The tree · The cell's settings
A person's biological age, read from the marks on their DNA, falls after a treatment
The chemical marks that tell a cell which genes to read drift with age in a regular enough way that a reading of them from a blood sample gives a "biological age". Whether a treatment can turn that reading back in a person is the question this leaf asks. In 2019 a small California trial gave nine men in their fifties and sixties a year of growth hormone with a second hormone (DHEA) and the diabetes drug metformin, aimed at regrowing the thymus (the gland that trains immune cells), and found that their readings on four such clocks had fallen by about a year and a half from the start (two and a half years below what was expected untreated), and the fall held six months after the course ended. There was no control group and only nine men, so it is a first human on a measurement, not a proof.
What would count
A person given a treatment afterwards reads younger on a validated clock built from the chemical marks on their DNA, compared with before and with untreated controls, in a peer-reviewed report that names the clock and the sample. For the clinic rung: a regulator approves a treatment on the strength of such a result, or a named clinical setting gives the treatment in routine care and publishes that it monitors the clock.
Who settles it: The peer-reviewed report; the regulator's approval record, or a named clinical setting's published practice, for the clinic rung.
Where it stands
First human. Reached 8 September 2019, on the record of Fahy and 9 others, 8 September 2019 (doi.org). Next rung within 5 to 20 years.
When it reaches the clinic: the project's estimate
This is the one thing on this page that is a judgment rather than a record. The project's estimate of the year it reaches the clinic is 2042, no earlier than 2032 and no later than 2085; the model draws from that range every run, with the likely year the most probable draw. Set 16 October 2026, a first pass awaiting an outside review.
| Rung | No earlier than | Most likely | No later than | |
|---|---|---|---|---|
| In clinical use | 2032 | 2042 | 2085 | feeds the year at the top |
Why. A controlled trial that turns a validated clock back is likely within a decade, since several are running; the clinic rung needs more, an approval that rests on such a result, which waits on a regulator accepting a clock as proof (a leaf on the measuring branch, likely around 2040). The likely year follows that; the earliest assumes a named clinic adopts a clock-monitored treatment in routine care and publishes it, which the test allows; the latest allows for the clocks never earning that standing.
Changes to this record
None since it was written on 16 October 2026. Every change to the stage or the estimate lands here with its date, the old value, the new one and the reason, and a change to the estimate never happens because a number looked wrong: it needs a dated reason and a source.
The last readings
- 17 October 2026 Quiet
Nothing in the window. No peer-reviewed, controlled trial appeared showing a validated DNA-mark clock turned back in a person. The controlled follow-up to the 2019 trial (TRIIM-X) has its results only in a Foresight Institute talk and a secondary Lifeboat Foundation summary dated 2026-06, both before the window and neither peer-reviewed; its registry entry was last updated in 2025-05 with no results posted, which the record's verify list already flags. The searches did not settle whether TRIIM-X is still running. The leaf stays at first human.source 1, source 2
What the story so far says about it
On the record
Notes
This leaf and the measuring branch meet here: a falling clock reading is only worth what the clock is worth, and the clock's own leaf is on that branch. The thymus side of the same trial has its place on the replacing-parts branch in the notes of the blood-stem-cell leaf. Clocks read from a person's DNA marks are sold to the public today; buying a reading is not the leaf.
Not yet verified
These facts in the record were written from memory or from a secondary source and have not yet been checked against the paper, the regulator's record or the registry. Nothing here is presented as settled until it is cleared, by checking it and either deleting the line or correcting the record.
- That the larger controlled follow-up (TRIIM-X) was still running on 2026-10-16 is unconfirmed (its registry entry was last updated in May 2025); no peer-reviewed results report was found in searches of Europe PMC.
- No animal rung is recorded: the nearest earlier report is a 2017 mouse study (Genome Biology, 2017-03-28) where dietary rapamycin left liver epigenetic age younger than in untreated mice, a slowed clock rather than a reversal, so it is not counted (the 2016 partial-resetting work used other markers).