Some health professionals have recently expressed concerns that exposure to highly potent cannabis products may trigger psychotic-like symptoms in certain consumers, particularly young males.
Such claims are hardly new. In fact, allegations that cannabis smoking caused ‘incurable insanity’ in certain users were widely promoted throughout the 1920s and 1930s — eventually influencing Congress to impose a blanket ban on the substance in 1937.
Today’s warnings are less sensational, but are nonetheless gaining mainstream media attention. As in the 1930s, those pushing this narrative are seeking a renewed crackdown on the plant, particularly in state-legal markets. But is there any merit to claims that today’s cannabis use poses unique harms to one’s mental health, particularly with respect to increasing one’s risk of suffering from a psychotic break? Fortunately, several studies published within the past few months shed some much-needed light on this subject.
In reality, acute cannabis-induced psychosis is rare, and those who experience it are typically either predisposed to psychosis or have a pre-existing psychiatric disorder. For example, Canadian researchers recently assessed mental or behavioral-related hospitalizations among a cohort of more than 23,000 medical cannabis patients. During the course of the study, only 26 subjects were hospitalized for exhibiting “disorders due to the use of cannabis.”
European data tells a similar story. In a study published in September in the journal Translational Psychiatry, an international team of scientists assessed incidences of cannabis-associated psychotic symptoms in a cohort of 230,000 consumers. They determined that fewer than one-half of one percent of them ever had experienced symptoms requiring medical intervention — a rate that was similar to that associated with alcohol — and that most of those who did so had been previously diagnosed with either bipolar disorder or psychosis.
So does data from Canada, which legalized cannabis for adults in 2018. In the ensuing years, investigators have failed to identify any “evidence of significant changes in cannabis-induced psychosis or schizophrenia [in] emergency department presentations,” according to a study published recently in the Canadian Journal of Psychiatry.
A just-published paper from researchers in the United Kingdom casts further doubt on the degree to which moderate cannabis use plays a significant role in triggering psychotic episodes. Investigators examined the association between cannabis use and incidences of psychotic disorders in clinically at-risk young adults. Researchers assessed subjects’ mental health at baseline and then followed them for a period of two years. In contrast to the findings of some other epidemiological studies, researchers determined that subjects who used cannabis were at no higher risk of experiencing a psychotic episode.
“There was no significant association between any measure of cannabis use at baseline and either transition to psychosis, the persistence of symptoms, or functional outcomes,” they concluded. (Authors theorized that in instances where such a relationship had been previously identified, subjects likely initiated their cannabis use at younger ages, engaged in more frequent use, and consumed more potent products.)
Here in the United States, a pair of recent studies have failed to link the adoption of state-level cannabis legalization laws with increased incidences of psychosis. In the first study, a team of researchers assessed the relationship between adult-use cannabis legalization and psychosocial functioning in a cohort of 240 pairs of identical twins. One twin resided in a jurisdiction where adult-use cannabis sales were legally permitted, while the other lived in a state where cannabis was criminally prohibited.
Authors reported that twins residing in legalization states were more likely than their counterparts to consume cannabis, but that they were not more likely to experience increased incidences of psychosis, substance abuse disorder, or other adverse outcomes. “Broadly speaking, our co-twin control and differential vulnerability results suggest that the impacts of recreational cannabis legalization on psychiatric and psychosocial outcomes are…minimal,” they concluded.
In the second study, published in January in an imprint of the Journal of the American Medical Association, Stanford University investigators evaluated the relationship between the adoption of statewide legalization laws and rates of psychosis-related health care claims among a cohort of over 63 million privately insured individuals over four years. They concluded: “[W]e did not observe a statistically significant association of state cannabis policy level with overall rates of psychosis-related diagnoses or prescribed antipsychotics.”
This is not to deny that some people with psychiatric disorders consume cannabis (it is well established that those suffering from psychosis and similar symptoms tend to consume all controlled substances at rates higher than those in the general population) or that, in some cases, cannabis use may exacerbate symptoms of psychosis or even trigger a psychotic episode. Like other psychotropic substances, cannabis is not innocuous.
In some instances, there are higher risk populations that may possess a greater likelihood of experiencing adverse events following its use. Those who suffer from certain psychiatric disorders, or who are predisposed to such events, likely fall into this category. But sensationalizing the potential risks of cannabis will do little to protect them. Calling for the re-criminalization of cannabis in state-legal markets won’t either.
Rather, the establishment of a regulated market designed to keep cannabis products away from young people, and that provides clear warnings to those specific populations who may be more vulnerable to its effects — coupled with a policy of consumer education — is the best way to protect public health and mitigate consumers’ risks.
This op-ed was originally published in Marijuana Moment.
Additional information on cannabis and mental health is available from NORML’s white paper, ‘Cannabis, Mental Health, and Context: The Case for Regulation.