Today, I was reminded by this Fox News affiliate video of a recent study out of Japan in which researchers actually suggest that adding small amounts of lithium to drinking water could reduce overall suicide rates, based on the fact that suicide numbers in Oita Prefecture, where traces of lithium had already been found in water supplies, have been comparatively low. Here is the BBC News summary of that research, and the short report from the British Journal of Psychiatry. (The full text requires a subscription.)
Said psychiatrist Allan Young in response to the Japan study, "this intriguing data should provoke further research." Indeed.