Quantification of Biological Aging in Young Adults

A research team led by Dan Belsky, Avshalom Caspi, and Terrie Moffitt at Duke University reports that the process of aging is already highly variable among people still in their 20s and 30s, and that young people aging rapidly are already showing signs of physical and cognitive decline.

PUBLICATION SOURCE: Proceedings of the National Academy of Sciences of the United States of America, to appear online the week of July 6, 2015.

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  • As we age, our risk for diseases affecting many different organ systems in our bodies rises. This implies that improving health in later life will require interventions that can actually slow the aging process, preventing multiple age-related diseases simultaneously.
  • Aging as a process of decline in the functioning of many organ systems simultaneously is already happening in young adults still decades away from developing age-related diseases.
  • Accelerated aging in young adults predicts the very same symptoms of advanced aging that we see in older adults: Deficits in physical and cognitive functioning, subjective feelings of ill-health, and even looking older to others.



  • Breakthroughs in research on aging in worms, flies, and mice are beginning to produce novel therapies to slow human aging. The first clinical trials are being designed now.
  • Currently, most translational research to slow aging in humans focuses on older adults.
  • Our findings show that by late life, processes of accelerated aging may already be well-entrenched and difficult to modify.
  • Intervention aiming to prevent multiple age-related diseases at once by slowing down the aging process may be most effective when delivered to recipients who are still relatively young.


 Two approaches to measuring aging. We measured Dunedin Study members’ aging in two ways. First, we took a snapshot of their physiologies when they were 38 years old. We used an algorithm developed out of the US Centers for Disease Control and Prevention’s National Health and Nutrition Survey (NHANES) to calculate a “Biological Age.” Although they were all chronologically 38 years old when their data were collected, Study members ranged in their Biological Age from under 30 to over 60. We next looked at how Study members’ bodies changed over time from when they were 26 years old to when they were 38 years old. We examined their cardiovascular, metabolic, and immune systems, their kidneys, livers, and lungs, their dental health, and their DNA (18 different biomarkers in all, see Figure below) when they were 26, 32, and 38.

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Image created using BioDigitalHuman

Remarkably, we were able to detect systematic age-related changed in the 18 biomarkers even though our young adult cohort was still decades removed from typical age of onset for most age-related chronic health conditions. The figure below shows the average time-trend for each of the 18 biomarkers. The graph below shows change on  a standardized scale. For biomarkers that typically decline with advancing age (e.g. cardiorespiratory fitness, lung function, telomere length), values were reversed so that “older” biomarker levels correspond to higher standardized scores.

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For each member of the Study, we calculated how each biomarker changed over the 12-year period. Finally, we composited these changes into a single index that quantified that person’s own “Pace of Aging.” Some Study members appeared to age not at all—they were physiologically the same when we saw them at age 26 and, 12 years later, when they were 38. Most study members aged at a normal pace—1 year’s worth of physiological change for each chronological year that passed. Some Study members aged much faster, aging 2 or 3 years physiologically with the passage of each chronological year.

The figure below illustrates variation in the Pace of Aging by showing the different aging trajectories the Study members would have if they had all been in the same physiological shape at age 26.

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Young adults who were aging more rapidly showed signs of aging commonly observed in older adults. Young adults we measured as aging faster showed worse balance and poorer motor coordination, they were physically less strong, and they reported having more trouble completing daily tasks like climbing stairs or carrying groceries. These fast-aging young adults also showed evidence of cognitive decline—compared to baseline testing they completed as children, their IQ scores had gone down by age 38. Photographs of their retinal microvasculature told a similar story, indicating increased risk for stroke and dementia.

Faster-aging Study members showed deficits in physical functioning

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Faster-aging Study members showed signs of declining cognitive functioning

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Changes in fast-aging young adults were visible to the naked eye. Study members who we measured as aging faster reported feeling in worse health. Age-related changes weren’t on the inside only. Duke University undergraduates who rated facial photographs of the Study members tended to rate the fast-agers as looking older.

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PARTICIPANTS: Participants were members of the Dunedin Multidisciplinary Health and Development Study, which tracks the development of a birth cohort of 1,037 children born in 1972-1973 in Dunedin, New Zealand. This birth cohort’s families represent the full range of socioeconomic status and health in the general population. Follow-ups have been carried out at ages 3, 5, 7, 9, 11, 13, 15, 18, 21, 26, 32, and most recently at age 38 years, when 95% of the living cohort members took part. We examined 954 cohort members who participated in repeated clinical assessments at ages 26, 32, and 38 years.

MEDIA CONTACT: Dan Belsky, Center for the Study of Aging and Human Development, Department of Medicine, Division of Geriatrics, Duke University School of Medicine.
dbelsky@duke.edu (t) 919-613-4534 (m) 919-357-8200


UNIVERSITIES INVOLVED: Duke University, Durham, NC, USA; University of Otago, Dunedin, NZ; Institute of Psychiatry, Kings College London, UK.


MAIN FUNDING SOURCES: The research was supported by the US National Institute on Aging (NIH AG032282; AG048895; T32 AG000029; P30 AG028716-08), the UK Medical Research Council (MRC MR/K00381X), and the New Zealand Health Research Council, which supports the Dunedin Multidisciplinary Health and Development Research Unit.


Complete PDF of article and supplement including press release and media fact sheet

The clip below is of an interview with BBC News Hour













12 thoughts on “Quantification of Biological Aging in Young Adults

  1. There were three areas I expected to see covered that weren’t addressed in this study:

    – Where were the links back to all of the measurements and predictions researchers made at the beginning of the study when these subjects were age 3? Other studies of these same subjects made such links, but it appears that only the cognitive testing link was made in this study. Are we really supposed to believe here in 2015 that scientists can’t determine any early-life causes for these dramatic later-life effects?
    – Where were the psychological tests? Are we also to believe that the subjects’ states of mind had nothing to do with their physical measurements?
    – I didn’t see any effort to use newer measures such as using the degree of epigenetic DNA methylation as a proxy to measure biological age. I would expect that these subjects’ historical tissue samples may have been available. The reviewer certainly was familiar with newer measures.


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