An Investigation of Psilocybin on Behavioural and Cognitive Symptoms of Adults With Fragile X Syndrome

Blister packs will contain five capsules of the study drug, Psilocybin 1.5mg. Subjects will be given blister packs with weekly doses at each visit including baseline (day 1), day 8, day 15, day 21, and day 28. Weekly blister packs will contain five doses (1-2 extra capsules depending on the week) to accommodate for flexibility in scheduling. Unused and open packages will be returned to study staff at each visit after baseline.