Neurocognitive functioning during symptomatic states and remission in bipolar disorder and schizophrenia: a comparative study

Abstract

Aims Patients with bipolar disorder present milder cognitive impairment in comparison to patients with schizophrenia. Psychotic symptoms are associated with poorer cognitive functioning in both disorders. We aim to compare cognitive dysfunction between bipolar disorder and schizophrenia across symptomatic and remitted states. Methods An extensive cognitive battery was used to assess bipolar disorder patients (32 in manic episodes with psychotic features, 44 in euthymia), patients with schizophrenia (41 symptomatic, 39 remitted), and 55 healthy controls. A global cognitive factor and six neurocognitive domain factors were identified using principal component analyses. Results Global cognition components differed according to both illness and remission status; working memory differed according to remission status regardless of diagnosis; verbal fluency differed according to diagnosis regardless of remission status. An omnibus F test revealed that the remission state had a significant impact on processing speed in schizophrenia. Conclusion Our data suggest that both disorders are associated with state dependent (i.e., global cognition and working memory) and diagnosis dependent (i.e., global cognition and verbal fluency) neurocognitive dysfunctions. Processing speed was exclusively influenced by symptomatic states of schizophrenia.