Cumulative lead exposure linked to increased Alzheimer’s and dementia risk, study finds

Republished from the U-M School of Public Health. Read the original here.

As dementia cases continue to rise in the United States, new research from the University of Michigan School of Public Health reveals that older Americans with cumulative lead exposure face a substantially higher risk of developing Alzheimer’s disease and dementia.

“This is the first empirical study to demonstrate that 18% of new dementia cases in the United States each year may be linked to cumulative lead exposure,” said Kelly Bakulski, Ph.D., associate professor of Epidemiology at Michigan Public Health and one of the study’s senior authors. “With approximately half a million Americans diagnosed with dementia annually, this translates to nearly 90,000 cases that could potentially be prevented—a truly significant figure.”

The study, published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, found that individuals with the highest quarter of bone lead levels had nearly three times (2.96) the risk of Alzheimer’s disease and more than twice (2.15) the risk of all-cause dementia compared to those in the lowest quarter.

The findings highlight cumulative lead exposure as an important, and often overlooked, environmental risk factor for dementia.

Cumulative exposure matters more than recent exposure

The research team analyzed data from participants in the National Health and Nutrition Examination Survey (NHANES), linked to Medicare claims and mortality records for up to 30 years of follow-up. Using machine learning algorithms, researchers estimated bone lead concentrations—a marker of cumulative lifetime exposure.

A key finding from the study: bone lead showed strong associations with dementia, while current blood lead levels did not.

According to Sung Kyun Park, professor of Epidemiology and Environmental Health Sciences and one of the study’s senior authors, this distinction is critical. Blood lead reflects only recent exposure with a half-life of about 30 days, while bone lead can persist for years to decades—making it a better biomarker for tracking the cumulative burden contributing to chronic diseases like dementia.

Most adults in the study were born before 1980, during an era of much higher environmental lead exposure from leaded gasoline and paint.

“Once lead enters the body, it can remain stored in the bones for decades,” said Xin Wang, first author and a research assistant professor in the school’s Department of Epidemiology. “As individuals age, lead may be released from the bones and migrate to organs such as the brain. This underscores the importance of assessing cumulative lead exposure when studying long-latency brain diseases, including dementia.”

The researchers emphasize that efforts to eliminate remaining lead sources in communities—from old paint and pipes to contaminated soil and industrial facilities—is critical to protect current and future generations from accumulating harmful lead exposure.

Additional authors: Erika Walker, Roger Albin, and Henry Paulson of the University of Michigan; Bhramar Mukherjee of the Yale School of Public Health; and Hiroko Dodge of Massachusetts General Hospital and Harvard Medical School.

Funding/disclosures: This research was supported by the National Institute on Aging (R01 AG070897, K01 AG084821, and P30 AG072931) and the National Institute of Environmental Health Sciences (P30 ES017885).

Paper cited: “Exposure to lead and incidence of Alzheimer’s disease and all-cause dementia in the United States.” Alzheimer’s & Dementia. DOI: 10.1002/alz.71075