UK Cannabis Study Needs More Diverse Participants

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Various efforts to attract non-white participants to the study have not succeeded, putting the study in jeopardy.

The largest study of its kind in the United Kingdom (UK) is struggling to have enough diverse participants in the London area sign up for its analysis on the various biological and social influences of cannabis on the brain (1). Cannabis and Me, which first began seeking participants in late 2022, currently has over 2200 participants already signed up and is looking for several more thousand in total (1,2).

“The study will use a combination of DNA genetic and epigenetics testing, psychological and cognitive analysis, and virtual reality to understand the link between a user’s biological makeup and the effect cannabis has on them,” stated the King’s College website (2). “In particular, the study will aim to identify the environmental (e.g. history of trauma), genetic and epigenetic markers that are most likely to cause mental health and social problems in users.”

The lead investigator in the study, Marta Di Forti MD, MRCPsych, PhD, expressed concerns over the implications that could result from the lack of diversity. “We will end up with findings that only represent the white population and they won’t be generalisable to black British people who therefore won’t be able to benefit from any advances our study leads to,” (1).


The study reportedly needs hundred more Black participants, yet recruitment efforts, such as social media and articles in Black newspapers, have not yet succeeded (2).

“If you don’t trust the police because of years of racist and corrupt police practices you lump all of the establishment together and it can be easier to say no than yes,” stated William Gadsby-Smith, who is leading the outreach (1).

Despite being a restricted drug, recent data suggested that millions of people in the UK use cannabis, though it remains illegal except with a physician’s recommendation (2). “Cannabis is consumed daily by many recreationally but also for medicinal reasons,” stated Dr. di Forti (2). “But in the UK, the prescription of medicinal cannabis remains rare. Our study aims to provide data and tools that can make physicians in the UK and across the world more confident, where appropriate, in prescribing cannabis safely."

Read our initial coverage of the study here.


  1. Booth, R. Cannabis brain effects study struggles to attract black UK users (accessed Oct 11, 2023).
  2. King’s college london spearheads the largest ever independent study into cannabis use (accessed Oct 11, 2023).