You can’t do anything about your chronological age, but it might be possible to turn back the clock on “biological age,” a small new study suggests.

The study found that a drug regimen appeared to reverse biological age, as measured by changes to DNA that accumulate as we get older.

In the study, nine healthy volunteers — all white men between 51 and 65 years old — took a cocktail of growth hormone, a diabetes medication, and a hormone supplement as part of a drug trial funded by the biomedical firm Intervene Immune in Los Angeles. Each volunteer self-administered the mixture a few times a week for a year, after which scientists took a look at their DNA. Distinctive marks adorning the DNA suggested that participants had shed 2.5 years off their biological ages, on average.

In other words, if the researchers had frozen time to perform the study, the volunteers would have emerged 2.5 years “younger” than they entered. In reality, a full year had passed, so the men gained back about 1.5 years of their lives, so to speak. “It has never been shown before that predicted biological age…can be reversed over time in the same individuals, and especially so after an intervention of this kind,” Sara Hägg, a molecular epidemiologist at the Karolinska Institutet in Solna, Sweden, told Live Science in an email.

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