 A large proportion of participants with bipolar disorder experience significant cognitive dysfunction, even when euthymic, after adequate treatment. The cognitive deficits in asymptomatic patients with bipolar disorder are very important for the participants psychosocial function. In this population, cognitive deficits have been associated with poor psychosocial functioning, such as inability to hold a job. Memantine is a glutamate N-methyl-D-aspartate NMDA receptor antagonist which has shown efficacy in cognitive dysfunction due to moderate to severe Alzheimer disease. 