Background In pharmacological doses, lithium successfully treats bipolar disorder and it can reduce violent crimes committed by individuals with this disorder. Aims To investigate whether naturally occurring lithium in drinking water lowers rates of violent crime in the general population. Method We examined lithium levels in the drinking water of the 274 municipalities of Kyushu Island in Japan and compared these with the crime rates in each municipality. Results We found that lithium levels were significantly and inversely associated with crime rates in 2009. Conclusions Our findings suggest that even very low levels of lithium in drinking water may play a role in reducing crime rates in the general population.
