Getting Real About the Link Between Cannabis and Psychosis

Derangement is in the detail

Amid the buzz over the legalization of medical and recreational marijuana, there are warnings about the negative consequences of cannabis use. Specifically, there is strong evidence linking frequent cannabis use to the increased risk of psychosis.

Several studies show that extreme exposure to THC (Tetrahydrocannabinol), the psychoactive compound in the drug, might cause one to loose touch with reality. A recent study narrowed down the definition of “extreme exposure to THC” to mean the frequent intake of high-potency cannabis products with more than 10 percent THC.


Studies suggest cannabis users may be susceptible to schizophrenia. Source

That same study also highlights the fact that these high-potency cannabis products are flooding the markets today, and those three European cities London, Paris, and Amsterdam where these high-potency products are more readily available, also have higher rates of new psychosis cases than the other cities studied.


The Link Between Frequent Cannabis Use and Psychosis

A recent study published in the Lancet Psychiatry shows that daily consumption of cannabis increases the risks of future psychotic episodes. The study quizzed 901 patients who turned up for psychosis treatments at mental health facilities in 11 cities, including Amsterdam, Barcelona, London, Paris, and other cities in Europe as well as in one location in Brazil. 

Together with over 1,200 healthy individuals in a control group, these psychosis patients were asked questions about their habits, most especially those relating to cannabis use. The psychotic patients were asked about the names of the specific weed strains they had been consuming prior to their first psychotic episode. The researchers then cross-referenced the collected names of the weed strains with data gathered by the European Monitoring Center for Drug and Drug Addiction and national data from various countries in order to ascertain the THC content in each of the strains.

The study found that daily pot users were three times more likely to develop psychoses than people who’ve never used the drug before. This risk increases with higher potency cannabis, as well as the greater the frequency of consumption. The study also showed that those who used cannabis from age 15 or younger have a slightly increased risk than those who started using it later.

The study also highlighted the fact that high potency cannabis is increasingly flooding the markets. This assertion is in line with a recent study which shows that the average potency of weed in Europe and the United States (US) jumped to 17.1 percent in 2017 from 8.9 percent in 2008.

The study goes further to link this increase in marijuana potency available in some markets to the increased rate of psychosis in these places. Suzanne Gage, a psychologist and epidemiologist at the University of Liverpool, wrote a review of the study. The study found that three European cities Amsterdam, London, and Paris where marijuana with the highest THC potency are sold, also have the highest rates of new psychosis cases 37.9 per 100,000 individuals per year in Amsterdam, 45.7 in London, and 37.9 in Amsterdam.


Studies suggest cannabis users risk exposure to schizophrenia and psychosis. Source


Why these studies may be misleading

One incontrovertible critique of the new study published in the Lancet Psychiatry is that there has been no corresponding increase in the global rate of new psychosis cases as the rate of cannabis use continues to increase worldwide. Nonetheless, the study established a correlation between the availability of highly potent cannabis products in cities and the relatively higher rate of psychosis cases in those cities.

Another critique that counters the study’s primary message is that it doesn’t establish a causal link between cannabis use and psychosis. The study doesn’t establish whether it’s innate psychotic tendencies that lead to cannabis use or the other way around. It would take a much longer time and a wider range of personal data to establish such causality.

NORML Director Paul Armentano, while commenting on the study in an interview with Rolling Stone, shared concerns about that same point. He noted that there is no answer in the study as to whether those that are “most likely to express psychotic symptoms possesses a shared vulnerability or predisposition to both cannabis use and psychotic symptoms.”

Nonetheless, the study is a rallying cry for cannabis users to be on the lookout for any characteristics of psychosis in order to arrest the trend in a timely fashion.


Final words

The effects of cannabis on the mind haven’t been fully explored. As a result, several questions exist, but there are correlations suggesting an increased vulnerability to psychosis for those who use cannabis excessively. Of course, counter arguments exist, raising a number of legitimate questions that bring doubt to those correlations, and there has been no claim of causality.

That being said, cannabis users should use their substance in reasonable doses and potency. While more research on the topic is needed, the correlations may be enough to decide on prevention, just in case.