Bipolar Patients Who Stopped Cannabis During a Manic Episode Had Similar Outcomes to Those Who Never Used | Research

The takeaway

In a two-year study, bipolar disorder patients who quit cannabis during a manic episode achieved recovery and remission rates similar to never-users, while those who continued had worse outcomes.

People with bipolar disorder who use cannabis and want to understand how it might relate to their clinical outcomes.

Quitting during a manic episode led to outcomes similar to never-users

What the researchers found

Researchers followed 1,922 adults with bipolar disorder over two years, dividing them into three groups based on cannabis use during a manic or mixed episode: current users (6.9%), previous users who quit during the episode (4.6%), and never-users (88.5%).

Patients who stopped using cannabis during their manic episode showed clinical and functional outcomes statistically similar to those who never used cannabis. In contrast, patients who continued using cannabis had significantly lower rates of recovery and remission, higher rates of recurrence, greater work impairment, and were less likely to be living with a partner.

Why it matters

For people with bipolar disorder who use cannabis, this study provides evidence that quitting during a manic episode may lead to outcomes comparable to those who never used. It also reinforces that continued cannabis use during bipolar episodes is associated with measurably worse clinical trajectories.

The numbers in context

1,922 patients analyzed. 6.9% current users, 4.6% previous users, 88.5% never users. Current users had lower recovery (p=0.004), lower remission (p=0.014), higher recurrence (p=0.014), and greater work impairment (p=0.016) compared to never users.

How the study worked

Data came from the European Mania in Bipolar Longitudinal Evaluation of Medication (EMBLEM), a 2-year prospective observational study across multiple European sites. Cannabis use was assessed between the 12-week and 24-month visits. Outcomes were analyzed using regression models controlling for confounding variables.

What this study cannot tell us

This was an observational study, so the association between cannabis cessation and better outcomes could reflect other differences between the groups. Patients who quit may have had less severe illness or better treatment adherence overall. Self-reported cannabis use may be inaccurate. The relatively small proportion of cannabis users limits statistical power.

How to read the evidence

This is a large prospective observational study with two years of follow-up, providing moderate evidence. However, it cannot prove that quitting cannabis caused the improved outcomes.

When this study was published

Published in 2015, using data from the EMBLEM study. The findings remain relevant to clinical discussions about cannabis and bipolar disorder.

The bigger picture

The relationship between cannabis and bipolar disorder is complex. While some patients report symptom relief from cannabis, this longitudinal data suggests that continued use during manic episodes is associated with worse long-term outcomes, and that stopping use can meaningfully improve the trajectory.

Questions still open

What factors help bipolar patients successfully stop cannabis use during manic episodes? Would these findings hold in depressive episodes of bipolar disorder as well?

Common questions

Does this mean cannabis causes worse bipolar outcomes?

The study found an association between continued cannabis use and worse outcomes, but as an observational study, it cannot prove causation. People who continued using cannabis may have differed from those who quit in ways that independently affected their outcomes.

If someone with bipolar disorder quits cannabis, will their outcomes improve?

The study found that those who quit had outcomes similar to never-users, which is encouraging. However, individual results vary, and quitting cannabis should be discussed with a healthcare provider as part of a comprehensive treatment plan.

Read the original research

Cannabis and bipolar disorder: does quitting cannabis use during manic/mixed episode improve clinical/functional outcomes?

Acta psychiatrica Scandinavica, 131(2), 100-10

View on PubMed ↗Publisher’s paper ↗

Citation

Zorrilla, I; Aguado, J; Haro, J M; Barbeito, S; López Zurbano, S; Ortiz, A; López, P; Gonzalez-Pinto, A. (2015). Cannabis and bipolar disorder: does quitting cannabis use during manic/mixed episode improve clinical/functional outcomes?. Acta psychiatrica Scandinavica, 131(2), 100-10. https://doi.org/10.1111/acps.12366