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Kim P C Kuypers

Department of Neuropsychology and Psychopharmacology, Faculty of Psychology and Neuroscience, Maastricht University, Maastricht, the Netherlands.

7 papers in the library · 60 citations · publishing 2024-2025

Papers

MDMA-assisted psychotherapy for PTSD: Growing evidence for memory effects mediating treatment efficacy.

Progress in neuro-psychopharmacology & biological psychiatry January 10, 2024 Mesud Sarmanlu, Kim P C Kuypers, Patrick Vizeli et al. 17 citations

MDMA-assisted psychotherapy for PTSD shows promising safety and efficacy in clinical trials, but its underlying mechanisms are not well understood. This review examines preclinical and clinical evidence suggesting that MDMA's effects on memory processes—specifically fear extinction and fear reconsolidation—may contribute to the treatment's success. The authors integrate findings from cognitive psychology and psychopharmacology to support this view and provide recommendations for future research.

Inter-individual variability in neural response to low doses of LSD.

Translational psychiatry July 15, 2024 Nadia R P W Hutten, Conny W E M Quaedflieg, Natasha L Mason et al. 16 citations

Repeated low doses of LSD (15 mcg) affect arousal, attention, and memory depending on a person's baseline cognitive state. In a randomized placebo-controlled trial with 53 healthy participants, LSD reduced resting-state EEG delta, theta, and alpha power (indicating stimulation) and enhanced pre-attentive processing during acute dosing sessions. LSD also blunted visual long-term potentiation (a marker of perceptual learning and memory) by the fourth dosing session. Stimulatory effects were strongest in individuals with low baseline arousal and attention, while inhibitory effects on memory were strongest in those with high baseline memory performance. Some EEG changes persisted at a one-week follow-up, suggesting possible neuroadaptations from repeated low-dose LSD.

Safety and Efficacy of Repeated Low-Dose LSD for ADHD Treatment in Adults: A Randomized Clinical Trial.

JAMA psychiatry June 1, 2025 Lorenz Mueller, Joyce Santos de Jesus, Yasmin Schmid et al. 14 citations

Repeated low doses of LSD (20 μg twice weekly for six weeks) did not reduce ADHD symptoms more than placebo in adults with moderate-to-severe ADHD. In a double-blind randomized trial with 53 participants, the LSD group showed an average 7.1-point improvement on the ADHD symptom scale, while the placebo group improved by 8.9 points—a difference that was not statistically significant. The treatment was physically safe and psychologically well tolerated. The findings suggest that microdosing LSD, despite popular interest, offers no advantage over placebo for ADHD symptom relief.

Safety and cognitive pharmacodynamics following dose escalations with 3-methylmethcathinone (3-MMC): a first in human, designer drug study.

Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology June 1, 2025 Johannes G Ramaekers, Johannes T Reckweg, Natasha L Mason et al. 8 citations

In a first-in-human trial, low to moderate doses of the synthetic cathinone 3-MMC were well tolerated and safe, with potential health risks only at high or excessive doses. 3-MMC caused dose-dependent increases in heart rate and blood pressure that were not clinically significant, along with feelings of subjective high. It also enhanced performance on several neurocognitive tasks, including processing speed, cognitive flexibility, psychomotor function, attention, and memory, while impulse control was unaffected. Participants reported mild dissociative and psychedelic effects, decreased appetite, and transient liking and wanting for the drug. The cardiovascular, psychostimulant, and psychotomimetic profile resembles that of amphetamine-related compounds.

Visual hallucinations originating in the retinofugal pathway under clinical and psychedelic conditions.

European neuropsychopharmacology : the journal of the European College of Neuropsychopharmacology August 1, 2024 Zeus Tipado, Kim P C Kuypers, Bettina Sorger et al. 5 citations

Psychedelics like LSD and psilocybin alter perception by activating serotonin receptors in cortical and subcortical brain regions, often causing visual disturbances or hallucinations. While current theories focus on disrupted communication between these brain areas, rare conditions like Charles Bonnet syndrome suggest the retinofugal pathway may also play a key role. Interneurons in the retina called amacrine cells could be the first site of psychedelic modulation, disrupting how visual information is hierarchically processed. This paper presents a new theory of psychedelic modulation in the retinofugal pathway, drawing parallels with clinical conditions to explain visual perceptual changes.

Daily self-assessment within a regimen of microdosing indicates enhanced psychological functioning on microdosing days relative to non-microdosing days.

Psychopharmacology October 11, 2025 Michelle St Pierre, Elena Argento, Jordyn Cates et al.

On days when adults microdose psychedelics, they report higher levels of wellbeing, productivity, creativity, connectedness, contemplation, and focus compared to days they do not microdose. The increase in creativity is especially pronounced among people who have previously used larger doses of psychedelics. These findings come from a large international survey of 1,435 adults who microdose, using daily-level self-reports that reduce reliance on memory. Because the study is observational and exploratory, the results should be interpreted cautiously.

Potential therapeutic effects of psychedelics in small doses: Is there a role for microdosing in psychiatry?

International review of neurobiology January 1, 2025 Iva Totomanova, Eline C H M Haijen, Petra P M Hurks et al.

Small doses of LSD and psilocybin produce subtle acute effects on neural connectivity, brain electrophysiology, blood pressure, sleep duration, pain perception, temporal processing, and mood, and reduce symptoms of depression and obsessive-compulsive behavior in patient samples. Extra-pharmacological factors such as baseline subjective state, expectations, and individual differences in drug metabolism influence treatment outcomes. Controlled microdosing studies suggest potential therapeutic applications, but large-scale clinical trials are still needed.