101 Facts About Ageing #44: Ageing, Telomere Length and Life Expectancy

As Daniel Patrick Moynihan, an American sociologist, politician, and diplomat once said: “Everyone is entitled to his own opinion, but not his own facts”. And we wholeheartedly agree. A shared set of facts is the first step to building a better world with longevity for all. In that spirit, we are creating a series that covers 101 indisputable facts about ageing, health and longevity.

As covered in fact #23, our telomeres, the protective caps at the ends of each chromosome, become shorter each time the cell divides. The graph below shows the mean white blood cell telomere length (in kilobases or 1000s of base pairs) during ageing for males and females. While there is an overall downward trend, there is considerable variation in telomere length between individuals. Telomere length at birth and the rate at which telomeres shorten is influenced by many genetic factors as well as environmental ones.

Having genetically longer or shorter telomeres is associated with modified risk for certain diseases. The graph below shows the relative increased risk of disease for someone whose white blood cell telomere length is one standard deviation longer than average. In other words, the further to the right of the line the coloured mark is, the greater the risk of disease with longer telomere length. The further to the left of the line, the lower the risk of disease with longer telomere length. The data suggests that people with longer genetically determined telomere length get more cancers on average, but suffer less from certain other diseases such as cardiovascular disease.

Despite the association with some cancers, longer telomere length is associated with increased life expectancy. At age 40, a white blood cell telomere length of more than 1 standard deviation longer than the mean is associated with approximately 2.5 years increased life expectancy compared with those whose telomere length is one standard deviation shorter than the mean. This effect declines following the age of 65.