The role of the 5-HT2a receptor in MDMA-induced effects on social cognition and prosocial behaviour

Randomised, double-blind, placebo-controlled within-subject crossover with four test days (minimum 7-day washout) comparing MDMA 75 mg, ketanserin 40 mg, the combination, and placebo in healthy volunteers.

Primary outcomes assess cognitive and affective empathy measures and tasks; secondary outcomes include social interaction and attitude tasks, memory, and drug and hormone concentrations in blood. Total participant burden approximately 18 hours over a minimum of 5 weeks.