Abstract
This study examined the stability of symptoms of schizophrenia over time, focusing on the stability of symptom structure. Symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS). The sample consisted of 215 chronic patients followed up for as long as 4 years. Exploratory factor analysis identified 6 factors. Several statistical techniques were used to examine the stability of these symptoms, including longitudinal confirmatory factor analysis. Low-to-moderate rank-order stability and high absolute stability of the factors were found, with the structure of the PANSS-assessed symptoms consistent over time. The results demonstrate that despite changes in the severity of symptoms in individual patients with schizophrenia, the factor structure and interrelatedness of symptoms have considerable stability over time.
