Largest-ever study into the effects of cannabis on the brain


The largest-ever independent study into the effects of cannabis on the brain is being carried out in the United Kingdom.

Even though cannabis is the most commonly used illegal drug in the United Kingdom and medicinal cannabis has been legal there since 2018 little is known about why some people react badly to it and others seem to benefit from it.

According to Home Office figures on drug use from 2019, 7.6% of adults aged 16-59 used cannabis in the previous year.

Medicinal cannabis in the United Kingdom can only be prescribed if no other licensed medicine could help the patient. At the moment, GPs can’t prescribe it, only specialist hospital doctors can. The National Health Service says it can only be used in three circumstances: in rare, severe epilepsy; to deal with chemotherapy side effects such as nausea; or to help with multiple sclerosis.

So, with cannabis being used both recreationally and medicinally, King’s College London is carrying out a wide-reaching scientific study into its effect on the human brain.

As part of the Cannabis&Me study, KCL needs to get 3,000 current cannabis users and 3,000 non–cannabis users to take part in an online survey, with a third of those survey respondents then taking part in a face-to-face assessment that includes virtual reality (VR) and psychological analysis. The study also aims to determine how the DNA of cannabis users and their endocannabinoid system impacts their experiences, both negative and positive, with the drug.

The study is spearheaded by Marta Di Forti, MD, PhD, and has been allocated over £2.5 million in funding by the Medical Research Council.

This news organization asked Dr. Di Forti about the study.

Question: How do you describe the study?

Answer: “It’s a really unique study. We are aiming to see what’s happening to people using cannabis in the privacy of their homes for medicinal, recreational reasons, or whatever other reason.

“The debate on cannabis has always been quite polarized. There have been people who experience adversities with cannabis use, especially psychosis, whose families may perhaps like cannabis to be abolished if possible. Then there are other people who are saying they get positive benefits from using cannabis.”

Q: So where does the study come in?

A: “The study wants to bring the two sides of the argument together and understand what’s really happening. The group I see as a clinician comes to severe harm when they use cannabis regularly. We want to find out who they are and whether we can identify them. While we need to make sure they never come to harm when using cannabis, we need to consider others who won’t come to harm from using cannabis and give them a chance to use it in a way that’s beneficial.”

Q: How does the study work?

A: “The first step of the study is to use an online questionnaire that can be filled in by anyone aged 18-45 who lives in the London area or can travel here if selected. The first set of questions are a general idea of their cannabis use: ‘Why do they use it?’ ‘What are its benefits?’ Then, general questions on what their life has been like up to that point: ‘Did they have any adversities in childhood?’ ‘How is their mood and anxiety levels?’ ‘Do they experience any paranoid responses in everyday life?’ It probably takes between 30 and 40 minutes to fill out the questionnaire.”


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