- A recent study suggests that higher cumulative lead exposure stored in bones is strongly associated with an increased risk of Alzheimer’s disease and other dementias.
- Individuals with the highest bone lead levels had nearly three times the risk of Alzheimer’s disease and more than double the risk of all-cause dementia compared with those with the lowest levels.
- Current blood lead levels were not significantly associated with dementia risk, highlighting that lifetime exposure, not just recent exposure, may play a critical role in later cognitive decline.
- Another recent study also indicates that lead exposure before birth may be associated with lower cognitive performance.
Dementia is a term describing several diseases that affect memory, problem-solving, language and behaviour. Estimates suggest that
Dementia typically occurs due to damage to or changes in the brain. Lead is a naturally occurring toxic metal that can negatively affect health.
Lead exposure occurs primarily through ingesting or inhaling lead-contamined dust, soil, paint, or water. Over time, exposure to high levels of lead can
A recent study, published in
Additionally, another study, published in Neurology, suggests that exposure to lead before birth may be associated with poorer thinking and memory skills decades later, particularly among females.
The study, led by researchers at the University of Michigan School of Public Health, highlights how historic environmental exposures, particularly from leaded gasoline, paint, and pipes before regulations dramatically reduced their use, may continue to affect cognitive health in people born before the 1980s.
The research team analyzed data from the
Using machine learning models, the researchers estimated participants’ bone lead levels, which act as a biomarker of cumulative lifetime exposure.
The body stores lead in the teeth and bones, where it can accumulate over time. Thus, these reflect a better measure of cumulative exposure, as blood lead levels only reflect recent exposure and clears relatively quickly.
The study found that higher bone lead levels were strongly associated with increased dementia risk. Individuals in the highest quarterile of bone lead levels had nearly three times the risk of Alzheimer’s disease compared with those with the lowest level.
For all-cause dementia, the risk more than doubled among those with highest cumulative lead exposure.
Kelly Bakulski, PhD, associate professor of Epidemiology at Michigan Public Health and one of the study’s senior authors was surprised by the magnitude of the increased risk:
“Yes, the findings were quite striking. This represents a great opportunity to help a lot of people by lowering lead exposure levels across the population.”
In contrast, the researchers found no significant link between current blood lead levels and dementia risk, underscoring the importance of long-term exposure measurements.
Similarly, Steve Allder, BMBS, FRCP, DM, consultant neurologist at Cognition Health, was also surprised at the findings.
“Historically, many studies on lead and cognitive decline relied on blood lead levels, which reflect recent exposure and typically show weaker associations. In contrast, bone lead represents decades‑long storage, and this study’s use of bone lead estimates likely captures the true long‑term burden much more effectively,” Allder told us.
“The finding that individuals in the highest quartile of cumulative lead exposure had nearly three times the risk of Alzheimer’s disease and more than double the risk of all‑cause dementia is notable and striking from a public health perspective,” he added.
Another recent study suggests that exposure to lead before birth may be associated with poorer thinking and memory skills decades later, particularly among females.
To assess prenatal exposure, researchers analyzed baby teeth that had been donated decades earlier. Between roughly 1958 and 1970, parents in the St. Louis, Missouri, area donated their children’s baby teeth as part of a radiation study. The research team tracked down the donors roughly 6 decades later.
A total of 715 people, now with an average age of 62, completed cognitive tests on their home computers and had their stored baby teeth analyzed.
The researchers found that higher levels of lead exposure during the second trimester of pregnancy were associated with lower cognitive test scores.
In particular, for female participants, every small increase in lead levels in their teeth during the second trimester of pregnancy was linked to lower cognitive test scores.
Although the study does not prove that prenatal lead exposure causes cognitive decline, but identifies a significant long-term association.
While public health initiatives are working to reduce lead exposure, legacy sources such as contaminated soil, aging infrastructure, and older housing with lead-based paint continue to pose risks, particularly in underserved communities.
Recent events such as the Flint water crisis and reports of
Due to lead’s persistence in the body, exposures from early life may contribute to neurodegenerative changes many years later.
Bakulski told Medical News Today how long-term lead exposure may contribute to neurodegeneration: “Lead has no normal physiologic function in the body, but it can hijack existing pathways. For example, it can enter cells by riding along the divalent metal transporter that normally transports iron.”
“Once in cells, it can cause general neurotoxicity by promoting oxidative stress, mitochondrial damage, and ER stress. In animal models with genetic susceptibility to produce amyloid and tau, lead exposure accelerates these processes,” she explained.
Speaking to MNT, Allder also highlighted how lead exposure can damage blood vessels and the blood–brain barrier, as well as alter epigenetic patterns that could predispose the brain to neurodegenerative changes decades later.
“These mechanisms overlap with known dementia pathways — oxidative stress, amyloid/tau aggregation, vascular dysfunction, and epigenetic vulnerability — providing biological plausibility for the epidemiological findings linking long‑term lead burden to dementia,” he noted.
Findings from the University of Michigan study suggest that potentially around 18% of new cases each year in the US may be linked to cumulative lead exposure.
Sung Kyun Park, ScD, MPH, professor of Epidemiology and Environmental Health Sciences and one of the study’s senior authors told MNT:
“While lead’s neurotoxicity is well-established, prior studies lacked data quantifying its impact on Alzheimer’s disease and dementia risk.”
“Using a nationally representative sample, we estimated the population attributable fraction and found that, for patella lead (a bone lead marker), up to 18% of new dementia cases in the U.S. each year could be linked to cumulative lead exposure, a striking figure.”
This could help explain part of the rising dementia burden in older populations today.
“In the US, if we were able to drop everyone’s bone lead levels to the 25th percentile, we may be able to prevent up to 18% of future dementia cases.”
– Kelly Bakulski, PhD
Additionally, findings from the other study add to growing evidence that early-life environmental exposures may influence brain health decades later.
These studies reinforce the need for continued efforts to eliminate remaining sources of lead exposure, particularly in environments where older housing and infrastructure still expose people to this neurotoxin.
“Rather than focusing on individual interventions, efforts should prioritize eliminating remaining sources of lead, such as old paint and pipes in aging infrastructure, especially in environmentally disadvantaged communities,” Park explained.
“Because lead exposure is unequally distributed, targeted policy action and resource allocation are needed to address these disparities,” he added.
“Overall, reducing environmental toxins and addressing legacy exposures through infrastructure investment and public health initiatives could potentially mitigate a portion of future dementia burden,” Allder told MNT.
Bakulski emphasized that there is strong evidence to suggest that air pollution causes dementia and Alzheimer’s disease.
“Policies to reduce air pollution, including from motor vehicles and industrial sources, save lives and prevent dementia,” she said.
“With this new study, we are part of a growing body of research that is starting to show that lead exposure likely also contributes to dementia and Alzheimer’s disease. Investment in infrastructure to reduce lead exposure will benefit public health in multiple dimensions, including the brain,” the researcher added.
The
- If living in a home built before 1978, have it checked by a licensed lead inspector. If rennovating an older home, use only approved methods for removing lead hazards.
- Contact the water provider to check if there is a lead service line connected to the home. Using filters or bottled water
can help to reduce exposure. - Try to avoid products, such as antique toys or toy jewelry, which may contain lead.
- Consume a dietary plan rich in calcium, iron, and vitamin C to help keep lead out of the body.
- Regularly wash hands and faces.
- Remove shoes when entering the house and change into clean clothes before coming home if a person works with lead.
Bakulski highlighted the protective role of calcium and maintaining good bone health to help reduce risk following potential exposure, noting that:
“When we are exposed to lead, it travels around our bodies in the bloodstream. Lead has a similar size and charge as calcium, and just like how our bodies take calcium out of the blood and plug it into our bones, lead can be stored in our bones. Any activities that keep our bones strong and healthy, like ensuring a diet with adequate calcium intake, will ensure that the old lead stays out of the way in our bones.”
Additionally, Allder also emphasized general brain health strategies to reduce dementia risk.
“Adopting well‑established dementia risk‑reduction behaviours — healthy diet, regular exercise, good cardiovascular control, mental stimulation, and sleep optimization — remains critical and is supported by a broad evidence base,” he concluded.
