Differences between unipolar depression and bipolar II depression in women

Bipolar disorder II (BPII) and unipolar depression (UD) are both characterized by episodes of major depression (MDE), however DSM-IV criteria for MDE are identical, regardless of diagnosis. As a result, misdiagnosis of BP II and UD is common, leading to inappropriate treatment. Because women are twice as likely as men to experience MDE, differentiating UD from BP II in the context of depression is especially important for women. We examined symptoms and clinical features of MDE in women with UD and BPII to compare presentations of the two disorders in women.

We compared characteristics of depressed women meeting DSM-IV criteria for BPII (n=48) or UD (n=48), matched on age.

Feelings of worthlessness occurred in 98% of participants with UD versus 85% with BPII (p=0.03). Participants with UD experienced either insomnia or hypersomnia, but participants with BPII were more likely to experience both simultaneously (p=0.04). Those with UD were significantly less likely to have >5 prior mood episodes compared to those with BP II (12% versus 61%; p<0.0001) and had a later age of onset (p=0.003).

Small sample size and exclusion criteria (i.e., comorbid substance abuse) may limit generalizability of findings.

Among a sample of women, number of prior episodes, feelings of worthlessness, age of onset, and sleep patterns distinguished between UD and BP II depressive episodes. A better understanding of differential presentation of BP II versus UD depression in women may help guide clinicians to more accurate diagnoses and, ultimately, better treatment.