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Lithium in drinking water linked to lower dementia rates

Long-term exposure to microlevels of lithium in drinking water may reduce dementia incidence, according to recent findings.

“Animal studies have found that long-term lithium treatment improves learning and memory, and human observational studies suggest that continued treatment with lithium may reduce the risk of dementia among patients with bipolar disorder. In bipolar disorder, treatment with lithium in usual therapeutic daily doses (600 to 2,400 mg) for mood stabilization increases the risk of chronic kidney disease in the elderly population,” Lars Vedel Kessing, MD, DMSc, of University of Copenhagen, Denmark, and colleagues wrote.

To determine if long-term exposure to microlevels of lithium in drinking water lowered dementia incidence, researchers analyzed longitudinal, individual geographic data on municipality of residence and data from drinking water measurements combined with time-specific data from all individuals aged 50 to 90 years with a hospital contact with a diagnosis of dementia from 1970 through 2013. The study cohort included 73,731 individuals with dementia and 733,653 controls.

Lithium exposure was significantly different between participants with dementia and controls (median 11.5 g/L vs. 12.2 g/L; P < .001).

Participants exposed to more than 15 g/L (IRR = 0.83; 95% CI, 0.81-0.85; P < .001) and 10.1 g/L to 25 g/L (IRR = 0.98; 95% CI, 0.96-1.01; P = .17) had lower dementia incidence, compared with those exposed to 2 g/L to 5 g/L.

Participants exposed to 5.1 g/L to 10 g/L (IRR = 1.22; 95% CI, 1.19-1.25; P < .001) had increased dementia incidence, compared with those exposed to 2 g/L to 5 g/L.

Researchers found similar associations for Alzheimer’s disease and vascular dementia.

“As Kessing and colleagues note, the findings should be interpreted cautiously. The association may reflect unmeasured, region-varying confounding factors. In addition, nonlinear exposure-risk associations may be present: could increasing the concentration of lithium in the drinking water increase the risk in a subgroup of the population?” John J. McGrath, PhD, MD, of the University of Queensland, St Lucia, Australia, and Michael Berk, PhD, of Aarhus University, Denmark, wrote in an accompanying editorial. “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. However, we also need to consider the political and social landscape regarding augmentation of drinking water (such as the ongoing debate around fluoride and dental caries). In the spirit of alchemy, could we convert lithium, a simple metal used as a mood stabilizer, into a golden public health intervention that could prevent dementia?” – by Amanda Oldt

Disclosure: Kessing reports working as a consultant for Lundbeck, AstraZeneca, and Sunovion. Please see the study for a full list of relevant financial disclosures.