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Association between naturally occurring lithium in drinking water and suicide rates: A systematic review and meta-analysis of ecological studies

Research output: Contribution to journalArticle

Anjum Memon, Imogen Rogers, Sophie Fitzsimmons, Ben Carter, Becci Strawbridge, Diego Hidalgo-Mazzei, Allan Young

Original languageEnglish
JournalBritish Journal of Psychiatry
Publication statusAccepted/In press - 1 Jun 2020

King's Authors

Abstract

Background
The prevalence of mental health conditions and national suicide rates are increasing in many countries. Lithium is widely and effectively used in pharmacological doses for the treatment and prevention of manic/depressive episodes, stabilising mood and reducing the risk of suicide. Since the 1990s, several ecological studies have tested the hypothesis that trace doses of naturally occurring lithium in drinking water may have a protective effect against suicide in the general population. We synthesised the global evidence on the association between lithium levels in drinking water and suicide mortality rates.
Method
The MEDLINE, EMBASE, Web of Science and PsycINFO databases were searched to identify eligible ecological studies published between 1st January 1946 and 10th September 2018. Standardized regression coefficients for total (i.e. both sexes combined), male and female suicide mortality rates were extracted and pooled using random effects meta-analysis. The study was registered with PROSPERO (number CRD42016041375).
Results
The literature search identified 415 articles; of these, 15 studies were included in the synthesis. The random effects meta-analysis showed a consistent protective (or inverse) association between lithium levels/concentration in publically available drinking water and total (pooled β -0.27 [95%CI: -0.47, -0.08]; p=0.002, I2=83.3%), male (pooled β -0.26 [95%CI: -0.56, 0.03]; p=0.08 I2=91.9%), and female (pooled β -0.13 [95%CI: -0.24, -0.02]; p=0.03, I2=28.5%) suicide mortality rates. Similar protective association was also observed in the six studies included in the narrative synthesis, and subgroup meta-analyses based on the higher/lower suicide mortality rates and lithium levels/concentration.
Conclusions
This synthesis of ecological studies supports the hypothesis that there is a protective (or inverse) association between lithium intakes from public drinking water and suicide mortality at the population level. Naturally occurring lithium in drinking water may have the potential to reduce the risk of suicide and may possibly help in mood stabilisation, particularly in populations with relatively high suicide rates and geographical areas with a greater range of lithium concentration in the drinking water. All the available evidence suggest that randomised community trials of lithium supplementation of the water supply might be a possible means of testing the hypothesis, particularly in communities (or settings) with demonstrated high prevalence of mental health conditions, violent criminal behaviour, chronic substance abuse and risk of suicide.

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