Telomeres are caps of repeated DNA sequences at the ends of chromosomes. A little telomere length is lost with each cell division, and cells with very short telomeres become senescent or undergo programmed cell death. This is one part of the mechanisms making up the Hayflick limit on the number of times a somatic cell can divide, ensuring turnover of somatic cells making up tissues. New cells with long telomeres are generated by adult stem cell populations. Average telomere length decreases with age, but only when considering large study populations. It is a very blurry measure of declining stem cell function and increased replication stress on cells resulting from the causative mechanisms of aging.
In particular, it is worth noting that telomere length is usually measured in white blood cells from a blood sample, not a tissue sample. Immune cells are subject to a dynamic characteristic of replication and replacement that is quite different from that of cells in tissue. Average telomere length in a sample of immune cells can vary from day to day, by burden of infectious disease, by psychological stress, and everything else that might adjust the behavior of the immune system distinctly from the behavior of tissues. This is one of the reasons why it is a poor biomarker of aging, of little use for planning on the part of any one individual. One does still see correlations in large study populations, however.
Biomarker tied to premature cell aging may signal stroke, dementia, late-life depression
Leukocyte telomere length, which reflects the length of the telomeres within white blood cells (leukocytes), is a known marker of biological aging. Telomeres gradually shorten with age, reducing their ability to protect the chromosomes' genetic material, leading to cellular aging and increased susceptibility to age-related diseases. The length of telomeres is affected by unchangeable factors such as genetics, ancestry, and gender, as well as modifiable factors such as lifestyle choices and environmental stressors, including pollution.
The current study uses data from more than 356,000 participants in the large UK Biobank to address three questions. When participants were recruited for the study between 2006 and 2010, they provided blood samples to analyze leukocyte telomere length. Additionally, they underwent a Brain Care Score assessment, a tool designed to quantify modifiable factors such as physical factors, lifestyle choices, and social interactions. Participants were followed for a median duration of 12 years to monitor the onset of stroke, dementia, or late-life depression.
Compared to participants with longer leukocyte telomeres, people with the shortest leukocyte telomere length had an 8% higher risk of stroke, a 19% higher risk of dementia, and a 14% higher risk of late-life depression. Overall, compared to participants with longer leukocyte telomeres, people with the shortest leukocyte telomere length had an 11% higher risk of developing at least one of the age-related brain diseases studied.
View the full article at FightAging
