‘Telomere’ Length, Aging, and Risk of Dying

Chromosomes are coiled strands of DNA packed into a nucleus. The tips of chromosomes are called “telomeres.” Telomeres shorten with every cell division, and shortened telomeres are associated with a greater risk of death.

Like plastic tips on the end of shoe laces, “telomeres” are caps on chromosomes that prevent a chromosome from fraying or deteriorating. Chromosomes are tightly coiled strands of DNA that fit into an area the size of a pin head in the “nucleus” (center) of nearly all of our bodies’ cells. (Incredibly if these chromosomes were uncoiled, DNA from a single cell would stretch 6 feet in-length!).

Perhaps it’s not surprising then that researchers are finding that shorter telomere length is associated with aging and disease. Recently researchers at Kaiser Permanente and the University of California, San Francisco looked at telomere length in chromosomes of over 100k people. The studies’ results are fascinating- among other things, researchers found that:

The 10% of people with the shortest telomere length had a more than 20% higher risk of dying than people with longer telomeres (even when controlled for age meaning that two individuals of say 50 years of age can have a different risk of dying as detected by differences in telomere length)
Telomere length was negatively correlated with age and smoking & drinking (telomere length tended to be shorter in individuals who were older and/or smoked & drank; in fact the increased death risk for those with the shortest telomere length is equal to drinking 20 to 30 alcoholic beverages a week or smoking for 20 to 30 years).

Perhaps surprisingly, telomere length did NOT appear related to:

Body Mass Index (BMI)
Exercise

What does this all mean?

Given the number and diversity of individuals tested for telomere length, this study is an important contribution to our understanding of the relationship between telomere length and one’s risk of dying. While the study confirms that shorter telomere length is associated with a greater risk of dying, there are still important unanswered questions. For example, it’s still uncertain how shortened telomere length may increase one’s risk of dying. Presently it’s unknown if shortened telomere length is a “symptom” (or sign) of aging or an actual cause of disease and death.

For example, our skin becomes more wrinkled as we age. Similarly, our chances of dying from cancer increase with age. One might falsely conclude that skin wrinkling causes terminal (fatal) cancer. However, both wrinkled skin and cancer deaths are associated with aging, but wrinkled skin does not cause terminal cancer.

Similarly, I imagine researchers will want to further investigate whether shortened telomere length directly causes death (ie by perhaps increasing one’s risk for cancer) or whether like wrinkled skin shortened telomere length is associated with aging but does not directly cause death. At the very least, telomere length may serve as a proxy (or more accurate measure) of one’s “age.” (Perhaps in the future "aging" will be measured by telomere length rather than the number of years one has lived).

Looking a bit further ahead, if researchers determine that shortened telomere length does indeed directly lead to death, one potential compound that may be exploited to delay aging and disease is “telomerase.” Telomerase is an enzyme naturally found in the body that can actually lengthen our telomeres. In the future, you’ll be hearing more about telomeres and telomerase, and eventually clinicians could utilize this knowledge to delay aging and diseases associated with aging.

Largest US Genetic BioBank Reveals Early Findings – discusses the above study within the context of a larger investigation of our DNA
Rush: Science and Technology in Our Acceleration Age discusses important related topics like DNA, DNA sequencing, the human genome, bioengineering, and gene therapy
Other Big in Science articles tagged gene therapy, dna sequencing, human genome, health & medicine,