reported a strong sense of insight during their psychedelic experience. The findings suggest that naturalistic psychedelic use in illegal settings may pose risks for certain individuals.
Drug and alcohol dependence
October 1, 2022
Otto Simonsson, Simon B Goldberg, Richard Chambers et al.
16 citations
Among a US-representative sample of 2,822 adults, 613 reported lifetime classic psychedelic use, and 1.5% of those users reported having a seizure while using a classic psychedelic—a rate similar to epilepsy prevalence in the general population. Nearly half of those who had a seizure were also taking antidepressants, mood stabilizers, or opioid replacement therapies at the time. Seizures were more common among respondents with a personal or family history of epilepsy. The findings suggest that classic psychedelic use may elevate seizure risk in certain people, especially those with a personal or family history of epilepsy.
Psychological medicine
April 1, 2024
Otto Simonsson, Walter Osika, Cecilia U D Stenfors et al.
15 citations
People who used psychedelics during a two-month period reported a greater increase in days of mindfulness meditation per week than those who did not. Among psychedelic users, experiencing personal insight during the most intense psychedelic session was linked to larger increases in both mindfulness and loving-kindness or compassion meditation practice. Conversely, more frequent loving-kindness or compassion meditation at the start of the study was associated with less severe feelings of death or dying during the subsequent psychedelic experience. These findings suggest a bidirectional relationship: psychedelics may boost meditation engagement, while meditation may reduce challenging psychedelic experiences.
Mindfulness
April 1, 2023
Charlotta Simonsson, Richard Chambers, Peter S Hendricks et al.
15 citations
People who have used classic psychedelics report meditating more often, specifically mindfulness meditation, but not loving-kindness or compassion meditation. Among those who had a psychedelic experience, both psychological insight and ego dissolution were linked to more frequent practice of both types of meditation. However, when both factors were considered together, only psychological insight predicted higher meditation frequency. These findings, from a survey of 2,822 U.S. adults, suggest that psychedelic experiences—especially those that produce psychological insight—may encourage regular meditation, though causality cannot be established.
Scientific reports
February 19, 2024
Rosalind G McAlpine, Matthew D Sacchet, Otto Simonsson et al.
13 citations
A 21-day self-directed digital course (DIPP) was co-designed to improve psychedelic preparation. The intervention, built on a four-factor model of psychedelic preparedness, was developed through two mixed-methods studies: interviews with 19 past high-dose psilocybin retreat attendees and co-design workshops with 28 current retreat participants. The course includes daily meditation, weekly module exercises, and mood tracking. The authors suggest DIPP offers a scalable, comprehensive tool to enhance safety and therapeutic benefits by addressing knowledge, psychophysical readiness, safety planning, and intention.
Journal of counseling psychology
March 1, 2024
Kevin M Riordan, Otto Simonsson, Corrina Frye et al.
12 citations
A two-week compassion-based meditation program delivered via the Healthy Minds Program app was tested in undergraduates with elevated depression or anxiety (N=351). Participants were randomly assigned to either one 20-minute meditation per day or two 10-minute meditations per day. Both groups showed improvements in psychological distress, experiential avoidance, fear of missing out, loneliness, and self-compassion from before to after the intervention, and daily distress and loneliness also improved over time. No significant differences were found between the two dosing schedules on any measure. When total daily meditation time is equal, distributing practice into shorter sessions does not affect outcomes for distressed beginners.
International Journal of Environmental Research and Public Health
July 1, 2022
Elin Pöllänen, Walter Osika, Otto Simonsson et al.
12 citations
People who have used classic psychedelics tend to report less speciesism and more solidarity with animals, though no link was found with their desire to help animals. Among those who used psychedelics, stronger ego dissolution during their most intense experience was associated with less speciesism, more animal solidarity, and a greater desire to help animals. These associations come from a large US-representative sample of 2,822 adults. The authors caution that the findings do not demonstrate causality and call for longitudinal studies to explore whether psychedelic use directly influences human–animal relations.
JAMA Health Forum
November 1, 2024
Otto Simonsson, Matthew W. Johnson, Peter S. Hendricks
10 citations
Psychedelic and MDMA therapies carry potential risks that must be better understood to ensure safe and ethical practice. This viewpoint identifies four key research goals: characterizing adverse effects, understanding how context influences outcomes, developing risk mitigation strategies, and establishing guidelines for safe administration. The authors argue that rigorous investigation of these risks is essential before widespread clinical adoption, emphasizing that safety concerns should be addressed proactively rather than reactively.
Mindfulness
September 1, 2023
Richard Chambers, Devon Stoliker, Otto Simonsson
10 citations
Mindfulness-Based Cognitive Therapy (MBCT) may be a valuable complement to psychedelic-assisted psychotherapy, potentially offering advantages over Acceptance and Commitment Therapy (ACT). This narrative review demonstrates that MBCT targets core processes such as acceptance, being present, concentration, decentering, and embracing difficulties. Strengthening these capacities through systematic meditation training may prove invaluable during the preparation, dosing, and integration phases of psychedelic-assisted psychotherapy. MBCT's emphasis on systematic mindfulness training and nonjudgmental presence aligns with psychedelic-induced states of consciousness, suggesting it may enhance navigation of challenging experiences during and after psychedelic sessions in ways ACT may not fully address.
Scientific Reports
September 30, 2023
Alexander V. Lebedev, Kasim Acar, Otilia Horntvedt et al.
9 citations
People who have used psychedelics are moderately more likely to endorse alternative facts and to believe that facts are politically influenced, compared with people who have never used them. This association held after accounting for demographics, psychiatric conditions, and other drug use. No link was found between psychedelic use and preferring intuition over evidence when verifying facts. Among other drugs examined, only alcohol showed a negative association with belief in alternative facts. The findings suggest that psychedelic use correlates with non-conformist thinking styles, which may stem from the drugs' psychological effects or from a shared trait predisposing people to unconventional beliefs and illicit substance use.
Journal of affective disorders
July 9, 2025
Otto Simonsson, Peter S Hendricks, Caroline M Swords et al.
8 citations
In a large observational study of US adults aged 18–50, naturalistic psychedelic use was modestly linked to increased depressive symptoms over time. Among 12,345 participants followed longitudinally, 505 reported psychedelic use. Those who used psychedelics in a 'risk context'—such as a negative mindset or lack of psychological support—showed a moderate increase in depressive symptoms compared to non-users and to users without such risks. This association was explained by more challenging psychedelic experiences in that context. The findings indicate that psychedelic use outside controlled therapeutic settings may not be generally beneficial and could worsen depressive symptoms under certain conditions.