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Associations between low-dose drinking water lithium exposure and Dementia: A nationwide U.S. ecological study
Hwang Se-Hyun, Jang Hyuna, Park Sung Kyun, Shin Hyeong-Moo. Environmental pollution (Barking, Essex : 1987), 2026-02-06
Topic: Risk, prevention and care in population studies
Lithium is a naturally occurring trace element with established neuroprotective and psychotropic properties at pharmacologic doses. Dementia is one of the most burdensome neuropsychiatric conditions in the United States. Although several epidemiological studies have examined associations between lithium in drinking water and dementia outcomes, findings remain inconsistent. We examined county-level associations between drinking water lithium concentrations and dementia prevalence, incidence, and mortality across the United States. Population-weighted lithium concentrations were estimated using data from the U.S. Environmental Protection Agency's Fifth Unregulated Contaminant Monitoring Rule (UCMR 5), which covers public water systems serving approximately 70.5% of the U.S. population. County-level dementia diagnoses and all-cause mortality among individuals with dementia were obtained from the U.S. Dementia DataHub, encompassing the entire Medicare population (∼62 million beneficiaries). We applied quasi-Poisson regression within generalized additive mixed models, including sex-stratified analyses. Compared with counties with low lithium concentrations, those with high concentrations had lower dementia prevalence (prevalence ratio [PR] = 0.965, 95% CI: 0.950, 0.981) and incidence (incidence rate ratio [IRR] = 0.958, 95% CI: 0.939, 0.978), exhibiting non-linear dose-response patterns. In contrast, all-cause mortality among individuals with dementia was higher in high-lithium counties (mortality rate [MR] = 1.017, 95% CI: 1.007, 1.027), although this association was largely attenuated after stratification by county-level Hispanic population percentage. These findings suggest inverse associations between low-level drinking water lithium concentrations and county-level dementia prevalence and incidence, while associations with mortality remain uncertain. Further studies incorporating individual-level data are needed to clarify the health effects of trace lithium exposure.
Key findings
- Compared with counties with low lithium concentrations, those with high concentrations had lower dementia prevalence (prevalence ratio [PR] = 0.965, 95% CI: 0.950, 0.981) and incidence (incidence rate ratio [IRR] = 0.958, 95% CI: 0.939, 0.978), exhibiting non-linear dose-response patterns.
- These findings suggest inverse associations between low-level drinking water lithium concentrations and county-level dementia prevalence and incidence, while associations with mortality remain uncertain.
Why it matters
This county-level study found that areas with high drinking water lithium concentrations had lower dementia prevalence and incidence, while associations with mortality remained uncertain. It is an ecological association and does not test lithium as a treatment, cure, or prevention for Alzheimer's disease.
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Study details
- Effect size70.5%
- Evidence strengthLow
How this study scored 35/100
Published in a peer-reviewed journal. Scored zero for study design, sample size, studied in people and randomised / blinded because the record does not state it.
| Component | Points | Why |
|---|---|---|
| Journal tier | 7 / 10 | Tier 3 — peer-reviewed journal (Environmental pollution (Barking, Essex : 1987)) |
| Journal's citation record | 3 / 4 | Environmental Pollution: journal h-index 385 (OpenAlex, 2026-10-29) |
| Study design | 0 / 12 | No study design recorded — scores zero, not guessed (not stated in the record — scored 0) |
| Strength of evidence | 1 / 5 | Rated “low” in our summary |
| Peer-review validation | 10 / 10 | Peer-reviewed. Published as an article in a named peer-reviewed journal. |
| How recent | 5 / 5 | 2026 — within 1 year(s) of the newest study here |
| Sample size | 0 / 4 | Participant count not stated — scores zero (not stated in the record — scored 0) |
| Effect reported | 2 / 3 | Effect reported as a number, without an interval or test |
| Studied in people | 0 / 3 | Not stated whether this was studied in people — scores zero (not stated in the record — scored 0) |
| Randomised / blinded | 0 / 2 | No randomisation or blinding stated — scores zero (not stated in the record — scored 0) |
| Times cited | 0 / 7 | Cited 0 times (OpenAlex, 2026-10-10) |
| Citations per year | 0 / 5 | 0.0 citations a year over 2 year(s) since 2026 |
| Impact for its field and year | 0 / 6 | Cited 0.0× the average for papers of its field and year (OpenAlex FWCI) |
| Cited by studies here | 0 / 6 | No other study in this library cites it |
| Still being cited | 0 / 4 | Cited 0 times in 2024–2026 (2026 still in progress; OpenAlex) |
| Senior author's track record | 2 / 4 | Last-listed author Hyeong‐Moo Shin: h-index 31 (OpenAlex, whole career) |
| Institution's track record | 2 / 3 | University of Michigan: institution h-index 2,240 (OpenAlex) |
| Multi-centre collaboration | 1 / 3 | OpenAlex lists 2 institution(s) in 1 country |
| Indexed in PubMed | 2 / 2 | Indexed in PubMed (PMID 41643982) |
| Free to read | 0 / 2 | Behind a paywall — scores zero |
| Total | 35 / 100 | — |
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Read the original
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Cite this study APA, Vancouver, BibTeX · download .bib or .ris
Built from the record alzhub holds for this paper, not looked up. Volume, issue and page numbers are not held in the record. Check the citation against the original before you use it.
APA 7th
Se-Hyun, H., Hyuna, J., Kyun, P. S., & Hyeong-Moo, S. (2026). Associations between low-dose drinking water lithium exposure and Dementia: A nationwide U.S. ecological study. Environmental pollution (Barking, Essex : 1987). https://doi.org/10.1016/j.envpol.2026.127766
Vancouver
Se-Hyun H, Hyuna J, Kyun PS, Hyeong-Moo S. Associations between low-dose drinking water lithium exposure and Dementia: A nationwide U.S. ecological study. Environmental pollution (Barking, Essex : 1987). 2026. doi:10.1016/j.envpol.2026.127766. PMID: 41643982.
BibTeX
@article{sehyun2026-41643982,
author = {Se-Hyun, Hwang and Hyuna, Jang and Kyun, Park Sung and Hyeong-Moo, Shin},
title = {{Associations between low-dose drinking water lithium exposure and Dementia: A nationwide U.S. ecological study}},
journal = {Environmental pollution (Barking, Essex : 1987)},
year = {2026},
doi = {10.1016/j.envpol.2026.127766},
pmid = {41643982},
url = {https://doi.org/10.1016/j.envpol.2026.127766}
}
Studies this one cites
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