Anxiety Explains the Link Between University Students’ Cannabis Use and Psychotic-Like Experiences

By Haley Bernusky

Cannabis Use is Common, and Risky

Cannabis is one of the most commonly used substances among Canadian university students aged 18-25, coming in second only to alcohol. While cannabis is often anecdotally considered to be the ‘lesser of two evils’ compared to alcohol, cannabis consumption comes with risks of its own. One of the most notable is that use of cannabis has repeatedly been shown to be associated with an increased risk for the development of psychosis. More specifically, research tells us that those who use cannabis early in life, who use more often, who use in high quantities, and/or use high-potency THC products are at particularly high risk of psychosis. As cannabis is popular among Canadian university students, it is important to identify risks that increase students’ chances of transitioning from cannabis use to the development of psychosis.

A Focus on Early Phase Psychosis and Early Intervention

Existing cannabis research has focused on studying those who are at clinical high-risk for developing psychosis (i.e., with attenuated but significant psychotic symptoms) or those already diagnosed with a psychotic disorder. Psychosis, however, exists on a spectrum ranging from less serious, short-lived symptoms of psychosis (also known as psychotic-like experiences or ‘PLEs’) to more serious and lasting psychotic disorders such as schizophrenia. Psychotic disorders, which present in approximately 1-3% of the population, are important to understand as they can be extremely debilitating. However, psychotic symptoms occurring earlier along the psychosis spectrum, such as PLEs, are much more common in the general population with a prevalence of 5-8%, persisting in approximately 20-30% of cases. These risk rates are even higher in younger samples of teens and young adults compared to older adults. Thus, PLEs are an important focus for research among young adults, as they may signal those who are at increased risk of progressing along the psychosis spectrum from short-lived psychotic symptoms to a lasting psychotic disorder.

What Role Might Anxiety Play?

While a link exists between cannabis use and the development of psychosis, the mechanisms that explain this association remain unclear. One possibility is that symptoms of anxiety play an explanatory role, as cannabis use has been shown to be related to increased anxiety, particularly at high frequencies/quantities of use. Anxiety has also been shown to be related to the development of PLEs. Therefore, we expected that anxiety would play an explanatory role in the link between cannabis use and PLEs.

The Present Findings and Their Implications

This study therefore investigated the possibility of anxiety symptoms acting as a potential mechanism to explain the link of cannabis use to PLEs in university students. We administered standardized questionnaires to 1,266 Canadian university students in their first or second year of studies at five universities across Canada. Questionnaires asked students about the frequency of their cannabis use, their frequency of anxiety symptoms, and the number of PLEs they had experienced. Our findings supported the hypothesis that greater cannabis use frequency would predict more frequent symptoms of anxiety, which, in turn, would predict greater numbers of PLEs. In other words, we found that the more frequently one uses cannabis, the more frequent their symptoms of anxiety become, an association which, in turn, increases one’s PLEs. This finding has important clinical implications, suggesting that anxiety symptoms should be targeted in those who use cannabis, through interventions such as cognitive-behavioral therapy in order to lower their risk for developing PLEs. It is possible that providing such anxiety-focused intervention might prevent these at-risk students from progressing along the psychotic spectrum toward disorder.

Furthermore, we were the first to evaluate the potential impact of biological sex assigned at birth (i.e., male/female) on the links of cannabis use to PLEs through anxiety. We found that anxiety symptoms help to explain the cannabis-to-PLEs association among university students, regardless of participants’ biological sex. The implications mentioned above therefore appear to be applicable to both male and female university students: interventions targeting anxiety symptoms may lower both male and female cannabis using students’ overall risk of developing/worsening their experiences of psychotic symptoms. As this work used cross-sectional survey data, it is a useful first step towards greater understanding of these associations; however, longitudinal replications are required prior to influencing intervention strategies.

Article Details
Do Anxiety Symptoms Mediate the Association Between Cannabis Use Frequency and Psychotic-Like Experiences in Emerging Adult Undergraduates?
Haley C. R. Bernusky, BSc (Hons.), Philip G. Tibbo, MD, FRCPC, Patricia J. Conrod, PhD, Fakir Md. Yunus, PhD, Matthew T. Keough, PhD, Kara D. Thompson, PhD, Marvin D. Krank, PhD, Allyson F. Hadwin, PhD, and Sherry H. Stewart, PhD
First published online May 17, 2023
DOI: 10.1177/07067437231176900
The Canadian Journal of Psychiatry

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