Efficacy of Psilocybin in OCD: a Double-Blind, Placebo-Controlled Study

This study aims to investigate the effects of oral psilocybin on OCD symptomatology and provide the first evidence of the neural mechanism that may mediate psilocybin’s purported therapeutic effects on OCD.

The study protocol has been published here.

Status Recruiting
Results Published No
Start date 13 November 2018
End date 01 October 2023
Chance of happening 100%
Phase Phase I
Design Blinded
Type Interventional
Generation First
Participants 30
Sex All
Age 21- 65
Therapy No

Trial Details

Aim 1: To investigate the effects of psilocybin on OCD symptomatology. OCD symptom severity will be assessed before treatment and 24 and 48 hours after treatment, one week after treatment, two weeks, one month, and three months after treatment. Hypothesis: We hypothesize that 0.25mg/kg of psilocybin will lead to greater symptom improvement than niacin (as the active-placebo-control agent) at all assessment points. Aim 2: To explore the relationship between the psilocybin-induced brain connectivity changes and neuronal activation following symptom provocation in OCD. Resting-state brain connectivity will be assessed before and 48 hours after treatment. Neuronal activation induced by OCD-relevant provocative stimuli will be assessed 48 hours after the treatment. Hypothesis: We hypothesize that (i) psilocybin will normalize abnormal fronto-striatal functional connectivity in patients with OCD; (ii) psilocybin will decrease activation of anterior cingulate cortices, amygdala, and putamen in response to symptom-provoking stimuli, and normalization of one or more of these abnormalities will correlate with improvement in symptomatology after psilocybin treatment. This study will pilot a single-center, randomized, active-placebo-controlled, double-blind design to examine the clinical and neural effects on OCD, of either 0.25mg/kg of psilocybin or active placebo-control agent (niacin 250mg), given along with non-drug preparatory and follow-up support appointments to 30 study participants.The duration of the randomized study phase is from consent until two weeks after drug administration. Participants will be followed for 12 weeks (3 months) post-study drug administration. Eligible participants will be admitted as an inpatient for at least 3 nights / 4 days surrounding the initial drug administration (or more, at the option of the subject and the investigator). Participants will be randomized into active medication and active-placebo-control groups, and will be blinded as to their study condition. This admission 2 nights prior to the drug administration will allow the participant to adjust to sleeping on the unit and allow them to settle in to the research unit routine. A return for an fmri scan (48 hours after the administration session) will be scheduled. The participants who received active-placebo-control will be offered the option to receive open-label psilocybin. Study Design

NCT Number NCT03356483

Sponsors & Collaborators

Yale University
The Yale Psychedelic Science Group was established in 2016.

National Alliance for Research on Schizophrenia and Depression
This company doesn't have a full profile yet, it is linked to a clinical trial.


Single-dose psilocybin for treatment-resistant obsessive-compulsive disorder: A case report
This pre-print case study (2022) explores the effects of single-dose psilocybin in an individual with OCD. Treatment led to improvements in OCD symptoms and positive changes to the individuals' emotions, social and work function, and quality of life.

Measures Used

Yale-Brown Obsessive Compulsive Scale
The Yale Brown Obsessive-Compulsive Scale (Y-BOSC) is considered the gold-standard to assess OCD severity. The scale consists of ten items and measures the severity and type of symptoms in people with OCD over the previous seven days. The scale is used at initial diagnosis as well as during follow up sessions after treatment. The scores range from 0 to 4, with higher scores indicating greater symptoms of OCD severity.

Montgomery-Asberg Depression Rating Scale
A ten-item diagnostic questionnaire used to measure the severity of depressive symptoms in patients with mood disorders.

Beck Depression Inventory
The Beck Depression Inventory (BDI) contains 21 self-report items, completed using a multiple-choice format. Scores range from 0-63 with higher scores associated with more severe depression.

Obsessive Compulsive Inventory-Revised
The OCI-R is an 18-item self-report questionnaire based on the earlier 84-item OCI. Participants rate the degree to which they are bothered or distressed by specific OCD symptoms in the past month.

Mystical Experience Questionnaire
The MEQ is a self-report measure that has been used to measure mystical-type experiences in laboratory studies of psychedelics. The scale was developed by Walter Pahnke in 1963 and covers the major dimensions of classic mystical experience: unity (internal and external), transcendence of time and space, noetic quality, sacredness, positive mood, and ineffability/paradoxicality. Variations of the MEQ exist; the MEQ-30 and the MEQ-43.

Data attribution

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