The Insidious Approach of Death

A friend recently attended their 20th highschool reunion, the sort of event that makes one feel very old. Worse, three of their classmates have already died.

I thought that sounded way statistically unlikely, especially given the group’s demographics, but I ran the numbers, and it turns out that it’s only a little unlikely. Given the small N, we’re probably talking about random chance making the class unlucky rather than a particular propensity for death, but it’s unfortunate either way.

Highschool reunions are also a great (by which I mean depressing) opportunity to see who has aged the most. Some classmates look hardly older than the last time you saw them, while others look like they got hit by a semi full of old. Hopefully not you, of course.

In “Quantification of biological aging in young adults,” Belsky et al confirm what I’ve long suspected: that different people age at radically different rates, not just emotionally/mentally, but also biologically.

From the abstract: “We 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. We developed and validated two methods by which aging can be measured in young adults, one cross-sectional and one longitudinal. Our longitudinal measure allows quantification of the pace of coordinated physiological deterioration across multiple organ systems (e.g., pulmonary, periodontal, cardiovascular, renal, hepatic, and immune function). We applied these methods to assess biological aging in young humans who had not yet developed age-related diseases. Young individuals of the same chronological age varied in their “biological aging” (declining integrity of multiple organ systems). Already, before midlife, individuals who were aging more rapidly were less physically able, showed cognitive decline and brain aging, self-reported worse health, and looked older.” (bold mine.)

” We scaled the Pace of Aging so that the central tendency in the cohort indicates 1 y of physiological change for every one chronological year. On this scale, cohort members ranged in their Pace of Aging from near 0 y of physiological change per chronological year to nearly 3 y of physiological change per chronological year.”

“Study members with advanced Biological Age performed less well on objective tests of
physical functioning at age 38 than biologically younger peers (Fig. 5). They had more difficulty with balance and motor tests (for unipedal stance test of balance, r = −0.22, P < 0.001; for grooved pegboard test of fine motor coordination, r = −0.13, P < 0.001), and they were not as strong (grip strength test, r = −0.19, P < 0.001).”

“Study members with older Biological Ages had poorer cognitive functioning at midlife (r = −0.17, P < 0.001). Moreover, this difference in cognitive functioning reflected actual cognitive decline over the
years. When we compared age-38 IQ test scores to baseline test scores from childhood, study members with older Biological Age showed a decline in cognitive performance net of their baseline
level (r = −0.09, P = 0.010).”

“Neurologists have also begun to use high-resolution 2D photographs of the retina to evaluate age-related loss of integrity of blood vessels within the brain. Retinal and cerebral small vessels
share embryological origin and physiological features, making retinal vasculature a noninvasive indicator of the state of the brain’s microvasculature (32). Retinal microvascular abnormalities are associated with age-related brain pathology, including stroke and dementia (33–35) … study members with advanced Biological Age had older retinal vessels (narrower arterioles, r = −0.20, P < 0.001; wider venules, r = 0.17, P < 0.001).”

“… these biologically older study members were perceived to be older by independent observers.”

“Based on Pace of Aging analysis, we estimate that roughly 1/2 of the difference in Biological Age
observed at chronological age 38 had accumulated over the past 12 y.”

“… our analysis was limited to a single cohort, and one that lacked ethnic minority populations. Replication in other cohorts is needed, in particular in samples including sufficient numbers of ethnic minority individuals to test the “weathering hypothesis” that the stresses of ethnic minority status accelerate aging.”

“Three Dunedin Study members had Pace of Aging less than zero, appearing to grow physiologically younger during their thirties.”

While I suspect measurement error is at play, I’d still like to know what those guys did.

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6 thoughts on “The Insidious Approach of Death

  1. It looks like the “Dunedin cohort” is a group of individuals in New Zealand. Of course it would be interesting to see how this broke down by race, class, etc. As for those individuals who got physiologically younger, I wonder if these are folks who weren’t particularly fit in their younger years and then joined Crossfit et al/cleaned up their diet in a mid-age crisis.

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    • NZ is pretty ethnically homogenous, so I bet they tried to get a basically all-white sample, but if I’m wrong, that would be interesting.

      Yes, that probably is what happened with them. Clean up your act, stave off death!

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