Telomere Length Associated with Mortality
The length of telomeres, which are compounds on the ends of chromosomes, have been linked to mortality and aging
--by Nina Lincoff
It’s the little things that make all the difference. The shortening of telomeres—compounds at the ends of chromosomes—is a known biomarker of aging. But beyond the association between shortened telomeres and the aging body, it is still unclear whether telomere length (TL) affects health, or is simply a by-product of aging.
Whatever the reason, the longer the TL, the better off you are.
The Genetic Epidemiology Research Study on Adult Health and Aging (GERA), a multi-ethnic study with an average participant age of 63 years, measured TL by synthesizing saliva samples from more than 100,000 individuals. Two years before the saliva samples were collected, participants were surveyed to determine their ethnic, behavioral, social, and demographic traits, which could potentially affect TL or be affected by it.
Kaiser Permanente and UCSF researchers presented their findings to the American Society of Human Genetics on the relationship between telomere length and mortality, controlling for age and gender. They reported that “TL is inversely correlated with age, and women have longer telomeres than men, except as young adults.”
Education and low body mass index (BMI) were associated with longer TL, while cigarette and alcohol consumption negatively affected TL. Adjusting for all these factors, researchers still found a strong relationship between TL and mortality.
The Expert Take
Two aspects of the findings were somewhat unexpected, said study author Cathy Schaefer, Ph.D, of the Kaiser Permanente division of research in Oakland, CA. “The first was the finding that body mass index was positively associated with telomere length; that is, the higher the body mass index, the longer the person's telomeres. This was true for men and women and in all age strata,” said Schaefer. Other studies have reported an association between obesity and shorter TL, and since this study population is very large, the confirmation is likely to be reliable.
The implication, said Schaefer, is that telomeres may play an important role in the processes of aging, disease susceptibility, and longevity.
The second surprising finding, said Schaefer, is that TL is “significantly and independently associated with risk of mortality.” She found that those individuals with the shortest telomeres had about a 23 percent greater chance of dying in the three years following telomere measurement.
Although the reason for the association between TL and mortality still requires further research, longer telomeres mark better health and a lower mortality rate, while shorter telomeres hint at aging and negative health outcomes. Although behavioral and environmental factors, such as BMI, smoking, and alcohol consumption, affect TL, the association between TL and mortality holds even after adjustment for these factors.
So, what can you do? Changing the DNA strands at the ends of one's chromosomes through a healthier lifestyle seems a bit far fetched, and at the present time, said Schaefer, “TL is useful mainly as a research tool to help with the understanding of aging…There is still a great deal that is not understood about TL and its relationship to health.”
this study reveals certain correlations between TL and behavioral
factors, Schaefer said that changing your behavior or environment might
not be very practical. However, practices like smoking are associated
with shorter TL, “and quitting smoking would undoubtedly improve health
in addition to preserving longer telomeres.” The same goes for ceasing
heavy alcohol consumption.
Overall, said Schaefer, healthy lifestyle practices are beneficial for preserving TL, which means that if you know it’s bad for you, it’s probably bad for your TL as well.
Source & Method
Following an in-depth, two-year survey of more than 100,000 participants to check for behavioral and environmental factors, saliva samples were collected. TL was then determined and adjusted to reflect length reduced by external factors.
The association between TL and aging has been observed before, although on a more micro level. Researchers in the United Kingdom observed an association between TL and the rapid aging of human marrow stromal cells when studying its potential utility for cell and gene therapy.