Frontiers in Pharmacology
November 8, 2017
Rainer Kraehenmann, Dan Pokorný, Helena Aicher et al.
115 citations
Lysergic acid diethylamide (LSD) increases primary process thinking—an early, implicit, associative, and automatic mode of thinking typical of dreaming—via activation of serotonin 2A (5-HT2A) receptors. In a placebo-controlled experiment with 25 healthy subjects, LSD (100 mcg orally) significantly raised the primary index, a measure of primary process thinking, compared with placebo. This increase correlated with feelings of disembodiment and a blissful state. Both the rise in primary process thinking and altered states of consciousness were fully blocked by the 5-HT2A receptor antagonist ketanserin, indicating that 5-HT2A receptor activation is necessary for these effects. Primary process thinking appears to organize inner experiences during both dreams and psychedelic states.
Journal of Affective Disorders Reports
February 6, 2021
Jerome Sarris, Daniel Perkins, Lachlan Cribb et al.
72 citations
Among 1,571 people who reported depression and 1,125 who reported anxiety at the time of consuming ayahuasca, 78% of those with depression said their symptoms were 'very much' improved (46%) or 'completely resolved' (32%), while 70% of those with anxiety reported 'very much' improvement (54%) or complete resolution (16%). Greater improvement was linked to mystical experiences, more ayahuasca sessions, and personal psychological insights. A small minority—2.7% with depression and 4.5% with anxiety—reported worsened symptoms. The authors note this cross-sectional survey cannot establish treatment efficacy and call for randomized controlled trials.
Psychoactives
April 16, 2024
Daniel Meling, Rebecca Ehrenkranz, Sandeep M. Nayak et al.
26 citations
Psychedelic research has returned after a period of suppression, but media coverage now often overstates benefits as much as it once overstated risks. The actual evidence is more mixed than commonly portrayed, so conclusions about effectiveness remain preliminary. Poor communication may mislead patients and misinform policy. This article reviews studies on psychedelics for depression, noting that effect sizes for other depression treatments—cognitive behavioral therapy, mindfulness, SSRIs, and ketamine—have decreased over time as trials improved. The authors suggest the same may happen for psychedelics: larger, better-controlled trials will likely show smaller, more realistic benefits. Clear communication is essential to set public expectations and guide policy.
Die Psychotherapie
February 15, 2024
Helena Aicher, Yasmin Schmid, Peter Gasser
20 citations
Since the late 1990s, psychedelics have experienced a renaissance, attracting increasing international attention. Scientific studies increasingly examine the possibilities and risks of psychedelic-assisted therapy (PAT). Since 2014, based on exceptional permits from the Swiss health authority (BAG), LSD, MDMA, and psilocybin have been used therapeutically within limited medical applications on a case-by-case basis. Over the past nine years, more than 1000 exceptional permits have been granted to about 60 therapists, and an estimated 2000 to 3000 treatments with psychedelics have been conducted.
Swiss Archives of Neurology Psychiatry and Psychotherapy
May 18, 2024
Helena Aicher, Peter Gasser
17 citations
Switzerland played an early and notable role in the 21st-century revival of psychedelic science, which has generated growing global interest in using psychedelics for research and therapy. In 2023, the Swiss Interest Group for Psychedelic-assisted Therapy was formed to establish a clear, widely accepted framework for such work. The group produced a first draft of treatment recommendations (S1 guidelines) that will be regularly updated to reflect new research and therapeutic findings.
Neuroscience Applied
January 1, 2025
Matthias E. Liechti, Peter Gasser, Helena Aicher et al.
16 citations
Switzerland's limited access program for psychedelic/MDMA-assisted therapy, started in 2014 with two physicians, had grown to about 100 physicians by 2024, treating 723 patients (245 with MDMA, 130 with LSD, 348 with psilocybin). Approximately 1660 treatments occurred in 2024, with patients typically receiving 2-4 sessions within 12 months. The program is authorized by the Swiss Federal Office of Public Health for patients with mostly incurable diseases where the substance can alleviate suffering and no alternatives exist or have failed. The article describes the program's history, legal requirements, costs, professional roles, education, patient characteristics, outcomes, and adverse effects, comparing it to similar programs in Canada and Australia.
Journal of Psychopharmacology
September 27, 2024
Daniel Meling, Klemens Egger, Jovin Mueller et al.
15 citations
In a double-blind, placebo-controlled study over a 3-day meditation retreat, 40 experienced meditators received either DMT-harmine or a placebo. Those who took DMT-harmine reported greater mystical-type experiences, non-dual awareness, and emotional breakthrough during the acute substance effects, and greater psychological insight one day later after adjusting for baseline differences. Mindfulness and compassion did not differ significantly between groups. At one-month follow-up, the DMT-harmine group rated their experience as more personally meaningful, spiritually significant, and well-being-enhancing than the placebo group. The findings suggest specific synergistic effects of DMT-harmine during meditation.
Journal of psychoactive drugs
November 23, 2024
Daniel Perkins, Jerome Sarris, Tessa Cowley-Court et al.
5 citations
People who consume ayahuasca in naturalistic settings—religious, traditional, or non-traditional—report better current mental health and greater psychological well-being, according to a large online survey of 7,576 participants from over 50 countries. More lifetime ayahuasca uses were linked to better mental health scores, and this association remained strong even after accounting for other factors and did not fade over time. Strong mystical experiences, self-insights, and community or social support were also tied to better mental health and well-being, whereas acute extreme fear during sessions and difficulty integrating the experience were linked to poorer outcomes. These patterns held for individuals both with and without a history of mental illness.
Die Psychotherapie
February 8, 2024
Helena Aicher, Peter Gasser
3 citations
Early study results suggest potential for psychedelics and MDMA in treating affective disorders. This paper argues that therapist training is crucial for safe and effective use in psychedelic-assisted therapy (PAT). Different contexts, such as study settings or psychotherapeutic practice, require different qualifications. For example, the responsibilities of sitter and therapist must be distinguished, with implications for training programs. This diversity is reflected in existing international offerings. Current practice in Switzerland is based on exceptional permits from the health authority for limited medical use of LSD, MDMA, and psilocybin.
bioRxiv (Cold Spring Harbor Laboratory)
December 9, 2025
Maria Niedernhuber, Dila Suay, Michael J. Mueller et al.
1 citation
Classic serotonergic psychedelics strongly alter conscious awareness, but how they change the temporal structure of brain activity has been unclear. In a double-blind, placebo-controlled study with 25 participants using high-density EEG, an ayahuasca-inspired formulation (intranasal N,N-DMT and buccal harmine) accelerated neural dynamics: microstate duration decreased and state transitions became more frequent. Surprisingly, the sequence of microstates became less random, showing higher first-order Markov structure. This restructuring involved reduced transitions into one state (M2) and increased prevalence and accessibility of two others (M3 and M5). The psychedelic state thus produces a syntactically reconfigured, highly metastable neural dynamic, not mere randomization.
Frontiers in Psychiatry
April 1, 2026
Jonathan Stellmacher, Christopher Schmidt, Helena Aicher et al.
Therapists in Switzerland who provide psychedelic-assisted therapy (PAT) adapt psychotherapeutic techniques to the psychedelic context but retain similarities to non-psychedelic practices. The psychedelic and psychotherapeutic elements work synergistically, amplifying general therapeutic factors such as trust, a sense of profundity, and the emergence of therapeutic experiences. Therapists agreed that psychedelics act as unspecific catalysts for psychotherapeutic processes, while also acknowledging unique interactions between the drug and therapy. For specific indications, incorporating psychedelics into long-term psychotherapy may strengthen therapeutic processes.
December 10, 2025
Johannes Jungwirth, Samuel Westenhöfer, Helena Aicher et al.
In a real-world clinical setting in Switzerland, 19 patients with treatment-resistant depression received one to four doses of psilocybin (20–35 mg). Depression severity, measured by the Montgomery–Åsberg Depression Rating Scale and the Beck Depression Inventory II, showed significant and clinically meaningful reductions from before to after treatment. Response rates were 33.3% and remission rates 22.2% on one scale; on the other, both were 27.8%. No serious adverse events occurred, and multiple dosing did not add benefit. These response and remission rates are lower than those seen in earlier controlled trials, but the findings provide some of the first real-world evidence for psilocybin's antidepressant effects.
Universität Zürich, ZORA
October 10, 2025
Wolfgang Emanuel Zürrer, Lionel Wettstein, Helena Aicher et al.
Salvinorin A, the main psychoactive compound in Salvia divinorum and a potent kappa opioid receptor agonist, has been tested in animal models of pain, stroke, addiction, and depression. It shows anti-nociceptive, anti-inflammatory, neuroprotective, and anti-addictive effects. However, findings on depression are inconsistent, with both antidepressant and depressogenic outcomes reported. Toxicity data indicate anxiogenic effects and motor and cognitive impairment, with minimal impact on vital parameters. Pharmacokinetic data show rapid onset, fast peak, and a half-life of about one hour. Sixteen structurally distinct analogues were identified with potentially improved safety and pharmacokinetic profiles.