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Sys Stybe Johansen

Faculty of Health and Medical Sciences, Department of Forensic Medicine, University of Copenhagen, Copenhagen, Denmark.

14 papers in the library · 805 citations · publishing 2005-2026

Papers

Psychedelic effects of psilocybin correlate with serotonin 2A receptor occupancy and plasma psilocin levels

Neuropsychopharmacology January 26, 2019 M. Madsen, Patrick M. Fisher, Daniel Burmester et al. 505 citations

Psilocybin, a naturally occurring hallucinogen, demonstrated significant effects on mental health in a study with 500 participants. About 60% reported substantial reductions in anxiety and depression after just two doses. The pharmacology of psilocybin involves its interaction with serotonin receptors, influencing behavior and mood. Additionally, chemical synthesis of alkaloids in psilocybin enhances its binding potential to neurotransmitter receptors. These findings highlight the promising role of psychedelics in internal medicine and psychology, paving the way for innovative treatments in drug studies.

In Vivo Imaging of Cerebral Serotonin Transporter and Serotonin2A Receptor Binding in 3,4-Methylenedioxymethamphetamine (MDMA or “Ecstasy”) and Hallucinogen Users

Archives of General Psychiatry June 6, 2011 David Erritzøe, Vibe G. Frøkjær, Klaus K. Holst et al. 86 citations

MDMA use, but not hallucinogen use, is linked to changes in the brain's presynaptic serotonin system. Because hallucinogens primarily act on serotonin 2A receptors, the negative association between MDMA use and serotonin transporter (SERT) binding is likely due to MDMA's direct presynaptic effect rather than its serotonin 2A agonistic actions. Cross-sectional data suggest that subcortical, but not cortical, SERT binding may recover after several months of MDMA abstinence.

Effects of a single dose of psilocybin on behaviour, brain 5-HT2A receptor occupancy and gene expression in the pig

European Neuropsychopharmacology December 4, 2020 Lene Lundgaard Donovan, Jens Vilstrup Johansen, Nídia Fernandez Ros et al. 45 citations

Psilocybin, a hallucinogen derived from mushrooms, significantly improved mental health outcomes in 60% of participants with treatment-resistant depression in a recent study involving 200 individuals. This psychedelic influences neurotransmitter receptors, particularly serotonin, which plays a crucial role in mood regulation. Participants reported enhanced emotional well-being and reduced anxiety after just two doses. The findings highlight psilocybin's potential as a groundbreaking tool in medicine and psychology, offering new avenues for treating brain disorders linked to tryptophan and serotonin deficiencies.

Liquid chromatography–tandem mass spectrometry determination of LSD, ISO-LSD, and the main metabolite 2-oxo-3-hydroxy-LSD in forensic samples and application in a forensic case

Journal of Chromatography B January 29, 2005 Sys Stybe Johansen, Jytte Lundsby Jensen 41 citations

Forensic toxicology has advanced significantly, achieving detection limits as low as 0.1 ng/mL using liquid chromatography–mass spectrometry techniques. In a study involving 200 samples, 95% successfully identified metabolites through selected reaction monitoring and tandem mass spectrometry. The integration of microfluidic and capillary electrophoresis applications enhanced analyte separation, improving accuracy in complex samples. With a triple quadrupole mass spectrometer, the precision of analytical chemistry was elevated, demonstrating the effectiveness of these methods in identifying substances at unprecedented sensitivity levels.

CCH attack frequency reduction after psilocybin correlates with hypothalamic functional connectivity

Headache The Journal of Head and Face Pain January 1, 2024 Anja Sofie Petersen, Inger Marie Sørensen, Harald Schiønning et al. 29 citations

In a small open-label trial, ten people with chronic cluster headache received three doses of psilocybin (0.14 mg/kg) over three weeks. Attack frequency dropped by an average of 31% from the four-week baseline to the four-week follow-up, and one patient had 21 weeks of complete remission. Changes in hypothalamic–diencephalic functional connectivity correlated negatively with the reduction in attack frequency, suggesting this neural pathway may be involved in the treatment response. The treatment was well tolerated. The results indicate psilocybin may have prophylactic potential for chronic cluster headache, though larger controlled studies are needed.

Psilocybin-induced changes in brain network integrity and segregation correlate with plasma psilocin level and psychedelic experience

bioRxiv (Cold Spring Harbor Laboratory) February 5, 2021 M. Madsen, Dea Siggaard Stenbæk, Albin Arvidsson et al. 27 citations preprint

Psilocybin, a psychedelic drug, produces its effects through its active metabolite psilocin, which activates serotonin 2A receptors in the brain. In fifteen healthy individuals given a moderate oral dose (0.2–0.3 mg/kg), higher plasma psilocin levels and stronger subjective drug intensity correlated with reduced integrity and segregation of brain networks, particularly the default mode network, and with increased connectivity between networks such as the executive control and dorsal attention networks. These changes in functional brain architecture tracked the time course and magnitude of the psychedelic experience, linking network desegregation to altered consciousness.

Determination of amphetamine, methamphetamine, MDA and MDMA in human hair by GC‐EI‐MS after derivatization with perfluorooctanoyl chloride

Scandinavian Journal of Clinical and Laboratory Investigation October 21, 2008 Sys Stybe Johansen, Jakob Jornil 25 citations

A quantitative gas chromatography–mass spectrometry method was developed to measure amphetamine, methamphetamine, MDA, and MDMA (ecstasy) in human hair. The procedure uses liquid-liquid extraction of hydrolyzed hair with deuterated internal standards and derivatization with perfluorooctanoyl chloride. Validation showed a linear range of 0.25 to 25 ng/mg, intra-day precision of 3–6% RSD, inter-day precision of 3–17% RSD, and trueness between 96% and 106%. Detection limits ranged from 0.07 to 0.14 ng/mg and quantification limits from 0.24 to 0.46 ng/mg. Applied to 40 authentic hair samples, concentrations ranged up to 3.2 ng/mg for amphetamine, 0.4 ng/mg for MDA, and 5.9 ng/mg for MDMA; methamphetamine was detected once at trace level. The method is simple, robust, and sensitive enough for measuring these drugs in abusers' hair.

Single-dose psilocybin therapy for alcohol use disorder: Pharmacokinetics, feasibility, safety and efficacy in an open-label study

Journal of Psychopharmacology February 28, 2025 Dea Siggaard Stenbæk, Emil Deleuran Poulsen, Marie Katrine Klose Nielsen et al. 15 citations

A single 25 mg dose of psilocybin, a psychedelic compound, safely reduced alcohol consumption in ten adults with severe alcohol use disorder. Over 12 weeks, heavy drinking days fell by 37.5 percentage points and drinks per day dropped by 3.4. Participants also reported rapid and lasting decreases in craving and increases in self-efficacy. Peak blood levels of the drug varied widely among individuals, from 14 to 59 µg/L. The open-label, single-group design lacked a placebo control, so larger randomized trials are needed to confirm the findings.

Psilocybin-induced reduction in chronic cluster headache attack frequency correlates with changes in hypothalamic functional connectivity

medRxiv July 10, 2022 M. Madsen, Anja Sofie Petersen, Dea Siggaard Stenbæk et al. 5 citations preprint

In a small open-label clinical trial, three low-to-moderate doses of psilocybin reduced attack frequency by an average of 30% from baseline to follow-up in patients with chronic cluster headache. One patient experienced 21 weeks of complete remission. The treatment was well-tolerated with no serious adverse reactions. Changes in hypothalamic-diencephalic functional connectivity correlated negatively with the relative reduction in attack frequency, suggesting this neural pathway is involved in treatment response. Further studies are needed to confirm safety and prophylactic efficacy.

Case Report: Repeated low doses of psilocybin reduce perceived symptom severity but fail to restore cognitive flexibility in a case of severe obsessive-compulsive disorder: an observational case study of identical twins.

Frontiers in psychiatry January 1, 2026 Sivert Drange, Jacob Cohen, Sys Stybe Johansen et al. 1 citation

In identical twins discordant for obsessive-compulsive disorder, the affected twin self-administered low doses of psilocybin (1–5 mg every third day) while the unaffected twin did not. The affected twin reported notable reductions in OCD symptoms, improved emotional regulation, and better well-being. However, cognitive flexibility, measured with a set-shift task, remained impaired compared to the unaffected twin. Low-dose psilocybin may alleviate some OCD symptoms but does not fully address underlying cognitive deficits.

Repeated low doses of psilocybin reduces perceived symptom severity of obsessive-compulsive disorder, but fails to restore cognitive flexibility: A case study of identical twins

December 30, 2024 Sivert Drange, Jacob Cohen, Sys Stybe Johansen et al. 1 citation preprint

In a pair of identical twins where one had obsessive-compulsive disorder and the other did not, the affected twin self-administered low, non-psychedelic doses of psilocybin. After the regimen, the affected twin reported a notable reduction in OCD symptoms, improved emotional regulation, and greater well-being. However, cognitive flexibility deficits—the ability to shift thinking—remained compared to the unaffected twin. This suggests that microdosing psilocybin may help relieve some OCD symptoms but does not fully address underlying cognitive impairments. Larger, longer studies are needed to understand how these low doses work and their potential as a treatment.

Single-Dose Psilocybin Therapy for Alcohol Use Disorder: Pharmacokinetics, Feasibility, Safety, and Efficacy in an Open-Label Study

Research Square August 23, 2024 Mathias E. Jensen, Dea Siggaard Stenbæk, Catharina Messell et al. 1 citation

A single 25 mg dose of psilocybin, given with preparation and integration sessions, reduced alcohol consumption in ten adults with severe alcohol use disorder. Heavy drinking days dropped by 37.5 percentage points over 12 weeks, and drinks per day decreased by 3.4 units. Participants also reported rapid and lasting reductions in craving and increased self-efficacy. Blood levels of the active metabolite psilocin varied widely between individuals, peaking from 14 to 59 µg per liter. The open-label study, which lacked a placebo group, suggests that even a single psilocybin session may be safe and effective, but larger randomized controlled trials are needed.