By Eleanor McDermid, Senior medwireNews Reporter
A large study confirms several factors that can distinguish patients with bipolar depression from those with unipolar depression, including higher trait impulsivity, aggression and hostility.
In line with previous studies, bipolar patients had more personal and familial evidence of mania, were younger at onset of depression and had more previous affective episodes than patients with unipolar depression.
“These findings highlight the importance of comprehensive history taking and of course of illness-related data in order to ascertain the diagnosis”, say researcher Maria Oquendo (New York State Psychiatric Institute and Columbia University, USA) and team.
The 151 bipolar I disorder patients in the study were aged an average of 17.5 years at onset of the first depressive episode and the 79 with bipolar II disorder were aged 19.9 years. By contrast, the 455 patients with unipolar depression were aged an average of 25.0 years.
The three groups were of similar age at the time of analysis, but the bipolar depression patients had a higher number of previous depressive and affective episodes than the unipolar depression patients, and had more often and from a younger age been previously treated with antidepressants, antipsychotics or mood stabilisers.
Bipolar patients more frequently had first- or second-degree relatives with mania, at 15.7% and 19.4% for the bipolar I and bipolar II groups, respectively, versus 5.4% for the unipolar depression group.
Despite being in a depressive phase, both bipolar groups had higher scores on the Young Mania Rating Scale than the unipolar group, at 5.3 to 5.6 versus 3.0, and they more often had psychotic symptoms, at 17.5% and 14.7% for the bipolar I and II groups, respectively, compared with 6.5% for the unipolar depression patients. They also had more comorbid psychiatric conditions.
Both bipolar groups had significantly more lifetime impulsivity, aggression and hostility than the unipolar group. However, this differed according to bipolar subtype, such that 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.
This finding “adds to currently scarce knowledge on traits differences between the two groups”, the team writes in European Psychiatry.
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