Scientists believe new ways to treat Alzheimer's, Parkinson's and Lou Gehrig's disease could emerge from research into another neurodegenerative disorder: mad-cow disease.

The rare bovine disorder, which infects cattle, and the human form, called Variant Creutzfeldt-Jakob disease, both fall into a category of so-called prion diseases, caused by aberrant proteins that spread aggressively from cell to cell.

While...