Reactive oxygen species and Alzheimer's disease

Although a consensus that Alzheimer's disease (AD) is a single disease has not been reached yet, the involvement of the amyloid precursor protein (APP) and beta A4 (A beta) in the pathologic changes advances our understanding of the underlying molecular alterations. Increasing evidence implicates oxidative stress in the neurodegenerative process of AD. This hypothesis is based on the toxicity of beta A4 in cell cultures, and the findings chat aggregation of beta A4 can be induced by metal-catalyzed oxidation and that free oxygen radicals may be involved in APP metabolism. Another neurological disorder, familial amyotrophic lateral sclerosis (FALS), supports our view that AD and FALS may be linked through a common mechanism. In FALS, SOD-Cu(I) complexes are affected by hydrogen peroxide and free radicals are produced. In AD, the reduction of Cu(II) to Cu(I) by APP involves an electron transfer reaction and could also lead to a production of hydroxyl radicals. Thus, copper-mediated toxicity of APP Cu(II)/(I) complexes may contribute to neurodegeneration in AD. (C) 1997 Elsevier Science Inc.