Lithium and its neuroprotective and neurotrophic effects: potential treatment for post-ischemic stroke sequelae

Post-stroke cognitive impairment has a high prevalence in stroke patients and is associated with poor short and long term outcomes, including a negative impact on functional recovery. There is evidence that post-stroke impairment is the direct result of stroke induced neurological injury. Gray matter atrophy has been implicated in the development of post-stroke cognitive impairment and is the result of a series of neurochemical processes that are activated by ischemia. Lithium, traditionally used as a mood stabilizer, has been recognized in the last 10 years for its robust neuroprotective and neurotrophic effects against diverse insults, such as ischemia, both in vitro and in vivo. This has generated several preclinical and clinical studies of lithium treatment for managing neurodegenerative diseases and cerebral ischemia. Evidence suggests that lithium may protect against the cerebral atrophy and neuronal degeneration induced by the neurochemical processes and pathways known to regulate cell death and atrophy after an ischemic event. Lithium-mediated neurotroprotective and neurotrophic effects involve mechanisms highly relevant to the post-stroke population including the increased expression of brain-derived neurotrophic factor (BDNF) and Bcl-2, and inhibition of GSK-3β. Lithium-induced increases in human gray matter have been reported and occur within a time frame consistent with the known effects of lithium through increased expression of BDNF, Bcl-2 and GSK-3β inhibition. This article reviews the evidence to support the use of lithium to reduce neuronal damage post-stroke through 1) mechanisms of excitotoxicity and post-ischemic inflammation; and 2) neurotrophic signaling cascades. Lithium's relevant actions in preclinical and clinical studies will be reviewed and presented to support the neuroprotective and neurotrophic effects of lithium as well as other clinical considerations in using lithium in the post-ischemic stroke population.