King’s College London Begins 6,000-Person Study on Cannabis, Mental Health

King’s College London, which is ranked one of the top 10 universities in the U.K., recently announced that it would be launching a study to examine the effects of cannabis on mental health.

The study will be led by Dr. Marta di Forti, a Medical Research Council (MRC) Senior Clinical Fellow, who has conducted cannabis-based research in the past. “We wish to reach out to those out there using cannabis, in particular those benefiting from it. Without their help we will continue to have a polarised debate on cannabis, with us thinking it is all bad and should be banned, and others believing that because it is a plant it cannot have adverse effects,” di Forti said.

The study, called “Cannabis & Me (CAMe)”, is fully funded by King’s College London. Di Forti initially submitted it to the MRC in 2019, and it was approved in 2020 with a $2.5 million grant. “The pandemic has delayed the start to this date. The study involves several collaborations and labs, which were all affected by COVID-19. Finally, everyone is ready to start,” di Forti explained. The study is set to run for five years, with early results published in 2023 or possibly early 2024.

In a description of the study’s purpose, authors explained the need for more research in light of the rapid increase of consumers across the globe.  “Therefore, at a time when cannabis use is increasing worldwide, this study focuses on understanding the wider impact of cannabis use on the physical and mental health of cannabis users. It also aims to identify environmental and biological factors, which can explain the different effects people experience when using cannabis, and in particular, identify those users more likely to experience mental health and social issues.”

The study will include 6,000 participants ranging from 18-45 years of age, and must reside in the London area. They will be required not only to take part in an online study, but must also agree to a face-to-face assessment, blood sample donation, and a VR experience (which will be used to measure an individual’s physiological response to specific situations). An important caveat to participation includes an individual having no previous or current diagnosis of psychotic disorders, and should not be receiving treatment for that condition.

Participants will be chosen for in-person interviews based on current cannabis consumption, or having “never/only twice” tried cannabis.

“The main aim of the study is to understand why a minority of cannabis users experience psychological and cognitive adverse effects—this is the clinical population I care for as a clinician,” di Forti said. “If we can identify the environmental and biological factors that make a minority susceptible to adverse effects when using cannabis daily either for medicinal or recreational reasons, we can inform safe prescribing and side-effects monitoring (we use virtual reality to test if or how cannabis affects reality perception).”

Di Forti also expressed the need for more information about possible negative effects, in addition to positive benefits. “We can also offer more information to the general public, to avoid adverse effects when using cannabis and how to recognise them,” she said. “Everyone in our society can recognise the negative effects of excessive alcohol consumption, but not everyone is familiar on how to identify the changes in thinking, processing and cognition that a minority experience when using cannabis.”

In the past, di Forti has conducted studies to analyze the link between cannabis use and psychotic disorders. In the results from a 2015 study, she came to the conclusion that “risk of individuals having a psychotic disorder showed a roughly three-times increase in users of skunk-like cannabis compared with those who never used cannabis.” The results of this study have been used to support anti-cannabis efforts, which di Forti does not approve of. “Sometimes the political debate about cannabis has used my data in a context which doesn’t necessarily represent my view, and this is what tends to upset me,” di Forti said in an interview with Cannabis Health. “People now associate me with the idea that nobody should use cannabis and that cannabis is a toxic substance, which is not what I think.”

Another recent study associated with King’s College London found evidence that teen and adult smokers are not less likely to be motivated because of their cannabis use. Cannabis use was also found to help those with COVID-19 experience less severe symptoms.