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Ever notice at your high school reunions how some classmates look ten years older than everybody else - and some look ten years younger. Now BBC reports that a study of people born within a year of each other has uncovered a huge gulf in the speed at which human bodies bodies age. The report tracked traits such as weight, kidney function and gum health and found that some of the 38-year-olds in the study were aging so badly that their "biological age" was on the cusp of retirement. "They look rough, they look lacking in vitality," says Prof Terrie Moffitt. The study says some people had almost stopped aging during the period of the study, while others were gaining nearly three years of biological age for every twelve months that passed. "Any area of life where we currently use chronological age is faulty, if we knew more about biological age we could be more fair and egalitarian," says Moffitt.
The researchers studied aging in 954 young humans, the Dunedin Study birth cohort, tracking multiple biomarkers across three time points spanning their third and fourth decades of life. They developed and validated two methods by which aging can be measured in young adults, one cross-sectional and one longitudinal. According to Moffit the science of healthspan extension may be focused on the wrong end of the lifespan; rather than only studying old humans, geroscience should also study the young. "Eventually if we really want to slow the process of aging to prevent the onset of disease we're going to have to intervene with young people."
Original Submission
(Score: 1, Informative) by Anonymous Coward on Wednesday July 08 2015, @07:58AM
Figure 1 shows exponentially increasing age-specific incidence of mortality and disability. This is an artifact of truncating at 80 years old. While you are more likely to *have* died or *have* developed a given disease as you age (ie cumulative probability), the probability of it happening *at* a given age will not keep increasing, it will peak. This error has lead to much nonsense regarding cancer, btw.
Figure 2 shows their calculation of biological age was normally distributed around the chronological age. Normal distributions arise when you are measuring something resulting from multiple independent additive events (eg https://en.wikipedia.org/wiki/Quincunx). [wikipedia.org] The presence of this normal distribution indicates their measure of biological age is nothing but chronological age+ independent sources of random noise. Almost nothing in biology is normally distributed.
Figure 3-7 are so binned, averaged, and standardized that they mean nothing to me. Maybe someone else can make something of those but I find them impossible to sanity check. They don't mention anything stopping them from sharing the raw data, or why they chose to do all that processing.
(Score: 0) by Anonymous Coward on Wednesday July 08 2015, @10:26AM
Sorry, the quincunx link should have pointed here:
https://en.wikipedia.org/wiki/Bean_machine [wikipedia.org]
Also, in the supplements they say how they calculated this. I can't copy/paste the equation but it is essentially adding up how much all of these differed from the average:
The problem is that as you add in more and more irrelevant things the distribution will approach normality.