Cells age due to a combination of factors, primarily accumulated damage and the expression of predetermined genetic information. This leads to progressive cellular dysfunction, manifesting as the aging process we observe in our bodies.
Cellular Damage and Aging
Over time, cells accumulate damage to their DNA, proteins, and other components. This damage can result from various sources, including:
- Oxidative stress: Free radicals, unstable molecules produced during normal metabolism, damage cellular components.
- UV radiation: Sunlight exposure causes DNA damage, contributing to aging.
- Environmental toxins: Exposure to pollutants can cause cellular damage.
- Errors in DNA replication: Mistakes during DNA copying lead to mutations that accumulate with age.
The body possesses repair mechanisms, but their effectiveness declines with age, allowing damage to accumulate and contribute to cellular dysfunction. As noted by the Max Planck Institute for Biology of Ageing (https://www.age.mpg.de/how-do-we-age), damage to genetic material, cells, and tissues that accumulates and cannot be repaired is a primary cause of aging. This is further supported by the National Institute on Aging (https://www.nia.nih.gov/news/does-cellular-senescence-hold-secrets-healthier-aging), which highlights that as we age, our bodies become less efficient at clearing damaged cells.
Genetic Programming and Aging
In addition to damage accumulation, our genes play a role in determining how we age. Certain genes may be programmed to promote aging-related changes, leading to:
- Telomere shortening: Telomeres, protective caps on chromosomes, shorten with each cell division. Critically short telomeres signal cellular senescence or death (https://www.medicalnewstoday.com/articles/318764).
- Changes in gene expression: As we age, the expression of certain genes changes, leading to altered cellular function.
- Accumulation of genetic defects in stem cells: Genetic defects build up in stem cells, impacting their ability to regenerate tissues (https://www.nature.com/articles/s41577-019-0236-2).
The interplay between genetic predisposition and accumulated damage determines the individual aging process. The NIH Intramural Research Program (https://irp.nih.gov/our-research/research-in-action/changing-cells-aging-bodies) highlights the complex relationship between aging and the development of age-related diseases such as diabetes.
Consequences of Cellular Aging
The cumulative effects of cellular damage and genetic programming lead to age-related changes in organs, tissues, and cells. All vital organs lose function over time (https://medlineplus.gov/ency/article/004012.htm, https://www.mountsinai.org/health-library/special-topic/aging-changes-in-organs-tissue-cells). These changes contribute to the overall decline in physical and cognitive function associated with aging. As stated in a New York Times article (https://www.nytimes.com/2024/03/20/well/live/aging-biology-dna.html), many age-related changes begin with damage and dysfunction within our cells and genes.
