People age at different paces: accumulating damage, dysfunction, and age-related disease comes earlier and faster for some. The current consensus is that some of that is genetic, some epigenetic, but (absent serious genetic abnormalities) most of the difference is due to commonplace lifestyle choices such as smoking, exercise, and calorie intake.
[Researchers have] found new evidence that links faster 'biological' ageing to the risk of developing several age-related diseases - including heart disease, multiple sclerosis and various cancers. "Although heart disease and cancers are more common as one gets older, not everyone gets them - and some people get them at an earlier age. It has been suspected that the occurrence of these diseases may in part be related to some people 'biologically' ageing more quickly than others."
The research team measured telomere lengths in over 48,000 individuals and looked at their DNA and identified seven genetic variants that were associated with telomere length. They then asked the question whether these genetic variants also affected risk of various diseases. As DNA cannot be changed by lifestyle or environmental factors, an association of these genetic variants which affect telomere length with a disease also would suggest a causal link between telomere length and that disease.
"These are really exciting findings. We had previous evidence that shorter telomere lengths are associated with increased risk of coronary artery disease but were not sure whether this association was causal or not. This research strongly suggests that biological ageing plays an important role in causing coronary artery disease, the commonest cause of death in the world. This provides a novel way of looking at the disease and at least partly explains why some patients develop it early and others don't develop it at all even if they carry other risk factors."