The tree · branch 8 of 8

Measuring ageing

The tools that say whether any of the above worked without waiting decades: biological age clocks read from blood or saliva, blood and imaging markers, and whether a regulator will accept any of them as proof that a treatment slowed ageing.

This branch groups none of the twelve published hallmarks of ageing: it is the tools that say whether any of the others has been dealt with. Without an accepted way to show that a treatment slowed ageing, every other branch's path from "shown in animals" to "in clinical use" runs through a trial that takes a working lifetime, and the model says so by requiring it.

Where this branch stands

required: the year cannot arrive until this branch is handled; handled when 2 treatments are in the clinic

2040handled, in the middle run
0of 5 in the clinic already
first humanfurthest stage reached

Nothing under this branch is in the clinic yet. In each run of the model a year is drawn for every treatment from its range, and the branch counts as handled when the second of those years arrives. Across all the runs, the middle year this branch is handled is 2040.

Marked required by the kickoff: without an accepted way to show that a treatment slowed ageing, every other branch's path from "shown in animals" to "in clinical use" runs through a trial that takes a working lifetime, and the model should say so.

5 treatments and tools

listed by how soon each could reach its next rung

A clock read from blood predicts a person's death and disease better than their age does First human clinic likely 2034, 2028 to 2060
Next rung within 5 to 20 years. A trial that slows ageing cannot wait thirty years to count deaths; it needs a reading, taken at the start and the end, that stands in for them.
A treatment slows a biological age clock in a controlled trial First human clinic likely 2037, 2030 to 2070
Next rung within 5 to 20 years. A clock is only useful to a trial if a treatment can move it, and the first clear case came from the oldest treatment in the field.
An age for each organ is read from the proteins in a person's blood First human clinic likely 2036, 2029 to 2070
Next rung within 5 to 20 years. A single number for a person's biological age hides that their heart may be old and their liver young.
A regulator accepts a marker of ageing as proof that a treatment slowed it Idea only clinic likely 2040, 2032 to 2080
Next rung within 5 to 20 years. Every treatment on this tree faces the same wall: to be approved for ageing, it must be shown to slow ageing, and the only accepted way to show that is to wait for people to get sick or die.
A regulator recognises ageing itself as a condition a drug can be approved to treat Idea only clinic likely 2045, 2034 to 2100
Next rung within 5 to 20 years. Drugs are approved for diseases, and ageing is not one on any regulator's list; so a drug that slowed ageing itself would have no label to carry it, and every drug on this tree is being tested instead against one disease of age at a time.

What would move this

the next test each treatment needs, and the branch's own line

A regulator accepting a marker of ageing as a trial endpoint, or recognising ageing itself as a condition a drug can be approved to treat.

A clock read from blood predicts a person's death and disease better than their age does Next rung: in clinical use. A regulator somewhere has approved it, or it is in routine use in a named clinical setting, so a doctor can give it to a patient outside a trial. Settled by peer-reviewed validation reports; the regulator's clearance record, or a named health system's published practice, for the clinic rung.
A treatment slows a biological age clock in a controlled trial Next rung: in clinical use. A regulator somewhere has approved it, or it is in routine use in a named clinical setting, so a doctor can give it to a patient outside a trial. Settled by the peer-reviewed trial report with its pre-registered plan; the regulator's approval record, or a named clinical setting's published practice, for the clinic rung.
An age for each organ is read from the proteins in a person's blood Next rung: in clinical use. A regulator somewhere has approved it, or it is in routine use in a named clinical setting, so a doctor can give it to a patient outside a trial. Settled by peer-reviewed validation reports; the regulator's clearance record, or a named health system's published practice, for the clinic rung.
A regulator accepts a marker of ageing as proof that a treatment slowed it Next rung: shown in animals. Shown to work in a living animal, in a peer-reviewed report. Settled by the regulator's own qualification record or its written agreement to the trial's main measure; the trial registry entry that names the agreed endpoint.
A regulator recognises ageing itself as a condition a drug can be approved to treat Next rung: shown in animals. Shown to work in a living animal, in a peer-reviewed report. Settled by the regulator's own approval record or written agreement; the trial registry entry of the running trial.

Its history

the handled year, computation by computation

The year was first computed on 17 October 2026, with this branch handled in the middle run by 2040. Every estimate under it is still a first pass. From the second computation on, this section charts the branch's handled year run by run, so a reader who sees the year at the top move can tell which branch moved it.

What the story so far says about it

the promises, the self-experiments and the papers that bear on this branch

Promised, in public

9 August 2022Nir Barzilai: A six-year trial of metformin against ageing in more than three thousand people aged sixty-five to seventy-nine at fourteen centres, starting in 2022, and by his own account promised for each year since about 2015. Verdict: missed.
26 September 2022Charles Brenner: No date or result: a critique holding that ageing is not a disease, that getting healthier is not age reversal, and that the book's claims of reversal in people are stories, not findings. Verdict: cannot be settled.
31 October 2023Bryan Johnson: A measured pace of ageing of zero, that is, no biological ageing at all over a calendar year, plus the rejuvenation of seventy-eight organs; no date. Verdict: cannot be settled.
29 November 2023XPRIZE: By 2030, a team demonstrating a treatment of one year or less that restores muscle, thinking and immune function in people aged sixty-five to eighty by at least ten years (twenty for the top prize); the grand prize of up to eighty-one million dollars is awarded that year. Verdict: not yet due, due 2030.
11 June 2024Bryan Johnson: A result about himself: a reading of 0.64 years of ageing per calendar year on one clock that reads the chemical marks on DNA (DunedinPACE), presented as meaning that he ages a year every nineteen months. Verdict: cannot be settled.

Tried on themselves, in public

2006David SinclairRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.
2013Dave PascoeRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.
2014Michael LustgartenRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.
2021Bryan Johnson, BlueprintRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.
2023Julie Gibson ClarkRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.
2023Bryan Johnson and Oliver Zolman, Rejuvenation OlympicsRunning. A claim about one person is a story, not a record, and it moves nothing on this branch.

On the record

7 September 2026Integration of proteomic aging clocks in a phase 2a clinical trial supports simultaneous geroprotective assessmentZhavoronkov and 12 others.
12 September 2024Metformin decelerates aging clock in male monkeysYang and 43 others.
9 February 2023Effect of long-term caloric restriction on DNA methylation measures of biological aging in healthy adults from the CALERIE trialWaziry and 21 others.
7 October 2024Implausibility of radical life extension in humans in the twenty-first centuryOlshansky and 3 others.
31 August 2023Biomarkers of aging for the identification and evaluation of longevity interventionsMoqri and 27 others.
3 January 2023Hallmarks of aging: An expanding universeLópez-Otín and 4 others.
6 June 2013The Hallmarks of AgingLópez-Otín and 4 others.
21 October 2013DNA methylation age of human tissues and cell typesHorvath.
12 May 2022Foreword to the Aubrey de Grey and Charles Brenner debate (Let's Talk Longevity newsletter)Gobel.
8 September 2019Reversal of epigenetic aging and immunosenescent trends in humansFahy and 9 others.
October 2019TAME: A Genuinely Good Use of 75 Million DollarsGrey.
15 June 2004Escape Velocity: Why the Prospect of Extreme Human Life Extension Matters NowGrey.
June 2016Metformin as a Tool to Target AgingBarzilai and 3 others.

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