Are Telomere Lengths Determined at Birth? New Study Suggests These Longevity Markers Show Greatest Loss and Changes During Early Childhood
As opposed to the chronological age that measures the number of years you’ve spent on earth, biological age assesses internal damage and dysfunction to DNA, cells, and tissues. While these two ages tend to line up during our younger years, they can drift further and further apart as we grow older. With an accelerated biological age, you’re more likely to experience an earlier onset of external aging, like wrinkles and hair loss, and chronic diseases, including dementia, heart disease, or vision loss. So, no matter how many candles are on your birthday cake this year, your cells, tissues, and organs may be telling a different story. One such way to measure this internal aging is through telomere length — the length of the protective caps at the ends of the DNA molecules inside our chromosomes.
Although we now know that telomere length is directly related to biological age, the changes they experience across the entire human lifespan, from birth to old age, is a lesser-researched piece of the aging puzzle. In a recent study published in the journal Psychoneuroendocrinology, Cowell and colleagues find that telomeres show the greatest attrition rates during infancy and early childhood, and are highly influenced by genetic heritability from mother to infant. With these results, the research team based out of Columbia University Mailman School of Public Health suggests that telomere lengths and fluctuations in our earliest years set the stage for late-life health and longevity.
The Self-Sacrificing Traits of Telomeres
Telomeres play an essential role in the aging process, as they sacrifice themselves to protect the rest of our DNA from damage and degradation necessary for sustaining proper cell function. Research has found that people with shorter telomeres have shorter lifespans and an increased risk of chronic diseases. "Given the importance of telomere length in cellular health and aging, it is critical to understand the dynamics of telomeres in childhood," says the senior author of the study, Julie Herbstman.
In this study, Cowell and colleagues looked at the telomere length of leukocytes — a type of immune white blood cell — in 224 children, starting at birth and continuing to measure at ages 3, 5, 7, and 9. They also looked at leukocyte telomere length in some of the mothers to determine genetic heritability and see if telomere length or degradation are passed down between generations.
Leukocyte telomere length is a commonly used method to study the dynamic changes that occur to telomeres over time. This is because circulating leukocytes are replenished from cells called hematopoietic stem cells (HSCs) — a type of stem cell that gives rise to other blood cells. Notably, HSCs express telomerase, the enzyme that extends telomere length. During DNA replication in egg and sperm cells, telomerase continually adds more of the repeating sequence to the end of the DNA, allowing for telomeres in these cells to remain intact. However, in somatic cells — which don’t pass down genetic information, like sex cells do — telomerase activity is low or non-existent, which causes the shortening of telomeres and eventual growth arrest, or senescence, of cells.
Tracking Telomere Lengths, From Mother to Child
Cowell and colleagues found that telomere attrition was highest between birth and age 3, after which the lengths were relatively stable throughout childhood and early adolescence. These results support the theory that leukocyte telomeres have more rapid shortening in the first years of life, when the pool of HSCs is becoming established. Similarly, previous research found that teenaged children had twice the rate of telomere shortening as their parents, suggesting that telomere lengths are primarily determined before the second decade of life — and, as this study indicates, perhaps starting at birth.
This increase in early-life telomere attrition may make these chromosomal endcaps particularly vulnerable to external influences — like environmental toxin exposure, UV radiation, or poor diet — during this crucial developmental window, which sets the benchmark for lifelong telomere length. However, despite this more rapid decline in telomere length in their early years, many children in this study actually experienced some telomere extension, with almost one-third of kids between age 5 and 7 showing a 15% or greater lengthening since the previous years.
In a smaller subset of participants, the research team also measured maternal telomere lengths, collected at the time of their child’s birth. Supporting the telomere length heritability theory, the mother-child pairs’ telomere lengths were highly correlated with one another. Children born to mothers with shorter telomeres (in the 50th percentile or less) also had shorter telomeres, both at birth and throughout the study period.
Maternal age was also slightly and inversely associated with telomere length, which would be expected with increasing age. However, other aspects of the mom’s health, like high tobacco exposure and obesity, were surprisingly not associated with telomere length. This indicates that heritability may play more of a role in adult telomere length than these other health risk factors thought to influence telomere length.
Can Telomere Lengths Change in Adulthood?
Despite the strong link between maternal and child telomere length, it’s still possible to preserve or extend telomeres in adulthood. As we’re guessing that you are older than age 3, it’s likely that you’ve already experienced the greatest telomere attrition rates you ever will. While this research suggests that adult telomere lengths are somewhat set at specific ranges determined in early childhood, there are still plenty of ways to promote telomere length in later life — including boosting NAD+ levels through its precursor NMN, habitual and moderate exercise, and consuming antioxidant-rich diets, to name a few.
Although this research only involved mothers (and not fathers) in a relatively undiverse sample — they were, for the most part, low-income, overweight or obese, in their mid-20s, and of minority populations (Dominican or African-American) — the authors take this as a positive. “Our study sample included low-income, minority women, which we consider a strength as this demographic has largely been understudied in telomere biology research,” Cowell and colleagues state.
This research adds to the evidence of telomere fluctuation in early life — and how that may impact life-long telomere length, biological age, and longevity. Cowell and colleagues summarize, “Future research is needed to understand the biological mechanisms driving variability in the rate of [telomere length] change during the first years of life as well as modifiable environmental factors that contribute to shifts in the rate of attrition.”
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Benetos A, Verhulst S, Labat C, et al. Telomere length tracking in children and their parents: implications for adult-onset diseases. FASEB J. 2019;33(12):14248-14253. doi:10.1096/fj.201901275R
Cowell W, Tang D, Yu J, et al. Telomere dynamics across the early life course: Findings from a longitudinal study in children [published online ahead of print, 2021 May 14]. Psychoneuroendocrinology. 2021;129:105270. doi:10.1016/j.psyneuen.2021.105270