Brain biometals and Alzheimer's disease - boon or bane?

Alzheimer's disease (AD) is the most common form of dementia. Several hypotheses have been put forward to explain the basis of disease onset and progression. A complicated array of molecular events has been implicated in the pathogenesis of AD. It is attributed to a variety of pathological conditions that share similar critical processes, such as oxidative stress, proteinaceous aggregations, mitochondrial dysfunctions and energy failure. There is increasing evidence suggesting that metal homeostasis is dysregulated in the pathology of AD. Biometals play an important role in the normal body functioning but AD may be mediated or triggered by disproportion of metal ions leading to changes in critical biological systems and initiating a cascade of events finally leading to neurodegeneration and cell death. The link is multifactorial, and although the source of the shift in oxidative homeostasis is still unclear, current evidence points to changes in the balance of redox transition metals, especially iron, copper (Cu) and other trace metals. Their levels in the brain are found to be elevated in AD. In other neurodegenerative disorders, Cu, zinc, aluminum and manganese are involved. This paper is a review of recent advances of the role of metals in the pathogenesis and pathophysiology of AD and related neurodegenerative diseases.