This study focused on a naturally occurring process called methylation, a chemical modification of one of the four building blocks that make up our DNA. Steve Horvath, the study’s author writes that while many healthy tissues age at the same rate as the body as a whole, some of them age much faster or slower. The age of diseased organs varied hugely, with some many tens of years ‘older’ than healthy tissue in the same person.
While earlier biological clocks have been linked to saliva, hormones & telomeres, the new research is the first to result in the development of an age-predictive tool that uses a previously unknown time-keeping mechanism in the body to accurately gauge the age of diverse human organs, tissues and cell types.
Horvath found that the methylation of 353 DNA markers varied consistently with age and could be used as a biological clock. The clock ticked fastest in the years up to around age 20, then slowed down to a steadier rate.
Unexpectedly, this new tool demonstrated that some parts of the anatomy, like a woman’s breast tissue, age faster than the rest of the body; the author of the new research found that a woman’s breast tissue routinely tests as being older than her chronological age by 2-3 years.
Whether the DNA changes cause aging or are caused by ageing is an unknown that scientists are now keen to work out.