Leo Sher, M.D.

A research report, “Patterns and predictors of conversion to bipolar disorder in 91 587 individuals diagnosed with unipolar depression” has been published in Acta Psychiatrica Scandinavica online ahead of print (1). In this study, researchers from Aarhus, Denmark, examined predictors of diagnostic conversion from unipolar depression to bipolar disorder.

In all, 91,587 individuals with unipolar depression treated in hospitals in Denmark (including Greenland and the Faroe Islands) in 1995-2016 were included in the study.  Thirty-nine per cent of the patients included in the study were diagnosed with a psychiatric disorder other than a mood disorder on or prior to the date of their index unipolar depression diagnosis. The cohort was followed up for 702,710 person-years. The average duration of follow up was 7.7 years (SD = 5.4 years).

During the follow-up period, 3,910 patients with unipolar depression developed bipolar disorder. The authors found that a parental history of bipolar disorder was the strongest predictor of conversion from unipolar depression to bipolar disorder. Psychotic depression, inpatient or emergency treatment, recurrent depressive disorder, greater depression severity, prior non-affective psychotic disorder, prior or comorbid alcohol use disorder, and a parental history of unipolar depression were also significant predictors of conversion from unipolar depression to bipolar disorder.

The observation that patients with unipolar depression that have comorbid psychotic symptomatology and/or a parental history of bipolar disorder are at an increased risk of conversion to bipolar disorder may be useful in clinical practice to identify patients with unipolar depression who are at a greater risk of developing bipolar disorder.

Reference

1. Musliner KL, Østergaard SD. Patterns and predictors of conversion to bipolar disorder in 91 587 individuals diagnosed with unipolar depression. Acta Psychiatr Scand. 2018 Mar 2. doi: 10.1111/acps.12869. [Epub ahead of print]