Does the duration of untreated psychosis affect prognosis in schizophrenia?

Clinical Dilemma: 'An 18-year-old patient, who has been suffering from a prolonged psychotic state, is hospitalized for the first time in his life in our department. We diagnose his condition as schizophrenia, and start anti-psychotic medication and supportive psychotherapy. His parents join the psycho-educational group for families in our department. After one of the group sessions, his parents worriedly approach us with the question whether the fact that their son had been psychotic and had not received anti-psychotic medications for many months before his hospitalization predicts a bad prognosis for his disease course and outcome. Does the duration of untreated psychosis (DUP) affect prognosis in schizophrenia?'