Relationships of local lithium concentrations in drinking water to regional suicide rates in Italy

Abstract

A proposed association between trace lithium concentrations in drinking water and risk of suicide was only partially supported, and mechanisms for potential clinical effects of trace levels of lithium are unknown.

Lithium in Drinking Water and Incidence of Suicide: A Nationwide Individual-Level Cohort Study with 22 Years of Follow-Up

“…Where the mean level was comparable to levels found in previous studies [6,7,13,14,15,16,17,18], the range in the present study was generally more narrow. Previous studies that found a significant association with suicide consistently reported the highest lithium exposure levels with up to 59 µg/L in the Oita prefecture in Japan [16], 121 µg/L in Greece [13], and 219 µg/L in Texas [7].…”

“…Potential confounders were selected based on the literature on central risk factors for suicide combined with a hypothesized association with lithium exposure, as well as findings from the reviewed literature on factors of influence on the association [6,7,13,14,15,16,17,18]. Covariates were included at an individual level and comprised gender and ethnicity (Danish origin, immigrant/descendant) as time constant confounders and age (10-year categories), employment (employed, unemployed, outside labor force) and civil status (cohabiting, living alone) as time-varying confounders.…”

“…Recently, a series of ecological studies [6,7,13,14,15,16,17,18] has addressed the potential effect of lithium in drinking water on suicide in the general population. Although evidence is pointing in the direction of an inverse association [19], contradictory findings have been reported in different regions and a causal relation is uncertain.…”

“…Although evidence is pointing in the direction of an inverse association [19], contradictory findings have been reported in different regions and a causal relation is uncertain. An essential limitation of previous studies [6,7,13,14,15,16,17,18] is that they have been conducted at an aggregate regional level prone to the possibility of ecological fallacy, where associations may be falsely overestimated compared to those established by individual-level analysis [20]. Therefore, for the first time, we investigate the association at an individual level using prospectively collected nationwide Danish register data.…”

Trace lithium is inversely associated with male suicide after adjustment of climatic factors

“…Thereafter, we showed an inverse association between lithium levels in drinking water and suicide rates for 18 municipalities of Oita prefecture in Japan in 2009 (Ohgami et al, 2009). However, this association was not found in a sample derived from 47 subdivisions in the East of England (Kabacs et al, 2011) and the association remains uncertain in a sample derived from 145 sites in Italy where lithium concentrations and local suicide rates were not significantly inversely related, except in 1980-1989, particularly among women, and also, based on weighted least-squared, bivariate regression modeling, lithium concentrations were significantly and negatively associated with overall suicide rates (in women and men), but only in 1980-1989(Pompili et al, 2015. A nationwide Austrian study found an inverse association between lithium levels in drinking water and suicide rates after adjustment of population density, per capita income, proportion of Roman Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/jad Catholics, as well as the availability of mental health service providers (Kapusta et al, 2011).…”