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Study Suggests Reaction Time Variability is an Aging Biomarker


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 [1].

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, 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.


[1] 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.

About the author

Steve Hill

Steve serves on the LEAF Board of Directors and is the Editor in Chief, coordinating the daily news articles and social media content of the organization. He is an active journalist in the aging research and biotechnology field and has to date written over 600 articles on the topic, interviewed over 100 of the leading researchers in the field, hosted livestream events focused on aging, as well as attending various medical industry conferences. His work has been featured in H+ magazine, Psychology Today, Singularity Weblog, Standpoint Magazine, Swiss Monthly, Keep me Prime, and New Economy Magazine. Steve is one of three recipients of the 2020 H+ Innovator Award and shares this honour with Mirko Ranieri – Google AR and Dinorah Delfin – Immortalists Magazine. The H+ Innovator Award looks into our community and acknowledges ideas and projects that encourage social change, achieve scientific accomplishments, technological advances, philosophical and intellectual visions, author unique narratives, build fascinating artistic ventures, and develop products that bridge gaps and help us to achieve transhumanist goals. Steve has a background in project management and administration which has helped him to build a united team for effective fundraising and content creation, while his additional knowledge of biology and statistical data analysis allows him to carefully assess and coordinate the scientific groups involved in the project.
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