Everyone has heard of Spanish explorer, Ponce De Leon, and his search for the Fountain of Youth. As the story goes, De Leon went on an expedition in 1513, voyaging overseas to current day Florida where he believed he would find the Fountain of Youth. He struggled across the land for months on his search. Finally, after being shot in the leg by a native’s arrow and struggling to continue, he abandoned his quest. Ponce De Leon and every other dreamer looking for a way to “turn back the years” slowly accepted the fact that time is inevitable and aging, unstoppable. But is it? Is it possible to turn back the clock or at least slow it down? In order to consider this, the questions of how and why we age must be answered. Scientists have worked for centuries to decipher the mystery of aging in order to answer those very questions. Here, we provide the scientific community’s most common theories on aging with a brief synopsis of each.
Cross-linking (Glycation)
Proposed in 1942 by Johan Bjorksten, this theory points to sugar as a cause of aging. Aging occurs when an accumulation of cross-linked proteins begins to damage the cells of the body. A cross-linked protein is one that has bonded in error with a glucose molecule. Once it is cross-linked, a protein can no longer perform its function as intended and body systems begin to break down. As a person continues to live, the more cross-links tend to happen, causing changes in the body that resemble aging. Cross-links are associated with loss of skin elasticity, stiffening of blood vessel walls, changes in the lens of the eye, poor healing and reduced joint mobility.
Free Radical Damage
The byproduct of normal cellular function, free radicals are formed during energy creation, as unstable oxygen molecules are produced that often bond with other molecules and proteins in the body, causing loss of function. The theory is that free radicals, over time, will cause the body to age. The impact of free radicals can be tempered naturally by antioxidants, a substance found in plants. Some evidence exists for this theory as it has been found that an increase of antioxidants can slow aging in mice; however, other research shows a positive correlation between increased free radicals and longer life.
Many scientists believe that free radicals have a hand in aging, but are not the primary cause.
Immunology
Medical experts have proven that with age comes a decrease in immune system function. This increases the risk of infections, disease and inflammatory diseases. Data suggests that diminished immune function is a symptom of aging, but some experts believe the reverse. Some theorists attribute symptoms of aging to a hampered immune system. The theory holds that increased cellular diversification due to mutation triggers an auto-immune response and causes the body to age. Experts point to the thymus (the area of the brain responsible for producing some immune cells) and the fact that it begins to shrink at 20 years of age, as evidence to support the theory.
Cell Membrane Solidification
This theory was conceived by Professor Imre Nagy of Debrechen University in Hungary. It’s a fact that as we grow older, the membranes of our cells begin to slowly solidify. This theory posits that membrane solidification impairs the cells’ ability to transfer chemicals or adequately conduct electrical processes. Over time, toxic accumulation begins to break down the cells. As the cells collectively breakdown, the overall body begins to show signs of aging.
Is it possible to turn back the clock or at least slow it down? In order to consider this, the questions of how and why we age must be answered.
Mitochondrial Decline
Some scientists believe that aging is caused by something located in the cell itself. Mitochondrion are known as the cell “battery,” housing the respiration and energy production processes. Decline theory states that as our cells and mitochondria age, energy output declines. Experts have found that mitochondrial DNA has a higher rate of mutation compared to nuclear DNA. As the amount of mutation reaches the critical threshold, the mitochondria begin to break down. This creates a chain reaction inside the cell causing cell death and the symptoms of aging.
Neuroendocrinology
This theory, also called the “aging clock theory,” was developed by Russian scientist, Vladimir Dilman. It states that “the effectiveness of the body’s homeostatic adjustments declines with aging – leading to the failure of adaptive mechanisms, aging and death.” The theory centers around the hypothalamic pituitary axis (HPA) – the system maintaining body homeostasis – losing efficiency, which causes an increase in body negative response and a decrease in physiological function. As systems become less regulated, hormone secretion declines, as well as the effectiveness of hormone receptors, causing symptoms of aging across different body processes and systems.
Somatic DNA Damage
This theory points to our genes as the aging determinant. As our bodies age, cells are constantly reproducing. Each time this happens, there is a chance that our genes will not be copied correctly. When this happens, it is called a mutation.
The body can correct or destroy some mutated cells, but not all. As mutations continue to occur and accumulate, they interfere with the body’s ability to function. Mutations happen naturally, but can be increased by toxins, radiation or injury.
Telomere Shortening
Telomeres are the caps of DNA which protect the ends of our chromosomes from damage. Science has found a direct correlation between the length of a person’s telomeres and the speed of aging. They function as a sort of biological clock for the body. Over time, the telomeres shorten as our cells divide – when they become short enough, a cell can no longer replicate and dies. Telomere shortening is tied to multiple age-related diseases such as diabetes, Alzheimer’s disease and cancer. The length of telomeres is due to genetics and therefore, differs amongst persons and cell types. Numerous labs across the world are working on a process to lengthen a body’s telomeres and therefore lengthen life, and human experiments are in the works. Some companies currently claim to be able to measure telomeres and calculate a person’s longevity score, but the accuracy of such a test is in question.
As history states, Ponce De Leon never actually went searching for a “fountain of youth.” It is a myth, but an intriguing one. Is it possible to quell aging? Is there a way to “live forever” – an internal fountain of youth, perhaps? Science is still looking and, quite possibly, narrowing the search.
References
Diggs, J. (2008). Neuroendocrine (aging clock) theory of aging. Encyclopedia of Aging and Public Health. Retrieved from link.springer.com/referenceworkentry/10.1007%2F978-0-387-33754-8_313
Physiopedia. (2019). Theories of aging. Physiopedia. Retrieved from physiopedia.com/Theories_of_Ageing
Stibich, M. (2019). The basics of the immunological theory of aging. Verywellhealth.com. Retrieved from verywellhealth.com/immunological-theory-of-aging-2224224
Stibich, M. (2019). The somatic mutation theory of aging.
Verywellhealth.com. Retrieved from verywellhealth.com/the-somatic-mutation-theory-of-aging-2224225
Stibich, M. (2019). The free radical theory of aging. Verywellhealth.com. Retrieved from verywellhealth.com/free-radical-theory-of-aging-2224227
