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Nat Rev Neurol. 2013 Jan;9(1):25-34. doi: 10.1038/nrneurol.2012.236. Epub 2012 Nov 27.

Deciphering the mechanism underlying late-onset Alzheimer disease.

Author information

1
Institute of Pharmacology and Toxicology, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.

Abstract

Despite tremendous investments in understanding the complex molecular mechanisms underlying Alzheimer disease (AD), recent clinical trials have failed to show efficacy. A potential problem underlying these failures is the assumption that the molecular mechanism mediating the genetically determined form of the disease is identical to the one resulting in late-onset AD. Here, we integrate experimental evidence outside the 'spotlight' of the genetic drivers of amyloid-β (Aβ) generation published during the past two decades, and present a mechanistic explanation for the pathophysiological changes that characterize late-onset AD. We propose that chronic inflammatory conditions cause dysregulation of mechanisms to clear misfolded or damaged neuronal proteins that accumulate with age, and concomitantly lead to tau-associated impairments of axonal integrity and transport. Such changes have several neuropathological consequences: focal accumulation of mitochondria, resulting in metabolic impairments; induction of axonal swelling and leakage, followed by destabilization of synaptic contacts; deposition of amyloid precursor protein in swollen neurites, and generation of aggregation-prone peptides; further tau hyperphosphorylation, ultimately resulting in neurofibrillary tangle formation and neuronal death. The proposed sequence of events provides a link between Aβ and tau-related neuropathology, and underscores the concept that degenerating neurites represent a cause rather than a consequence of Aβ accumulation in late-onset AD.

PMID:
23183882
DOI:
10.1038/nrneurol.2012.236
[Indexed for MEDLINE]
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