Predictive value of thought disorder in new-onset psychosis.

OBJECTIVE This research addresses the relationship of formal thought disorder in the early stages of psychotic illness to the long-term outcome of mental health many years later. The specific topic of concern was to evaluate the prognostic significance of thought disorder on the severity of psychosis over time. METHODS Subjects with new-onset psychosis were evaluated on a variety of measures including education, physical health, Brief Psychiatric Rating Scale scores. They were also given the Thought, Language, and Communication Scale to evaluate thought disorder. Subjects were interviewed again at 10 and 20 years to evaluate variations in outcome. Appropriate statistical methods were used to evaluate changes in the level of functioning over time. RESULTS Thought disorder was not unique to schizophrenia. Bipolar patients presented with significant positive thought disorder at the onset of psychosis. Overtime positive thought disorder gradually improved in most patients. Negative thought disorder was more persistent, especially in subjects with schizophrenia. Initial psychosis with thought disorder characterized by poverty of content seemed to be associated with poor long-term outcome. CONCLUSION Formal thought disorder can predict outcome in some cases of psychosis. Not all types of thought disorder have the same prognostic implication. Positive forms of thought disorder (pressured speech, tangentiality) had no significant predictive value. Negative thought disorder (particularly poverty of speech and poverty of content) tend to predict a chronic, more unrelenting course of illness.