Biology & Longevity
Healthspan vs Lifespan
Adding years to life and adding function to years are different goals, measured with different instruments.
August 17, 2026 · 5 min read · Novanta Research
Two distinct endpoints
Lifespan is total years lived. Healthspan is the portion of those years spent free of significant chronic disease and functional impairment. An intervention can extend one without extending the other, and in animal models this dissociation has been observed in both directions.
Measurement problems
Lifespan is trivially easy to measure and takes a lifetime to observe. Healthspan is the reverse: it can be assessed continuously but has no single agreed definition. Grip strength, gait speed, cognitive testing, frailty indices and biomarker panels are all used, and they do not always agree.
This measurement gap is the practical reason longevity research is hard to compare across studies.
Compression of morbidity
The goal most often stated in the literature is compressing morbidity — pushing the onset of decline closer to the end of life rather than simply extending the declining period. Whether current interventions achieve this in humans remains unresolved.
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