UW ADAI - Symposium - 2022 - Cannabis Use and Psychiatric Comorbidity
(September 16, 2022) - Summary

Environmental Factors
[ Event Details ]

A research analysis portrayed cannabis consumption, particularly among youth, as one of the top “environmental factors that need to be considered” in mental health policymaking.

Here are some observations from the Friday September 16th University of Washington Addictions, Drugs, and Alcohol Institute (UW ADAI) 2022 Symposium on “High-THC Cannabis in Legal Regulated Markets.”

My top 2 takeaways:

  • Hasin spoke about "Cannabis Use and Psychiatric Comorbidity: Epidemiology and Association with High-Potency Cannabis Products" and emphasized meta-analyses framing cannabis as a risk multiplier for mental health problems (audio - 18m, video, presentation)
    • “I'm going to be presenting to you today on cannabis use and some issues with psychiatric comorbidity,” established Hasin, who acknowledged that “I was originally asked to limit the talk to the effects of cannabis potency and the risk for psychosis, but it became clear in looking into that that a broader topic was needed.”
    • Beginning with “measurement issues in general for cannabis,” Hasin contrasted “alcohol where…a general marketing policy” created understanding about “how much alcohol is in beer and wine and hard liquor. There is such a thing as a standard drink where you can really ask people about a standard drink and compute how much ethanol they're consuming.” She recognized that “not everybody in a survey will know what a standard drink is, but when you're conducting the survey you can present them with enough information that they can give you more accurate answers about how much alcohol they're consuming.”
      • However, the “picture’s really very different for cannabis,” Hasin reported, elaborating that “in Washington state, people know more about what they're using and what the potency is and the quantities because of the way the market has evolved here in terms of how it's sold.”
      • She felt that research on consumption showed “across the country, there's wide differences by state and when you look across time.” Hasin brought up “older studies” focused on “lifetime-ever use, how often do they use, but that's about as far as they [go] in terms of quantifying use.”
      • Hasin asserted “there have been studies that show that consumer knowledge of [tetrahydrocannabinol] THC levels in the products that they use is pretty low,” leading to “a challenge to figure out the relationship between anything other than ever used or not, and psychiatric outcomes.”
        • While consumer knowledge of other cannabinoids, terpenes, terpenoids, flavonoids, and compounds present within cannabis products may be similarly low—in part due to required packaging and labeling emphases on THC and cannabidiol (CBD) content---a similar lack of awareness and curiosity about the diversity of cannabis product constituents appeared to be prevalent among the research community represented at the UW ADAI Symposium. THC—and merely delta-9-THC—occupied nearly all attention to the exclusion of more nuanced research agendas.
    • Contemplating “state laws and cannabis potency,” she compared her study of access to high cannabinoid concentration products with prior speakers.
    • Hasin wanted to address “mental disorders and conditions” including those “other than psychosis.” She shared a series of prior studies finding “a statistically significant increase risk across all of these studies” that cannabis use in adolescence was associated with increased odds of depression and suicidal ideation/attempts. However, she hadn’t seen “a statistically significant increase in the risk for anxiety disorders.”
    • Turning to the topic of psychotic episodes and psychosis, Hasin first “talk[ed] about that relationship regardless of potency.” She commented that there’d been “a lot of interest in these topics” and enough studies completed that “meta-analyses are really how one needs to look to see aggregated results and what they add up to.”
      • The analyses Hasin presented covered both studies about cannabis and psychotic symptoms, as well as diagnoses of the condition, and “across all of these studies, with varying levels of strengths of the relationship, as cannabis intensity exposure increases so does the risk for this psychotic disorder.” Using a forest plot, she believed the studies demonstrated “quite a substantial effect for the use of cannabis and the risk for these psychosis outcomes.”
      • For individuals “that already have a diagnosis of psychosis,” Hasin attested that other studies had shown “an increased risk for poor outcome among the patients who continued to use cannabis.” She referenced a study of data from the National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III) she’d worked on which had “Self-reported psychotic disorders by past-year cannabis variables (non-medical use)” for 2001-2002 and 2012-2013. Noting a condition “was only considered positive if the psychotic disorder had been diagnosed by a doctor or another medical professional,” Hasin told attendees the data showed a “statistically significant increase in psychosis between the two studies” for non-medical cannabis consumption. This would mean “as the level of cannabis intensity increased, there was an increasing risk for the self-reported psychotic disorders,” she said, rising prior to legal cannabis sales beginning in 2014. Hasin estimated that those meeting the criteria of cannabis use disorder (CUD) had their chances for psychosis “increased by about five-fold.”
      • Looking at information from Denmark, Hasin described “a psychiatric register where everyone that's treated in…any type of medical setting gets added to the register. So, it's possible to track psychiatric disorders over time,” she commented, and “over a period when cannabis use increased in Denmark, these researchers looked at…what happened to rates of cannabis induced psychosis using the registry data.” She relayed their findings that incidences of both psychosis and schizophrenia had gone up over the same period.
    • Hasin next discussed “the topic that I was originally asked to speak about, which is cannabis potency and the risk of psychosis.”
      • Highlighting a 2015 study out of the United Kingdom, she said researchers there classified “different types of cannabis use including one kind called ‘skunk’ which was known as being a higher potency type of cannabis,” though “if you look at how skunk was defined…by today's standards That's not particularly high potency at all.” Researchers had looked at first “incidents of psychosis” using a “carefully matched set of community controls,” she revealed “the prevalence of any lifetime cannabis use was pretty similar in the psychotic patients and in the control group, suggesting that there was no particular risk from any lifetime cannabis use.” However, Hasin remarked that those favoring “skunk” strains, “were much more prevalent in the group of psychotic patients than they were in the community controls, suggesting that there was risk that was conferred by using skunk…and using skunk every day really had the largest increase in odds.”
      • In 2019, researchers replicated the study in other countries, and “we see a pretty pronounced difference for using the high potency form between the case groups,” she added, and those using the “more highly potent form of THC daily were at the greatest risk.”
      • Hasin mentioned “discussion of all of these relationships by geneticists who posed the possibility that maybe there was a common genetic variant that gave rise both to cannabis use and a psychosis. This led to a lot of discussion and a lot of studies.” Her conclusion was that questions about genetic predispositions to cannabis or psychosis needed “an acknowledgment that psychosis is a complex condition. There are a lot of genetic and environmental factors, but it seems clear that cannabis use is one of those…environmental factors that needs to be considered.”
    • Hasin concluded that “it's entirely safe to say that cannabis use is highly associated with increased risk for psychotic disorders and increased risk for relapse.” Moreover, she informed the group that since “most research on the effects of cannabis potency was conducted during years when high potency cannabis was pretty weak by today's standards…it's reasonable to conclude that today's very high potency cannabis products might confer even greater risk for psychosis.” Hasin observed that “although psychotic disorders are fairly rare in the general population, they are very debilitating disorders, and very burdensome to patients, and their families, and to society as a whole.” She found there could be a public health justification limiting “marketing of very high potency cannabis products in ways that can be done effectively.” Believing that “cannabis use is widely seen as harmless by the general population,” Hasin called for new studies “in today's settings where people would be able to say more about what they were using, how often they were using, and what the potency was.” This could be a way “to really see what's going on with these relationships” in the current “cannabis landscape,” she added.

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