Lithium is a staple prescription for bipolar depression and suicidal tendencies. But it is also a naturally occurring element, with traces found in most of the world’s drinking water, and that raises a question: Do levels of lithium in tap water correlate with suicide rates? A recent study by a team of Japanese doctors says yes.
Published May 1 in the British Journal of Psychiatry, the study reported that 18 municipalities in southwest Japan, towns with relatively low levels of lithium saw higher suicide rates than towns with relatively high levels. The lithium content ranged from 0.7 to 59 micrograms, much lower than the 200 to 400 milligrams usually prescribed to bipolar patients (and much, much lower than the toxicity threshold). Nevertheless, the researchers speculated that even very low levels of lithium can have a cumulative, prophylactic effect on mood swings that might induce suicidal thoughts, completely separate from the effect large doses have on mood disorders. The implication, says lead researcher Takeshi Terao in response to an email inquiry, is that “adding lithium to drinking water may be useful to prevent suicide.”
But even Terao admits that further study is needed. Among other concerns, not enough is known about the long-term effects of even low levels of lithium, according to Dr. Allan H. Young, the director of the Institute of Mental Health at the University of British Columbia. Still, given the immense social costs of suicide, the team in Japan concluded in a follow-up paper that adding lithium to drinking water offers “an easy, cheap and substantial strategy for world-wide suicide prevention.”