A study published in the JAMA Psychiatry revealed that people who had higher levels of lithium in their drinking water had reduced odds of developing dementia. According to the researchers, lithium is a naturally-occurring metal that can be found in varying amounts from area to area.
To carry out the study, a team of researchers at the University of Copenhagen examined water samples from 151 waterworks in Denmark. The scientists also looked at the medical records of more than 73,000 Danish people with dementia and more than 733,000 healthy controls and calculated their lithium exposure levels.
The results showed that people exposed to 5.1 and 10 micrograms of lithium per liter of drinking water had a 22 percent lower odds of developing dementia than those exposed to only two to five micrograms per liter. Likewise, those exposed to 15 micrograms or more were 17 percent less likely to have the cognitive disease.
Researchers said the study was the first of its kind to demonstrate a link between the presence of lithium in drinking water and the lower incidence of dementia. The findings suggest that long-term lithium exposure may be tied to declines in dementia cases, the research team said.
"It is potentially exciting that low doses of a drug already available in the clinic could help limit the number of people who develop dementia. [Our analysis] suggests that a treatment that could delay dementia by just five years would mean that 666,000 fewer people develop dementia by 2050 [in the UK]," Dr. David Reynolds, from the charity Alzheimer's Research U.K., told BBC online.
Outside experts offered varying opinions on the recent study.
David Smith, a professor emeritus of pharmacology at Oxford University, noted that the study's findings were significant given its large sample size. However, he stressed that the study did not show a linear relationship between lithium exposure and dementia. (Related: Lithium orotate: Can this naturally occurring alkali metal cure your mental woes?)
Smith also stated that the findings do not have any public implications, and that people should readily avoid adding lithium salts to public tap water supplies as the required amount remains unclear.
The Alzheimer's Society had a rather neutral response on the research, stating that it might work in theory but may warrant further investigation.
"Lithium triggers a number of useful responses in brain cells. However, despite some success in animals, there hasn't been enough positive research of lithium in people with dementia to yet convince us that it works. More research including clinical trials are needed, and until then we should not consider increasing lithium in drinking water. In high doses, or even at low doses in some people, lithium can be toxic so it is important that people consult with their doctor before they consider taking it as a supplement," Alzheimer's Society's research head Dr. James Pickett told the Daily Mail online.
Prof Tara Spires-Jones, from University of Edinburgh's Centre for Discovery Brain Sciences, looked at the possibility of other variables affecting dementia risk in people.
"This association does not necessarily mean that the lithium itself reduces dementia risk. There could be other environmental factors in the area that could be influencing dementia risk. Nonetheless, this is an interesting result that will prompt more research into whether lithium levels in the diet or drinking water may modify risk of dementia," Professor Spires-Jones said.
Professor Simon Lovestone of the University of Oxford's psychiatry department lauded the findings. He also highlighted the need for studies that will examine whether regular and small doses of lithium could effectively keep dementia at bay.