Lithium is a natural mineral but is toxic to the body when consumed in high doses. This study found very small micro-levels of lithium added to drinking water may reduce the risk of developing dementia later in life, although more studies are need.
Lars Vedel Kessing, MD, DMSc; Thomas Alexander Gerds, MSc, PhD; Nikoline Nygård Knudsen, MSc; et al. Association of Lithium in Drinking Water With the Incidence of Dementia JAMA Psychiatry. doi:10.1001/jamapsychiatry.2017.2362 http://jamanetwork.com/journals/jamapsychiatry/fullarticle/2649277