A study published in Nature Medicine has identified a potential blood-based biomarker for Alzheimer's disease. Specifically, the level of a set of 10 lipids predicted, with an accuracy of over 90%, whether or not an older individual would develop mild cognitive impairment or Alzheimer's disease within 2–3 years.

“These findings are potentially very exciting,” says Simon Lovestone, a neuroscientist at the University of Oxford, UK ( Nature News , 9 Mar 2014). Simon Ridley of the charity Alzheimer's Research UK notes that “detecting the disease at this pre-symptomatic stage has so far proved difficult” and that “a blood test to identify people at risk of Alzheimer's would be a real step forward for research” ( Guardian , 9 Mar 2014). In addition, “the preclinical state of the disease offers a window of opportunity for timely disease-modifying intervention”, says study author Howard Federoff ( Guardian , 9 Mar 2014).

Having a test that detects Alzheimer's disease before any clinical symptoms appear would raise important ethical issues. “If this does develop in the future people must be given a choice about whether they would want to know, and fully understand the implications,” according to Doug Brown of the Alzheimer's Society ( BBC News , 9 Mar 2014). Study author Mark Mapstone says: “We may not have any therapy yet but there are things we can do — we can get out financial and legal affairs in order, plan for future care, and inform family members.” ( New Scientist , 9 Mar 2014).

Before these issues become a reality, the results “require replication and validation by other scientists in larger and more diverse populations”, according to Maria Carrillo of the Alzheimer's Association ( WebMD , 9 Mar 2014), especially in light of the currently limited sensitivity and specificity of the test.