Early versus late risk factors for deficit and nondeficit schizophrenia.
AIM: We examined whether timing of known risk factors for schizophrenia may influence the development of schizophrenia with primary negative symptoms. METHOD: This cross-sectional single-centre study in England used a clinical cohort of 167 clozapine-treated schizophrenia patients. Deficit and nondeficit schizophrenia models were used as clinical proxies of patients with and without primary negative symptoms respectively. Patients were assessed using the Schedule for the Deficit Syndrome. We examined previously replicated risk factors (family history of psychosis, advanced paternal age, male gender, birth weight