MDMA (ecstasy) increases sociability and empathy, likely through the release of oxytocin. A single-letter variation in the oxytocin receptor gene (OXTR rs53576) influences how people respond to the drug. In a double-blind, within-subjects study, 68 healthy volunteers with past MDMA experience received placebo, 0.75 mg/kg, or 1.5 mg/kg of MDMA. At the higher dose, individuals with the A/A genotype did not show the increase in sociability seen in G allele carriers. No genotypic differences appeared at the lower dose or in cardiovascular or other subjective effects. The results suggest MDMA-induced sociability depends on oxytocin signaling and that genetic variation in the oxytocin receptor modulates the drug's social effects.
A double-blind, placebo-controlled experiment with 24 healthy infrequent cannabis users tested how THC (15 mg oral) affects context-based memory illusions. Participants memorized object pictures on scenes (e.g., a cat on a beach) after THC or placebo. Two days later sober, they discriminated seen objects from similar lures, with context reinstated or changed. THC impaired memory for perceptual details compared to placebo. Context reinstatement increased both correct recognition and false recognition in both conditions. THC did not interact with context effects overall, but post hoc analyses showed THC magnified the context illusion when objects were semantically congruent with their encoding contexts and abolished it when incongruent. Results suggest THC impairs encoding of specific object information more than item-context associations, potentially sparing or increasing distorting effects of context.