Medical Research

Using Cannabidiol Gel to Treat Fragile X Syndrome

Written by Loren Devito, PhD

While many people benefit from the use of topical cannabis for skin conditions or arthritis, children with a rare genetic condition may also soon receive benefit from transdermal cannabis as well. A clinical trial of a cannabinoid (CBD) gel was found to be effective in treating behavioral symptoms associated with a condition called Fragile X syndrome. [1]

People with Fragile X syndrome have mild or moderate intellectual disability, prominent facial features, delayed motor and language development, and social impairments like those seen in autism, among other symptoms like epilepsy and cardiovascular conditions. [2]

This condition is caused by dysfunction of a gene called FMR1. This gene is broken, or “fragile,” in a certain part of the X chromosome, and thus the disease is named after its cause. Since FMR1 produces the protein FMRP that is vital to cell function, damage to this gene affects many different systems in the body. [2]

Several approaches can help people manage their symptoms, including special education, speech/motor therapy, and behavior training. But, to date, there are no therapies that can slow or stop this condition. However, there are many different compounds currently in clinical testing–including CBD.

But why CBD?

Research has indicated that Fragile X syndrome is associated with disruption of the endocannabinoid system (ECS). In fact, a pre-clinical study showed that targeting the ECS might improve cognitive impairment and other symptoms associated with the disease. [3] This evidence in addition to studies demonstrating CBD’s effectiveness in treating anxiety motivated researchers to pursue the link between the ECS and Fragile X syndrome using a CBD-based therapy. [4]

Zynerba Pharmaceuticals presented data on results from their Phase 2 study, called FAB-C (Treatment of Fragile X Syndrome Anxiety and Behavioral Challenges with CBD), of a transdermal CBD gel to treat children with Fragile X syndrome. In this trial, researchers treated five girls and fifteen boys 6-17 years old with the CBD compound (called ZYN002) for 12 weeks; thirteen of those children continued with the trial for another 24 months. [1]

Children treated with ZYN002 saw significant improvements in anxiety, compulsive and manic/hyperactive behavior, and other types of social behaviors compared to before they started treatment. Additional data presented at a recent conference indicate that these improvements were sustained over a two-year period. The treatment was well tolerated, meaning that it didn’t cause any significant side effects.

Zynerba has initiated a Phase 3 trial to further evaluate the safety and efficacy of ZYN002 in a larger group of patients. The use of CBD as a transdermal gel may have led to its efficacy, as topicals bypass the digestive system and allow for direct absorption. This method of administration could also minimize side effects and allow the use of a lower dose. [5]

“These data are consistent and compelling, and suggest that ZYN002 may have a clinically meaningful and durable effect on the most common observable behaviors associated with childhood and adolescent Fragile X syndrome,” said Honey Heussler, DM who led the trial in a press release.

The FDA agrees with this statement as well, since they granted the treatment orphan drug designation. This means that the FDA will help the company develop the treatment and hopefully get it to patients faster.

Learn more about the Phase 3 trial, called CONNECT-X, which is currently underway after completing enrollment.

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  1. Heussler H, et al. “Transdermal Cannabidiol (CBD) Gel for the Treatment of Fragile X Syndrome (FXS).” Available at: Accessed July 10, 2020.
  2. Ciaccio C, et al. Fragile X syndrome: A review of clinical and molecular diagnoses. Ital J Pediatr. 2017;43(1):1-12.
  3. Busquets-Garcia A, et al. Targeting the endocannabinoid system in the treatment of Fragile X syndrome. Nat Med. 2013;19(5):603-607.
  4. Blessing EM, et al. Cannabidiol as a potential treatment for anxiety disorders. Neurotherapeutics. 2015;12(4):825-836.
  5. Bonn-Miller, et al. “US Patent 10,213,390 B1: Treatment of Fragile X with Cannabidiol.” Available at: Accessed: July 10, 2020.

About the author

Loren Devito, PhD

Loren DeVito, PhD is a neuroscientist and science writer with expertise in cannabis science and medicine. She is committed to communicating evidence-based information about cannabis and its healing properties. Learn more about her work at

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