Is ascorbate Dr Jekyll or Mr Hyde in the Cu(Aβ) mediated oxidative stress linked to Alzheimer's disease?

Evaluation of the pro versus antioxidant activity of ascorbate regarding Cu(Aβ) induced reactive oxygen species production in the context of Alzheimer's disease shows that a protective activity can only be observed at high ascorbate concentration for exogenous molecules but not for the amyloid-β peptide itself.