A recent study has found that the protein neurofilament light chain (NfL), known as a marker of nerve damage in humans, is also present in the blood of various animals. Researchers from DZNE and the Hertie Institute for Clinical Brain Research (HIH) at the University of Tübingen published their findings in "PLOS Biology." The team suggests that NfL could serve as a biomarker to help assess biological age and estimate life expectancy in animals.
NfL is released into the bloodstream when neurons change or degenerate, either due to disease or normal aging. Sensitive analysis techniques can detect its presence in blood samples. In elderly people, higher concentrations of NfL have been linked with an increased risk of death, indicating a connection between neurological aging and mortality.
Dr. Carina Bergmann, part of Jucker's research group, observed similar patterns in mice. Over four months, researchers monitored 44 older mice and found that those with slowly increasing NfL levels tended to live longer. Mice with faster-rising levels had shorter lifespans.
"Our data therefore suggest that life expectancy of mice can be estimated from the rate of change of NfL levels – similar to what has been reported for aging humans," says Bergmann.
The study included not only cats, dogs, horses, and mice—studied most extensively—but also sampled 53 other animal species such as rabbits, lions, monkeys, elephants, reptiles, and birds. Collaborators included the zoo in Stuttgart, Germany; the Vetsuisse Faculty at the University of Zurich; and a veterinary diagnostics laboratory. NfL was detected in all mammal samples but only some reptiles and birds—a crocodile and a parrot among them—which may be due to differences in their NfL protein sequences making detection harder with current assays.
"Overall, however, our data show that analysis methods from dementia research are also promising for veterinary medicine when it comes to assessing the biological age, neurological health, and life expectancy of animals," says Jucker.
