Higher Levels of Lithium Linked to Lower Suicide Rates

Myriad factors are known to be capable of influencing suicide risk, and now another one seems to have been added to that list. It's the level of the element lithium in tap water.

At first glance, the notion may be hard to believe. Yet lithium is a natural trace element found in variable amounts in food and water, and therapeutic doses of lithium can stabilize the moods of patients with bipolar disorder. Furthermore, a 1990 study found that Texas counties with higher levels of lithium in tap water had lower suicide rates than Texas counties with lower levels.

In addition, a 2009 study found that Japanese cities with higher levels of lithium in tap water had lower suicide rates than Japanese cities with lower levels. And now a new study has come up with comparable findings for Austria—districts with higher levels of lithium in tap water had lower suicide rates than those with lower levels.

These new results, obtained by Nestor Kapusta, M.D., an assistant professor of psychiatry at the Medical University of Vienna, and colleagues were published in the May British Journal of Psychiatry.

Austria, a country of 8.3 million people, is divided into 99 districts. Kapusta and his colleagues obtained information about the amount of lithium in tap water in each of these districts from 2005 to 2009. They also obtained information about the suicide rates per 100,000 people in these districts over the same five-year period. They then looked to see whether there was a relationship between the average amount of lithium in tap water and the average number of completed suicides.

Significant Relationship Found

They found a statistically significant inverse relationship—the greater the amount of lithium present, the fewer the suicides. For instance, the highest average level of lithium was found in the Mistelbach region northeast of Vienna. Although this region did not have the lowest average suicide rate among the districts, its average suicide rate ranked 15 out of all 99 districts.

Kapusta and his group then reanalyzed their findings while considering factors known to be capable of influencing suicides in Austria, such as income, religion, and availability of mental health service providers. There was still a significant, inverse relationship between the amount of lithium present in tap water and the number of completed suicides.

Thus, while the study does not prove a causal relationship, it does suggest the possibility that lithium in tap water may temper suicide risk.

As for the argument that perhaps Austrians prefer to drink bottled rather than tap water, Kapusta told Psychiatric News that because Austrian tap water is of high quality, most Austrians do drink tap water. But even if Austrians didn't drink tap water, the lithium present in it could still be absorbed into their bodies via cooking and bathing, he said.

Should Lithium Be Added to Tap Water?

So if lithium in tap water can indeed help counter suicides, should traces of lithium be added to tap water to help protect people from suicide, just as fluoride is often added to tap water to help protect people from dental caries? Not at this time, Kapusta stated. "The scientific evidence is growing, but it is still low and needs to be further strengthened," he said. Also, it's possible that raising the levels of lithium in tap water might have adverse effects on unborn babies, since lithium concentrations in the brain increase during the first trimester of gestation. Additionally, lithium can cause adverse effects such as hypothyroidism, kidney failure, and other problems.

Currently, no country or city appears to be adding lithium to tap water to reduce the risk of suicides, Takeshi Terao, M.D., Ph.D., told Psychiatric News. Terao, a professor of neuropsychiatry at Oita University in Japan, was one of the researchers who conducted the 2009 study demonstrating an inverse link between levels of lithium in tap water and suicides in Japan.

Credit: Timothy Forbes/istockphoto

Perhaps the best resource for learning whether lithium can prevent suicides and whether levels of lithium in tap water should be increased as a suicide-prevention measure may lie in a region in northern Chile called Salar de Atacama. Ground water in this region contains some of the highest lithium levels in the world. Kapusta and his colleagues are now obtaining suicide statistics from that region and considering other issues, such as renal and thyroid function. "If any American psychiatrists are interested in such a venture, we look forward to collaboration," he said.

An abstract of "Lithium in Drinking Water and Suicide Mortality" is posted at <http://bjp.rcpsych.org/cgi/content/abstract/198/5/346>.