A Study to Assess the Safety and Efficacy of ASP4345 as Add-on Treatment for Cognitive Impairment in Subjects With Schizophrenia on Stable Doses of Antipsychotic Medication

This Study Tests Whether BI 409306 Prevents Patients With Schizophrenia From Becoming Worse. This Study Looks at How Well Patients Tolerate BI 409306 and How Effective it is Over 6 Months