Cannabis use was not associated with cognitive impairment in people with first-episode psychosis
Among 89 people with first-episode psychosis, lifetime cannabis users showed no differences from non-users on verbal memory, verbal fluency, or attention, though cannabis users had more positive symptoms and non-users had more negative symptoms.
Quick Facts
What This Study Found
Of 89 FEP patients, 61 (68.5%) were lifetime cannabis users. Cannabis users had significantly more positive psychotic symptoms, while non-users displayed more negative symptoms. There were no differences between groups on tests of verbal memory, verbal fluency, or attention.
Key Numbers
89 FEP patients; 61 (68.5%) lifetime cannabis users. Cannabis users: more positive symptoms. Non-users: more negative symptoms. No cognitive differences on any task.
How They Did This
Cross-sectional study of 89 people diagnosed with first-episode psychosis. Cannabis use defined as 3+ times/week for 4+ weeks. Cognitive battery assessed verbal memory, verbal fluency, and attention. Controlled for recency of use and other illicit substance use.
Why This Research Matters
The concern that cannabis compounds cognitive deficits in psychosis has treatment implications. This finding of no additive cognitive effect is reassuring but must be interpreted carefully.
The Bigger Picture
This adds to a mixed literature on cannabis and cognition in psychosis. The symptom profile differences (more positive symptoms in users, more negative in non-users) may reflect different illness subtypes rather than direct cannabis effects.
What This Study Doesn't Tell Us
Cross-sectional; relatively small sample; lifetime use definition does not capture current exposure; limited cognitive battery (3 domains); cannot determine if pre-existing cognitive abilities differ.
Questions This Raises
- ?Do cannabis users and non-users with psychosis represent different illness subtypes?
- ?Would more sensitive cognitive measures detect differences?
Trust & Context
- Key Stat:
- No cognitive differences between cannabis users and non-users with first-episode psychosis
- Evidence Grade:
- Small cross-sectional study with limited cognitive measures in a first-episode psychosis population.
- Study Age:
- Published in 2020.
- Original Title:
- The relationship between cannabis use and cognition in people diagnosed with first-episode psychosis.
- Published In:
- Psychiatry research, 293, 113424 (2020)
- Authors:
- de Vos, Chloé, Leopold, Karolina, Blanke, Elisabeth S, Siebert, Stefan, Baumgardt, Johanna, Burkhardt, Eva, Bechdolf, Andreas
- Database ID:
- RTHC-02502
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis worsen thinking problems in psychosis?
This study found no evidence that cannabis use added to cognitive impairment in first-episode psychosis. Cannabis users and non-users performed similarly on verbal memory, fluency, and attention tests.
Why did cannabis users have different symptoms?
Cannabis users had more positive symptoms (hallucinations, delusions) while non-users had more negative symptoms (withdrawal, flat affect). This could mean cannabis is associated with a different presentation of psychosis rather than simply making existing illness worse.
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Cite This Study
https://rethinkthc.com/research/RTHC-02502APA
de Vos, Chloé; Leopold, Karolina; Blanke, Elisabeth S; Siebert, Stefan; Baumgardt, Johanna; Burkhardt, Eva; Bechdolf, Andreas. (2020). The relationship between cannabis use and cognition in people diagnosed with first-episode psychosis.. Psychiatry research, 293, 113424. https://doi.org/10.1016/j.psychres.2020.113424
MLA
de Vos, Chloé, et al. "The relationship between cannabis use and cognition in people diagnosed with first-episode psychosis.." Psychiatry research, 2020. https://doi.org/10.1016/j.psychres.2020.113424
RethinkTHC
RethinkTHC Research Database. "The relationship between cannabis use and cognition in peopl..." RTHC-02502. Retrieved from https://rethinkthc.com/research/de-2020-the-relationship-between-cannabis
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.