title: Impairments of working memory in schizophrenia and bipolar disorder: the effect of history of psychotic symptoms and different aspects of cognitive task demands.
abstract: Comparisons of cognitive impairments between schizophrenia (SZ) and bipolar disorder (BPD) have produced mixed results. We applied different working memory (WM) measures (Digit Span Forward and Backward, Short-delay and Long-delay CPT-AX, N-back) to patients with SZ (n = 23), psychotic BPD (n = 19) and non-psychotic BPD (n = 24), as well as to healthy controls (HC) (n = 18) in order to compare the level of WM impairments across the groups. With respect to the less demanding WM measures (Digit Span Forward and Backward, Short-delay CPT-AX), there were no between group differences in cognitive performance; however, with respect to the more demanding WM measures (Long-delay CPT-AX, N-back), we observed that the groups with psychosis (SZ, psychotic BPD) did not differ from one another, but performed poorer than the group without a history of psychosis (non-psychotic BPD). A history of psychotic symptoms may influence cognitive performance with respect to WM delay and load effects as measured by Long-delay CPT-AX and N-back tests, respectively. We observed a positive correlation of WM performance with antipsychotic treatment and a negative correlation with depressive symptoms in BPD and with negative symptoms in SZ subgroup. Our study suggests that WM dysfunctions are more closely related to a history of psychosis than to the diagnostic categories of SZ and BPD described by psychiatric classification systems.
authors.affiliation: Department and Clinic of Psychiatry, Wroclaw Medical University Wroclaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Frydecka
authors.affiliation: Faculty of Medicine, Psychogeriatric Research Center, Institute of Psychiatry, Ain Shams University Cairo, Egypt.
authors.forename: Abeer M
authors.initials: AM
authors.lastname: Eissa
authors.affiliation: Faculty of Medicine, Psychogeriatric Research Center, Institute of Psychiatry, Ain Shams University Cairo, Egypt.
authors.forename: Doaa H
authors.initials: DH
authors.lastname: Hewedi
authors.affiliation: Faculty of Medicine, Psychogeriatric Research Center, Institute of Psychiatry, Ain Shams University Cairo, Egypt.
authors.forename: Manal
authors.initials: M
authors.lastname: Ali
authors.affiliation: Institute of Computer Science, Wroclaw University of Technology Wroclaw, Poland.
authors.forename: Jarosław
authors.initials: J
authors.lastname: Drapała
authors.affiliation: Department and Clinic of Psychiatry, Wroclaw Medical University Wroclaw, Poland ; Department of Genetics, Wroclaw Medical University Wroclaw, Poland.
authors.forename: Błażej
authors.initials: B
authors.lastname: Misiak
authors.affiliation: Department and Clinic of Psychiatry, Wroclaw Medical University Wroclaw, Poland.
authors.forename: Ewa
authors.initials: E
authors.lastname: Kłosińska
authors.affiliation: School of Social Sciences and Psychology, Marcs Institute for Brain and Behaviour, University of Western Sydney Sydney, NSW, Australia.
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Phillips
authors.affiliation: School of Social Sciences and Psychology, Marcs Institute for Brain and Behaviour, University of Western Sydney Sydney, NSW, Australia.
authors.forename: Ahmed A
authors.initials: AA
authors.lastname: Moustafa
keywords: history of psychosis; psychotic vs. non-psychotic bipolar disorder; schizophrenia; working memory