Randomised, placebo-controlled crossover neuroimaging study (n=50) using oral dexfenfluramine (40–60 mg) challenge with [18F]-altanserin PET to compare 5-HT release capacity in current MDMA users, former users, and MDMA‑naïve controls.
Randomised crossover design: participants receive placebo and an oral (+)dexfenfluramine challenge in random order on two days separated by seven days; PET imaging with [18F]-altanserin is performed to assess 5‑HT2A receptor availability following challenge.
On each dosing day subjects receive placebo or 60 mg (+)FEN (reported range 40–60 mg), followed two hours later by intravenous administration of ~250 MBq [18F]-altanserin and dynamic PET acquisition for 90 minutes; cognitive testing (CANTAB) and repeated psychometric measures accompany scanning.
Primary aim is to quantify serotonin release capacity and compare current and former MDMA users with controls to investigate potential long-term MDMA-related alterations in serotonergic neurotransmission and associated cognitive/affective changes.
Oral (+)dexfenfluramine challenge (active) in crossover with placebo.
Oral (+)FEN challenge 40–60 mg (single application); given in random order vs placebo.
Matching placebo comparator in crossover.
Matching placebo capsule