AbetaPP is involved in Cu homeostasis in mouse and man. In vitro observations and in vivo data obtained from AbetaPP mouse models at least provide strong evidence that AbetaPP and Abeta overproduction enables intracellular Cu to be transported out of the cell. The increased Cu efflux seems to lead to a Cu deficiency and a subsequently reduced SOD-1 activity. Studies have shown that a disturbed metal-ion homeostasis with elevated serum Cu levels occurs in Alzheimer and Down's patients and lowered levels in post-mortem AD brain. We conclude that bioavailable Cu has beneficial and specific effects in Alzheimer's disease transgenic mice, and suggest that our observation can be regarded as a proof-of-concept for a prophylactic approach to overcome the observed CNS Cu deficiency in the brain of Alzheimer's disease patients.