The BBC report mentions studies with similar results in 1980s. I remember them from my grad school days in 1970s. However... note that these are epidemiologica

The BBC report mentions studies with similar results in 1980s. I remember them from my grad school days in 1970s. However... note that these are epidemiological studies, and demonstrated (as I recall) that bipolar (aka manic-depressive) depressive illness is lower in areas of U.S. with higher natural lithium. Even if it could be demonstrated that lithium-ingestion in water did reduce incidence of bipolar illness, this would not be expected to improve depression among those with the more common, uni-polar depression:: There has never been evidence that lithium is a "mood enhancer" or "psychoactive" - only that deficiencies of lithium may bring out or aggravate latent bipolar depressive illness. — A (non-clinical) psychology Ph.D.