UW ADAI - Symposium - 2024 - Keynote - Marta Di Forti
(September 19, 2024) - Summary

A keynote presenter offered historical context while summarizing academic literature on cannabis and psychosis before addressing prevention, treatment, and answering attendee questions.

Here are some observations from the Thursday September 19th University of Washington Addictions, Drug, and Alcohol Institute (UW ADAI) Symposium titled, “Cannabis, Schizophrenia, and Other Psychotic Disorders: Moving Away from Reefer Madness Toward Science."

My top 4 takeaways:

• UW ADAI Research Scientist Beatriz Carlini introduced keynote speaker Marta Di Forti, a King’s College London Professor, who commented on her cannabis research background.
  • Following Carlini’s opening remarks, she described the “honor and pleasure” of hosting Di Forti who led “the first Cannabis Clinic for patients with psychotic disorders in [the United Kingdom], starting 2020.” Her work involved looking at the “role of cannabis in psychosis, in its underlying biology,” with Carlini noting Di Forti “employs technologies such as virtual reality and genetic data, DNA methylation data and…peripheral levels of endocannabinoids from human participants and also animal models.” She voiced her gratitude to Di Forti giving a keynote speech “all the way from [London] to us today” (audio - 1m, video - UW ADAI).
  • Di Forti began by establishing how her research was “entirely centered on the relationship between cannabis use and psychotic disorder.” She said that “my research team is looking at virtual reality, is looking at genetic, epigenetic, and also some animal model research.” Di Forti promised her remarks would offer a “journey of what has been the past and the present of the work that I've been contributing to, together with the extraordinary…world community of researcher[s]” (audio - 2m, video - UW ADAI).
  • Di Forti spearheaded the largest independent study on cannabis in the United Kingdom in 2022. Additional articles involving cannabis which Di Forti was part of include:
    • “The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study” (2019)
    • “Cannabis use as a potential mediator between childhood adversity and first-episode psychosis: results from the EU-GEI case–control study” (2023)
    • “Cross-ancestry genetic investigation of schizophrenia, cannabis use disorder, and tobacco smoking” (2024)
  • On October 16th, Di Forti was one of the contributing researchers in a study which found that “high-potency cannabis leaves a distinct mark on DNA.”

• Di Forti summarized existing research on cannabis use and psychosis and the likelihood of developing a psychotic disorder.
  • “I don't want to assume that everybody agrees that there is a causal link between cannabis use and psychotic disorder,” she stated. However, she noted there had been meta-analyses conducted “which has summarized all the existing epidemiological literature that has explored this link, and they've all converged, which is very unusual…in the epidemiology of psychotic disorder.” This meant that someone who had ever used cannabis “at some point in their lifetime...they would all have a doubling in the risk of developing later on psychotic disorder” (audio - 6m, video - UW ADAI, presentation).
  • She went on to describe how her research team adjusted for other factors known to contribute to the development of psychosis and still found that daily use of high-potency cannabis significantly increased the risk of developing a psychotic disorder. The work indicated people with higher levels of exposure to cannabis had a four times greater risk of developing a psychotic disorder. Di Forti asserted other studies from Portugal, the United States, and Canada had similar findings, offering an assessment that “where there is lots of high potency cannabis consumption. There is lots of cases of psychotic disorder” (audio - 19m, video - UW ADAI).
  • Di Forti then showed data from a 2020 study which compared incidence rates for psychotic disorders and high-potency cannabis use in cities across Europe, including London, Amsterdam, and Paris, showing a correlation between the two
    • According to Di Forti, a study from Portugal which compared the number of hospitalizations for psychotic disorders associated with cannabis use before and after the decriminalization of cannabis in 2001 found a 27% increase in hospitalizations for cannabis-associated psychotic disorders between 2000 and 2015.
  • She lauded Danish research since “they have this extraordinary population registry where…your data are uploaded when you're born and throughout all your life, that can be linked with your school records and…health records and so on” which let researchers there “plot how the incidence rate of schizophrenia had actually changed over time between the early [19]70s and 2016.” The data suggested “the incidence rate of schizophrenia had actually changed over time…you can see there is a big variation, and a big shoot up in the 90s that then sort of remains high, and then has got another shoot up in the early 2000,” she said.

• Di Forti discussed treatment and recovery studies specific to cannabis and psychosis, touching on continued use following diagnosis, while also highlighting the work of the UK Cannabis Clinic for Patients with Psychosis.
  • Di Forti went over research conducted on the impact of continued cannabis use after the onset of a psychotic disorder. She stressed the importance of helping people understand that continued cannabis use negatively impacts their chances of recovery. Di Forti cautioned that continued cannabis use can cause psychotic symptoms to “flare up with much more intensity” (audio - 4m, video - UW ADAI).
    • She mentioned how continued cannabis use “following the onset of a psychotic disorder” would have “a very profound negative impact on your clinical and functional outcome.” She explained that people who continue to use cannabis after developing a psychotic disorder are more likely to be hospitalized, stay in the hospital for a longer time, and experience more severe symptoms.
  • Considering prevention approaches, Di Forti emphasized that she was often asked by those who started “using cannabis in my early teens. ‘I've considered [stopping], but will this reduce my risk of developing psychosis later on?’” Her team had made a graph comparing the level of cannabis use and the “weeks since cessation.” She said they’d determined that the “longer people have been off cannabis, lower becomes their risk of developing a psychotic disorder.” Unfortunately, for those who have “been using daily high potency cannabis, even if you stop, compared to other people, you will take longer, and perhaps your risk will never completely reversed, which is an important public education message” (audio - 2m, video - UW ADAI).
    • She showed a video which compared how cannabis fit in amongst other environmental and genetic risk factors for psychosis disorders in which a speaker noted “frequent use of potent strains of cannabis…might cause users to experience symptoms of psychosis, especially if the other ingredients and conditions are also contributing to that outcome.” A patient discussed how participating in the clinic’s program helped him reduce his anxiety, increase his confidence and motivation, and re-engage with life (audio - 4m, video - UW ADAI).
  • Switching gears to “tertiary prevention,” which Di Forti articulated as what “I try to practice in my work as a clinician,” she told attendees some people were advised to use cannabis for anti-anxiety reasons following a psychosis diagnosis. However, she warned, “if you continue to use cannabis following the onset of a psychotic disorder, or you even start using…this is going to have a very profound negative impact on your clinical and functional outcome” (audio - 3m, video - UW ADAI).
    • Experts had acted “for many, many decades with this completely wrong assumption that if you develop a psychotic disorder, you were doomed to a bad outcome, and…you were never going to recover, or…recover, just very little.” But Di Forti suggested they’d since discovered “around 30%, a majority of other people, some of them fully recover, some of them might have a reoccurrence of episode, but they can actually go back to a reasonable level of functioning.” While this was encouraging, she stressed health practitioners ought to be “informing people of the risk of cannabis in relation to psychosis, you can prevent the onset of psychosis. You can also give chance to young people who have developed psychosis to change the course of the illness.”
    • Moreover, some people used cannabis medicinally in lieu of other medications, yet “even if you take your anti-psychotics religiously, you will still relapse, more likely and faster than those who are not using cannabis,” she said. Such medications could help patients feel more functional, which may make them more receptive to reducing their cannabis use, she added.
  • Di Forti concluded by describing the work of the Cannabis Clinic for Patients with Psychosis, an effort she established in London in 2019 to give “bespoke service for young adults who have a psychotic disorder and they are using cannabis.” With the help of charitable funding, the clinic was critical in bringing “together our colleagues, friends who are experts in both addiction and psychosis…to use something that has worked well in psychosis and worked well in addiction, bring it together and make it workable and adjustable and tailored to the needs of this population of young adults” (audio - 7m, video - UW ADAI).
    • Di Forti described the clinic’s patients, sharing that they were predominantly male and that the majority were unemployed and socially isolated. She claimed statistics showed that 73% of the 46 patients who completed the clinic’s program had completely stopped using cannabis and that most of the remaining patients reduced their cannabis use to less than once per week. Additionally, patients were reporting significant reductions in paranoia, delusions, and anxiety.
    • Patients at the clinic set their own goals around reducing cannabis consumption as they attend individual and group sessions that helped them track their progress, prepare to deal with peer pressure, and access addiction support strategies. As part of reduction in use, Di Forti described how patients would “gently substitute” other activities such as exercise or social activities. “For instance, we have a breakfast club that we run in the morning now once a month. So even coming out to the breakfast club and not using…that morning, it's a way to prove yourself that you can do a morning without cannabis,” she stated.
    • Rebuffing any notion that changes in use and psychotic symptoms were “coincidence,” Di Forti said there was statistical evidence “that it is the change in cannabis use that drives the change in this measure of symptoms and level of functioning…the majority of them, baseline, were doing nothing, and at the follow up, the majority of them have gone back to work and study, which…tells me that have improved so much in the psychopathology that they can go back to to function…and get good quality of, of life.” She hoped to secure funding to “continue the work we began with the Cannabis Clinic.”
  • Di Forti concluded by thanking her team at the clinic, crediting them for trying to avoid coming across as judging or “patronizing” cannabis users. Instead she said they endeavored to “give [patients] a space and time [to] talk about their relationship with cannabis, where it comes from, how long has been there, they can give them a chance to make changes.” She emphasized that the clinic was also offering online events and always evaluating “how we can improve the care we provide, how we can improve the choice of medication we prescribe, and we get them more on board, overall, with the treatment” (audio - 4m, video - UW ADAI).

• Questions from attendees centered on what those with psychosis and schizophrenia might “gain” from cannabis, and the best policy recommendations to address youth health risks.
  • Washington State Liquor and Cannabis Board (WSLCB) Public Health Education Liaison Kristen Haley moderated the discussion following the keynote. After inquiring after Di Forti’s cat’s name (Rob Roy), she asked what “people with psychosis and schizophrenia gain from using cannabis and…what sorts of things do you think can replace cannabis in their treatment and recovery?” (audio - 5m, video - UW ADAI)
    • Di Forti explained that people with schizophrenia and psychosis may use cannabis to mitigate the negative feelings associated with their psychotic symptoms, such as hallucinations and delusions. Moreover, cannabis “gives you that high which detaches you from reality,” so people may temporarily feel less bothered by the symptoms of psychosis, she commented. “So while you are intoxicated, you sort of feel less bothered and less distressed by the belief that you have your delusion,” added Di Forti, indicating some patients found that cannabis aided in “tolerating being in a social context.”
  • Haley also shared a participant question regarding “what sorts of policy systems and environmental strategies” Di Forti would advise “for this issue and keeping people safe and healthy?” (audio - 2m, video - UW ADAI)
    • Di Forti began by suggesting that the United States had done a better job than the United Kingdom at developing public health education strategies to address cannabis use. While the UK had “no public education strategy to prevent harmful effect of cannabis use,” she called for public education campaigns involving social media influencers and celebrities to endorse “information with the young people about cannabis in a nonjudgmental way” as a form of positive peer influence.
    • “I think we should do more…like it has been done for alcohol and, and tobacco and other substances,” Di Forti concluded, “or as it has been done in other…area[s] of medicine, when there’s been lots of education on healthy eating and more generally, lifestyle.”
    • Studies around the impact of peer circles as they relate to youth cannabis and substance use include:
      • “Innovative Routes for Enhancing Adolescent Marijuana Treatment: Interplay of Peer Influence Across Social Media and Geolocation” (2016)
      • “Peer Influence and Adolescent Substance Use: A Systematic Review of Dynamic Social Network Research” (2020)
      • “Parent and Peer Influences and Longitudinal Trajectories of Cannabis Use from Adolescence to Young Adulthood” (2022)
      • “The influence of peer’s social networks on adolescent’s cannabis use: a systematic review of longitudinal studies” (2023)

Information Set