In recent years researchers have made good progress towards a biomarker of age based on patterns of DNA methylation that change over time. The trick here is pulling out meaningful changes that are characteristically related to aging in much the same way in everyone versus the much larger set of changes that vary widely between individuals. As aging is a process of damage accumulation, some of these epigenetic changes in DNA methylation are responses to that damage, meaning that somewhere in all of this is a methodology to rapidly evaluate potential rejuvenation treatments that are based on repair of damage. That is the real significance of this ongoing field of research:
Researchers studied chemical changes to DNA that take place over a lifetime, and can help them predict an individual's age. By comparing individuals' actual ages with their predicted biological clock age, scientists saw a pattern emerging. People whose biological age was greater than their true age were more likely to die sooner than those whose biological and actual ages were the same.
Four independent studies tracked the lives of almost 5,000 older people for up to 14 years. Each person's biological age was measured from a blood sample at the outset, and participants were followed up throughout the study. Researchers found that the link between having a faster-running biological clock and early death held true even after accounting for other factors such as smoking, diabetes and cardiovascular disease.
Researchers measured each person's biological age by studying a chemical modification to DNA, known as methylation. The modification does not alter the DNA sequence, but plays an important role in biological processes and can influence how genes are turned off and on. Methylation changes can affect many genes and occur throughout a person's life. "The same results in four studies indicated a link between the biological clock and deaths from all causes. At present, it is not clear what lifestyle or genetic factors influence a person's biological age. We have several follow-up projects planned to investigate this in detail."