Dysfunction of the Left Dorsolateral Prefrontal Cortex is Primarily Responsible for Impaired Attentional Processing in Schizophrenia

OBJECTIVE: The results for finding the deficit in the anterior cingulate (ACC) in schizophrenic patients (SZ) have been inconsistent according to the studies that used different Stroop tasks, which is unlike the deficit in the dorsolateral prefrontal cortex (DLPFC). In order to explore for the core region that's responsible for the selective attention deficit in SZ, we examined the results of a functional neuroimaging study, which involved the performance of the Stroop task using high or low prefrontal cortex related loads in SZ. METHODS: Ten schizophrenic patients and healthy controls (HC) received functional magnetic resonance imaging (fMRI) during a Short/Long-term latency Stroop task. The changes in the neural activity were determined in well-known Stroop related regions of interest (ROIs) that consisted of the DLPFC, ACC, the parietal lobule and in the whole brain regions for both the main and interaction effects of latency, and the results of the short-term and long-term latency Stroop conditions were compared. RESULTS: The response times for both the congruency and latency effects were more prolonged in the schizophrenics than in the HC. For the congruency effect, the schizophrenics showed significantly less activation in the same site of the left DLPFC in both the short-term and long-term latency conditions, as compared with the HC. For the latency effect, the regions of the left-side language network were over- or under-activated in the schizophrenics, as compared with the HC. Any interaction effect was not found for both the behavioral and fMRI results. CONCLUSION: Our results indicate that the deficit in the left DLPFC is the core impairment of attentional processing in schizophrenics, regardless of other possible interactions such as the latency effect.

Comparison between Logistic Regression and Artificial Neural Networks as MMPI Discriminator

OBJECTIVES: The purpose of this study is to 1) conduct a discrimination analysis of schizophrenia and bipolar affective disorder using MMPI profile through artificial neural network analysis and logistic regression analysis, 2) to make a comparison between advantages and disadvantages of the two methods, and 3) to demonstrate the usefulness of artificial neural network analysis of psychiatric data. PROCEDURE: The MMPI profiles for 181 schizophrenia and bipolar affective disorder patients were selected. Of these profiles, 50 were randomly placed in the learning group and the remaining 131 were placed in the validation group. The artificial neural network was trained using the profiles of the learning group and the 131 profiles of the validation group were analyzed. A logistic regression analysis was then conducted in a similar manner. The results of the two analyses were compared and contrasted using sensitivity, specificity, ROC curves, and kappa index. RESULTS: Logistic regression analysis and artificial neural network analysis both exhibited satisfactory discriminating ability at Kappa index of greater than 0.4. The comparison of the two methods revealed artificial neural network analysis is superior to logistic regression analysis in its discriminating capacity, displaying higher values of Kappa index, specificity, and AUC(Area Under the Curve) of ROC curve than those of logistic regression analysis. CONCLUSION: Artificial neural network analysis is a new tool whose frequency of use has been increasing for its superiority in nonlinear applications. However, it does possess insufficiencies such as difficulties in understanding the relationship between dependent and independent variables. Nevertheless, when used in conjunction with other analysis tools which supplement it, such as the logistic regression analysis, it may serve as a powerful tool for psychiatric data analysis.

Compensatory Neural Correlates of Selective Attention Deficit in Schizophrenics Showing Normal Accuracy during Stroop / 신경정신의학

OBJECTIVES: This study investigated the compensatory neural correlate of selective attention deficit in schizophrenics showing near-normal performance. METHODS : A 'modified Stroop' was developed that can be used measure the response time during functional imaging. An event-related functional magnetic resonance imaging study was carried out in 10 clinically stabilized schizophrenics and 10 healthy controls during the performance of a 'modified Stroop'. In the 'modified Stroop', the subjects were required to respond with a two-button mouse to whether or not the color of a subsequent word corresponded to one of T-shirt. The significantly activated brain regions were investigated in a voxel-wise t-test of the Stroop load. RESULTS : Schizophrenics, compared with healthy controls, showed poorer response time, but had similar accuracy. Compensatory activation in the right inferior frontal gyrus (IFG) was observed in schizophrenics. The left paracingulate sulcus was less activated in the schizophrenics than in the healthy controls. CONCLUSION : These results suggest that, in schizophrenics showing a normal accuracy during the Stroop, selective attention deficits might be related to the left paracingulate sulcus as well as the anterior cingulate. In addition, their deficits may be compensated with the right IFG.

Quality of Life in the First Admitted Schizophrenic Patients: A Retrospective Follow-up Study / 신경정신의학

OBJECTIVES: One object of this study is to provide a descriptive level of quality of lift(QOL)in a group of the first admitted schizophrenic patients through interviews being performed after two or five years of follow-up, and comparing them with patients in psychotic disorders other than schizophrenia. Another object is to identify clinical variables on the first admission which correlate to QOL factors, after two or five years of follow up. METHODS: A total of 73 subjects of the first admitted patients with schizophrenia(n=57) and psychotic disorders other than schizophrenia(other psychotic disorders group, n=16) were selected. A Quality of Life Scale(QLS) measuring 21 items of life variables was used. Demographic and psychiatric data were obtained through medical records and psychiatric RESULTS: Schizophrenia group(n=57) showed moderate decrease(mean 3.7 of 6) in all aspect of Quality of life. However, the schizophrenia group displayed a relatively high score in relations with household members(mean=5.2) only among 21 QOL items. Comparison to other psychotic disorders group(n=16), schizophrenia group showed a significant decrease in almost all aspects of QOL. We significant difference was obtained between the 2 year(n=27) and the 5 year(n=30) group. Duration of the first admission showed a significant correlation with current quality of life in the schizophrenic group. CONCLUSIONS: The significantly decreased score of quality of lit: suggests the need for careful observation and therapeutic concern for the early stage of schizophrenia. The schizophrenic group's relatively high score in relations with household members in this period may provide the importance of rehabilitation to improve their quality of life. Duration of the first admission may be a useful predictor of their subsequent quality of life.