A protein made in nerve cells and found in the blood could predict mortality in people of advanced age.
Mathias Jucker at the University of Tübingen in Germany and his colleagues tracked levels of the protein neurofilament light chain (NfL) in the blood of 180 people in their nineties and 135 people who were 100. Previous studies have shown that NfL levels rise after brain damage and the onset of neurodegenerative disease.
In both nonagenarians and centenarians, lower NfL levels were correlated with longer survival and were a better predictor of mortality than were activity levels or cognitive functioning. The trend held in men and women, and in mice too: mice on a low-calorie diet, a regimen that has been associated with extended life, had lower NfL levels and lived longer than mice in a control group.
The authors say this biomarker could help to assess health in ageing people. However, they note one limitation: older adults who opt into studies like this are healthier than are ageing people generally.