Response to the article in La Presse: MARKED INCREASE IN PSYCHOSIS AMONG YOUNG PEOPLE, CONCERNS ABOUT CANNABIS BY LOUISE LEDUCQuébec

A text that clearly lacks journalistic rigor!

In response to this article, which is more of an opinion piece than journalism, I would like to highlight several facts that were not mentioned, perhaps deliberately omitted, yet are crucial. Let's set the record straight. 

TEMPORAL CORRELATION VS. CAUSALITY

The article discusses a 60% increase in psychosis diagnoses among 14–20-year-olds between 1997 and 2023 and suggests that this is largely attributable to cannabis use. However, neither the study cited nor the article prove a direct link. Only a correlation over time.
Therefore, an increase in diagnoses observed over more than 25 years does not allow this increase to be attributed to a single factor, namely cannabis use, since:

• several variables may change simultaneously;
• diagnostic criteria and access to mental health care have changed;
• social and medical behaviors vary between generations.

The mistake made in this article, linking the increase in diagnoses of psychotic disorders among 14- to 20-year-olds to cannabis use, is a common confusion between temporal correlation and causality.

This is especially true given that, over the same period, we also observe:

• an exponential increase in the use of social media among adolescents, which is known to have devastating effects on their mental health;
• a marked increase in prescriptions for psychostimulants and antidepressants among young people, which also have significant effects;
• a significant improvement in early detection and increased awareness of psychotic disorders among clinicians.

Furthermore, according to Statistics Canada data, cannabis use among young people has remained relatively stable since the 1990s. Notably, between 2018, the year of legalization, and 2024, the proportion of 15- to 29-year-olds who had used cannabis in the past three months declined slightly.

In this context, the repeated association between cannabis use and psychosis is more of an editorial choice than factual information, especially since the authors of the study themselves conclude that “further research is needed to identify the factors that may contribute to the trends observed in this study.”

THE HISTORICAL EVOLUTION OF CANNABIS USE

Available data (Canadian and international) show that:

• Cannabis use among young people is not a new phenomenon.
• Higher levels of use already existed among cohorts born between the 1950s and 1980s (baby boomers and Generation X), often without a parallel explosion in psychosis diagnoses.

This proves that if cannabis use were a determining factor, we would have observed:

•  a comparable increase in psychosis in previous cohorts;
• or, at the very least, intergenerational continuity of effects.

The fact that this is not mentioned at all in the article greatly weakens the argument put forward.

THE RADICAL TRANSFORMATION OF LIFESTYLES: A NEGLECTED FACTOR

On the other hand, the analysis presented almost entirely ignores the transformations in young people's lifestyles since the 1990s. These transformations are well documented in public health and sociology. Among the factors not mentioned, yet which are nevertheless significant, are:

• sedentary lifestyles;
• constant digital hyperconnectivity (screens, social media, continuous cognitive stimulation);
• fragmented sleep and disrupted circadian rhythms;
• paradoxical social isolation (strong virtual connectivity, but weak deep social ties);
• increased academic and economic pressure, combined with chronic uncertainty about the future (economy, climate, geopolitics).

These factors have proven effects on anxiety, emotional dysregulation, attention disorders, and psychotic vulnerabilities.
To mention them as secondary variables while putting cannabis at the forefront is an inexcusable ideological bias for any journalist worthy of the name.

CRITICAL OMISSION: EXPLOSION IN THE PRESCRIPTION OF PSYCHOSTIMULANTS AND PSYCHOTROPIC DRUGS

A particularly worrying blind spot is the lack of discussion about the excessive prescription of psychostimulants and psychotropic drugs to children and adolescents since the 1990s. However, several significant trends are known:

• a marked increase in ADHD diagnoses;
• early and prolonged prescription of psychostimulants;
• co-prescriptions with antidepressants and anxiolytics in adolescence.

However, psychostimulants are explicitly associated in the medical literature with:

• psychotic episodes;
• manic or dissociative states;
• an increased risk in certain vulnerable profiles.

This highlights a significant bias: what is medicalized tends to be treated as “neutral” in the analysis, while the effects of cannabis are amplified.

Moreover, a recent study published in the journal Research Integrity and Peer Review highlights the existence of comparable biases in clinical studies and concludes that they compromise the quality of truly evidence-based medical practice.

DETECTION BIAS AND DIAGNOSTIC INFLATION

It is also important to note that between 1997 and 2023, the mental health system underwent profound changes. Over time, there was greater recognition of early symptoms, broader diagnostic criteria, a lower threshold for clinical intervention, and an increase in detection and monitoring programs.

Much of the observed increase can therefore be explained by increased detection rather than actual incidence, as well as earlier diagnosis of disorders that were previously uncodified or classified differently.

MEDIA BIAS AND SENSATIONALIST FRAMING

From a journalistic standpoint, the text exhibits several biases:

• cannabis is highlighted because it is socially and politically polarizing, which captures attention, often at the expense of rigor and factual accuracy;
• oversimplification of a complex, multifactorial phenomenon;
• there is a lack of counter-expertise on the interpretation of the data.

The editorial choice to make cannabis the central theme, rather than treating it as one factor among others (as is done in the study), biases the interpretation and tends to reinforce a conclusion that goes beyond the data actually presented.

JOURNALISTIC OBJECTIVITY: RIGOR TO BE APPLIED TO ALL SUBJECTS COVERED

Recognizing that cannabis can act as an aggravating or triggering factor in certain vulnerable individuals is scientifically sound. However, suggesting, either explicitly or implicitly, that it is the main driver of the increase in psychosis among young people is more a matter of opinion than an analysis conducted with the impartiality required by the code of ethics.

A rigorous reading of the data leads instead to the conclusion that:

• the increase in psychosis is multifactorial;
• social, medical, and technological changes play a major role;
• cannabis cannot be isolated without producing an analytical distortion.

Failing to apply such rigor when dealing with an issue as sensitive as the mental health of young people is troubling. This is especially true given that it can divert attention from the most pressing structural determinants and run counter to the public interest, which should be at the heart of all journalism.

Pierre Leclerc
President and CEO of the Quebec Hemp and Cannabis Industry Association (AQIC) and Former Chief of Staff to the Minister for Rehabilitation, Youth Protection, Public Health, and Healthy Living. Responsible for the Cannabis Regulation Act.