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Study breakdown

Veterans with bipolar disorder who currently used cannabis had better working memory and functioning

Cross SectionalPreliminary evidence
The takeaway

Among 254 veterans with bipolar disorder, those currently using cannabis had higher working memory and functional capacity scores than those with past use or no use.

Clinicians treating bipolar disorder, veterans considering cannabis use, and researchers studying substance use in mood disorders.

Current users had higher working memory than past users and non-users

What the researchers found

Current cannabis use in veterans with bipolar I disorder was associated with higher working memory performance and higher functional capacity compared to both past cannabis users and non-users, while also being associated with PTSD and lifetime suicidal ideation.

Why it matters

This study presents a nuanced picture: current cannabis use in bipolar disorder was linked to better cognitive and functional scores but also to PTSD and suicidal ideation, highlighting the complexity of cannabis effects in this population.

The numbers in context

254 veterans (84.6% male). 5.1% current cannabis users, 14.5% past cannabis users. Current users showed higher working memory and functional capacity than past users and non-users.

How the study worked

Cross-sectional analysis of 254 U.S. veterans with bipolar I disorder from a large-scale nationwide study. Categorized into current cannabis use (n=13), past cannabis use (n=37), past other drug use (n=77), and no drug use (n=127). Compared on clinical, cognitive, and functional measures.

What this study cannot tell us

Very small current cannabis user group (n=13). Cross-sectional design cannot establish causation. Predominantly male veteran sample limits generalizability. Possible selection bias: those functioning better may be more able to maintain cannabis use.

How to read the evidence

Preliminary: cross-sectional design, very small current user group (n=13), cannot establish causation.

When this study was published

Published in 2022.

The bigger picture

The finding that current cannabis users with bipolar disorder performed better cognitively challenges simplistic narratives about cannabis harm in mental illness, though the small sample and cross-sectional design limit interpretation.

Questions still open

  • Are the cognitively higher-functioning individuals simply the ones who can sustain cannabis use? Would longitudinal data show the same pattern? Does cannabis type, frequency, or method of use matter in bipolar outcomes?

Common questions

Does this mean cannabis improves cognition in bipolar disorder?
Not necessarily. This is a cross-sectional study, so it could be that people with better baseline functioning are more likely to use cannabis, rather than cannabis improving functioning.
Why were current users also more likely to have PTSD?
The study cannot explain why, but it may reflect self-medication patterns where veterans with PTSD and bipolar disorder turn to cannabis for symptom relief.
How many current cannabis users were studied?
Only 13 out of 254 veterans were current cannabis users, which is a very small group for drawing strong conclusions.

Read the original research

Multimodal Correlates of Cannabis Use among U.S. Veterans with Bipolar Disorder: An Integrated Study of Clinical, Cognitive, and Functional Outcomes.

Journal of dual diagnosis, 18(2), 81-91

Citation

Selloni, Alexandria; Bhatia, Gagandeep; Ranganathan, Mohini; De Aquino, Joao P. (2022). Multimodal Correlates of Cannabis Use among U.S. Veterans with Bipolar Disorder: An Integrated Study of Clinical, Cognitive, and Functional Outcomes.. Journal of dual diagnosis, 18(2), 81-91. https://doi.org/10.1080/15504263.2022.2053264

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