A total of 10 subjects who meet all the inclusion criteria and does not meet any of the exclusion criteria will be enrolled into the study. Any subjects prematurely terminated from the study will be replaced to ensure 10 subjects complete the study. A study coordinator will contact referring clinicians, caregivers, and subjects to pre-screen for initial eligibility. Those deemed eligible will be invited for an in-person screening along with the participating caregiver. The screening visit will be approximately two hours long and will consist of informed consent, diagnostic interview, physical examination, drugs of abuse test (DOA), ECG, medical/treatment history review, and demographic forms. A pregnancy test will be performed on females of child-bearing during screening, baseline, and end-of-study visits. All eligible subjects will enter the treatment arm of the study.~Subjects and caregivers will return to the clinic for a baseline visit within three weeks of their screening completion. Baseline visit will include saliva/buccal swab collection, and clinician and self-report assessments for subjects and caregivers. These assessments will include the Vineland Adaptive Behavior Scales-Third Edition (VABS-3), Clinical Global Impressions-Improvement scale (CGI-I), Visual Analog Scale-Treatment Satisfaction (VAS-TS), the Anxiety, Depression and Mood Scale (ADAMS), and the Systematic Assessment For Treatment Emergent Events (SAFTEE). Digital assessments may also be performed at the baseline visit or at home at the discretion of the qualified investigator. Digital assessments will include the NIH Toolbox Cognitive Battery Modified for Intellectual Disabilities (NIH-TCB), the Trail Making Test (TMT), and the Multifaceted Empathy Test for juveniles (MET-J).~The study drug will be dispensed in blister packs to monitor adherence and improve subject compliance. Blister packs will be prepared and distributed at each subsequent visit. Subjects will return to the clinic for study visits on day 8, 15, 22, and 28 (study end date). Subjects and caregivers will complete the assessments described above. Subjects will provide additional saliva/buccal swab samples at day 15 and day 28.
Diverse symptomatology makes Fragile X Syndrome (FXS) difficult to treat, and currently there are no approved prevention or treatment methods for FXS. Current therapies, including pharmaceutical and behavioural interventions, offer a patchwork of solutions that have limited efficacy and high toxicity. The current study aims to examine psilocybin as a safe treatment alternative with the ability to improve markers of cognition, communication, mood, behavior as well as markers of neuroinflammation, serotonin levels in exosomes, and neuroplasticity at sub-hallucinogenic doses (microdosing).~The overall objective of this study is to assess the feasibility of low-dose psilocybin as a therapeutic option for individuals living with FXS and to improve diagnostic parameters of FXS, as well as therapeutic responses with the use of biomarkers.