Taken together, Cu has beneficial roles in the course of AD based on the following observations: (i) it promotes the non-amyloidogenic processing of APP and thereby lowers the Aβ production in cell culture systems, (ii) it increases lifetime and decreases soluble amyloid production in APP transgenic mice, and (iii) in a clinical trial with AD patients, the decline of Aβ levels in CSF, which is a diagnostic marker, is diminished. Here, APP is linked to Alzheimer disease.