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Four definitions
Here are 4 distinct definitions of an aging or longevity intervention:
Extends Lifespan (EL) : An intervention that by itself extends lifespan (and healthspan, but not just healthspan), in normal study populations. Normal study populations for mice means normal lab mice fed normally. For humans it means modern, developed-country (e.g., US) populations, i.e. the populations most normal clinical trials are currently drawn from.
Extends Lifespan Universally (ELU) : An intervention that by itself extends lifespan (and healthspan, but not just healthspan) universally in all reasonable strains & conditions. For mice universality means it would extend lifespan even of long lived strains or even of wild mice who survived predation and other environmental hazard. For humans, it means working for all normal human populations regardless of culture, geography, or historical era.
Mitigates Aging Pathology (MAP) : An intervention that treats some age-related pathology that underlies several diverse age-related diseases, thereby mitigating all of these diseases. I.e., an intervention that embodies the geroscience hypothesis. The TAME trial’s multimorbidity endpoint is essentially a special case of this. Extending healthspan (without necessarily extending lifespan) fits best into this definition, though see below.
Indefinite Lifespan Necessity (ILN) : An intervention that successfully treats an age-related pathology that must eventually be treated in order to fully eliminate adult biological aging and age-related diseases or equivalently in order to achieve indefinite lifespans. Ie, an intervention that fixes something that would eventually cause age-related pathology & death even if all other aspects of aging were fully cured.
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It is inappropriate to think of only things that extend lifespan as being “in” the aging or longevity field. It is inappropriate to say that the ITP should be the only yardstick by which progress in the field is measured, and inappropriate to lose all faith in an intervention as relevant to aging if it happens to fail in the ITP. It is inappropriate to declare GLP-1 drugs to be longevity drugs for everyone. It is inappropriate to claim that no FDA approved interventions exist for aging or are coming soon since several that satisfy definition MAP are now FDA approved and more are in late-stage trials. It is inappropriate to ignore the idea of potentially eventually fully fixing every aspect of aging (as the Hallmarks paper arguably effectively did by ignoring all prior published work on SENS).Lastly, it is probably inappropriate, and certainly impractical, to try to get everyone in the field to agree on fundamental definitions, let alone to agree on branding/marketing angles for the field (as much as such exercises may still be valuable and their motivations are understandable, and the dedication to the field of the people leading them is beyond question). People outside the field are often drawn more strongly to some of these definitions than others, and in some cases are even repulsed by some of them but sometimes others outside the field are specifically drawn most strongly (or even only) to the very ones that repulse some other people.
Regardless, the field can and will continue to make progress scientifically, clinically, and in terms of public awareness and support.
How these definitions influence my work
Definition MAP is essentially the definition I use for AgingBiotech.info, for deciding whether something is in-scope for the aging/longevity field as a whole vs. out-of-scope (eg, just health broadly, or too disease-specific). It is essentially the definition I used throughout 2025 when discussing and giving talks on FDA approvals of aging interventions and those in phase 3 clinical trials.
Definition ILN is what I strive to invest in with my investing activities.
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