[Results of investigations on the association between lithium levels in drinking water and suicidal behaviour in the population: a narrative review].

INTRODUCTION: The risk of suicide is determined by the interplay of several interrelated factors from which psychiatric (especially affective) disorders are the most powerful predictors. Lithium, a mood stabilizer (which is also used to augment the efficacy of antidepressant therapy) has a well-established antisuicidal effect. In the last decades several studies investigated whether there is an association between the amount of lithium in tap water and suicide risk in the population.

METHODS: A PubMed search was conducted to identify papers investigated the association between lithium levels in drinking water and suicide risk of the population. A "forward citation search" was also performed using the Google Scholar. Relevant papers were also tried to identify by going through the reference lists of the studies found during the Pubmed search ("backward citation search").

RESULTS: We identified more than 10 original studies on this topic. The majority of results suggest that higher lithium levels in drinking water are associated with decreased risks of suicide. Although, results are surprisingly concordant methodological limitations may decrease the validity of the findings.

CONCLUSIONS: Results indicate that lithium intake from tap water in doses far below those used in the clinical practice may have suicide-preventive effects. This raises the possibility that lithium supplementation of tap water may open a new avenue in suicide prevention. In Hungary, where there is a stable in time spatial inhomogeneity of the suicide rate it would be especially interesting to test whether regional differences in lithium content of tap water contribute to this phenomenon.