BACKGROUND AND PURPOSE:

• Animal studies show lithium improves learning and memory
• Human observational studies suggest lithium treatment may reduce the risk of dementia in individuals with bipolar disorder
• Kessing et al. (JAMA Psychiatry, 2017) sought to assess whether incidence of dementia is associated with long-term exposure to microlevels of lithium in drinking water

METHODS:

• Population-based, nested case-control study
• Longitudinal data on municipality of residence, lithium levels drinking water measurements and incidence of dementia (inpatient and outpatient)
• Primary outcome
  • Dementia diagnosis
• Secondary outcomes
  • Alzheimer disease
  • Vascular dementia diagnoses

RESULTS:

• A total of 73,731 patients with dementia and 733,653 controls were included in the study, age 50-90 years
• Lithium exposure differed between patients with a diagnosis of dementia (median, 11.5 µg/L) and controls (median, 12.2 µg/L; (P < .001)
• Compared with individuals exposed to 2.0 – 5.0 µg/L, the incidence rate ratio (IRR) of dementia was
  • Decreased in those exposed to more than 15.0 µg/L (IRR, 0.83; 95% CI 0.81-0.85; P < .001) and 10.1 to 15.0 µg/L (IRR, 0.98; 95% C 0.96-1.01; P = .17)
  • Increased with 5.1 to 10.0 µg/L (IRR, 1.22; 95% CI 1.19-1.25; P < .001)
• Secondary outcomes: Similar patterns to the above were identified when Alzheimer disease and vascular dementia were studied

CONCLUSION:

• Long-term increased lithium exposure in drinking water is correlated with lower incidence of dementia, with lower levels associated with higher risk
• Confounding factors could not be excluded, such as differing availability of healthcare which could impact whether a patient would receive a formal diagnosis

Learn More – Primary Sources

Association of Lithium in Drinking Water With the Incidence of Dementia

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