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Jan Schepers

3 papers in the library · 36 citations · publishing 2022-2026

Papers

Cannabis containing equivalent concentrations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) induces less state anxiety than THC-dominant cannabis

Psychopharmacology October 13, 2022 Nadia R. P. W. Hutten, Thomas R. Arkell, Frederick Vinckenbosch et al. 36 citations

Vaporized cannabis containing both THC and cannabidiol (CBD) produces less anxiety than THC alone, but this effect depends on a person's baseline anxiety level. In a placebo-controlled trial with 26 healthy recreational cannabis users, THC-dominant cannabis (13.75 mg THC) and THC/CBD-equivalent cannabis (13.75 mg each) both increased self-rated state anxiety compared to placebo, though the combination caused significantly less anxiety than THC alone. When baseline anxiety was low, CBD completely counteracted THC-induced anxiety; when baseline anxiety was high, CBD did not counteract it. Trait anxiety did not influence the results, and objective measures of attention bias showed no effects.

Trajectories of psychedelic-assisted change: An observational study of a psilocybin retreat program followed by psychotherapeutic interventions

Journal of Psychedelic Studies July 3, 2026 Henry J. Whitfield, Jan Schepers, Natasha L. Mason et al.

After a psilocybin truffle retreat, two different psychotherapy interventions—one focused on self-perspective taking and cognitive defusion (ACT-SPT) and another on reexperiencing the psychedelic memory network (ACT-PMNR)—produced different trajectories of change. ACT-PMNR continued to improve participants' anxiety, well-being, and life functioning during the post-psilocybin period, whereas ACT-SPT trajectories drifted back toward baseline. Long-term follow-up of ACT-PMNR showed significant improvements across all measured outcomes, with post-therapy changes exceeding those from the retreat alone. Targeted post-psilocybin psychotherapy may build on initial retreat results, but randomized studies are needed to confirm these findings.

A randomised placebo-controlled study of the effects of lysergic acid diethylamide microdosing (15 μg) on pain perception in healthy volunteers.

Br J Pain September 4, 2025 Mauro Cavarra, Nadia R. P. W. Hutten, Jan Schepers et al.

A single 15 μg dose of lysergic acid diethylamide (LSD) did not significantly alter pain perception in healthy volunteers compared to placebo in a randomized controlled trial. The study used a double-blind design to test whether a microdose of LSD would produce analgesic effects, but found no meaningful difference between the LSD and placebo conditions on measures of pain tolerance or threshold.