Researchers have uncovered that the chemical changes that occur in a person's DNA over a lifetime can be telling of that individual's age. By comparing actual ages with biological clock age predicted with the help of the DNA changes, it may be possible to determine how long a person will live.
In a study published in the journal Genome Biology, researchers in four independent studies collectively tracked down nearly 5,000 older adults for up to 14 years. Blood samples were taken from the subjects when the studies began and were used to check for chemical changes in their DNA that will clue researchers of their biological ages.
It turned out, subjects whose biological ages were greater than their real age were likelier to die sooner than others in the study whose biological and actual ages match. Even after taking into consideration factors like cardiovascular disease, diabetes and smoking, researchers still saw a link between early deaths and biological clocks running faster than usual.
With all four studies indicating the same results, a link between deaths and DNA clocks has been securely established. However, Riccardo Marioni, from the University of Edinburgh's Center for Cognitive Ageing and Cognitive Epidemiology and lead author for the study, added that genetic factors and lifestyle may still play a role in influencing the biological age of a person. Researchers are just not yet clear on how these factors affect DNA changes, acknowledging the need for further research to attain answers.
A person's biological age is measured by studying chemical changes in DNA called methylation. When a chemical change occurs, it doesn't affect the DNA sequence itself but contributes to biological processes. The chemical change, however, influences how genes may be expressed.
"This new research increases our understanding of longevity and healthy ageing. It is exciting as it has identified a novel indicator of ageing, which improves the prediction of lifespan over and above the contribution of factors such as smoking, diabetes, and cardiovascular disease," said Ian Deary, also from the Center for Cognitive Ageing and Cognitive Epidemiology, and corresponding author for the study.
The study was supported by the Biotechnology and Biological Sciences Research Council and the Medical Research Council. Researchers from University of Queensland, University of California, Los Angeles, Harvard University, Boston University, the U.S. National Heart, Lung and Blood Institute and the Lieber Institute for Brain Development at the Johns Hopkins University also contributed to the study.
