Differentiating bipolar disorders from unipolar depression by applying the Brief Assessment of Cognition in Affective...

Scholars continue to argue about whether bipolar disorders (BD) and unipolar depression (UD) are distinguishable with regard to neurocognitive function. This study aims to explore the cognitive profiles of UD and BD by applying the Brief Assessment of Cognition in Affective Disorders (BAC-A) for neuropsychological assessment.

This cross-sectional study included 68 patients with UD, 67 patients with BD, and 135 healthy control subjects. We evaluated the participants' cognitive functions at euthymic status using the BAC-A, which is made up of six traditional cognitive subtests and the Affective Processing Test. We then used a discriminant function analysis (DFA) to determine whether cognitive performance can be used to distinguish these participant groups.

Healthy controls demonstrated better performance in all subtests of the BAC-A than both the UD and BD patients, with the exception of delayed recognition of affective interference. Compared with the BD group, the UD group exhibited better performance in working memory and emotion inhibition. Furthermore, using all BAC-A indexes, a total of 70% of participants could be correctly classified using a DFA model, and the discriminating validity between UD and BD was superior to using either the traditional cognitive domains or the Affective Processing Test alone.

We have found that UD patients may exhibit an intermediate performance between healthy subjects and BD patients in working memory and emotional inhibition tests. The BAC-A can potentially assist in differentiating BD patients from UD patients at euthymic status in clinical settings.