Longitudinal courses of thought disorder in schizophrenia and schizoaffective disorder.

This research examined the longitudinal courses of thought disorder in schizophrenia, schizoaffective disorder, and other psychotic and nonpsychotic disorders. One-hundred-eighty young psychiatric inpatients were prospectively diagnosed at an early stage of illness and followed up and evaluated for thought disorder at 2, 4.5, and 7.5 years post-index hospitalization. Patterns of thought disorder were examined in relation to diagnosis, index thought disorder, demographic characteristics, prognostic factors, clinical states of psychosis, outcome at followup, and treatment. Courses of frequent and persistent thought disorder were most frequently found in schizophrenia. The prevalence and course of thought disorder over time in schizoaffective disorder laid between those in schizophrenia and those in other psychotic disorders. Demographic factors were not predictive of the course of thought disorder. Diagnosis, the presence of thought disorder at index, pre-index work and academic competence, and pre-index social functioning were associated with courses of thought disorder (when courses were classified as remitted/infrequent and frequent/persistent). The longitudinal relationships between thought disorder and psychosis suggested that, in schizophrenia, thought disorder is not simply a function of psychosis. Thought disorder appeared more closely tied to the presence of psychosis over time in schizoaffective disorder. Increased inquiry into the factors associated with different courses of thought disorder across psychiatric disturbances appears merited.