A Study of RO4917523 in Patients With Treatment Resistant Depression

Inclusion Criteria: * adult patients, 18-65 years of age; * recurrent major depressive disorder, without psychotic features; * at least 3 lifetime treatment failures, at least 2 of which must have occurred within the current depressive episode; * baseline minimal severity defined by a HAM-D score of 18 or above; * willing to be hospitalized for at least 16 consecutive days. Exclusion Criteria: * history of bipolar disorder, schizoaffective disorder or schizophrenia; * history of psychosis, including psychotic depression; * significant past or present neurological disorder, including seizures, stroke and/or head trauma.