Symptom factors in early-onset psychotic disorders

OBJECTIVE: To examine the factor structure of symptom ratings in early-onset psychotic illnesses. METHOD: Subjects were drawn from a 2-year prospective study of early onset psychotic disorders. Principal components analysis with orthogonal (varimax) rotation was used to create factors from baseline ratings on the Schedule for Positive Symptoms, the Schedule for Negative Symptoms, and the Brief Psychiatric Rating Scale for Children. RESULTS: Youths with schizophrenia (n = 27), bipolar disorder (n = 22), and psychosis not otherwise specified (n = 20) were included. Four symptom factors were identified: negative symptoms, positive symptoms, behavioral problems, and dysphoria. Negative symptoms were predictive of the diagnosis of schizophrenia and treatment with antipsychotic medications. Neither behavior problems nor dysphoria were predictive of diagnosis. In subjects who completed follow-up assessments at year 1 (n = 49) and year 2 (n = 39), negative symptoms and behavioral problems predicted poorer functioning. CONCLUSIONS: The four factors are clinically relevant, with both treatment planning and prognostic implications. Negative symptoms best differentiated schizophrenia from the other disorders. Behavior problems and dysphoria were nonspecific problems that occurred in all three disorders, which likely leads to misdiagnosis in community settings.