Amyloid beta-peptide: biphasic dose responses.

This article summarizes recent findings indicating that amyloid beta-peptide displays neurotoxic and neurotrophic effects, depending on concentration. Mechanistic findings revealed that reactive oxygen species mediate both the toxic and neurotropic responses as a function of concentration with low doses being neutotrophic, while higher doses were toxic. The data reveal a potential biological function for amyloid beta-peptide within an optimal concentration zone. These findings suggest the critical role of dose in understanding disease causation and clinical therapeutics for Alzheimer's disease.