Related Experiment Videos
Lead (Pb) in Alzheimer's Dementia: A Systematic Review of Human Case- Control Studies
Eric E Brown1,2,3, Parita Shah2,3, Bruce G Pollock1,2,3
1Department of Psychiatry, University of Toronto, Toronto, ON, Canada.
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.