Subtypes in schizophrenic disorders: frequencies in long-term course and premorbid features.

The subclassification of schizophrenic disorders according to four diagnostic systems (DSM-III-R, ICD-10, the positive vs. negative dichotomy and Schneider's first rank symptoms) was compared over the long-term course of the disease in 148 narrowly defined schizophrenic patients. A total of 595 episodes were classified over a mean observation period of 23 years (range 10-50 years). Initially, paranoid/positive subtypes predominated, while later in the course episodes fulfilling the symptomatological criteria of residual/negative subtypes became more frequent. Disorganised/hebephrenic and catatonic subtypes were found to be rare. Some premorbid features were investigated as non-symptomatological validators for subclassification. Significant differences were found with regard to age at onset. Patients whose first episode was paranoid or positive had the highest age at onset. Patients with initial disorganised/hebephrenic or "residual" episodes had the most unfavourable premorbid social adjustment, even when the influence of age at onset was discounted. The diagnostic systems investigated showed similarities and differences as a result of the underlying concepts. Methodological implications are discussed.