Aging is associated with an increase in the prevalence of various diseases. One important variable in determining lifespan is the length of telomeres. These are the ends of chromosomes that protect our genes. Without telomeres, cells cannot replicate. Telomeres prevent the degradation of chromosome ends, allowing the replication of healthy new cells and preventing accidental chromosome fusion. Each time a new cell replicates, the telomeres continue to shorten. Once they are completely gone, we cannot produce new cells, which is called replicative senescence. The Hayflick limit, in essence, places a limit on our lifespan. Once our cells can no longer replicate, some undergo apoptosis or programmed cell death. Other cells may remain in senescence for a time but may undergo significant changes associated with various pathologies.
Cell senescence is an age-related pathology that takes place by two mechanisms. The first is the limited ability to create new cells to maintain tissue health. The second is the release of senescence-associated secretory phenotype (SASP), which affects nearby cells. This can lead to inflammation, alter tissue structures, and even lead to the production of abnormal cells, such as malignant cells and tumors (Tchkonia et al., 2013).
SASP can exhibit antagonist pleiotropy (AP). Antagonistic pleiotropy is the mechanism whereby genes that are favored by natural selection, as they may be beneficial, such as those related to reproduction, are expressed one way earlier in life. These same genes that were beneficial during reproductive years may become harmful later in life. Evolution is primarily concerned with spreading our genes and procreation. After that, genetic factors that favor living into older age might be less likely to be passed on through natural selection.
As a result of all this, aging is associated with a decline in our physical and cognitive state and performance. After the age of 30, our fluid intelligence, synonymous with processing speed and previously known as performance IQ, begins to decline. Pregnancy after age 35 has been referred to as geriatric pregnancy. This has now been changed to the more politically correct term, advanced maternal age (AMA). As mentioned previously, evolutionary processes such as natural selection have focused primarily on procreation to spread genes at our early reproductive age. There has been no obvious drive for evolutionarily advantageous things for older age to develop. Rose wrote, “…aging occurs because of the extensive absence of adaptive genomic information required for survival to, and function at, later adult ages, due to the declining forces of natural selection during adult life” (Rose, 2009, p. 444).
In conclusion, if we wish to live in optimal health after age 30, we need to take self-care seriously, including diet, exercise, meditation, mental health (emotional regulation and decreasing stress), supplements, and medications.
For more information about this, please consider taking Dr. Modestino’s course, Psy 3600: Issues in Aging at Curry College.
References
Rose, M. R. (2009). Adaptation, aging, and genomic information. Aging, 1(5), 444–450. https://doi.org/10.18632/aging.100053
Tchkonia, T., Zhu, Y., van Deursen, J., Campisi, J., & Kirkland, J. L. (2013). Cellular senescence and the senescent secretory phenotype: Therapeutic opportunities. Journal of Clinical Investigation, 123(3), 966–972. https://doi.org/10.1172/jci64098
Comments