Does stimulation of the serotonin system increase prosocial behavior? A comparative pharmacological neuroscience study with healthy individuals

In this study, we aim to investigate whether stimulation of the serotonin system with psychedelic substances has a lasting effect on social behavior. By social behavior, we mean aspects such as empathy, morality, trust, selflessness, compassion, or even the size and quality of a social environment. We will compare the two psychedelic substances MDMA and psilocybin with the non-psychedelic substance methylphenidate.
In total, we will include 120 healthy study participants. They will be randomly divided into three groups (MDMA, psilocybin, and methylphenidate).
The study consists of three appointments. At the first appointment, a medical health check will be conducted, and it will be verified whether a person is suitable to participate in the study. Additionally, baseline assessments of social behavior will be conducted through tasks and questionnaires on the computer. At the second appointment, the study participants will receive either MDMA, psilocybin, or methylphenidate, without knowing which substance it is (blinding). The examiner also does not know who receives which substance (double-blinding). Four weeks later, the third appointment will follow, during which further assessments of social behavior will be conducted through tasks and questionnaires on the computer. Three months after the study ends, we will send the study participants additional questionnaires that they can fill out online on a voluntary basis.

The study investigates whether stimulation of the serotonin system can increase prosocial behavior in the long term. This is explored through the intake of different substances, some of which are psychedelic. As an intervention, the study participants will receive one of three substances orally in capsule form: MDMA (100 mg), psilocybin (15 mg), or methylphenidate (60 mg).
MDMA ("Ecstasy") has a serotonergic, noradrenergic, and dopaminergic effect. Psilocybin ("Magic Mushrooms") is a classic psychedelic and has a serotonergic effect. Methylphenidate (Ritalin®), which is used as an active placebo, has a noradrenergic and dopaminergic effect.

The study investigates whether stimulation of the serotonin system can increase prosocial behavior in healthy individuals. Consequently, only healthy individuals will be included in the study.