Related Experiment Video
Updated: May 7, 2026
Frailty Assessment in an Aging Mouse Model
Published on: September 23, 2025
A clinical frailty index in aging mice: comparisons with frailty index data in humans
Jocelyne C Whitehead1, Barbara A Hildebrand2, Michael Sun1
1Department of Pharmacology.
Abstract:
We previously quantified frailty in aged mice with frailty index (FI) that used specialized equipment to measure health parameters. Here we developed a simplified, noninvasive method to quantify frailty through clinical assessment of C57BL/6J mice (5-28 months) and compared the relationship between FI scores and age in mice and humans. FIs calculated with the original performance-based eight-item FI increased from 0.06 ± 0.01 at 5 months to 0.36 ± 0.06 at 19 months and 0.38 ± 0.04 at 28 months (n = 14). By contrast, the increase was graded with a 31-item clinical FI (0.02 ± 0.005 at 5 months; 0.12 ± 0.008 at 19 months; 0.33 ± 0.02 at 28 months; n = 14). FI scores calculated from 70 self-report items from the first wave of the Survey of Health, Ageing and Retirement in Europe were plotted as function of age (n = 30,025 people). The exponential relationship between FI scores and age (normalized to 90% mortality) was similar in mice and humans for the clinical FI but not the eight-item FI. This noninvasive FI based on clinical measures can be used in longitudinal studies to quantify frailty in mice. Unlike the performance-based eight-item mouse FI, the clinical FI exhibits key features of the FI established for use in humans.
Insights
A new noninvasive clinical method accurately quantifies frailty in aging mice. This simplified frailty index (FI) mirrors human frailty patterns, enabling better longitudinal studies in mouse models of aging.
Area of Science:
- Gerontology and Aging Research
- Animal Models of Human Disease
- Biomedical Sciences
Background:
- Frailty quantification in aged mice traditionally requires specialized equipment.
- Existing performance-based frailty indices (FI) in mice may not fully capture aging trajectories.
- Translating frailty measures between species is crucial for understanding aging.
Purpose of the Study:
- To develop and validate a simplified, noninvasive clinical method for quantifying frailty in mice.
- To compare the relationship between frailty index (FI) scores and age in mice and humans.
- To assess if a clinical FI in mice exhibits similar characteristics to human FI.
Main Methods:
- Development of a 31-item noninvasive clinical frailty index (FI) for C57BL/6J mice (5-28 months).
- Comparison of FI scores derived from the clinical FI versus an eight-item performance-based FI.
- Analysis of human FI data from the Survey of Health, Ageing and Retirement in Europe (n=30,025).
- Comparison of the exponential relationship between FI scores and age across species.
Main Results:
- The clinical FI showed a graded increase in scores with age in mice.
- The eight-item performance-based FI showed a steeper increase in scores.
- The exponential relationship between age and normalized FI scores was similar in mice (clinical FI) and humans.
- The clinical FI in mice demonstrated key features consistent with human FI.
Conclusions:
- A noninvasive, 31-item clinical frailty index provides a valid method for quantifying frailty in aging mice.
- This clinical FI method allows for longitudinal studies and better parallels human frailty assessment.
- The findings support the use of this clinical FI for improved translational aging research.
