A large-scale trial is set to test whether cannabinoids can effectively treat Parkinson’s psychosis symptoms, according to Parkinson’s UK.

Investigators will study the safety and efficacy of CBD to alleviate the hallucinations and delusions that trouble some people with the disease, reported the London-based charity. The group is investing $1.5 million in the nearly four-year trial.

During the first phase, investigators will focus on finding an optimum dose. In the second stage, 120 people with Parkinson’s-related psychosis will take part in a 12-week double-blind, placebo-controlled study. Recruiting will begin in early 2020.

In a recent survey, people with Parkinson’s showed significant interest in using cannabis-derived products “if robust evidence became available that they are safe and effective in treating Parkinson’s symptoms,” the charity reported. In fact, 59% of people with Parkinson’s who had never used the products said they would consider using them to control symptoms. 

There are currently no medications licensed for use in the United Kingdom to treat Parkinson’s-related psychosis. In the U.S., the Federal Drug Administration has approved pimavanserin to address the symptoms.

Parkinson’s UK is partnering with King’s College London to conduct the research.