Bipolar or unipolar depression: How to distinguish between these two conditions, which can have very different treatment response remains a difficult question without really satisfying answers. As noted in the picture to the right, misdiagnosis is common and can have serious consequences. An article in European Psychiatry adds to the literature pointing to certain features that increase the odds that someone who is depressed has a bipolar depression.
In brief, the article found that the following predicted a bipolar depression –
- Younger age at onset (first depressive episode before age 15).
- History of psychotic symptom (hearing voices, paranoia). Symptoms during the current episode did not distinguish the two types of depression, but a history of ever having psychotic symptoms did.
- Presence of any manic symptoms when depressed (for example, impulsivity). This was measured using the Young Mania Rating Scale. It fits with a number of other studies suggesting that features of a “mixed episode” are predictive of a greater risk of a bipolar depression.
- Family history of mania.15.7% and 19.4% for the bipolar I and bipolar II groups, respectively, versus 5.4% for the unipolar depression group.
- More episodes (more than 7 previous mood episodes of any kind).
- Greater impulsivity or hostility. Both bipolar groups had significantly more lifetime impulsivity, aggression and hostility than the unipolar group. However, this differed according to bipolar subtype. Patients with bipolar I disorder had the highest average levels of impulsivity and aggression, whereas the highest average hostility rating occurred in the bipolar II disorder group. See the chart to the right. Impulsivity, aggression and hostility were assessed by Barratt Impulsivity Scale (BIS), the Brown-Goodwin Aggression Inventory (BGAI), and the Buss-Durkee Hostility Inventory (BDHI).
According to the authors: “These findings highlight the importance of comprehensive history taking and of course of illness-related data in order to ascertain the diagnosis.”