MDMA and prosocial behavior: The role of the 2a-serotonin receptor

Randomised, double-blind, four-way crossover in recreational MDMA users comparing MDMA 75 mg, ketanserin 40 mg, the combination, and double placebo; minimum 7‑day washout.

Participants attend four 4h15 sessions with blood sampling and cardiovascular monitoring; primary endpoints are cognitive and affective empathy measured with tasks such as the multifaceted empathy test.