During the COVID-19 pandemic in Norway, cannabis-induced psychosis episodes declined while amphetamine and poly-substance psychosis increased, and patients who experienced recurrent episodes were more likely to have psychosis triggered by different substances.
Psychiatrists, dual-diagnosis clinicians, and drug policy researchers
Cannabis psychosis declined; stimulant psychosis rose during COVID
What the researchers found
Despite fewer individuals being diagnosed with substance-induced psychosis (SIP) during COVID, total SIP episodes increased. Cannabis-induced psychosis declined while amphetamine- and multi-substance-induced psychosis rose. Patients with recurrent episodes were 50% more likely in 2020 (RR 1.50) and 30% more likely in 2021 (RR 1.30) to have psychosis induced by different substances than in 2019.
Why it matters
The shifting patterns of substance-induced psychosis during the pandemic likely reflect changes in drug availability and pricing, demonstrating how supply-side disruptions affect clinical presentations.
The numbers in context
Norwegian Patient Register 2019-2021; fewer SIP patients but more episodes during COVID; cannabis-induced psychosis declined; amphetamine/multi-substance SIP increased; recurrent SIP by different substances: RR 1.50 (2020) and 1.30 (2021) vs 2019
How the study worked
Retrospective cohort study analyzing data from all individuals with comorbid mental health and substance use disorders registered in the Norwegian Patient Register (2019-2021). Poisson regression and Sankey diagrams examined SIP occurrence, risk, and substance trajectories.
What this study cannot tell us
Register-based data depends on clinical coding accuracy; cannot determine individual substance use patterns directly; pandemic effects on healthcare access may have reduced SIP diagnoses rather than actual cases; Norway-specific drug markets may not generalize
How to read the evidence
National registry data covering all diagnosed cases, though limited by clinical coding accuracy and inability to separate healthcare access changes from true incidence changes.
When this study was published
2024 study analyzing 2019-2021 data
The bigger picture
The finding that drug supply disruptions during COVID shifted which substances caused psychosis highlights the vulnerability of people with dual diagnoses to market-level changes they cannot control.
Questions still open
- Did the decline in cannabis-induced psychosis reflect reduced cannabis availability or reduced help-seeking? What happens to psychosis patterns when drug markets return to pre-pandemic norms?
Common questions
How did COVID affect substance-induced psychosis?
Did people switch between substances?
Read the original research
Frequency and patterns of substance-induced psychosis in persons with concurrent mental health and substance use disorders during the COVID-19 pandemic: A Norwegian register-based cohort study.
European psychiatry : the journal of the Association of European Psychiatrists, 67(1), e82
Citation
Leonhardt, Marja; Bramness, Jørgen G; Rognli, Eline Borger; Lien, Lars. (2024). Frequency and patterns of substance-induced psychosis in persons with concurrent mental health and substance use disorders during the COVID-19 pandemic: A Norwegian register-based cohort study.. European psychiatry : the journal of the Association of European Psychiatrists, 67(1), e82. https://doi.org/10.1192/j.eurpsy.2024.1797
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