Thought disorder. A function of schizophrenia, mania, or psychosis?

Does thought disorder emerge solely as a function of psychosis, or is it a function of diagnosis? The present research investigated whether thought disorder is more frequent in specific diagnostic groups, such as schizophrenia and mania, than in other types of psychotic disorders. The frequency and severity of positive thought disorder was assessed in 324 Research Diagnostic Criteria and DSM-III schizophrenics, manics, other psychotic patients, and nonpsychotic patients, and a normal comparison group. Fifty-seven percent of the sample were first hospital admissions. Patients were tested at the acute phase of their disorder, within the first 2 weeks of hospitalization, with three cognitive tests. Scores from these three tests were scaled to obtain a composite index of the severity of positive thought disorder. Diagnostic factors were more salient to the severity of disordered thinking than was psychosis. Thought disorder was significantly more frequent in schizophrenia and mania than in other psychotic disorders (p less than .05). The frequency of patients with severe thought disorder was reduced as one moved down the hierarchy of manic, schizophrenic, schizoaffective, and depressed psychotic disturbances (p less than .001). Rather surprisingly, the current research suggests that nonpsychotic manic patients may be as thought disordered as psychotic manic patients at acute phases of disturbance. This would indicate that the presence of positive thought disorder in mania is not primarily a function of most of these patients' being psychotic at the acute phase of disturbance. Thought disorder was not simply a function of psychosis.(ABSTRACT TRUNCATED AT 250 WORDS)