Research into how iron, copper, zinc and other metals work in the brain may help unlock some of the secrets of degenerative diseases like Alzheimer's and Parkinson's. Iron and copper appear to accumulate beyond normal levels in the brains of people with these diseases, and a new, Australian study published Sunday shows reducing excess iron in the brain can alleviate Alzheimer's-like symptoms—at least in mice. A genetic mutation related to regulating iron is linked to ALS, or Lou Gehrig's disease. Zinc, on the other hand, appears to impair memory if its levels get too low or if it gets into...