Examination and Comparison of Cognitive and Executive Functions in Clinically Stable Schizophrenia Disorder, Bipolar Disorder, and Major Depressive Disorder

Abstract

Background. Schizophrenia (SC), bipolar disorder (BD), and major depressive disorder (MDD) are associated with various cognitive and executive dysfunctions. The aim of the present study was to evaluate and compare cognitive and executive dysfunctions in schizophrenia, bipolar disorder, and major depressive disorder. Materials and Methods. Sixty-four schizophrenia patients, 68 bipolar patients, 62 patients with major depressive disorder, and 75 healthy individuals participated in the present study. All participants were assessed with the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), Young Mania Rating Scale (YMRS), Positive and Negative Syndrome Scale (PANSS), Beck Depression Inventory (BDI-II), Trial Making Test (TMT), Four-Choice Reaction Time Task, Ruler Drop Method (RDM), Tower of London (TOL) task, and the Wisconsin Card Sorting Task (WCST). Data were analyzed by chi-square, Kolmogorov-Smirnov, and independent t -tests; ANOVA; and MANOVA. Results. In the cognitive function, the scores of SC, BD, and MDD patients were lower than those of healthy individuals. Also, the scores of MDD patients were lower than those of other patients, and the scores of BD patients were lower than those of SC patients. In the executive function, the scores of SC, BD, and MDD patients were lower than those of healthy individuals. Moreover, the scores of the MDD group were higher than those of the BD and SC groups, and the scores of the SC group were higher than those of the BD group. Conclusion. Patients with SC, BD, and MDD have poorer cognitive and executive functions than healthy individuals, even when these patients are in a stable state. Assessment of cognitive and executive functions in SC, BD, and MDD patients can help in understanding the pathology of these disorders.

Prefrontal Cortex Activation During Verbal Fluency Task and Tower of London Task in Schizophrenia and Major Depressive Disorder

“…However, there have been no previous fNIRS study of TOLs in MDD patients. Our results showed that MDD patients planned and dealt with problems less effectively than HCs but had higher accuracy than SZ patients, which suggested that executive function impairment was more severe in SZ patients and were consistent with a previous study (15). Perhaps the TOL task could better distinguish between mental disorders and HCs due to both patient groups showing poorer TOL performance.…”

“…Combining our results with some previous studies has found that SZ patients have poorer task performance and cognitive function than MDD patients, such as in the VFT (20,24), the TOL task (15), and the n-back task (34), which reflect executive function and working memory. Our results showed that SZ patients exhibited significantly decreased hemodynamic changes than the MDD patients in specific regions in the DLPFC during the two tasks, which indicated that the DLPFC is crucial for executive function.…”

“…A previous fNIRS study found reduced prefrontal activation during TOL in first-episode SZ (14). A study compared cognitive and executive function in SZ and MDD patients, which showed that patients' performance was lower than HCs, and SZ performed worse than MDD (15). However, no study has compared the brain activation patterns between SZ and MDD patients during the TOL task and VFT task using fNIRS.…”

Effect of Modified Bifrontotemporal Electroconvulsive Therapy on Executive Function in Patients With Psychiatric Illness

“…The low scores on executive function tests before treatment do not come as a surprise because, in repeated researches, it has been pointed out that patients with schizophrenia, depressive disorder, and bipolar disorder have poorer executive functions as compared with healthy individuals, even when these patients are in a stable state. [47][48][49][50] Research also suggests that schizophrenic patients have profound executive impairments at the beginning of the illness, which is progressive in nature. 47 The findings of this study are in line with the previous study by Peräkylä et al, 49 who had concluded that ECT significantly improves executive functions while alleviating depressive symptoms in depressed patients.…”

Psychological and neuropsychological underpinnings of attention-deficit/hyperactivity disorder assessment

“…This demonstrates an important benefit of these tests to distinguish between attentional difficulties attributable to ADHD (neurocognitively) and those attributable to depression, both which can look similar on rating scales asking about everyday attention. This may not be as clean for diagnoses of schizophrenia and bipolar disorder though, which have been found to be associated with some deficits on neuropsychological tests of EF (e.g., Afshari et al, 2019). Future research may need to look at the specificity of these tests for distinguishing patterns of deficit between those with ADHD and those with schizophrenia or bipolar disorder (and indeed those with comorbidities).…”