Objective: This study was aimed to compare the intelligence of schizophrenic patients with that of other psychiatric disorders patients and evaluate the characteristics according to intellectual decline after the onset of schizophrenia.
Methods:The study groups comprised 91 patients who performed intelligence test (Korean Wechsler Adult Intelligence Scale: K-WAIS) from January 1999 to December 2000: 43 with schizophrenia, 15 with mood disorder, and 33 with other psychiatric diagnoses according to the DSM-IV criteria. These 3 diagnostic groups were compared each other by current and estimated premorbid intelligence. Schizophrenia patients were classified into 3 groups based on intellectual decline patterns and examined their characteristics and the correlations of clinical variables among the groups.
Results:Compared to the non-schizophrenic patients, schizophrenic patients demonstrated no significant difference in premorbid and full scale IQ (FSIQ), but had a significantly lower mean value for performance IQ (PIQ). Twenty five patients (58%) with schizophrenia maintained premorbid intellectual functioning of average levels or above. Those who displayed IQ decline of 10 points or greater from premorbid levels had significantly younger age of onset. And age of onset in schizophrenia was inversely correlated with IQ decline.
Conclusion:There were common deficits of PIQ in patients with schizophrenia especially in executive function and psychomotor speed. They showed different clinical and cognitive characteristics according to intellectual decline patterns after the onset of schizophrenia. (Schizophrenia Clinics 2003;6:63-69) |
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