Intervention: Memantine
Trial phase: Phase 4
ATC code: N06DA52 | N06DA53 | N06DX01
SMILES: CC12CC3CC(C)(C1)CC(N)(C3)C2
Sex: All
Age groups: Adult | Older Adult
Healthy volunteers: No
Participants at risk: 48
Group description: Memantine 5 mg tablet once per day for 1 week; dose increase if tolerated to memantine 5 mg twice a day, in the morning and the evening in Week 2; dose increase if tolerated to memantine 5 mg in the morning and memantine 10 mg in the evening in Week 3; dose increase if tolerated to memantine 10 mg twice a day, in the morning and the evening Weeks 4 to 12.
Eligibility criteria:
Inclusion Criteria:

Diagnostic and Statistical Manual-IV (DSM-IV) diagnostic criteria for any bipolar disorder [type I, type II, and not otherwise specified (NOS)] (diagnosed with the use of the Structured Clinical Interview for DSM-IV-TR Mood Module (SCID Mood Module)
Written informed consent
Men or women aged 18-65
A baseline Hamilton-D 17 score of < 10 at screen and baseline visits.
A baseline Young Mania Rating Scale score of < 10 at screen and baseline visits.
No acute episodes of depression or mania for the previous 12 weeks.
Massachusetts General Hospital Cognitive and Physical Functioning Scale: Cut-off: >15 or Everyday Cognition Self-Report Form: Average of all items >1.5 or Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): <12 years education, RBANS total scale score of <85 =12 years education, RBANS total scale score of <93 >12 years education, RBANS total scale score of <100
Able to read and understand English.

Exclusion Criteria:

Patients meeting any of the following criteria will be excluded from the study:

Participants with suicidal ideation where outpatient treatment is determined unsafe by the study clinician. These patients will be immediately referred to appropriate clinical treatment.
Pregnant women, nursing mothers, or women of childbearing potential who are not using a medically accepted means of contraception (defined as oral contraceptive pill or implant, condom, diaphragm, spermicide, intrauterine device (IUD), s/p tubal ligation, partner with vasectomy).
Serious or unstable medical illness, including liver impairment, kidney impairment, cardiovascular, hepatic, respiratory, endocrine, neurologic or hematologic disease.
History of seizure disorder, brain injury, any history of known neurological disease [multiple sclerosis, degenerative disease such as amyotrophic lateral sclerosis (ALS), Parkinson disease and any movement disorders, etc].
History or current diagnosis of the following DSM-IV psychiatric illness: organic mental disorder, schizophrenia, schizoaffective disorder, delusional disorder, psychotic disorders not otherwise specified, major depressive disorder, patients with substance dependence disorders, including alcohol, active within the last 12 months.
History of multiple adverse drug reactions.
Patients with mood congruent or mood incongruent psychotic features within the last 12 months.
Clinical or laboratory evidence of hypothyroidism.
Patients who have had an episode of acute depression or mania during the 12 weeks prior to enrollment.
Patients who have had electroconvulsive therapy (ECT) within the 6 months preceding enrollment.
Patients taking drugs which alkalinize the urine.