There is a growing list of aging biomarkers available to researchers that help them measure how well someone is aging and assess how aging interventions are working in preclinical testing.
Some clinical biomarkers, such as DNA methylation and telomere length, are commonly used in labs. Other biomarkers, such as blood pressure, grip strength, heart rate variability, visual reaction time, and decision reaction time, are non-invasive and easy to test.
Currently, DNA methylation is generally regarded as the gold standard for aging biomarkers, although new techniques, such as cell functional age, are attempting to challenge that. The sensible choice, of course, would be to combine both methods to further improve the accuracy of results.
It is important for the research community to establish a range of quality biomarkers, and there is an urgent need for better ones, as many of the current ones have limitations. If a panel of biomarkers is used, this improves the accuracy of results, although the research community should reach a consensus on what biomarkers to use.
If researchers can create a suitable, accurate, and cost-effective panel of biomarkers, then such a panel could be used to assess the effectiveness of potential therapies that target aging processes. Being able to accurately demonstrate the efficacy of rejuvenation therapies is critical in bringing them to market and ultimately to us.
Exploring reaction time as a biomarker for aging
Today, we take a look at the Sydney Memory and Ageing Study, which involved 861 participants aged 70 to 90 over an eight-year period and investigated the link between intra-individual variability of reaction time (IIVRT) and all-cause mortality .
It has long been known that there is an association between IIVRT and dementia and mortality, but the researchers wanted to find out the extent to which IIVRT is an independent predictor of mortality.
The researchers had participants complete two computerized reaction time tests every two years and included comprehensive medical and neuropsychological assessments during these tests. They recorded both mean reaction time and intra-individual variability of reaction time using a touch-screen test, and dementia diagnoses were made by a panel of experts.
The researchers concluded that IIVRT, not mean reaction time, was a significant predictor of mortality. The greater IIVRT uniquely predicted a shorter time to death, and lower global cognition and dementia in older individuals did not explain this link.
The study results suggest that the variability of reaction time, not mean reaction time, is a significant predictor of mortality. Therefore, it could be a useful biomarker of aging that might become part of a panel in order to assess how well someone is aging and that person’s risk of death.
We are currently hosting the AgeMeter project on Lifespan.io, which includes reaction time as one of its panel of biomarkers. If you are interested in supporting the development of an easy-to-use aging biomarker system for both home and clinical use, check out the campaign page.
 Kochan NA, Bunce D, Pont S, Crawford JD, Brodaty H, Sachdev PS (2017) Is intraindividual reaction time variability an independent cognitive predictor of mortality in old age? Findings from the Sydney Memory and Ageing Study. PLoS ONE 12(8): e0181719. https://doi.org/10.1371/journal.pone.0181719