Correlation of Lifetime Symptom Dimensions with Cognitive Function and Other Clinical Characteristics in Schizophrenia Patients / 대한정신분열병학회지

OBJECTIVES: Considering large diversity of clinical presentation of schizophrenia, it is important to identify valid clinical subtypes or dimensions that might have homogeneous biological underpinning. The current study aimed to explore lifetime symptom-based dimensional phenotypes in patients with chronic schizophrenia, and to investigate their correlation with cognitive functions and other clinical characteristics. METHODS: Lifetime-based symptoms and additional clinical variables were measured using the Diagnostic Interview for Genetic Studies and the Schedule for the Deficit Syndrome in 315 clinically stable patients with chronic schizophrenia. Through principal components factor analysis, eight dimensional phenotypes were obtained. Comprehensive neuropsychological tests were administered for 103 out of 315 patients, and domain scores were calculated for cognitive domains defined in the MATRICS consensus battery. RESULTS: 'Non-paranoid delusion factor' including delusions of grandiose or religious nature, showed significant negative correlation with processing speed, working memory, attention/vigilance, and general cognitive ability, and positive correlation with intra-individual variability. 'Negative symptom factor' showed significant negative correlation only with general cognitive ability. Those two factors were also negatively correlated with function levels measured by Global Assessment Scale (GAS), and associated with poor treatment responses. CONCLUSION: Symptom-based dimensional phenotypes of schizophrenia measured on a lifetime basis showed discriminative correlation with cognitive function domains, global functioning level, and overall treatment responses, indicating their possibility as valid phenotype axes of schizophrenia having homogeneous biologic basis.

Intra-Individual Neuropsychological Test Variability : A Comparison of Patients with Schizophrenia, Their Siblings, and Healthy Controls / 신경정신의학

OBJECTIVES: Intra-individual variability of cognitive performance across different tests or domains has been reported as an important index of cognitive function. The aim of the current study is to examine the intra-individual variability across different cognitive domains and tests in patients with schizophrenia, their unaffected siblings, and normal controls. We also compared the variability among three patient sub-groups divided according to the duration of illness. METHODS: Comprehensive neurocognitive tests were administered in order to stabilize patients with schizophrenia (n=129), healthy siblings (n=38) of the patients, and normal controls (n=110). Intra-individual variability was computed from the variance of the scores of six cognitive domains of the Measurement and Treatment Research to Improve Cognition in Schizophrenia consensus battery. We examined intra-individual variability across six factor-based cognitive scores and individual test scores of each cognitive domain. RESULTS: Compared to the normal control and sibling groups, patients showed significantly increased intra-individual variability across six cognitive domains and individual cognitive tests of each domain. Compared to the normal control, siblings showed significantly increased intra-individual variability only across individual tests of the processing of speed domain. Among patient sub-groups, those with the longest duration of illness (> or =11 years) showed significantly higher intra- individual variability across six cognitive domains and across individual tests of the processing of speed domain compared to the other two groups. CONCLUSION: This study identified cognitive dissonances across six cognitive domain schizophrenia patients. These cognitive characteristics were not observed in the sibling groups and seemed to progress during the course of illness.