Alzheimer disease begins decades before any symptoms, such as memory loss, start to show. Consequently, early diagnosis increases the chances of slowing the disease down with drugs. A new study on an inherited form of the disease shows that a protein called GFAP is a possible biomarker for very early stages of the disease. The study, conducted by researchers at Karolinska Institutet and published in the journal Brain, could one day lead to an earlier detection of this serious and common disease.