Cognitive deficits are core features of schizophrenia and they are also observed in bipolar disorder with psychotic episodes. Clinical symptom severity and cognitive performance might be related and they both affect everyday functioning.

To examine the patterns of cognition and clinical symptoms in patients with psychosis spectrum disorders.

To learn how clinical symptom severity affect the cognitive performance in the two patient groups.

Twenty-five bipolar and 40 schizophrenic patients were enrolled in the study. The following measures were used to assess the cognitive performance: Digit Span Task, Corsi Blocks Task, Tower of Hanoi Task, Visual Patterns Test, Letter and Category Fluency Tasks, Wisconsin Card Sorting Test. The Positive and Negative Syndrome Scale (PANSS) was also administered. The two groups were compared with Mann-Whitney test; the connections between clinical scales and cognitive measures were investigated through partial correlation.

The bipolar patients showed better performance on the majority of the cognitive tasks. The schizophrenic group had higher scores on all subscales of the PANSS (p < 0.016). In the bipolar group only the Negative scale of the PANSS was correlated with the backwards task of the Corsi Blocks (p = 0.022 r = −0.584). The cognitive performance of the schizophrenic patients was more related to the clinical symptoms.

Our results are in accordance with the notion that clinical symptoms are correlated to cognitive performance. Improving working memory processes might ease the coping with everyday difficulties caused by the symptoms, so this should be considered during the treatment of these patients.