The Journal of Nervous and Mental Disease
March 4, 2014
Peter Gasser, Dominique Holstein, Yvonne Michel et al.
752 citations
In a small pilot study, 12 patients with anxiety related to life-threatening diseases underwent two sessions of LSD-assisted psychotherapy, receiving either a full 200-microgram dose or a low 20-microgram active placebo, with the placebo group later crossing over to the full dose. At a 2-month follow-up, trait anxiety decreased with a large effect size, and state anxiety also dropped significantly. These anxiety reductions persisted for 12 months. No serious adverse effects occurred beyond one day after treatment. The findings suggest that, under careful medical supervision, LSD can reduce anxiety, supporting the need for larger controlled trials.
Journal of Psychopharmacology
November 11, 2014
Peter Gasser, Katharina Kirchner, Torsten Passie
458 citations
In patients with anxiety linked to life-threatening diseases, LSD-assisted psychotherapy produced lasting benefits. Twelve months after treatment, none of the ten participants reported adverse reactions, and significant reductions in anxiety (measured by the STAI) were sustained. Qualitative interviews revealed that most participants experienced insightful, cathartic, and interpersonal encounters; 77.8% reported reduced anxiety and 66.7% reported improved quality of life. Subjective accounts pointed to facilitated access to emotions, confrontation of unknown anxieties and resources, and intense peak experiences as key psychological mechanisms. These experiences helped restructure emotional trust, situational understanding, habits, and worldview. The findings suggest that medically supervised LSD therapy can be safe and yield enduring benefits.
Biological Psychiatry
November 29, 2014
Yasmin Schmid, Florian Enzler, Peter Gasser et al.
425 citations
Lysergic acid diethylamide (LSD), a well-known hallucinogen, significantly influenced mood and perception in a recent crossover study involving 60 participants. Those receiving LSD reported a 70% reduction in feelings of derealization and depersonalization compared to a placebo. Additionally, serotonin receptor activity was linked to improved prepulse inhibition, suggesting potential benefits for psychosis and schizophrenia. While heart rate increased by 15% and blood pressure rose moderately, adverse effects remained minimal, highlighting the need for further exploration of psychedelics in clinical psychology and psychiatry.
Biological psychiatry
February 1, 2023
Friederike Holze, Peter Gasser, Felix Müller et al.
294 citations
LSD-assisted therapy produced long-lasting reductions in anxiety and comorbid depression symptoms up to 16 weeks in patients with anxiety related to a life-threatening illness. In a double-blind, placebo-controlled crossover trial with 42 patients, LSD treatment led to significant decreases in anxiety scores compared to placebo, with a large effect size. Similar improvements were seen in depression ratings. Positive acute subjective drug effects and mystical-type experiences correlated with long-term anxiety reductions. Mild, transient side effects occurred in 19% of patients, and one serious adverse event (acute transient anxiety) was reported.
Progress in neuro-psychopharmacology & biological psychiatry
February 2, 2018
Simon Reiche, Leo Hermle, Stefan Gutwinski et al.
125 citations
Anxiety and depression are common in people with life-threatening diseases, harming quality of life and prognosis. Serotonergic hallucinogens like LSD and psilocybin were first studied in the 1960s, and interest has recently revived. A systematic review of clinical trials from 1960 to 2017 identified 11 eligible trials with 445 participants: 7 on LSD (323 participants), 3 on psilocybin (92), and 1 on DPT (30). Four more recent randomized controlled trials (104 participants) had higher methodological quality than earlier studies. Evidence supports that these substances reduce anxiety and depression in patients with life-threatening diseases, with anecdotal reports of improved quality of life and reduced fear of death. Side effects were low in studies following safety guidelines.
Frontiers in Psychiatry
February 3, 2021
Sara Tai, Elizabeth M. Nielson, Molly Lennard-Jones et al.
87 citations
A therapist training program for psilocybin therapy, developed for a phase IIb international, multicenter, randomized controlled study of treatment-resistant depression, is described. The manualized approach, based on evidence-based psychotherapeutic methods and approved by the FDA, includes online learning, in-person training, applied clinical training, and ongoing mentoring. After training 65 health care professionals across the US, Canada, and Europe, feedback indicated that didactic and experiential learning helped build conceptual understanding and skills. Clinical training and participant care under experienced therapists were most beneficial and challenging. Rigorous, scalable training requires collaboration among public, academic, and industry partners.
Journal of Psychopharmacology
October 8, 2020
Yasmin Schmid, Peter Gasser, Peter Oehen et al.
82 citations
Lysergic acid diethylamide (LSD) and 3,4-methylenedioxymethamphetamine (MDMA) are being reinvestigated as treatments for psychiatric disorders. In Switzerland, a compassionate use program allowed 18 patients (12 women, 6 men, aged 29–77) with posttraumatic stress disorder and major depression to receive LSD (100–200 µg) or MDMA (100–175 mg) in group settings from 2014–2018. Drug-assisted sessions occurred about every 3.5 months after 3–10 psychotherapy sessions. LSD produced pronounced alterations of consciousness and mystical-type experiences, with effects largely comparable to those in patients or healthy subjects treated alone in research settings. The data may inform further controlled studies of substance-assisted psychotherapy.
Frontiers in Psychiatry
April 25, 2022
Peter Oehen, Peter Gasser
70 citations
In Switzerland, a restricted medical use of scheduled psychotropic drugs is permitted for treatment-resistant conditions with preliminary evidence of efficacy. Since 2014, clinicians have obtained 50 licenses and developed a psychedelic-assisted group therapy model using MDMA and LSD. Most patients had chronic complex post-traumatic stress disorder (c-PTSD), dissociative, and other post-traumatic disorders. The model uses MDMA first to enhance motivation and therapeutic alliance, then introduces LSD to deepen processing once emotional regulation and trauma tolerance improve. Most participants improved by clinical judgment, with no serious adverse events. C-PTSD required more psychedelic sessions than single-trauma PTSD. Recurrent depression was a frequent problem needing special attention.
The British journal of psychiatry : the journal of mental science
September 1, 2024
Friederike Holze, Peter Gasser, Felix Müller et al.
32 citations
A long-term follow-up of a double-blind, placebo-controlled crossover trial found that LSD-assisted therapy produced sustained reductions in anxiety and depression for up to 94 weeks after the last treatment. Participants who received LSD first showed a decrease of 21.6 points on the State-Trait Anxiety Inventory, and those who received LSD second showed a decrease of 16.5 points, both statistically significant. Comorbid depression also improved, with Beck Depression Inventory scores dropping by 8.1 and 8.9 points in the two groups. Personality traits shifted toward lower neuroticism and higher extraversion. Patients attributed lasting positive effects to the psychedelic experience.
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.
Psychedelic Harm Reduction
January 1, 2026
Michael Koslowski, Peter Gasser
6 citations
Psychedelic substances show therapeutic promise but can cause distressing episodes known as challenging experiences or bad trips. Three case reports illustrate the problem and inform strategies for management. A stepwise approach is outlined, including helpful interventions, supportive care, and rescue medication, to ensure well-being and prevent complications or long-term harm.
Journal of psychopharmacology (Oxford, England)
June 10, 2025
Torsten Passie, Anja Loizaga-Velder, Alicia Danforth et al.
4 citations
A consensus-based model curriculum for education and training in substance-assisted psychotherapy (SAP) covers theoretical topics and practical components including apprenticeship observation, ongoing clinical supervision, and self-experience for trainees. The model, developed by authors with extensive SAP experience, also addresses peer and conventional supervision, respect for intercultural differences, and teachings about indigenous use of related substances. It is largely adapted to western industrialized countries with established graduate-level psychotherapy training. The curriculum may be valuable for psychedelic researchers, those training therapists for research studies, and those preparing for clinical work outside research settings.
Journal of Psychopharmacology
March 31, 2025
Tomislav Majić, Timo Torsten Schmidt, Anna Gröticke et al.
4 citations
A new questionnaire called the Afterglow Inventory (AGI) reliably measures pleasant psychological effects that can occur days after a psychedelic experience, such as with psilocybin or LSD. The AGI captures five distinct dimensions: vitality, transpersonal aspects, inspiration/creativity, interpersonal relationships, and relationship to nature. In an international online survey of 1,323 people who had recently used a psychedelic and 157 controls, the AGI successfully distinguished between the two groups. Stronger and more positive acute psychedelic experiences were associated with higher afterglow scores. This tool may help researchers understand how short-term afterglow effects connect to longer-term therapeutic outcomes.
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.
Frontiers in psychiatry
January 1, 2025
Peter Gasser, Matthias E Liechti, Friederike Holze
2 citations
A 64-year-old man with traumatic life experiences and neuropathic pain from chemotherapy was treated with LSD and MDMA. Initial 200 µg LSD doses produced no acute effects, but 400 µg doses led to subjective effects and lasting therapeutic benefits. Switching to MDMA—both high doses (150-175 mg) and repeated low doses (12.5-25 mg)—resulted in marked improvements in neuropathic pain that persisted after treatment stopped. MDMA mini/microdosing has not been widely studied; this case documents benefits of low-dose MDMA for pain disorders, though further research is needed.
October 22, 2024
Tomislav Majić, Timo Torsten Schmidt, Anna Gröticke et al.
1 citation
preprint
A new questionnaire called the Afterglow Inventory (AGI) was developed and validated to measure the pleasant, temporary psychological effects that sometimes follow the acute phase of a psychedelic experience. An international online survey of 1,323 people who had taken a psychedelic and 157 who had taken a non-psychedelic substance in the past four weeks identified five key factors: vitality, transpersonal aspects, inspiration/creativity, interpersonal relationships, and relationship to nature. The 24-item AGI successfully distinguished psychedelic users from controls, and its overall score was positively correlated with the intensity and positive valence of the acute effects. The AGI may help researchers better understand how acute, subacute, and long-term effects of psychedelics relate to each other.