Recent research in bipolar disorder points at the relevance and persistence of cognitive deficits in bipolar patients (BPD) even beyond acute episodes of depression or mania. Impairments were found in attention, processing speed, memory and executive functioning. Up to now, the mechanisms, why some BPD do not reach their former level of cognitive performance and psychosocial functioning, while others are remitted completely, is not understood. In this study we aimed to identify a’deficit vs. nondeficit subgroup’ within BPD. For this purpose, we investigated the association between demographic and disease specific variables and the cognitive performance of BPD. The test performance of 70 remitted outpatients (Bipolar-Type I and II) was compared to 70 healthy controls (HC). Participants performed an extensive neuropsychological test battery.

As expected our sample of euthymic BPD performed significantly worse than HCs in three of eight cognitive domains, namely Planning, Cognitive Flexibility and Divided Attention. In line with previous findings, more than a half of the euthymic BPD did not have any neuropsychological deficits. We found no significant correlations between test performance and clinical variables. But interestingly, we revealed significant associations between subthreshold depressive symptomatology and psychomotor slowing, impaired long term and working memory.

In sum, these results suggest the presence of cognitive subgroups in bipolar disorder. However, we found no evidence of underlying etiologies: Clinical characteristics seem to have no influence. However, our results indicate that cognitive deficits found in euthymic BPD could result from a subdepressive syndrome and not per se by disease characteristics.