Lead, cadmium and Alzheimer’s disease

Lead and cadmium are toxic heavy metals that have been associated with numerous health outcomes even at low levels of exposure. It is important to understand the roles of these toxicants in the etiology of Alzheimer’s disease (AD). This chapter reviews the experimental and epidemiologic literature of the associations between AD and lead and cadmium. Lead can cross the blood–brain barrier and accumulate in the brain. Cadmium can reach the brain through the blood–cerebrospinal fluid barrier or the olfactory nervous system. Experimental studies suggest that lead and cadmium can increase amyloid-β deposition and tau expression through oxidative stress, neuroinflammation, and apoptosis in neuronal cells. Epidemiologic studies have shown associations of lead and cadmium with cognitive impairment in adults, although the evidence linking lead or cadmium to AD in humans is very limited. Given their widespread exposure, reduced exposure could have a significant impact on the global burden of AD.