ClinicalTrials.gov record NCT06261450

Effect of CBD on the Brain

Record copied from ClinicalTrials.gov: Oct 10, 2026AI summaries generated: Jul 27, 2026

Effect of CBD on the GABAergic System in Patients with Fragile X Syndrome.

StatusNot yet recruitingThe study has been registered but has not started enrolling. Sites and contacts may not be listed yet.
Study typeInterventionalA study in which researchers assign participants to one or more interventions, such as a drug, procedure, device, behavioural programme or other approach, to measure their effects.
PhasePhase 2A study that tests whether a treatment has the intended effect and continues to check safety, usually in a larger group than phase 1.
Healthy volunteersAcceptedPeople who do not have the condition being studied who are allowed to take part. Some studies include both people with the condition and healthy volunteers; others may enrol only healthy volunteers.
Age7 years old to 55 years old
SexAll
AI summaryWhat this study is about, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

A Phase 2 interventional study testing short-term brain effects of one oral cannabidiol (CBD) dose in people with Fragile X Syndrome and in healthy controls. Each participant receives one CBD dose and one matching placebo dose in randomized order, with a three-week gap. Brain measures (TMS, MRS, MRI) are recorded before and about two hours after each dose.

What it is studying. The study tests whether a single oral CBD dose produces measurable, short-term changes in the brain's inhibitory (GABA) system in people with Fragile X Syndrome, using transcranial magnetic stimulation (TMS) and magnetic resonance spectroscopy (MRS) alongside MRI.

What the researchers hope to learn. To define the relevance of the endocannabinoid (eCB) system for Fragile X Syndrome and to characterize acute CBD effects on GABA-related measures (TMS-derived intracortical inhibition/facilitation and MRS-estimated GABA concentrations).

What this study is about

The study's own summary, as published on ClinicalTrials.gov. Underlined terms have a short explanation.

This proposal focuses on the therapeutic relevance of the endocannabinoid (eCB) system for the treatment of Fragile-X syndrome (FXS), the primary hereditary cause of autism spectrum disorder (ASD). Although most individuals with FXS have moderate to severe intellectual disability (ID), caregivers are mainly concerned about aggressive behavior and anxiety problems, hallmark features of the condition. Concurrent lines of evidence suggest that targeting the endocannabinoid (eCB) system by administration of cannabidiol (CBD) could upregulate GABAergic functions and correct inhibitory deficits presumed responsible for the neuropsychiatric phenotype of FXS. However, the eCB system and its effect on the brain remains unexplored in FXS patients. This clinical trial aims to define the therapeutic relevance of the eCB system for FXS using a multimodal neuroimaging approach to finely characterize the acute effects of oral CBD on the principal inhibitory neurotransmitter system (GABA) in a large cohort of FXS patients.

Interventions being studied

Being studied in this trial does not mean the treatment or procedure is approved or available for this condition.

Drug
  • CBD Oral Solution (eCBD system Target)
  • Placebo

Eligibility

The criteria exactly as listed on ClinicalTrials.gov. Only the study team can say whether they apply to you.

Inclusion criteria

  • Eligibility criteria for FXS participants will include:
  • age between 7 and 55 years, molecular diagnosis of FXS,
  • intelligence quotient (IQ) <70,
  • aberrant behavior questionnaire score (ABC-C) > 20,
  • <3 psychoactive drugs, drug stable for > 3 months.
  • Eligibility criteria for the control group:
  • 18 and 55 years old,
  • be in good general health, with no history of neurological or psychiatric disorders.
  • Eligibility Criteria for all Participants:
  • A minimum weight of 60 kg;
  • no history of liver problems (A complete blood profile to measure liver enzyme levels (bilirubin, aspartate aminotransferase (AST), argininosuccinate lyase (ASL), alanine transaminase (ALT), alkaline phosphatase (ALP), gamma-glutamyl transferase (GGT)) will be obtained before randomization for all participants).

Exclusion criteria

  • The presence of an absolute contraindication to the use of TMS and MRI / MRS (ie presence of metal in the head).
  • Individuals with ALT / ASL levels greater than 3 times the upper normal baseline, or if bilirubin exceeds 2 times the upper baseline,

Study description and what participation involves

The registry record has no detailed description beyond the summary above.

AI summaryWhat participation may involve, in plain languageShow ▾Hide ▴

AI-written from the registry record, not the study's own wording. May contain errors or omissions. Check the registry text on this page and the original record ↗ before acting on it.

Participants are randomized to receive one single oral dose of CBD solution and one single oral placebo in a crossover design (each person receives both, in random order) with the second administration about three weeks later. Before randomization participants will have blood tests to check liver enzymes and bilirubin. At each dosing visit they will have baseline and about 2‑hour post‑dose assessments that include Transcranial Magnetic Stimulation (TMS) tests and MRI/MRS scans to measure brain GABA and related outcomes. Expect two treatment visits (one per dose) and the required safety testing and brain imaging; TMS and MRI/MRS are procedures with specific safety requirements (see exclusion for metal in the head).

How the study is structured. Randomized, triple-masked (participants, investigators, assessors), two-period crossover. Each participant receives one single oral CBD dose and one placebo dose in randomized order, with about three weeks between doses. Brain measurements are taken before and roughly two hours after each administration to compare CBD versus placebo effects.

Questions you could ask

These questions are suggestions for a conversation with the study team or your own clinician, not advice.

  • Some participants receive a placebo. How is that decided, and what happens for placebo-group participants when the study ends?
  • The registry says recruitment has not started. When is it expected to open, and can I register interest now?
  • No sites are listed on the registry yet. Where will the study take place?
  • Which of the eligibility criteria would need to be checked with tests before I could join?

More on fragile X syndrome

Clinical trials20 trials listed for fragile X syndromeEvery trial the registry lists for fragile X syndrome, with recruitment status, phase and sites, updated from ClinicalTrials.gov.See all trials →Research updatesWhat changed in fragile X syndrome researchLatest monthly update: September 2026. Includes: Multiple behavior challenges. New research summarized each month in plain language, with links to every source paper.Read the latest update →

Important dates

Study start
May 1, 2025 (estimated)
Primary completion
Dec 15, 2027 (estimated)
Study completion
Dec 15, 2027 (estimated)
Target enrollment
50 participants (estimated)
Last updated on registry
Feb 17, 2025
Data verified
Oct 10, 2026

Sponsor and research team

The lead sponsor funds and oversees the trial. A pharmaceutical or biotech company sponsor typically means the study is testing that company's drug or device; a hospital, university, or government agency usually indicates investigator-initiated or publicly funded research.

Lead sponsor
Université de Sherbrooke
Principal investigator
Francois Corbin, Full professor, Department of biochemistry
Université de Sherbrooke
Collaborators
  • Canadian Institutes of Health Research (CIHR)
  • Jazz Pharmaceuticals
  • Centre de recherche du Centre hospitalier universitaire de Sherbrooke

Central study contact

If you're interested in participating, the central contact can answer general questions about the study — including eligibility requirements and how to find a recruiting site near you. Actual eligibility is determined by the site's medical team.

Participating sites

Study locations have not been posted on ClinicalTrials.gov yet. This study is not yet recruiting, so sites may be added when recruitment begins. The central study contact above may be able to tell you about planned sites.

Terms used on this page · explanations by MedicalUpdates.ai

cohort
A group of people who share a characteristic, such as a diagnosis, and are studied together. 'Prospective' means they are followed forward from enrolment; 'retrospective' means existing records are reviewed.
Eligibility criteria
The rules the study team uses to decide who may take part. They are usually split into inclusion criteria and exclusion criteria.
control group
The group the study treatment is compared with. It may receive a placebo, an existing treatment (active comparator), a sham procedure, or no intervention.
randomization
Participants are assigned to the study groups by chance, like a coin toss, rather than chosen by the doctor or the participant. This is done so the groups are comparable.
contraindication
A reason a particular test or treatment should not be used for a person, for example a metal implant that rules out an MRI scan.
MRI
A scan that uses magnets and radio waves, not X-rays, to make detailed pictures of the inside of the body. Some implants and metal objects mean a person cannot have one.
baseline
Measurements taken at the start of the study, before any study treatment, so that later results can be compared with them.
Inclusion Criteria
The conditions a person must meet to be considered for the study, for example a confirmed diagnosis, an age range or a test result.
Exclusion Criteria
The conditions that rule a person out even if they meet the inclusion criteria, for example other illnesses, certain medicines or pregnancy.

The study record on this page is reproduced from ClinicalTrials.gov, a database of the U.S. National Library of Medicine, where it was submitted by the study sponsor. MedicalUpdates.ai does not own this content, is not affiliated with or endorsed by ClinicalTrials.gov, NIH, or the U.S. Government, and does not verify the record. Plain-language notes, the glossary and the questions above are added by this site; text in the boxes marked "AI summary" was written by an AI model and may contain errors. Registry records change over time. Check the original record for the current version and discuss eligibility or participation with a qualified healthcare professional.

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