Distinguishing between first-admission schizophreniform disorder and schizophrenia

Background: The validity of schizophreniform disorder remains controversial. Past research suggests that cases of schizophreniform disorder may be: (1) atypical cases of affective disorders, (2) cases of schizophrenia in early course, or (3) a heterogeneous group of disorders including a subgroup with benign course and outcome which maintains this diagnosis in the long term. Method: We tested the validity of the schizophreniform disorder diagnosis by comparing the socio-demographic and baseline clinical characteristics, 24-month course and outcome, and 6- and 24-month research diagnoses of 34 cases initially diagnosed with schizophreniform disorder, and 128 cases with schizophrenia, drawn from a cohort of 628 first-admission patients in the Suffolk County Mental Health Project. Results: Compared to patients with schizophrenia, those with schizophreniform disorder were more likely to remit fully by 6 months and retain this status by 24 months. Only about half of the patients with schizophreniform disorder were re-diagnosed with schizophrenia or schizoaffective disorder at 24-month follow-up, 13% were re-diagnosed with affective disorders and 19% retained the diagnosis of schizophreniform disorder. In contrast, 92% of cases with a baseline diagnosis of schizophrenia retained this diagnosis at 24-month follow-up. The findings were similar in comparisons with schizophrenia patients having onset of symptoms within 6 months of hospitalization. Conclusions: Schizophreniform disorder is a heterogeneous category, which includes a small group with benign psychotic disorders who maintain this diagnosis over at least 24 months. Better delineation of this subgroup has important treatment implications.