Association between lithium levels in drinking water and suicide rates: Role of affective disorders

The study aimed to assess the association between lithium levels in drinking water from public supplies and suicide rates in different municipalities of Lithuania in relation with incidence of affective disorders.

53 drinking water samples were analysed from the main public drinking water systems of the country's municipalities. Lithium levels were determined using the ion chromatography method. Information on all registered affective disorders across all age groups and gender within the 5-year period was obtained from the Department of Statistics, and was averaged across the investigation time period. For the statistical analysis, lithium levels were averaged per municipality and plotted against suicide standardized mortality rates per 100,000 populations, within the 5-year period.

We found that lithium levels in drinking water are positively associated with the incidence of affective disorders. Our findings suggest higher incidence rates of affective disorders in the municipalities with a lithium level in drinking water above median compared to those in the municipalities with a lithium level below median and with the same socio-demographic and psychiatric characteristics. Suicide mortality rates are inversely associated with lithium levels in drinking water only in municipalities with higher lithium levels (above median) and with a high rate of affective disorders.

Based on our study results and insights we generate the following hypothesis for the further research, that lithium level in drinking water might have an important protective effect against suicide rates in the population with affective disorders.