Summary: A recent study found that trace concentrations of lithium in drinking water are associated with slower increases in Alzheimer’s disease mortality. The research also linked those low lithium levels to reduced rates of obesity and type 2 diabetes in the same regions.

Source: IOS Press.

Trace Lithium in Drinking Water Linked to Reduced Alzheimer’s Mortality and Lower Rates of Obesity and Diabetes

Researchers at Brock University report that small, naturally occurring amounts of lithium in tap water are associated with slower increases in Alzheimer’s disease deaths across Texas counties. The study, published in the Journal of Alzheimer’s Disease, also found that counties with higher trace lithium levels experienced lower rates of obesity and type 2 diabetes—two conditions known to increase Alzheimer’s risk.

Postdoctoral fellow Val Fajardo and Assistant Professor Rebecca MacPherson analyzed lithium measurements from public water sources alongside county-level health data. Their team, which included Associate Professor Paul LeBlanc, examined average lithium concentrations from 6,180 water samples collected since 2007, covering 234 of Texas’s 254 counties. They compared changes in age-adjusted Alzheimer’s disease mortality between two time periods—2000–2006 and 2009–2015—and adjusted analyses for demographic and environmental factors.

Key Findings

• Counties with lithium levels above the median (40 micrograms per litre) showed smaller increases in Alzheimer’s disease mortality over time compared with counties below the median.
• There was a statistically significant negative correlation between trace lithium concentrations and changes in Alzheimer’s mortality (p = 0.01, r = –0.20).
• The association persisted after adjusting for most risk factors, although it was attenuated when accounting for physical inactivity, obesity, and type 2 diabetes.
• Prevalence of obesity and type 2 diabetes were themselves negatively correlated with trace lithium levels in drinking water, and both conditions positively correlated with increases in Alzheimer’s mortality.

Study Methods and Scope

The study averaged lithium concentrations from thousands of public well samples to estimate county-level exposure. Researchers computed changes in age-adjusted Alzheimer’s mortality by subtracting aggregated rates from 2000–2006 from aggregated rates between 2009–2015. Aggregating multi-year data improved the reliability of mortality estimates for more counties. Statistical analyses controlled for gender, race, education level, rural residency, air pollution, and physical inactivity, as well as obesity and type 2 diabetes.

Interpretation and Cautions

While the findings are consistent with previous laboratory and epidemiological research suggesting neuroprotective effects of lithium, the authors caution against any immediate public health interventions such as adding lithium to municipal water supplies. The concentrations observed in this study are trace, naturally occurring amounts far lower than the therapeutic doses used to treat mood disorders. More research is required to confirm causality, understand mechanisms, and evaluate potential benefits and risks before policy recommendations could be considered.

Context in Existing Research

This Brock University analysis follows other international studies that have observed associations between naturally occurring lithium in water and reduced rates of dementia. Together, these emerging population-level findings support further investigation into whether low-dose lithium exposure influences metabolic health and neurodegeneration risk over the long term.

Article: “Examining the Relationship between Trace Lithium in Drinking Water and the Rising Rates of Age-Adjusted Alzheimer’s Disease Mortality in Texas.”

Authors: Val Andrew Fajardo; Val Andrei Fajardo; Paul J. LeBlanc; Rebecca E.K. MacPherson.

Journal: Journal of Alzheimer’s Disease. Published online November 28, 2017. doi:10.3233/JAD-170744

Abstract (Condensed)

Background: Alzheimer’s disease mortality rates have increased over time. Lithium has known neuroprotective properties at therapeutic doses. Objective: To assess the relationship between trace lithium in drinking water and changes in Alzheimer’s disease mortality across Texas counties.

Methods: Researchers averaged 6,180 public well samples collected since 2007 to estimate lithium levels for 234 counties. They calculated changes in age-adjusted Alzheimer’s mortality by comparing aggregated rates from 2000–2006 with rates from 2009–2015. Correlational analyses adjusted for demographic and environmental factors, physical inactivity, obesity, and type 2 diabetes.

Results: Overall age-adjusted Alzheimer’s mortality increased by 27% (p < 0.001). Changes in Alzheimer’s mortality were negatively correlated with trace lithium levels (p = 0.01, r = –0.20). The negative association remained after controlling for most covariates, though physical inactivity, obesity, and diabetes attenuated the relationship. Obesity and type 2 diabetes were positively correlated with Alzheimer’s mortality increases and negatively correlated with trace lithium levels.

Conclusion: Trace lithium in drinking water is inversely associated with increases in Alzheimer’s disease mortality and with prevalence of obesity and type 2 diabetes, which are important Alzheimer’s risk factors. Further research is needed to explore causality and public health implications.

These findings add to an evolving literature on environmental trace elements and neurodegenerative disease risk. They highlight the need for additional population studies and mechanistic research before considering any changes to drinking water policy.