Aging 101: Hallmarks

Growing old is one of the only things that is assured in life. You are born as a small baby, and slowly grow into an adult. You get to live a unique life full of adventures, and different experiences, forging friendships and relationships along the way. As you live and grow, your body and mind experiences a plethora of changes. Until finally one day, you cease to exist. The million, if not trillion dollar question is; “What exactly is causing us to reach that point of no return? “ To gain a better perspective to the question we need to explore what exactly aging is, and looking at the 9 hallmarks of aging (Austad n.d.) , and how environmental factors can affect it is a great start.

Aging, as we all know, is the process of becoming old. At first, we get stronger and smarter but at some point we peak, and our body and mind start to decline. We can see the telltale signs of aging; graying hair, wrinkling skin, and fragile bones (WHO 2021). These occur as a result of changes within cells in your body, which ultimately affect the health and function of your tissues, then organs, and eventually your whole body.  The 9 hallmarks of aging are key contributors to these processes (Barbose et al. 2019), and understanding them is vital for understanding how we age. Below, we will briefly go into each of them using the works of Austad and Barbose et al. to help guide our understanding. 

1. Genomic instability refers to how your DNA is under constant attack by agents such as free radicals and radiation. These agents physically damage or alter  DNA, causing mutations, adding extra segments, or deleting parts altogether.  While there are repair mechanisms to fix the damage, it can still sometimes be missed, or the repair machinery might simply not be able to keep up with the rate of damage.
2. Telomere attrition is a type of genomic instability, and it refers to the shortening of the regions at the end of chromosomes called telomeres. Telomeres, although part of the DNA, do not encode for any proteins. Rather, they protect the parts of the chromosomes/DNA that do. However, each time a cell divides, the telomeres become shorter and shorter. Eventually, in order to protect the information within the chromosomes, the cell stops dividing entirely to prevent the loss of coding DNA from going through more cell division. 
3. Epigenetic alterations refer to modifications to the epigenome, which is responsible for regulating the transcription of genes or in a sense, turning sections of DNA “on” and “off”. As the epigenome changes, it disrupts its normal activity of regulating which genes are transcribed.
4. Loss of proteostasis refers to the loss of the proper maintenance of proteins’ configurations and concentrations. Form is equal to function for proteins, and thus the loss of properly formed proteins has drastic effects on cells. 
5. Deregulated nutrient-sensing refers to dysfunctional (excessive or deficient ) recognition of vital nutrients. This either results in certain metabolites being produced excessively leading to premature aging, or insufficient quantities of substances required to slow aging. 
6. Mitochondrial dysfunction refers specifically to abnormal mitophagy—the process of degrading old mitochondria and synthesizing new ones. Being crucially important to cells, mitochondrial problems can decrease energy production, as well as increase free radical production, damaging complex molecules such as DNA. 
7. Cellular senescence refers to the process by which cells stop dividing into further cells, but also don’t die. These cells accumulate with age. Not only do these cells stop working properly but they can secrete damaging substances into the extracellular environment which further contributes to aging.
8. Stem cell exhaustion refers to the declining ability of stem cells to replicate with age. Stem cells are crucial for tissue regeneration in the body, and the loss of their replicative abilities has serious consequences.
9. Altered intercellular communication refers to an increase in impaired intercellular communicative ability. Proper communication, through hormones for example,  is essential for maintaining ideal cell and tissue health, and its impairment contributes to aging.

Now, it is important to understand that these are all natural processes that have been taking place within human beings for thousands of years. These are all part of intrinsic aging (Nunez 2021), which refers to aging as a result of natural, predetermined processes. This differs from extrinsic aging, which is caused by external, environmental factors such as UV damage, drug and alcohol consumption, and poor nutrition, all of which lead to the aforementioned hallmarks. The more we engage in harmful behaviors, the greater impact we will observe in our bodies. 

Now, after reading about how every little thing within and around you is slowly ticking away at you, and making you age, you are probably rightfully questioning what you can do to slow the process. Although there isn’t much to slow down intrinsic aging, we’ve identified a few options for you to help slow/reduce the effects of extrinsic aging.

1. Eat a healthy, nutritious diet that ensures all your macronutrients are met (Nunez 2021). Your body can only be as healthy as the fuel you provide it with, so make sure to avoid unnecessary processed foods and focus on providing your body with all the nutrients it requires from natural sources. Fruits, vegetables, whole wheats, and lean proteins are great for you! (PS: Check out our interview with Luigi Fontana for more information on proper nutrition)
2. Avoid alcohol and drug consumption as much as possible. Alcohol depletes vitamin A levels in the body, thus drastically reducing collagen in the body (Riley 2022). Collagen is needed for skin health, and without it, wrinkles and other deformations can form.
3. Wear protective sunscreen. The sun is constantly bathing you in its harmful UV rays which can lead to free radicals forming in your body (Swanson 2016). As mentioned earlier, free radicals damage DNA, and are a major contributor to aging.

Aging is a normal part of life. Taking care of your body by being mindful of what you expose yourself to and what you intake is key to staying healthy and preventing premature aging. Advancements in medicine and cellular biology are continually being made to the point where one day we may be able to greatly slow aging down. If you are interested in learning about biological immortality, or life-extension therapy as it is more commonly known, check out our previous post!

Sources

1. Austad S. What are the hallmarks of aging? American Federation for Aging Research. [accessed 2022 Jul 25]. https://www.afar.org/hallmarksofaging
2. WHO. Ageing and health. World Health Organization. 2021 Oct 4 [accessed 2022 Jul 25]. https://www.who.int/news-room/fact-sheets/detail/ageing-and-healt
3. Barbosa MC, Grosso RA, Fader CM. Hallmarks of aging: An autophagic perspective. Frontiers in Endocrinology. 2019;9. doi:10.3389/fendo.2018.00790
4. Nunez K. Why do we age, and can anything be done to stop or slow it? Healthline. 2021 Mar 23 [accessed 2022 Jul 26]. https://www.healthline.com/health/why-do-we-age#forms-of-aging
5. Riley L, editor. New Jersey Rehab and Recovery Center that really works! North Jersey Recovery Center. 2022 May 9 [accessed 2022 Jul 25]. https://northjerseyrecovery.com/does-alcohol-make-you-look-older/
6. Swanson C. Born to die: Why do humans get old? Science World. 2016 Jun 14 [accessed 2022 Jul 27]. https://www.scienceworld.ca/stories/born-die-why-do-humans-get-old