The Role of Metals in the Etiology of Alzheimer's Disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and the most common cause of dementia, affecting millions of men and women worldwide. It is characterized by the accumulation of extracellular amyloid-beta (A beta) plaques and neurofibrillary tangles inside neurons and dystrophic neurons. Several risk factors are associated with the early onset and progression of the disease. Although the initiating molecular events are not entirely known, in recent years it has become evident that environmental and/or nutritional factors may play a causal, disruptive, and/or protective role in the development of AD. While a direct causal role for aluminum or other transition metals (copper, zinc, iron) in AD has not yet been definitively demonstrated, epidemiological evidence suggests that elevated levels of these metals in the brain may be linked to the development or progression of AD. This review summarizes studies which implicate a role for several metals in contributing to or causing AD.