Contrasts between Remitted Schizophrenic Patients and Euthymic Bipolar Patients on Verbal Memory and Learning / 신경정신의학

ABSTRACT

OBJECTIVES: This study was to investigate the verbal memory and learning ability in remitted schizophrenic patients and euthymic bipolar patients in order to explore trait-dependent cognitive deficits of each disorder. METHODS: Verbal memory was assessed with KAVLT(the Korean version of Rey Auditory Verbal Learning Test) in outpatients with remitted schizophrenia(N=30), euthymic bipolar disorder(N=28), and normal control(N=72). KAVLT is made for assessment of immediate supraspan memory, registration, retention, retrieval, recognition, learning strategy, and interference effect. Several confounding factors including age, sex, educational level, attention span, residual psychopathology, and extrapyramidal symptoms were controlled among 3 groups. Patient groups were matched according to the age of onset, duration of illness, and frequency of hospitalization. RESULTS: 1) The performance of bipolar group generally fall between the performance of schizophrenia and normal controls, while being most impaired in retroactive interference. Schizophrenic group showed significant impairment on most variables of KAVLT in comparison with the groups of bipolar disorder and normal control. 2) Within group analysis revealed that residual negative symptoms, duration of illness, and number of admission were highly correlated with the impairment of verbal memory and learning in schizophrenics. Number of depressive episodes and age were negatively correlated with verbal memory and learning among bipolar disorder patients. CONCLUSIONS: Both remitted schizophrenia and euthymic bipolar patients showed distinctive impairment in verbal memory and learning compared with controls. These results suggest that specific impairment of verbal memory and learning in remitted state can be a trait-dependent marker in both diseases. These deficits can give clues to the understanding of the pathophysiology and searching for more appropriate therapeutic interventions of mental disorders to improve cognitive deficits in remitted patients.