Balint Izsak1, Anna Hidvegi2, Lajos Balint3, Tibor Malnasi4, Marta Vargha4, Tamas Pandics4, Zoltan Rihmer5, Peter Dome6. 1. National Public Health Center, Budapest, Hungary; Eotvos Lorand University, Doctoral School of Environmental Sciences, Budapest, Hungary. 2. Department of Internal Medicine I, Military Hospital, Hungarian Defense Forces Medical Center, Budapest, Hungary. 3. Demographic Research Institute of the Hungarian Central Statistical Office, Budapest, Hungary; Department of Sociology, University of Pécs, Pécs, Hungary. 4. National Public Health Center, Budapest, Hungary. 5. Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary; Nyiro Gyula National Institute of Psychiatry and Addictions, Budapest, Hungary. 6. Department of Psychiatry and Psychotherapy, Semmelweis University, Budapest, Hungary; Nyiro Gyula National Institute of Psychiatry and Addictions, Budapest, Hungary. Electronic address: dome_peter@yahoo.co.uk.
Abstract
BACKGROUND: In recent decades, a series of ecological studies from various countries have attempted to reveal whether there is an association between trace amounts of lithium in drinking water and suicide mortality. With some notable exceptions, results have indicated that there is an inverse association between these two variables. Since Hungary had extremely high rates of suicide with a persistent spatial pattern, we consider that our country is ideal to investigate this research question. METHODS: We carried out our research on Hungarian data at the level of districts (n = 197). The dependent variable was the age- and gender-standardized mortality ratio for suicide (sSMR). Our main explanatory variable was the tap water lithium level (Li) from public drinking water supply systems using their own water source (n = 1 325). Those data, which give full national coverage, were aggregated to the level of districts. Confounding factors were religiosity, alcohol consumption and income. Various regression models were used for statistical calculations. RESULTS: Findings from our most appropriate regression model - adjusted for relevant confounding variables and able to handle spatial autocorrelation and heteroscedasticity - suggest a significant (p < 0.05) and a trend-like (p < 0.1) negative association between Li and sSMR in the total population and among males, respectively. However, such an association was not found between these two variables among females. CONCLUSION: In line with the majority of findings from other countries, our results indicate that the intake of lithium with drinking water may have a gender-dependent suicide-protective effect.
BACKGROUND: In recent decades, a series of ecological studies from various countries have attempted to reveal whether there is an association between trace amounts of lithium in drinking water and suicide mortality. With some notable exceptions, results have indicated that there is an inverse association between these two variables. Since Hungary had extremely high rates of suicide with a persistent spatial pattern, we consider that our country is ideal to investigate this research question. METHODS: We carried out our research on Hungarian data at the level of districts (n = 197). The dependent variable was the age- and gender-standardized mortality ratio for suicide (sSMR). Our main explanatory variable was the tap water lithium level (Li) from public drinking water supply systems using their own water source (n = 1 325). Those data, which give full national coverage, were aggregated to the level of districts. Confounding factors were religiosity, alcohol consumption and income. Various regression models were used for statistical calculations. RESULTS: Findings from our most appropriate regression model - adjusted for relevant confounding variables and able to handle spatial autocorrelation and heteroscedasticity - suggest a significant (p < 0.05) and a trend-like (p < 0.1) negative association between Li and sSMR in the total population and among males, respectively. However, such an association was not found between these two variables among females. CONCLUSION: In line with the majority of findings from other countries, our results indicate that the intake of lithium with drinking water may have a gender-dependent suicide-protective effect.