Journal of Psychopharmacology
September 20, 2024
Abigail E Calder, Benjamin Rausch, Matthias E Liechti et al.
17 citations
In Switzerland, where psychedelic-assisted therapy (PAT) is permitted under a limited medical use program, patients receiving PAT and healthy volunteers given LSD or psilocybin reported similar overall drug effects and mystical experiences. However, patients reported lower ratings of ego dissolution. Depressive symptoms, measured by the Montgomery-Åsberg Depression Rating Scale, significantly decreased in patients. The strongest predictor of antidepressant improvement was relaxation during the session, while mystical-type experiences did not predict antidepressant effects. Most patients had mild adverse effects that resolved within 48 hours. Hourly assessments of drug effects may better predict clinical outcomes than retrospective measures of mystical experience.
Current topics in behavioral neurosciences
April 29, 2025
Abigail E Calder, Vincent J Diehl, Gregor Hasler
14 citations
Psychedelic experiences that involve extreme horror, helplessness, or perceived threats can be traumatizing. Such traumatic psychedelic experiences are rare, extreme, and largely preventable, arising from frightening drug effects, unsafe settings, or the emergence of pre-existing trauma. While some people recover quickly, others develop prolonged anxiety, sleep disturbances, derealization, or other trauma-related symptoms. The chapter covers causes, phenomenology, potential outcomes, prevention, and strategies to minimize negative impact.
Biological psychiatry global open science
March 1, 2025
Abigail E Calder, Clifford Qualls, Gregor Hasler et al.
5 citations
The Hallucinogen Rating Scale (HRS) is a widely used questionnaire for measuring subjective effects of psychedelics and other psychoactive drugs. By analyzing 991 questionnaires from 18 studies involving 13 substances, researchers identified 8 factors with good internal consistency that map onto psychedelic effects. The factor model fit the data better than previous models and showed dose responses for most drugs. Patterns on the 8 factors clearly distinguished classic psychedelics (psilocybin, DMT) from dissociatives (ketamine, salvinorin A), empathogens (MDMA), stimulants (methylphenidate, amphetamine), and THC. The meaningfulness factor uniquely differentiated psychedelics from all other substances, supporting the HRS as a psychometrically sound tool for measuring drug-induced altered states.
Journal of psychopharmacology (Oxford, England)
May 1, 2026
Vincent J Diehl, Abigail E Calder, Gregor Hasler
A new questionnaire, the Helioscope Questionnaire, measures how psychedelics such as psilocybin and MDMA alter the processing of traumatic memories during an experience, a process called the helioscope effect. In an online survey of 468 people who had used psychedelics or MDMA, the 21-item scale captured three factors: protection, exposure, and avoidant-distress. A composite score from protection and exposure subscales predicted positive changes in mood and attitude afterward, while avoidant-distress predicted negative changes. Having a trip sitter was linked to stronger protection and exposure scores, and MDMA use was linked to less avoidant-distress. The scale adds a new way to assess therapeutic mechanisms beyond existing measures.