Current methods for measuring cannabis use in psychosis patients are inadequate
Self-report questionnaires used to assess cannabis use in psychosis patients were designed for other populations and may be inaccurate due to psychotic symptoms, cognitive deficits, and desire to conceal use.
Quick Facts
What This Study Found
Cannabis assessment tools used in psychosis research were originally developed for healthy individuals or people with cannabis use disorder. In psychosis patients, the accuracy of self-report may be compromised by symptoms, cognitive impairment, and motivated concealment. Urinary THC screening is sometimes used in acute episodes but not routinely. Quantitative blood/urine cannabinoid measurement could provide more reliable data but is rarely used.
Key Numbers
Cannabis use is common in people with psychotic disorders. Self-report accuracy may be impaired by three factors: psychotic symptoms, cognitive deficits, and desire to conceal use from clinicians.
How They Did This
Narrative review examining current approaches to assessing cannabis use in people with psychotic disorders, comparing self-report tools with biological measures and discussing limitations specific to this population.
Why This Research Matters
Accurate cannabis use measurement is critical for managing psychosis, since use is linked to symptom worsening, poor treatment adherence, and relapse. If clinicians and researchers are relying on flawed measurement tools, they may be underestimating the problem.
The Bigger Picture
The relationship between cannabis and psychosis is one of the most important questions in psychiatric research. But if the measurement of cannabis use in this population is fundamentally flawed, the entire evidence base may be biased, potentially underestimating the true impact of use on outcomes.
What This Study Doesn't Tell Us
Narrative review without systematic methodology. Does not quantify the degree of measurement error. Biological measures have their own limitations (detecting use window, cost, invasiveness).
Questions This Raises
- ?Would routine quantitative cannabinoid testing in psychosis patients improve clinical outcomes?
- ?How large is the gap between self-reported and biologically verified cannabis use in this population?
- ?Could passive monitoring approaches supplement self-report?
Trust & Context
- Key Stat:
- Three factors compromise self-report accuracy in psychosis
- Evidence Grade:
- Narrative review synthesizing clinical observations. Does not present new data or use systematic methodology, but raises important methodological concerns.
- Study Age:
- Published in 2024 in Cannabis and Cannabinoid Research.
- Original Title:
- Assessing Cannabis Use in People with Psychosis.
- Published In:
- Cannabis and cannabinoid research, 9(1), 49-58 (2024)
- Authors:
- Chesney, Edward(13), Lawn, Will(15), McGuire, Philip(21)
- Database ID:
- RTHC-05200
Evidence Hierarchy
Summarizes existing research without a strict systematic method.
What do these levels mean? →Frequently Asked Questions
Why is it hard to measure cannabis use in psychosis patients?
Three factors make self-report unreliable: psychotic symptoms can impair accurate recall, cognitive deficits common in psychosis affect questionnaire performance, and patients may hide use when clinicians have advised against it.
What would be a better way to measure cannabis use?
The authors suggest quantitative measurement of cannabinoid levels in blood or urine would provide more accurate data than asking patients or using questionnaires, though this approach is rarely used in clinical practice or research.
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Cite This Study
https://rethinkthc.com/research/RTHC-05200APA
Chesney, Edward; Lawn, Will; McGuire, Philip. (2024). Assessing Cannabis Use in People with Psychosis.. Cannabis and cannabinoid research, 9(1), 49-58. https://doi.org/10.1089/can.2023.0032
MLA
Chesney, Edward, et al. "Assessing Cannabis Use in People with Psychosis.." Cannabis and cannabinoid research, 2024. https://doi.org/10.1089/can.2023.0032
RethinkTHC
RethinkTHC Research Database. "Assessing Cannabis Use in People with Psychosis." RTHC-05200. Retrieved from https://rethinkthc.com/research/chesney-2024-assessing-cannabis-use-in
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.