Evening chronotype and cannabis use disorder both independently predicted earlier mood symptom onset in bipolar disorder | Research

The takeaway

Among 212 people with bipolar I disorder, both evening chronotype and cannabis use disorder independently predicted earlier onset of mood symptoms, with those who started cannabis after mood symptoms appearing having the earliest onset.

Psychiatrists, bipolar disorder researchers, chronobiology scientists, and patients with co-occurring bipolar disorder and cannabis use.

What the researchers found

Lower morningness (evening chronotype) and CUD were independently associated with earlier age of mood symptom onset in bipolar disorder. There was no interaction between the two. Patients who began cannabis use after mood symptoms started had earlier mood onset than those who used cannabis first, suggesting circadian disruption may be an underlying factor linking both CUD and BD.

Why it matters

The finding that people who started cannabis after mood symptoms had earlier onset challenges the simple narrative that cannabis causes bipolar symptoms. Instead, disrupted circadian rhythms may predispose people to both conditions independently.

The numbers in context

212 participants with BD I. Lower morningness and CUD both independently associated with earlier mood onset. No interaction effect. Post-mood-onset cannabis initiators had earlier mood symptom onset than pre-mood-onset initiators.

How the study worked

Cross-sectional analysis of 212 participants with bipolar I disorder from the Pharmacogenomics of Bipolar Disorder study, examining chronotype (BALM scale), CUD diagnosis, and mood symptom variables including episodes per year and age of onset.

What this study cannot tell us

Cross-sectional design cannot establish causal direction. Self-reported chronotype and cannabis use history subject to recall bias. BD I only; findings may not apply to BD II. BALM scale is a simplified chronotype measure.

How to read the evidence

Reasonable sample from a well-characterized bipolar cohort with an interesting analytical approach, though cross-sectional design and self-report measures limit causal inference.

When this study was published

2024 publication.

The bigger picture

Circadian rhythm disruption is emerging as a transdiagnostic risk factor connecting mood disorders and substance use. If circadian dysfunction drives both bipolar symptoms and cannabis use, treating the circadian disruption could potentially address both problems.

Questions still open

Would circadian-targeted interventions (light therapy, sleep scheduling) reduce both CUD and mood episode frequency in bipolar disorder?
Do genetic variants that affect circadian rhythms also predict CUD risk in bipolar populations?

Common questions

What is chronotype?

Your natural preference for when to sleep and wake. 'Evening types' (night owls) prefer later sleep and wake times, while 'morning types' prefer earlier schedules. Chronotype is partly genetic and is increasingly linked to mental health outcomes.

Does cannabis cause bipolar disorder?

This study found that many people with bipolar disorder started using cannabis after mood symptoms began, not before. The researchers suggest disrupted circadian rhythms may independently predispose people to both bipolar disorder and problematic cannabis use.

Read the original research

Co-morbid cannabis use disorder and chronotype are associated with mood symptom onset in people with bipolar disorder.

Journal of psychiatric research, 180, 327-332

View on PubMed ↗Publisher’s paper ↗

Citation

Miranda, Alannah; Holloway, Breanna M; Perry, William; Minassian, Arpi; McCarthy, Michael. (2024). Co-morbid cannabis use disorder and chronotype are associated with mood symptom onset in people with bipolar disorder.. Journal of psychiatric research, 180, 327-332. https://doi.org/10.1016/j.jpsychires.2024.11.007