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What wrinkles say about your biological age

The skin is the largest organ in the human body and has numerous important roles. Its main function is of course to act as a barrier between our internal and external environment but it also plays key roles related to immunity, sensation, temperature regulation, protecting against dehydration, vitamin D generation and reducing the harmful effects of UV radiation. Although skin ageing is often seen by many as a purely cosmetic concern, as skin ages it degenerates, getting progressively worse at performing its many functions.

A 69-year-old man who drove a delivery truck for 28 years shows damaged skin on the left side of his face. New England Journal of Medicine.

The epidermis is the outermost layer of skin and is therefore one of the first lines of defence against the outside world. With age this outer layer becomes progressively thinner, less hydrated and fat-rich and the quality and quantity of vital proteins degrades. This ultimately leads to compromised permeability of the outer skin layer predisposing the skin to a variety of skin abnormalities and conditions. Similarly, the mid-skin layer known as the dermis also degrades. In a healthy state the dermis maintains the skin’s structural integrity as it is rich in proteins such as collagen and elastin. With ageing this integrity is progressively reduced.

Additionally, just like all bodily tissue, as skin ages an increased number of cells enter senescence. Senescence is the natural process by which old and damaged cells stop replicating and enter a zombie-like state. Whereas they would normally be removed by our immune system, as we age these senescent cells accumulate and release a highly inflammatory cocktail of chemicals - termed the SASP (senescence-associated secretory phenotype). SASP is known to be a leading cause of low grade chronic inflammation which creeps throughout the entire body such that the inflammatory chemicals produced by these senescent cells affects healthy cells. In skin the problematic effects of senescent cells is aggravated by the numerous negative external stimuli such as sunlight (UV radiation), pollution and smoking. Skin which has been prematurely aged by UV damage carries a particularly heavy load of senescent cells.

Whilst it has long been recognised that ageing causes skin to deteriorate and degrade in appearance as well as function, it is now becoming evident that skin ageing may actually be driving whole body ageing due to this low grade chronic inflammation - inflammaging.

Inflammaging plays a crucial role in the development of many of the chronic diseases of ageing including obesity, Alzheimer’s Disease and type 2 diabetes. Correspondingly inflammatory skin conditions such as eczema and psoriasis are also risk factors for age-associated chronic health conditions. For example, individuals with psoriasis have a higher prevalence of type 2 diabetes and metabolic syndrome and exhibit a higher incidence of cardiac events. Conversely, individuals with chronic diseases of ageing have an increased dysfunction of the epidermis.

Sunscreen blocks UV rays that causes skin damage. The woman applied it to her face, but not her neck. The Journal of the European Academy of Dermatology and Venereology.

So what can we do to preserve the integrity of this vital interface between the internal human body and the external environment? Protection from sunlight is the single most important thing you can do to protect your skin. Sunlight exposure (UV radiation) causes accelerating of the natural ageing of skin.

There are two types of UV radiation - UVA and UVB. UVA radiation makes up the great majority of the sun’s UV rays and it penetrates the skin to manage both the epidermis and dermis causing  sunburn, premature ageing, wrinkling, and certain skin cancers. UVB radiation only goes as deep as the epidermis and causes sunburn, skin cancer and also contributes to ageing. Using a broad spectrum protects against these two types of UV radiation where PA indicates protection grade of UVA and SPF indicates duration of UVB protection. A full spectrum sunscreen protects from both UVA and UVB as well as other forms of light. Protecting your skin from harmful radiation minimises DNA damage which would otherwise accelerate the senescence process.

Other lifestyle factors like having a healthy, balanced diet, getting regular exercise and sufficient quality sleep as well as not smoking and minimising alcohol consumption all contribute to delaying skin ageing. Regular application of topical emollients may also effectively improve epidermal function of ageing skin and therefore positively influence skin inflammation and possibly systemic inflammation.

Although a complete understanding of the mechanisms involved in the ageing process a yet to be fully understood one important hallmark of ageing is inflammaging. This low-level systemic inflammation is likely due to malfunctioning of the immune system, also known as immune senescence. Excessive inflammation of the skin - the largest organ of the body which is uniquely located in direct contact with the internal and external environment - may lead to chronic inflammation throughout the body which may increase the risk of some of the chronic diseases of ageing. 

If you would like to test your personal risk factors for developing chronic diseases of ageing, and find out if you have high markers of inflammation find out more about the Longevity Annual health check and download the longevity doctor guide to healthy living.


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