This 2015 New Zealand human study used the same subjects of the More from the researchers that found people have the same personalities at age 26 that they had at age 3 study. These researchers used 10 biologic age markers of subjects at age 38 to find that their biological ages ranged from 28 to 61.

Researchers assessed subjects’ pace of aging at ages 26, 32, and 38 with 11 more biomarkers, including leukocyte telomere length. Three of the initial 10 biomarkers weren’t used because measurements were taken only at age 38.

These researchers also assessed physical functioning, physical limitations, cognitive testing, retinal imaging, self-rated health, and facial aging. There was a fascinating graph in the supplementary material of the effect on each of these assessments of successively leaving out each of 18 pace-of-aging biomarkers.

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

1. Where were links back to all relevant measurements and predictions made when these subjects were ages 3, 5, 7..? Other studies of these same subjects made such links, but only cognitive testing was linked back in this study. Were these researchers trying to pretend that these dramatic later-life physical measurements weren’t effects of earlier-life causes?
2. Where were psychological measurements? Are we to believe that subjects’ states of mind had no relationships to their biomarkers?
3. I didn’t see any effort to use newer measures such as The degree of epigenetic DNA methylation may be used as a proxy to measure biological age study. I’d expect that these subjects’ historical tissue samples were available. The peer reviewer certainly was familiar with newer biomarkers.

http://www.pnas.org/content/112/30/E4104.full “Quantification of biological aging in young adults”