There is a possibility that lithium maybe useful for brain development as studies show a 3% increase in grey matter of brain within 4 weeks. The dose in the study is way too large and it may in fact much more effective in VERY low dosage lithium. I take lithium water (250 mg per liter of water) and the amount of water I take is 1/15 so that amounts to between 10-15 mg every other day average. I take it to increase my metabolism, and gout as lithium carbonate will dissolve uric acid, of course taken together with vitamin C. However, what is most important to you is that lithium in event of a brain injury due to lack of circulation or clotting will prevent brain damage and in fact prevent your brain from dying with proper supplementation of low dose lithium. Because of increasing grey matter, it is therefore possible that taking lithium will help improve problems related to speech impairment.
Toxicity of lithium can further be reduced by taking one tablespoon of linseed oil per day plus 400 iu Vitamin E. It is possible that lithium (I am speculating here) against Parkinson's Disease, Graves Disease, and Alzheimer Disease in prevention progression of brain damages. It is possible that Lithium may one day may used to protect against Mad Cow's Disease (along with DMSO of course).
Here is the link to an excellent article on low dosage Lithium by Jonathan Wright, M.D.