Red Flags for Bipolar

Transformation by Robert Lovejoy

Clues that a depressive episode is a bipolar type

STUDY: Niktabe SD et al, European Journal of General Practice 2026

STUDY TYPE: Systematic review

FUNDING: Independent

Background

Bipolar disorder and unipolar depression often look identical at first presentation: Depression. This review searched for features, visible during a depressive episode, that point to a risk for bipolar disorder before mania surfaces.

The Study

• A systematic review, following PRISMA guidelines, of 36 studies.

Results

• Eight features pointed toward bipolar disorder: early onset, frequent recurrence, family history of bipolar disorder, cyclothymic temperament, past suicide attempts, postpartum onset, psychotic features, and mixed features.
• Family history carries the strongest signal, with heritability estimated at 85% in a twin study.
• Psychotic features were 4.6 times more common in bipolar disorder, and mixed features were three times more frequent.
• Between 21% and 54% of women with postpartum depression actually met criteria for bipolar disorder.
• Past suicide attempts were nearly four times more common, and recurrence ran at roughly twice the rate of unipolar depression over 20-year follow-up.
• Episode severity, atypical features, hyperthymic temperament, and comorbidities like ADHD, anxiety, or substance use didn’t reliably distinguish the two.

Limitations

Observational studies. Criteria for markers not standardized (eg, how many episodes is “recurrent”). Postpartum findings may be skewed by underrepresentation of that population.

Practice Implications

1. Don’t rely on screening instruments for bipolar. They miss 30-40% of cases, and won’t detect forgotten manias or those that haven’t appeared.
2. Ask about age of onset, frequency of depression, family history of bipolar disorder, postpartum onset, and mood-worsening on an antidepressant.
3. The Bipolarity Index captures these markers in a 100-point scale. The Rapid Mood Screener is a shorter, patient-rated version.

—Chris Aiken, MD
Director, Psych Partners
Editor in Chief, Carlat Psychiatry Report

What’s Your Take? Share in Comments