A prediction model using clinical interviews correctly identified 73% of recent-onset psychosis patients who would continue using cannabis, with lower functioning, urbanicity, and lack of coping strategies as key predictors.
Psychiatrists treating early psychosis; researchers developing targeted substance use interventions; clinical program designers.
73% prediction accuracy from clinical assessment alone
What the researchers found
Clinical interview data alone predicted continued cannabis use with 73% accuracy in 109 recent-onset psychosis patients. The model generalized to 73 clinical high-risk patients. Lower functioning, specific substance use patterns, urbanicity, and lack of alternative coping strategies were the strongest predictors.
Why it matters
Continued cannabis use worsens outcomes in psychosis. If clinicians can identify which patients are most likely to keep using, they can target interventions more effectively. This study shows that standard clinical assessments may be sufficient for this prediction.
The numbers in context
109 ROP patients, 73 CHR patients. Clinical assessment accuracy: 73% (p<0.05). Cognitive and MRI data did not significantly improve prediction (ps>0.065). Key predictors: lower functioning, substance use patterns, urbanicity, lack of alternative coping strategies.
How the study worked
Prospective study of 109 recent-onset psychosis (ROP) patients who reported lifetime cannabis use at baseline. Machine learning models tested whether clinical assessments, cognitive tests, and brain MRI could predict cannabis use between baseline and 9-month follow-up. The model was validated in 73 clinical high-risk patients.
What this study cannot tell us
Moderate sample size (109 ROP, 73 CHR). "Continued use" was defined as any cannabis use in 9 months, not frequency or quantity. The model needs testing in larger, more diverse populations before clinical implementation.
How to read the evidence
Moderate: prospective design with cross-validation and external validation in a second patient group, though moderate sample sizes.
When this study was published
Published in 2022.
The bigger picture
The finding that brain scans and cognitive tests added nothing beyond clinical interviews is practically important: it means clinicians do not need expensive neuroimaging to identify at-risk patients. The coping strategies finding also points to a specific intervention target.
Questions still open
- Would targeted coping skills interventions reduce continued cannabis use in the identified high-risk patients? Does the 73% accuracy hold across different cultural contexts and healthcare settings?
Common questions
Can doctors predict which psychosis patients will keep using cannabis?
Do brain scans help predict cannabis use in psychosis patients?
Read the original research
Pattern of predictive features of continued cannabis use in patients with recent-onset psychosis and clinical high-risk for psychosis.
Schizophrenia (Heidelberg, Germany), 8(1), 19
Citation
Penzel, Nora; Sanfelici, Rachele; Antonucci, Linda A; Betz, Linda T; Dwyer, Dominic; Ruef, Anne; Cho, Kang Ik K; Cumming, Paul; Pogarell, Oliver; Howes, Oliver; Falkai, Peter; Upthegrove, Rachel; Borgwardt, Stefan; Brambilla, Paolo; Lencer, Rebekka; Meisenzahl, Eva; Schultze-Lutter, Frauke; Rosen, Marlene; Lichtenstein, Theresa; Kambeitz-Ilankovic, Lana; Ruhrmann, Stephan; Salokangas, Raimo K R; Pantelis, Christos; Wood, Stephen J; Quednow, Boris B; Pergola, Giulio; Bertolino, Alessandro; Koutsouleris, Nikolaos; Kambeitz, Joseph. (2022). Pattern of predictive features of continued cannabis use in patients with recent-onset psychosis and clinical high-risk for psychosis.. Schizophrenia (Heidelberg, Germany), 8(1), 19. https://doi.org/10.1038/s41537-022-00218-y
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