Pot-facts.ca has published a collection of studies indicating that the idea that cannabis causes psychosis is a scam – a rationale created by certain academics sensitive to the needs of the powerful in order to justify hard drug regulations for cannabis and a cartel pot economy.
The evidence that this is the case just keeps piling up.
This author (David Malmo-Levine) did a review of 50 studies on cannabis and psychosis . . . the only one that argues there’s a causal relationship AND attempts to address the general population statistics (that always indicate that cannabis use rates have skyrocketed between the 1960s and the 1990s while psychosis rates have flatlined) is Radhakrishnan:
Gone to Pot – A Review of the Association between Cannabis and Psychosis, Rajiv Radhakrishnan, Samuel T. Wilkinson, and Deepak Cyril D’Souza, Front Psychiatry. 2014; 5: 54. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4033190/
Of the ten studies that argued there was a causal relationship between cannabis use and psychosis, (Zammit, Arseneault, Fergusson, Malone, De Berardis, Raver, Parakh, Gilman, Radhakrishnan, Volk) Radhakrishnan was the only one that acknowledged the general population stats, but attempted to explain them as a matter of a time lag between cannabis use rates increasing and schizophrenia increasing:
“Notably, although meta-analytical studies suggest that cannabis might account for between 8 and 14% of schizophrenia cases (25, 207), the fourfold increase in the rates of cannabis use over the last four decades (198, 355) has not resulted in a commensurate 40–70% increase in prevalence of schizophrenia. Some studies suggest that the rates of schizophrenia may be decreasing (356), while others suggest the contrary (357, 358). The discrepancy between the recent changes in the rates of cannabis consumption and relative stability of schizophrenia rates are difficult to explain in the context of the findings reviewed above; one possible explanation is that schizophrenia rates are lagging behind increased rates of cannabis consumption.”
Of course, cannabis use rates began increasing in the early 1970s, by all accounts, if not earlier, and psychosis rates have still remained static as of 2020, so 50 plus years is quite the “lagging” to have occurred. A much simpler and more realistic answer is that there is no causal relationship, and that the desire to attempt to create a relationship where none exists should not be viewed as a result of an honest appraisal of the evidence of the inherent harmfulness of cannabis, rather, it should be seen in the context of the 125 year history of academics, journalists, police and policy makers inventing that causal relationship in spite of a lack of evidence, for the duo purposes of maintaining informal white supremacy and satisfying corporate greed through denying universal access to our co-evolutionary plant partner.
A more recent study is
Cannabis and Psychosis: a Critical Overview of the Relationship
Charles Ksir 1, Carl L Hart 2 3 4 5 Curr Psychiatry Rep., 2016 Feb;18(2):12.
From the abstract:
“Evidence reviewed here suggests that cannabis does not in itself cause a psychosis disorder. Rather, the evidence leads us to conclude that both early use and heavy use of cannabis are more likely in individuals with a vulnerability to psychosis.”
Later the same year, another study was done recognizing the general population stats and the obvious conclusion the impartial observer would arrive at:
On October 12th, 2016, a literature review in a journal called Clinical Psychology Review was published online. The review was called “Medical cannabis and mental health: A guided sytematic review,” was written by lead author Zach Walsh of the University of British Columbia and his associates, and featured a key insight into the nature of cannabis psychosis – that the lack of increase in schizophrenia is a compelling counter:
“Indeed, the observation over the past several decades that rates of schizophrenia have remained constant despite dramatic increases in cannabis use presents a compelling counter to causal models of cannabis use and schizophrenia (Rajapakse & Rodrigo, 2009).”
“Medical cannabis and mental health: A guided systematic review,” Zach Walsh, Raul Gonzalez, Kim Crosby, Michelle S. Thiessen, Chris Carroll, Marcel O. Bonn-Miller, Clinical Psychology Review 51 (2017) 15–29 blogs.ubc.ca/walshlab/files/2015/06/Review-Article.pdf
In spite of this overwhelming evidence of no causal relationship between cannabis and psychosis, academics insist on attempting to suggest this is indeed the case. On March 19th, 2019, NPR published an article titled “Daily Marijuana Use And Highly Potent Weed Linked To Psychosis.” This article pointed to a study that was designed to respond to the general population stats that disproved causality:
“One critique of the theory that weed contributes to psychosis risk has been that while more people are using weed worldwide, there hasn’t been a corresponding rise in rates of psychosis, Gage explains. But the new study shows that cities with more easily available high-THC weed do have a higher rate of new diagnoses of psychosis. ‘That’s a really interesting finding, and that’s not something anyone has done before,’ she adds. However, the study doesn’t prove causality, cautions Dr. Diana Martinez, a psychiatrist and addiction researcher at Columbia University. ‘You can’t say that cannabis causes psychosis,’ she says. ‘It’s simply not supported by the data,’ she says. Lisdahl agrees. In order to show causality, one would have to follow people over time — before they started using weed to years later when they have their psychotic episodes, she says. ‘You need twins in the studies, you need genetic information,’ among all other kinds of data, she says. Psychotic disorders such as schizophrenia and bipolar are complicated, ‘multifaceted disorders,’ Gage notes. ‘In all psychotic disorders, there is this multiple hit hypothesis,’ Martinez says. Many factors influence whether and how these disorders manifest.”
“Daily Marijuana Use And Highly Potent Weed Linked To Psychosis,” March 19, 2019
But it’s not simply a matter of not having studied enough twins, or not having studied people before they started using pot. There’s also the matter of actually proving that some cities have more “high-THC weed” than other cities, and that cities with increased incidents of psychosis weren’t cherry-picked for this study.
One would also have to consider the effects of pot prohibition – and hemp over-regulation – on the availability of high-CBD pot cultivars or high-CBD hash, and how much pot prohibition and hemp over-regulation interfered with the ability of humanity to use cannabis properly and to its full potential.
A look at the study in question confirms that the effects of pot prohibition might have on CBD/THC ratios or proper use techniques were not considered as confounding factors – or even worthy of study:
“Our potency variable does not include the proportion of another important cannabinoid, cannabidiol (CBD), because reliable data on this were available for only England and Holland.”
“The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): a multicentre case-control study,” Marta Di Forti, PhD Diego Quattrone, MD Tom P Freeman, PhD Giada Tripoli, MSc Charlotte Gayer-Anderson, PhD Harriet Quigley, MD Victoria Rodriguez, MD Hannah E Jongsma, PhD Laura Ferraro, PhD Caterina La Cascia, PhD Prof Daniele La Barbera, MD Ilaria Tarricone, PhD Prof Domenico Berardi, MD Prof Andrei Szöke, PhD Prof Celso Arango, PhD Andrea Tortelli, PhD Eva Velthorst, PhD Prof Miguel Bernardo, PhD Cristina Marta Del-Ben, PhD Prof Paulo Rossi Menezes, PhD Prof Jean-Paul Selten, PhD Prof Peter B Jones, PhD James B Kirkbride, PhD Prof Bart PF Rutten, PhD Prof Lieuwe de Haan, PhD Prof Pak C Sham, PhD Prof Jim van Os, PhD Prof Cathryn M Lewis, PhD Prof Michael Lynskey, PhD Prof Craig Morgan, PhD Prof Robin M Murray, FRS theEU-GEI WP2 Group, The Lancet Psychiatry, VOLUME 6, ISSUE 5, P427-436, MAY 01, 2019
https://www.thelancet.com/journals/lanpsy/article/PIIS2215-0366(19)30048-3/fulltext
In other words, “we could have also chosen to study the effects of CBD cannabis use on psychosis in two countries, but we chose instead to limit our study the effects on high-THC cannabis in six countries, because had we also studied CBD cannabis we might not have found cannabis use to be one of the ‘risk factors for psychosis’ that we assumed it was. We didn’t want to appear biased, so we made it sound like it was a matter of preferring a larger amount of data instead of a preferring a predetermined outcome.”
The study was reported on in various newspapers, with some doing their very best to push Reefer Madness 2.0. In one article from the HealthDay website, NORML Deputy Director Paul Armentano confirmed that cannabis was a hard drug that needed to be kept out of the hands of young people (and, therefore, distribution needed to be kept in the hands of those lucky enough to be able to afford to navigate the tight regulations needed for such a hard drug):
“The jittery, delusional potheads of the old movie ‘Reefer Madness’ have prompted eye rolls and chuckles over the years, but a new study argues that the cult classic might contain a kernel of truth. . . . More studies using different designs ‘could help us to triangulate evidence and get a better idea of whether it’s truly a causal effect,’ Gage said. Despite his skepticism, Armentano allowed that ‘the concerns raised in this paper ought to be taken seriously, and they provide an argument in favor of better regulation of the plant so that it can be better kept out of the hands of young people and those who may be at higher risk for an adverse reaction. Maintaining cannabis prohibition, unfortunately, achieves neither result,’ he concluded.”
“Can High-Potency Pot Make You Crazy?” March 19, 2019
Aside from the endorsement of hard drug regulations, the actual in-context statements from Paul Armentano and NORML are worth considering, due to the fact that they are a seldom-heard, articulate argument against a causal relationship between cannabis and psychosis:
“That said, it remains premature at best, and sensational at worst to claim that a causal relationship exists between marijuana use and psychiatric disorders on the basis of this new paper. That is because, by the observational nature of its design, this study at best can only demonstrate a correlation. Nonetheless, despite this limitation, the authors boldly ‘assume causality.’ Given the fact that such a cause-and-effect relationship remains unproven and there as of yet exists no consensus among experts that such causation exists, their assumption is, at best, highly questionable. Moreover, it is well established that those with psychiatric illness typically use all intoxicants at greater rates than do the general public, so the fact that those admitted to institutions for first-episode psychosis are more likely to consume cannabis than are those in the general population is hardly surprising. But it is not evidence that marijuana in any way causes the condition. Rather, this association may exist because many psychiatric patients are self-medicating with cannabis. Or, this relationship may persist because many people predisposed to psychosis are similarly predisposed to also using cannabis — a theory that is supported by many experts in the field. Perhaps most importantly, the fact that cannabis has been used by various populations for decades at disparate rates, yet rates of psychosis and other psychiatric disorders have generally remained static over this same period of time, strongly argues against a direct causal relationship.”
“NORML Responds To Latest Cannabis and Psychosis Claims,” PAUL ARMENTANO, NORML DEPUTY DIRECTOR, MARCH 20, 2019
“Will smoking cannabis make you psychotic? Not likely,” BY PAUL ARMENTANO, OPINION CONTRIBUTOR — 03/24/19
Other coverage of the study suggested that “high concentrations” can “potentially cause psychotic symptoms in anybody,” but then qualified that suggestion with the following proviso:
“The study is the latest to link psychosis with marijuana. Still, there is still no definitive proof that cannabis causes psychosis, according to an editorial comment published with the study.”
“Daily use of potent pot linked to psychosis,” The Philadelphia Inquirer, Philadelphia, Pennsylvania, March 20th, 2019, p. A2
These provisios are written in such a way as to suggest that proof of causality is right around the corner, rather than written in such a way as to suggest that the last nail in the coffin of causality would be driven in if only someone wrote a literature review that gathered and assessed all the studies that compared cannabis use rates with psychosis incidence rates and then combined that with all the studies that suggested CBD was an effective anti-psychotic, and then compared psychosis incidence in populations with easy access to high-CBD products to those without such access, and then loudly publicized their findings.
Until the myth of Reefer Madness 2.0 is fully debunked in the mass media, the hard drug regulations for pot – and the cartel, and the further arrests and punishments that come with it – will persist, as will the over-regulation of industrial hemp. If humans want to evolve beyond scapegoating and live in harmony with each other and their environment, exposing the fraud of “cannabis psychosis” is essential.