Long-term Study of FK949E in Elderly Bipolar Disorder Patients

Inclusion Criteria: * Diagnosis of bipolar I or II disorder as specified in the Diagnostic and Statistical Manual of Mental Disorders, 4th edition, Text Revision (DSM-IV-TR), with a major depressive episode * Able to participate in the study with understanding of and compliance with subject requirements during the study in the investigator's or subinvestigator's opinion * Male subjects must agree to take appropriate contraceptive measures with condoms during the study period. * Female subjects must be confirmed to have no childbearing potential during the study period Exclusion Criteria: * Concurrent or previous history of DSM-IV-TR Axis I disorders, except bipolar disorder, within the last 6 months before informed consent * Concurrence of DSM-IV-TR Axis II disorder that was considered to greatly affect patient's current mental status. * The Young Mania Rating Scale (YMRS) total score of 13 points or more. * Nine or more mood episodes within the last 12 months before informed consent. * Lack of response to at least 6-week treatment with at least 2 antidepressants for the current major depressive episode in the investigator's or subinvestigator's opinion * The current major depressive episode persisting for more than 12 months or less than 4 weeks before informed consent. * History of substance dependence (other than caffeine and nicotine) or alcohol abuse or dependence. * Treatment with a depot antipsychotic within the last 49 days before primary registration. * Unable to suspend antipsychotics or antidepressants after primary registration * Treatment with two or more of mood stabilizers (lithium carbonate and/or sodium valproate) and lamotrigine, if these drugs, except one of either drug, cannot be suspended after primary registration. * Unable to suspend antiepileptics (except lamotrigine and sodium valproate), antianxiety agents, hypnotics, sedatives, psychostimulants, antiparkinsonian agents, cerebral ameliorators, antidementia agents, or anorectics, except those specified as conditionally-allowed concomitant drugs, from 7 days before primary registration * Electroconvulsive therapy within the last 83 days before primary registration. * A possible need of psychotherapy during the study period (unless the therapy has been commenced at least 83 days before primary registration). * The Hamilton Depression Rating Scale (HAM-D17) suicide score of 3 points or more, history of suicide attempt within the last 6 months before informed consent, or the risk of suicide in the investigator's or subinvestigator's opinion