Among 265 patients with first-treatment psychosis, cannabis use was not associated with negative beliefs about antipsychotic medications, suggesting other factors explain poor medication adherence in cannabis-using patients.
Psychiatrists and mental health clinicians working with psychosis patients who use cannabis.
No association between cannabis use and negative medication beliefs
What the researchers found
Neither lifetime cannabis use, current use, nor cannabis abuse diagnosis was associated with negative beliefs about medicines as measured by the BMQ questionnaire. However, patients with lifetime cannabis use were more likely to be male, younger at psychosis onset, and have higher alcohol and tobacco use.
Why it matters
Cannabis use predicts poor medication adherence in psychosis patients. If not through negative medication beliefs, clinicians need to identify the actual barriers to compliance in cannabis-using patients.
The numbers in context
265 first-treatment psychosis patients. Cannabis users were younger at onset, more likely male, higher alcohol and tobacco use. No significant association between any cannabis measure and BMQ scores.
How the study worked
Cross-sectional study of 265 patients with first-treatment schizophrenia spectrum disorder. Cannabis use assessed across three measures (lifetime, current, abuse/addiction). Medication beliefs measured using the validated Beliefs about Medication Questionnaire (BMQ). GLM analyses controlled for age and sex.
What this study cannot tell us
Cross-sectional design. Self-reported cannabis use. BMQ may not capture all dimensions of medication attitudes relevant to this population.
How to read the evidence
Well-designed clinical study with validated instruments, though cross-sectional design limits causal inference.
When this study was published
Published in 2022.
The bigger picture
The null finding is informative: it redirects the search for why cannabis-using psychosis patients have poor medication adherence toward other mechanisms like forgetting, side effect sensitivity, or competing priorities.
Questions still open
- If not beliefs, what drives poor medication adherence in cannabis-using psychosis patients? Could intoxication-related forgetting or lifestyle factors be more important?
Common questions
Do cannabis-using psychosis patients dislike their medications more?
Why do cannabis-using patients still have worse adherence?
Read the original research
Lifetime Cannabis Use Is Not Associated With Negative Beliefs About Medication in Patients With First Treatment Psychosis.
Frontiers in psychiatry, 13, 824051
Citation
Gjerde, Priyanthi B; Steen, Synne W; Vedal, Trude S J; Steen, Nils Eiel; Reponen, Elina J; Andreassen, Ole A; Steen, Vidar M; Melle, Ingrid. (2022). Lifetime Cannabis Use Is Not Associated With Negative Beliefs About Medication in Patients With First Treatment Psychosis.. Frontiers in psychiatry, 13, 824051. https://doi.org/10.3389/fpsyt.2022.824051
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