Recent Understanding of the Molecular Mechanisms of Alzheimer?s Disease

Alzheimer's disease (AD) is the most common neurodegenerative disorder in the aged population. Pathological hallmarks of AD are the presence of extracellular senile plaques and intracellular neurofibrillary tangles. Extracellular plaques consist of aggregated amyloid-β (Aβ) peptides derived from sequential proteolytic cleavage of the amyloid precursor protein (APP) by β- and γ-secretase. Neurofibrillary tangles are composed of a hyperphosphorylated form of the microtubule-associated protein tau. This review summarizes the current understanding in the molecular mechanisms leading to Aβ generation as well as hyperphosphorylation of tau and the mechanisms of Aβ-induced neurotoxicity including Ca2+ dyshomeostasis, mitochondrial dysfunction, increased oxidative stress, cholinergic dysfunction and neuroinflammation finally resulting in neuronal/synaptic dysfunction and neuronal loss.