May 12, 2011 — Geographical areas with higher natural lithium concentrations in the drinking water have lower mortality rates from suicide, according to new research published in the May issue of the British Journal of Psychiatry.
The finding, similar to that from 3 different countries on different continents, adds to the evidence that lithium in the drinking water may have beneficial effects for mental health, Nestor D. Kapusta, MD, from the Medical University of Vienna, Austria, and colleagues write.
"This should stimulate further research in low-level effects of lithium," Dr. Kapusta told Medscape Medical News. "We know much about therapeutic levels — 450 to 900 mg of lithium carbonate per day — but very little about natural levels."
Dr. Kapusta, a psychiatrist who is engaged in suicide research and prevention, noted that many questions about suicide remain unanswered despite 100 years of research by the likes of Emile Durkheim, Sigmund Freud, and Alfred Adler.
"One of the most interesting questions for me is why is the geographical distribution of suicides so persistent over decades in many countries? Why do we have regions which seem to be 'suicide geysers,' while others seem protective?" he said.
"Since I was working on these questions, the pilot study of Ohgami and colleagues sparked the idea in me to replicate their findings in another country. I was skeptical in the beginning," he confessed.
To evaluate the association between local lithium levels in drinking water and suicide mortality, Dr. Kapusta and his team examined a nationwide sample of 6460 lithium measurements and then compared suicide rates across 99 districts in Austria.
They found that the overall suicide rate and the suicide mortality ratio were inversely associated with lithium levels in drinking water. These associations remained significant after sensitivity analyses and adjustment for socioeconomic factors.
In the 10 most lithium-depleted regions in Austria, the suicide rate was 16 per 100,000, whereas in the 10 most lithium-rich regions; the suicide rate was just 11 per 100,000.
|Dr. Nestor D. Kapusta|
"This suggests a protective effect of lithium on suicide," Dr. Kapusta said.
Because the study is cross-sectional and based on aggregated data, we cannot be sure that the association is causal, he added.
Glenn Currier, MD, MPH, from the University of Rochester Medical Center in New York, echoes these statements.
"Because suicide is a relatively rare event, small differences in rates from area to area are often difficult to explain," he told Medscape Medical News.
"Lithium levels in the water supply are only 1 possible factor associated with rate variances. However, something as basic as availability of better mental health services in low suicide areas could also help reduce rates."
"It is not easy to prove causality in research anyway. There are several criteria which need to be fulfilled to increase the probability of causality. Although we have evidence for a couple of them, further research will be necessary to support the probability of causality between natural lithium in drinking water and suicide mortality."
In an accompanying editorial, Allan H. Young, MBChB, PhD, chair of psychiatry at Imperial College London, United Kingdom, points out that lithium is an established treatment for affective disorders "with good evidence of antisuicidal properties."
He adds that patients with bipolar disorder who are taking lithium have lower rates of Alzheimer's disease and that a recent study of lithium in amnestic miimal cognitive impairment showed potential benefits.
"This should stimulate further, larger-scale studies," he concludes.
Dr. Kapusta and Dr. Young have disclosed no relevant financial relationships.
Medscape Medical News © 2011 WebMD, LLC
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Cite this: More Lithium in Drinking Water Equals Lower Suicide Rates - Medscape - May 12, 2011.