A simple blood test, initially developed for research into human neurodegenerative diseases like Alzheimer’s and ALS, may hold the key to estimating biological age and predicting lifespan across a wide range of animal species. Researchers at the German Center for Neurodegenerative Diseases (DZNE) and the Hertie Institute for Clinical Brain Research (HIH) at the University of Tübingen have discovered that levels of a protein called neurofilament light chain (NfL) increase with age in mice, cats, dogs, and horses, mirroring patterns observed in humans.
NfL is released into the bloodstream when neurons grow damaged or degenerate, whether due to disease or the natural aging process. Measuring NfL levels offers a minimally invasive way to assess neurological health, and potentially, overall biological age. This discovery, published in the journal PLoS Biology, could have significant implications for veterinary medicine and comparative aging research, offering a standardized biomarker for assessing the effectiveness of interventions aimed at extending healthy lifespan in animals.
“In neurodegenerative diseases such as Alzheimer’s and ALS, NfL is found at elevated levels in the blood. However, the concentration also rises in healthy people with age,” explained Professor Mathias Jucker, research group leader at DZNE and HIH. “We have now observed a very similar age-related increase in mice, cats, dogs, and horses.”
Predictive Power Demonstrated in Mice
The link between NfL levels and lifespan isn’t merely correlational. Researchers, led by Dr. Carina Bergmann, monitored the blood of 44 older mice over four months. They found that mice with slowly rising NfL levels tended to live longer, while those with more rapid increases in NfL experienced 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,” Bergmann stated.
This finding builds on previous research demonstrating a connection between NfL concentration and mortality risk in elderly humans, suggesting a fundamental link between neurological aging and overall health. The ability to predict lifespan based on a simple blood test could revolutionize how we approach aging interventions, both in human and veterinary medicine.
A Cross-Species Biomarker?
The study expanded beyond the initial four species to include a sampling of over 50 others, including rabbits, lions, monkeys, elephants, reptiles, and birds. This broader investigation, conducted in collaboration with the Stuttgart Zoo in Germany, the Vetsuisse Faculty at the University of Zurich, and a veterinary diagnostics laboratory, revealed that NfL was detectable in the blood of all mammals examined. However, detection in reptiles and birds was more limited, with NfL identified in a crocodile and a parrot.
Researchers hypothesize that variations in the NfL protein sequence across different species may explain these discrepancies. The assay used in the study may not be sensitive enough to detect slight differences in the protein structure of certain animals. Despite this limitation, the overall findings strongly suggest that NfL has the potential to serve as a valuable cross-species biomarker.
“however, our data indicate 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,” Jucker concluded.
Implications for Animal Welfare and Aging Research
The potential applications of this research are far-reaching. For veterinarians, NfL testing could provide a new tool for assessing the overall health and aging process in companion animals and livestock. It could help identify animals at risk of age-related neurological decline and inform preventative care strategies. For researchers studying aging, a standardized biomarker like NfL could facilitate comparisons across species, accelerating the development of interventions to promote healthy aging.
The study also highlights the surprising parallels between aging processes in humans and other animals. By leveraging insights from human dementia research, scientists are opening new avenues for understanding and addressing the challenges of aging across the animal kingdom. Further research is needed to refine the accuracy of NfL-based lifespan predictions and to explore the underlying mechanisms driving age-related changes in NfL levels.
The team plans to continue investigating the role of NfL in aging and disease, with a focus on identifying factors that influence NfL levels and developing more sensitive assays for detecting the protein in a wider range of species. The next step involves larger-scale studies to validate these findings and explore the potential for using NfL as a therapeutic target.
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