The protein neurofilament light chain (NfL), which is considered a marker for nerve damage and neurodegenerative diseases in human medicine, can also be detected in the blood of numerous animal species. In mice, cats, dogs and horses, its concentration increases with age – similar to humans. Researchers from the German Center for Neurodegenerative Diseases (DZNE) and the Hertie Institute for Clinical Brain Research (HIH) at the University of Tübingen report on this in the journal PLOS Biology.

NfL is released when nerve cells are damaged or die due to disease or natural aging. The biomarker enters the bloodstream and can be measured using highly sensitive methods. In humans, the NfL concentration increases not only in diseases such as Alzheimer’s or ALS, but also in the healthy aging process. The Tübingen researchers have now found a comparable pattern in several mammal species.

They examined mice in particular detail: In 44 older animals, the NfL level was tracked in the blood for four months. A slow increase in concentration was associated with a longer remaining life expectancy, a rapid increase with shorter life expectancy. The results suggest that the temporal course of NfL levels can predict the remaining lifespan of mice – a relationship that has also been observed in older people.

In cooperation with the Wilhelma Zoological and Botanical Garden Stuttgart, the Vetsuisse Faculty of the University of Zurich and an animal diagnostics laboratory, the scientists randomly analysed blood samples from over 50 other animal species, including hares, lions, monkeys, elephants as well as reptiles and birds. In all mammals examined, NfL was detectable in the blood. In reptiles and birds, detection was only possible in isolated cases – presumably because the protein sequence there deviates more strongly from the human form and the test used does not detect it.

The data suggest that NfL analyses from dementia research could also be useful in veterinary medicine, said Prof. Mathias Jucker, research group leader at the DZNE and HIH. The biomarker offers potential to estimate the biological age, neurological health and life expectancy of animals.

First author Dr. Carina Bergmann emphasized that the marker shows predictive power for individual lifespan in mice. In the future, the results could help to detect and evaluate age-related neurological changes in animals at an earlier stage.

The study was published in PLOS Biology on February 23, 2026.

Original Paper:

Neurofilament light chain may serve as a cross-species blood biomarker to assess aging and predict mortality, Carina Bergmann et al., PLOS Biology (2026), DOI: 10.1371/journal.pbio.3003606

Editor: X-Press Journalistenbüro GbR

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