Background:
Alzheimer’s Dementia (AD) has a complex pathophysiology that is incompletely
understood. Chronic, low-level environmental lead (Pb) exposure is associated with cognitive
impairment, hypertension and mortality, and has been proposed as a potential cause of AD.
Objective:
We aimed to review the literature to clarify the potential role of Pb in AD and to guide future
research.
Methods:
Through a series of systematic reviews, we identified case-control studies comparing AD to
controls on 6 measures of Pb exposure or accumulation: blood, bone, cerebrospinal fluid, hair/nail, postmortem
pathology, and urine. We completed meta-analyses where possible.
Results:
The number of identified case-control studies of AD, by measurement method, was: 15 by
blood, 0 by bone, 5 by Cerebrospinal Fluid (CSF), 3 by hair/nail, 3 by postmortem, and 1 by urine. Two
meta-analyses were possible for 7 studies reporting whole blood Pb and for 8 studies of serum Pb. Both
were negative. The largest study of CSF Pb showed lower levels in AD. Similarly, lower hair Pb levels
were found in AD.
Conclusion:
The available case-control studies are insufficient to draw conclusions on the role of Pb in
AD. Most methods do not address long-term or early-life exposure. The preferred measure of chronic Pb
is in bone, which has not been utilized in case-control AD studies. Future research should measure bone
Pb in AD, together with other biomarkers, such as amyloid and tau imaging, and markers of cerebrovascular
pathology.