The recent recognition of lithium as a neurotrophic agent has generated the first studies of lithium treatment for managing brain diseases. Clinically, lithium has now been shown to increase brain gray matter volume in bipolar patients. This effect is potentially important in stroke because gray matter loss has been implicated in the development of cognitive impairment after stroke, a result of the series of brain processes that are activated by lack of oxygen due to stroke. Our primary objective is to examine the effects of lithium on total brain gray matter volume in the post-stroke population, as measured by volumetric magnetic resonance imaging (MRI) with the hope that lithium may increase gray matter volume in post-stroke patients and lead to greater cognitive and functional rehabilitation. This study will provide valuable information on the tolerability of lithium, and its effects on clinical outcomes relevant to stroke, providing the information needed for designing a large-scale clinical trial.