The medical field is reconsidering the definition of Alzheimer’s disease. Until recently, doctors assessed people for the illness mainly by using subjective cognitive tests. Now, genetic counselor Laura Hercher explains, blood tests that look for telltale biomarkers can indicate someone has the pathology well before the onset of symptoms. The advancement has led scientists to debate whether someone with only biomarkers and no symptoms should get an Alzheimer’s diagnosis. The answer has knotty implications, Hercher points out: “Would you go to a surgeon or hire a lawyer who was biomarker-­positive for Alzheimer’s disease?” On the flip side, what if the field advances to the point of prevention? Then a doctor might be able to treat a person with “pre-Alzheimer’s.” As my mom suffers through mid-stage Alzheimer’s, I’m watching every advance with hope for a future where the disease becomes preventable and treatable.