There is a substantial body of evidence suggesting that cognitive deficits in schizophrenia (SΖ) andbipolar disorder (BD) persist after the subsidence of active symptoms. However, it is unclear whetherthe cognitive deficits observed in patients with BD are quantitatively or qualitatively similar tothose in SΖ patients. The aim of the study was to assess and compare the cognitive functioning ofpatients with clinically stable SZ and BD. To the best of our knowledge, this is the first study includinga comparison of the Theory of Mind between patients with SZ and BD. General intelligence,attention, speed of processing, working memory, verbal memory and learning, visuospatial ability,executive functions and ToM were assessed in 21 patients with SZ in remission, 23 euthymic BDtype I patients, and 27 healthy controls (HC), using WAIS-Vocabulary, Block design, and Digit span,Babcock Story Recall Test, Rey Auditory Verbal Learning Test, Stroop Word-Colour Test, WisconsinCard Sorting Test, Trail Making Test, and Faux Pas Recognition Test. The three groups were matchedfor gender, age and education. The SZ and BD groups were also matched in terms of illness durationand the age of the onset of the illness. To be enrolled in the study patients should have beenclinically stable for 3 months, operationalized as no change in total Brief Psychiatric Rating Scale,Hamilton Depression Rating Scale (<8), and Young Mania Rating Scale (<6). One-way ANOVA withpost hoc Bonferroni corrections was used for the between groups comparisons. Both BD and SCpatients were significantly impaired in general intellectual ability, verbal memory and learning, andexecutive functions compared to HC. Patients with SZ performed significantly worse than patientswith BD on verbal memory tasks, whereas BD group did not have significant lower score than SZ inany task. SZ patients performed worse than HC group on attention, processing speed and immediatememory tests, while BD patients on visuospatial ability and working memory. Both SZ and BDgroups did not differ from HC regarding Theory of Mind. Our results indicate that stable SZ and euthymicBD exhibit similar profiles of cognitive impairment, consistently with previous studies suggestingthat the differences are related to the extent and degree of impairments, rather than beingqualitative. Finally, our findings offer support to the hypothesis that the Theory of Mind does notrepresent a trait marker of schizophrenia or bipolar disorder.
Key words: Schizophrenia, bipolar disorder, cognitive deficits, Theory of Mind
G. Konstantakopoulos, N. Ioannidi, P. Patrikelis, A. Soumani, P. Oulis, D. Sakkas, G.N. Papadimitriou, D.Ploumpidis (page 195) - Full article in Greek