New twin study highlights environmental risk factors for skin ageing

Controlling for genetic factors by investigating a number of twin pairs helped researchers in Ohio tease out the effects of a number of lifestyle factors on skin ageing.

The study, published in a recent issue of the Archives of Dermatology, involved 65 twin pairs, ten of which were monozygotic twins (genetically identical). Questionnaires requiring self reported information about skin type, skin cancer history, cigarette and alcohol consumption and weight were administered and a clinical assessment of photodamage for each individual performed.

According to the study, led by Kathryn J. Martires at the Western Reserve School of Medicine, Cleveland, Ohio, when controlling for genetic factors, a number of environmental features affecting skin appearance become apparent.

Sunscreen use, for example, was negatively correlated with the extent of an individual’s photodamage, as was alcohol consumption.

Although the questionnaire did not ask for the details of the alcohol consumed, the researchers suggest that the negative relationship could be due to the protective effects of some alcoholic beverages such as red wine which contains polyphenols with strong antioxidant properties.

However, cigarette smoke was positively correlated with photodamage – the more cigarettes smoked or a history of smoking was associated with an aged appearance of skin.

This, the researchers stated, fits with previous research and is likely to be related to the cigarette smoke inducing matrix metalloproteinases which degrade the structural proteins in the skin.

Weight found to correlate​

Self reported weight was also found to correlate with the photodamage score, but the relationship changed as participants got older.

In individuals younger than 45, excess fat seemed to correlate with higher levels of photodamage. According to the researchers this finding is contradictory to previous Danish research that reported the higher the body mass index the lower the levels of facial ageing.

According to the study, the relationships between self reported weight, lipid intake and levels of photodamage to the skin are complicated. A number of animal studies have suggested that higher fat intake could increase skin sensitivity to UV damage; but, in contrast some lipids may potentially have antoxidative and therefore protective effects.

In addition, in individuals older than 45 the relationship was reversed and higher weight was correlated with reduced photodamage. The researchers suggested that although excess fat might make skin more susceptible to UV damage, it could also mask the appearance of wrinkles in older age.

According to the researchers, theirs is one of the few twin studies examining the link between environmental factors and photodamage.

Source: Archives of Dermatology​
​Vol 145, No 12, Dec 2009, pages 1375- 1379
Factors that affect skin aging​
​Kathryn J. Martires, Pingfu Fu, Amy M. Polster, Kevin D. Cooper, Elma D. Baron