Higher Levels of Lithium in Drinking Water May Lower Dementia Risk

A study published in JAMA Psychiatry in August attempts to answer the question, “Could lithium, a naturally occurring element in drinking water, reduce the incidence of dementia?”

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Without a cure or treatment that slows or stops the progression of dementia, researchers have been looking to prevention—such as targeted interventions and modifiable risk factors associated with dementia.

The mood stabilizer lithium has been considered as a potential treatment for Alzheimer’s disease (AD). Positive evidence in several small clinical trials has suggested that low-dose lithium may improve cognition. Lithium blocks an enzyme crucial to the development of AD’s plaques and tangles and has been shown to prevent AD in mice.

“The prospect that a relatively safe, simple, and cheap intervention (i.e., optimizing lithium concentrations in drinking water) could lead to the primary prevention of dementia is a tantalizing prospect,” wrote John J. McGrath, M.D., Ph.D., of the Queensland Centre for Mental Health Research in Australia, in an accompanying editorial.

In the current study, Lars Vedel Kessing, M.D., D.M.Sc., of the University of Copenhagen and colleagues found that higher concentrations of lithium in the drinking water in areas of Denmark were associated with a lower risk of developing dementia.

The researchers measured lithium in drinking water from 151 communities around Denmark and mapped where people with dementia and age- and sex-matched controls lived from 1986 to 2013. They collected longitudinal, individual geographic data on municipality of residence and data from drinking water measurements combined with time-specific data from all patients aged 50 to 90 with a hospital contract and with a diagnosis of dementia from January 1, 1970, through December 31, 2013. The mean lithium exposure in drinking water since 1986 was estimated for all study individuals.

A total of 73,731 patients with dementia and 733,653 controls were included in the study. The researchers found that higher long-term exposure to lithium in drinking water was associated with a lower incidence of dementia, but this association was nonlinear. Compared with people exposed to the lowest levels of lithium (up to 5 μg/L), people exposed to 5.1 to 10 μg/L had a 22 percent higher risk of dementia, people exposed to 10.1 to 15 μg/L had about the same risk of dementia, and people exposed to 15 μg/L or more had a 17 percent lower risk of dementia.

The study’s authors do not suggest increasing lithium in the water supply; it is unclear how much lithium would be safe and effective to use.

“There is strong epidemiological evidence in animal and human studies that certain low levels of lithium are neuroprotective,” Anna Fels, M.D., a practicing psychiatrist in New York City and a clinical professor of psychiatry at Weill Cornell Medical College, told Psychiatric News. “More studies should be done, and if they continue to find benefits, there should be ways the public could access water with lithium in tablets or another form that is measured and pharmaceutical grade.”

“If the findings of Kessing and colleagues are supported in future studies, even a marginal reduction in the incidence of dementia could result in major societal and economic gains,” wrote McGrath. ■