As different individuals age at different rates, ageing research necessitates the development of techniques for measuring biological age – that is to say, the true age of our cells as opposed to simply the number of years we have been alive. More practical and accurate measurements of biological ageing will help researchers measure the effectiveness of lifestyle changes and emerging anti-ageing therapies.
In their new study, the researchers aimed to develop a blood test that could be given at the start and end of a randomized controlled trial to determine if the treatment had slowed participants’ pace of aging. Slowing the pace of aging is an emerging frontier in medical research as a novel approach to preventing multiple chronic diseases.
The authors’ analysis focused on DNA samples derived from white blood cells. They analyzed chemical tags on the DNA called methylation marks. DNA methylation is an epigenetic process that can change the way genes are expressed. DNA methylation marks change as we age, with some marks being added and others lost. “We focused our analysis on DNA methylation in white blood cells because these molecular markers are relatively easy to measure and have shown great promise in previous research on aging,” explains Belsky.
The authors used a machine-learning technique called “elastic-net regression” to sift through data on more than 400,000 different DNA methylation marks to find the ones that related to the physiological changes captured in their Pace of Aging measure. In the end, the analysis identified a set of 46 methylation marks that, together, measured Pace of Aging. The 46 marks are combined together in an algorithm the researchers named “DunedinPoAm” for Dunedin (P)ace (o)f (A)ging in (m)ethylation. The average person has a DunedinPoAm value of 1—indicating a single year of biological aging per chronological year. Among Dunedin Study participants, the range of values extends from just above 0.6 (indicating an aging rate nearly 40 percent slower than the norm) to nearly 1.4 (indicating an aging rate 40 percent faster than the norm).