Comparison of Cognitive Control Deficits in Patients with Schizophrenia and Bipolar I Disorder / 신경정신의학

Methods@#Three groups were included in this study: remitted schizophrenia patients (n=56), patients in euthymic states of bipolar I disorder (n=52), and healthy control (n=57), who were matched on sex, age, years of education. The Continuous Performance Test of the AX version (AXCPT) was used to evaluate the cognitive control function. Intelligence, psychopathology, and psychomotor speed were also examined. The degree of cognitive control deficits was assessed by the commission error rates, correct response times, and the d’ values. @*Results@#Both patient groups performed worse in the AX and BX trials than the healthy control. Both patient groups showed a delayed response in all trials than the healthy control. The d’ value was the highest in the healthy control group, but there were no significant differences between the two patient groups. The profile of defects in the two patient groups was the same, with the BX trial having the highest defects in the order of the AX, BY, and AY trials. @*Conclusion@#These findings indicate that cognitive control is impaired in patients with schizophrenia and bipolar I disorder. Impairments in cognitive control are likely to be a possible shared pathophysiological marker for both disorders.

Comparison of Cognitive Controls in Patients with Bipolar I Disorder and Their Unaffected First-Degree Relatives

OBJECTIVES: This study intended to identify the deficits of cognitive control among patients with bipolar I disorder and their first-degree relatives, and identify the possibility of cognitive control as an endophenotype of bipolar disorder. METHODS: The study included three groups: euthymic states patients with bipolar I disorder (n = 55), unaffected first-degree relatives of probands with bipolar I disorder (n = 30), and a healthy control group (n = 51), that was matched on age, sex, and years of education. The AX version of the continuous performance test (CPT) was used to examine cognitive control. Error rate, correct response times of each subsets (AX, BX, AY, BY), and d' as an indication of accuracy sensitivity index were calculated. Psychopathology, intelligence, and psychomotor speed were also assessed. RESULTS: Patients with bipolar I disorder showed significantly worse error rates in the AX (p = 0.01) and BX (p = 0.02) subsets and d' (p = 0.05) than the others. They also showed more delayed correct response times than the healthy control group and first-degree relatives in all subsets (p < 0.01). But first-degree relatives showed neither high error rates nor delayed correct response times than healthy control group. CONCLUSIONS: These findings suggest that cognitive control is impaired in bipolar I disorder but less likely to be an endophynotype of bipolar I disorder.

Comparison of Cognitive Control Deficits in Patients with Schizophrenia and Their Unaffected First-Degree Relatives / 신경정신의학

OBJECTIVES: This study aimed to identify the differences in the profiles of cognitive control deficits among schizophrenic patients and endophenotypes. METHODS: The study examined three groups: remitted patients with schizophrenia (n=54), unaffected first-degree relatives of the probands with schizophrenia (n=36), and a healthy control group (n=51), which were all matched for age, sex, and years of education. The AX version of the continuous performance test was used to examine cognitive control. The error rate, correct response times of each subset (AX, BX, AY, BY), and d′ as an indication of the accuracy sensitivity index were calculated. The psychopathology, intelligence, and psychomotor speed were also assessed. RESULTS: Patients with schizophrenia showed significantly poorer error rates and d′ in the AX and BX subsets than the others. They showed more delayed correct response times than the healthy control group in all subsets. The first-degree relatives also showed more delayed correct response times in the BX and AY subsets than the healthy control group, but were similar to the patients. CONCLUSION: These findings suggest that cognitive control is impaired in schizophrenia and endophynotypes possibly share this delayed information processing from the higher loading states of cognitive control.

Shared and Distinct Neurocognitive Endophenotypes of Schizophrenia and Psychotic Bipolar Disorder

OBJECTIVE: Schizophrenia and bipolar disorder are characterized by the presence of neurocognitive impairments on the psychosis continuum. The present study aimed to explore the shared and distinct endophenotypes between these disorders. METHODS: The study included 34 probands with remitted schizophrenia and 34 probands with euthymic bipolar disorder who had a history of psychotic symptoms that met the Diagnostic and Statistical Manual of Mental Disorders 4th edition (DSM-IV) criteria, unaffected first-degree relatives of probands (31 relatives of probands with schizophrenia and 29 relatives of probands with bipolar disorder), and 34 healthy controls. Cognitive assessments were performed using the digit span, continuous performance, Rey auditory and visual learning, complex figure, verbal fluency, Wisconsin card sorting, and finger tapping tests. RESULTS: Probands with schizophrenia showed the most generalized and severe cognitive deficits across cognitive domains (working memory, verbal learning and memory, visual memory, verbal fluency, and executive function). Some domains of cognitive function (working memory, verbal learning, and memory) were also impaired in probands with bipolar disorder, but to a lesser degree than in probands with schizophrenia. All probands and relatives showed a common deficit in working memory compared to healthy controls. Relatives of probands with schizophrenia also showed verbal fluency dysfunction. Cognitive performance of all relatives was intermediate to the performance of both patients and healthy controls. CONCLUSION: These findings suggest that a deficit in working memory could be a shared endophenotype of genetic vulnerability to schizophrenia and psychotic bipolar disorder, and verbal fluency could be a candidate endophenotype for schizophrenia specifically.