1. - To assess efficacy on neurological function, ataxic, depressive and quality of life scores of Lithium Carbonate in patients with SCA3 through the Scale for the Assessment and Rating of Ataxia (SARA), 9-Hole Peg Board test, 8m walking time, PATA repetition rate, Click Test, SCA Functional Index (SCAFI), Composite Cerebellar Functional Score (CCFS), Beck Depression Inventory, Barthel Index and WHOQol after 6 and 12 months of follow-up.