Higher cumulative lead exposure was associated with an increased risk of Alzheimer’s disease and all-cause dementia in a large, nationally representative US cohort, according to new research published in Alzheimer’s & Dementia.
The study analyzed data from the National Health and Nutrition Examination Survey (NHANES), linking baseline lead measurements to Medicare claims and National Death Index records for up to 30 years of follow-up. In the more recent NHANES cycles (1999 to 2016), individuals with the highest estimated patella bone lead levels had nearly three times the risk of developing Alzheimer’s disease and more than double the risk of all-cause dementia compared with those in the lowest exposure group.
Notably, blood lead levels – an indicator of recent exposure – were not associated with dementia risk. In contrast, estimated bone lead, which reflects cumulative exposure over decades, showed consistent associations with incident disease. Bone acts as a long-term reservoir for lead, releasing it gradually into circulation with age-related bone turnover.
The findings serve as a stark environmental message; the authors estimated that if bone lead levels in the population were reduced to the 25th percentile, approximately 18 percent of new all-cause dementia cases might be prevented. This projected impact exceeds that of several established modifiable dementia risk factors identified in recent prevention frameworks.
Most adults in the study were born before 1980, when environmental lead exposure from gasoline, paint, and industrial sources was considerably higher. Although blood lead levels have declined nationally, cumulative body burden remains in bone for decades. The results suggest that historical exposure may continue to influence neurodegenerative disease risk in aging populations.
As dementia prevalence rises with population aging, these data position cumulative lead exposure as a potentially preventable contributor to neurodegenerative disease burden in the US.
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