Parkinson’s UK is teaming up with King’s College London for a £1.2 million ($1.5 billion) clinical trial to gauge the potential benefits of CBD.

There are 145,000 Brits that suffer from Parkinson’s and it causes psychosis, hallucinations, and delusions in more than half of them. Researchers believe CBD could help alleviate the symptoms of Parkinson’s-related psychosis.

A six-week pilot study will see Parkinson’s patients in the south of England take up to 1 gram of CBD per day in the form of oral capsules. This is to help researchers ascertain the optimum dose.

Then 120 people with Parkinson’s-related psychosis will be recruited to take part in a 12-week double blind, placebo-controlled study.

“If successful, this trial could result in people with Parkinson’s being able to access a regulated medicine, rather than reverting to expensive unregulated supplements that haven’t been monitored for their effectiveness,” said Dr Arthur Roach, Director of Research at Parkinson’s UK.

The charity has conducted a survey that suggested patients would use cannabis-derived products if robust evidence became available to show that they are safe and effective in treating Parkinson’s symptoms.

CBD oil is legal in the UK provided the THC content is not above 0.2%. Britain legalized medical cannabis last year, but doctors have not been able to prescribe it to more than a handful of patients due to rigid NHS guidelines.

Campaigners are battling to change that situation, but they were recently dealt a blow when NHS watchdogs ruled that cannabis should not be used to treat multiple sclerosis and chronic pain.

CBD oil is on sale at health stores, supermarkets, and convenience stores across the UK, but most Brits still believe it is illegal. A survey conducted on behalf of Dr. Ed, a new CBD oil supplier founded by neuroscientist Dr. Edward Jones, asked 2,000 Brits for their thoughts on CBD.

Two-thirds said they thought it was outlawed, while 80% said it is “dodgy” and that it is the same as smoking cannabis. The study found CBD is most widely used by women aged 45 to 60, as 67% of them claimed to have taken or considered taking the oil, whereas only 21% of respondents aged 25 to 30 were open to trying it.