Linear thinking about biological age clocks

This 2020 review by a Hong Kong company’s researchers compared and contrasted measures of biological age: “More than a dozen aging clocks use molecular features to predict an organism’s age, each of them utilizing different data types and training procedures. We offer a detailed comparison of existing mouse and human aging clocks, discuss their technological … Continue reading Linear thinking about biological age clocks

Do epigenetic clocks measure causes or effects?

The founder of the PhenoAge epigenetic clock methodology authored this 2020 article: “The Ge[r]oscience paradigm suggests that targeting the aging process could delay or prevent the risk of multiple major age-related diseases. We need clinically valid measures of the underlying biological process and/or classification criteria for what it means to be biologically, rather than chronologically, … Continue reading Do epigenetic clocks measure causes or effects?

A blood plasma aging clock

This 2019 Stanford human study developed an aging clock using blood plasma proteins: “We measured 2,925 plasma proteins from 4,331 young adults to nonagenarians [18 – 95] and developed a novel bioinformatics approach which uncovered profound non-linear alterations in the human plasma proteome with age. Waves of changes in the proteome in the fourth, seventh, … Continue reading A blood plasma aging clock

An epigenetic clock review by committee

This 2019 worldwide review of epigenetic clocks was a semi-anonymous mishmash of opinions, facts, hypotheses, unwarranted extrapolations, and beliefs. The diversity of viewpoints among the 21 coauthors wasn’t evident. 1. Citations of the coauthors’ works seemed excessive, and they apologized for omissions. However: Challenge 5 was titled “Single-cell analysis of aging changes and disease” and … Continue reading An epigenetic clock review by committee

A GWAS meta-analysis of two epigenetic clocks

This 2019 UK human study conducted a meta-analysis of genome-wide association studies of two epigenetic clocks using 13,493 European-ancestry individuals aged between ten and 98 years: “Horvath-EAA, described in previous publications as ‘intrinsic’ epigenetic age acceleration (IEAA), can be interpreted as a measure of cell-intrinsic ageing that exhibits preservation across multiple tissues, appears unrelated to … Continue reading A GWAS meta-analysis of two epigenetic clocks

A strawman argument against epigenetic clocks

This 2019 review of epigenetic clocks by Washington cancer researchers ignored the elephant in the room, and repeatedly returned to an argument for randomness as a cause for aging and disease: “A time-dependent stochastic event process, like epigenetic drift, could lead to cancer formation through the accumulation of random epigenetic alterations that, through chance, eventually … Continue reading A strawman argument against epigenetic clocks

Developmental disorders and the epigenetic clock

This 2019 UK/Canada/Germany human study investigated thirteen developmental disorders to identify genes that changed aspects of the epigenetic clock: “Sotos syndrome accelerates epigenetic aging [+7.64 years]. Sotos syndrome is caused by loss-of-function mutations in the NSD1 gene, which encodes a histone H3 lysine 36 (H3K36) methyltransferase. This leads to a phenotype which can include: Prenatal and … Continue reading Developmental disorders and the epigenetic clock

An hour of the epigenetic clock

This 2018 presentation by the founder of the epigenetic clock method described the state of the art up through July 2018. The webinar was given on the release day of The epigenetic clock now includes skin study. Segments before the half-hour mark provide an introduction to the method and several details about the concurrently-released study. … Continue reading An hour of the epigenetic clock

Epigenetic clock statistics and methods

This 2018 Chinese study was a series of statistical and methodological counter-arguments to a previous epigenetic clock study finding that: “Only [CpG] sites mapping to the ELOVL2 promoter constitute cell and tissue-type independent aDMPs [age-associated differentially methylated positions].” The study used external data sets and the newer epigenetic clock’s fibroblast data in its analyses to … Continue reading Epigenetic clock statistics and methods

A slanted view of the epigenetic clock

The founder of the epigenetic clock technique was interviewed for MIT Technology Review: “We need to find ways to keep people healthier longer,” he says. He hopes that refinements to his clock will soon make it precise enough to reflect changes in lifestyle and behavior.” The journalist attempted to dumb the subject down “for the … Continue reading A slanted view of the epigenetic clock