MedWire News: There are limited differences between bipolar II disorder (BDII) depression and unipolar depression, say Australian scientists who suggest previously suggested differences can be explained by age, gender, and severity.
While previous studies comparing BD and depression have found that the former is characterized by a more severe mood state, lability of mood, and psychotic and atypical features, it is noteworthy that the majority of the studies have involved patients with bipolar I disorder.
To compare the depressive symptom profile of BDII patients with that of unipolar depression patients, Gordon Parker and colleagues from the University of New South Wales in Sydney studied 394 outpatients attending a specialist depression clinic. All participants were assessed using the Mood Assessment Program.
In all, 119 patients had BDII, 104 had melancholic unipolar depression, and 171 had non-melancholic unipolar depression. There were no significant differences between BDII and unipolar depression patients in gender distribution or state depression severity scores.
BDII patients were significantly younger than both unipolar depression and melancholic unipolar patients, at 38.5 versus 42.7 and 46.4 years, respectively, and non-melancholic unipolar patients were significantly younger than melancholic patients, at 40.5 years.
While BDII patients and unipolar patients showed minimal differences in symptom severity scores, BDII patients were more likely to report their thinking as slowed and feel less of a need to be close to people.
Interestingly, melancholic unipolar depression patients were more likely to report anticipatory and consummatory anhedonia, non-reactivity, psychomotor slowing and weight loss than non-melancholic patients.
BDII patients differed from melancholic unipolar patients only in terms of inability to derive pleasure from normal pleasurable activities and weight loss, and from non-melancholic patients in terms of feeling physically slowed, having slowed thinking, feeling paralysed, and having less of a need to be close to people. Different results were seen with prototypic symptom patterns, indicating the findings are affected by rating strategies and age.
“We conclude that our study found limited differentiation of bipolar II depression from unipolar, melancholic and non-melancholic depression, and that differences highlighted in the few previous reports may reflect age, gender and severity differences,” the team writes in the journal Acta Psychiatrica Scandinavica.
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