The Hydrogen Peroxide and its Importance in Alzheimer's and Parkinson's Disease

Alzheimer's disease (AD) and Parkinson's disease (PD) are highly prevalent neurodegenerative disorders that cause progressive motor dysfunction, cognitive impairment, and shortened of life expectancy. Both disorders are characterized by the progressive accumulation of insoluble protein deposits such as amyloid-β plaques, tau-containing neurofibrillary tangles, α-synuclein and ubiquitin containing Lewy bodies in selected neurons in AD and PD, respectively. During the last few years, it has been established a significant percentage of patients having clinical and pathological features of both diseases. Thus, the pathological cascades of the two diseases might overlap. Based on previous in vitro and in situ studies, we propose an unified molecular cascade model wherein hydrogen peroxide (H2O2) is a paramount molecule involved in intracellular signalization that induces neuronal loss in AD and PD. This review may contribute to understand the importance of H2O2 -generated by Aβ[1-42] / Aβ[25-35], α-synuclein and by either the enzymatic or metalcatalyzed oxidation of dopamine, and to highlight its implication in the design of therapeutic strategies in both diseases.