A Study of RO4917838 in Combination With Antipsychotic Treatment in Patients With Schizophrenia.

Inclusion Criteria: * adult patients, 18-60 years of age; * diagnosis of schizophrenia (based on screening tests); * outpatients, with no hospitalization for worsening of schizophrenia within 3 months; * medically and psychiatrically stable over prior 1 month and psychiatrically stable without symptom exacerbation within prior 3 months; * currently taking no more than 2 antipsychotic drugs. Exclusion Criteria: * began a new non-medication treatment for schizophrenia or other psychiatric condition within last 3 months; * on \>1 antidepressant, or a change in dose of antidepressant within 3 months; * alcohol or substance abuse or dependence within 3 months; * has previously received RO4917838.