Among 552 young cannabis users tracked from age 19 to 22, psychotic-like experiences were not associated with changes in cannabis use, but later age of first use predicted greater increases over time.
Youth mental health researchers, harm reduction advocates, clinicians working with young cannabis users
549 of 552 ever-users reported at least one psychotic-like experience by age 19
What the researchers found
Mean cannabis use increased from age 19 to 22. Age of first cannabis use was positively associated with change in use between the two time points (later starters increased more). Psychotic-like experiences at either age were not significantly associated with changes in cannabis use.
Why it matters
If psychotic-like experiences prompted people to quit cannabis, it could act as a natural protective mechanism. This study found no such self-correcting pattern, suggesting that experiencing psychotic symptoms does not reliably lead young users to reduce their consumption.
The numbers in context
552 ever-users analyzed; nearly all (549) reported at least one psychotic-like experience at age 19; mean cannabis use increased from age 19 to 22; perceived stress was positively associated with psychotic experiences at age 22
How the study worked
Longitudinal study from the IMAGEN cohort, initially recruited at age 14 in European high schools. Among 552 ever-users of cannabis, psychotic-like experiences were measured with the Community Assessment of Psychic Experiences (CAPE) at ages 19 and 22, along with quantitative cannabis use data. Perceived stress was assessed at age 22.
What this study cannot tell us
Only two time points (ages 19 and 22). Self-reported cannabis use and psychotic experiences. Nearly universal endorsement of at least one psychotic-like experience at age 19 limits variance. Perceived stress measured at only one time point.
How to read the evidence
Longitudinal design from a well-established European cohort, though limited to two time points with self-reported measures.
When this study was published
Published in 2021 using data from the IMAGEN study cohort.
The bigger picture
The finding that psychotic-like experiences do not trigger cannabis reduction challenges the assumption that negative experiences naturally lead to behavior change. The stress-psychosis link independent of cannabis also highlights the complexity of psychosis risk.
Questions still open
- Why does later cannabis onset predict steeper increases in use? Could the stress-psychosis association be a stronger driver of psychotic experiences than cannabis itself in this age group?
Common questions
Did psychotic-like experiences cause young people to stop using cannabis?
What predicted changes in cannabis use?
Read the original research
Are psychotic-like experiences related to a discontinuation of cannabis consumption in young adults?
Schizophrenia research, 228, 271-279
Citation
Daedelow, Laura S; Banaschewski, Tobias; Berning, Moritz; Bokde, Arun L W; Brühl, Rüdiger; Burke Quinlan, Erin; Curran, H Valerie; Desrivières, Sylvane; Flor, Herta; Grigis, Antoine; Garavan, Hugh; Hardon, Anita; Kaminski, Jakob; Martinot, Jean-Luc; Paillère Martinot, Marie-Laure; Artiges, Eric; Murray, Hayley; Nees, Frauke; Oei, Nicole Y L; Papadopoulos Orfanos, Dimitri; Paus, Tomáš; Poustka, Luise; Hohmann, Sarah; Millenet, Sabina; Rosenthal, Annika; Fröhner, Juliane H; Smolka, Michael N; Walter, Henrik; Whelan, Robert; Wiers, Reinout W; Schumann, Gunter; Heinz, Andreas. (2021). Are psychotic-like experiences related to a discontinuation of cannabis consumption in young adults?. Schizophrenia research, 228, 271-279. https://doi.org/10.1016/j.schres.2021.01.002
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