Cognitive impairment among an Egyptian sample of patients with schizophrenia and bipolar disorders: a comparative study

Background The cognitive profile among patients with schizophrenia (SZ) and bipolar disorder (BD) has varied widely across different studies. The aim of the current study was to compare different cognitive domains using psychometric and neurophysiological tests in patients with SZ to those with BD. A case–control study was conducted on 30 BD, 30 SZ and 30 age and sex matched control group. Each subject was submitted to the following: Wechsler Adult Intelligence Scale-3rd edition (WAIS-III), Montreal cognitive assessment scale (MoCA), Brief Visuospatial Memory Test-Revised (BVMT-R), Memory Assessment Scales (MAS), and the P300 event related potential (ERP). Results SZ and BD patients had significantly lower total and subscales of WAIS-III scores than the control group. SZ patients had significantly higher deterioration index (DI) than controls, while absence of such significant between BD and controls. SZ patients reported significantly lower MoCA scores and subitems, especially in visuospatial, naming, attention, delayed recall, and orientation subtests than controls. Only visuospatial and delayed recall scores were significantly decreased in BD than controls. SZ patients performed poorer on BVMT-R subscales than the control group. Both SZ and BD groups had lower mean values of all subscales except verbal assessment in the four memory tests. P300 latencies and amplitude had no significant difference among the three groups, although the BD group had a shorter P300 latency. Conclusion Patients with SZ and BD had significantly lower scores on various cognitive function domains in comparison to controls with more affection in SZ. The frequency of mood episodes, disease duration, and education level must be considered.