Old age

As humans get older, the skin becomes thinner, less elastic, drier and more finely wrinkled. The degree to which the skin becomes visibly aged is related largely to genetics and photo-ageing. In other words, wrinkle formation is determined by the traits inherited from parents and the extent to which someone has exposed themselves to sunshine over their lifetime. Intrinsic ageing describes the natural biological processes which it is not possible to control and extrinsic ageing the impact that the environment and exposure to it has on the skin. It is possible to get a sense of the impact of extrinsic factors by comparing the skin of a sun-exposed and non-sun-exposed site. In an elderly person, particularly, there is a marked difference between the texture and colouring, the former being much smoother and less wrinkled.

The changes highlighted in Table 2.4 mean that older skin is increasingly sensitive and less able to cope with external stressors on the skin. Thus the skin has less innate ability to cope with external agents such as perfumes in topical products, extremes of temperature, urine and faeces. These factors are discussed further in Protecting the skin and preventing breakdown.

Table 2.4 Skin changes caused by ageing.   Changes in the skin Consequence   Epidermal turnover slows Thinner skin   Less effective barrier function More prone to infection/dryness   Less flexible and tough collagen More prone to wrinkles and sheering   Less evenly distributed melanin More prone to sun damage   Fewer sweat glands Less effective temperature control   Less sebum production Increased skin dryness

Overexposure to UV radiation is responsible not only for the effects of ageing but also more worryingly for skin cancers. Basal and squamous cell carcinomas are both closely associated with prolonged sun exposure and whilst they are rarely life threatening, they can be locally destructive and need to be properly diagnosed and treated. Malignant melanomas are also associated with sun exposure, although burning is generally thought to be a high risk factor. Skin malignancies are discussed later in Skin cancer and its prevention.