The hallucinogen psilocybin induces a psychosis-like state in healthy people that resembles early schizophrenia. In human volunteers, these effects were blocked in a dose-dependent manner by the serotonin-2A antagonist ketanserin or the atypical antipsychotic risperidone, but were increased by the dopamine antagonist and typical antipsychotic haloperidol. This provides the first human evidence that psilocybin-induced psychosis results from serotonin-2A receptor activation, independent of dopamine stimulation. The findings suggest that serotonin-2A overactivity may play a role in schizophrenia and that blocking this receptor may contribute to antipsychotic benefits.
MDMA and its analogues are amphetamine derivatives that produce an altered emotional state. For over a decade, ecstasy has been the second most common recreational drug among young adults, especially in the techno scene, after cannabis. A recent survey indicates a shift toward classic amphetamine and hallucinogen use, possibly due to concerns about ecstasy's neurotoxicity and somatic risks. Among hallucinogens, psilocybin mushrooms and LSD are most used. This review summarizes the psychological and somatic effects of hallucinogens, amphetamines, and entactogens.