There is a study that was published in 2010, in the British Journal of Dermatology.
An 8-year longitudinal study on the progression of expression lines into persistent wrinkles
- Methods: Standardized images were captured at baseline and at 8 years of 122 women (ages 10–72 years, skin types I–VI) with and without a smiling expression. The wrinkle pattern with expression at baseline was compared with the pattern without expression at 8 years. Severity of facial wrinkling was quantified using computer-based image analysis. Skin colour, hydration, sebum and pH were measured at baseline. A structured questionnaire captured demographic and lifestyle data at baseline and at 8 years.
- Results: Each subject’s unique pattern of persistent facial wrinkling observed without expression at year 8 was predicted by the pattern of lines observed with a smiling expression at baseline. Having a drier, more alkaline stratum corneum, a lighter complexion, being middle-aged (40s) or becoming menopausal were associated with faster persistent wrinkling.
Temporary facial wrinkles visible only with a smiling expression in 1999 were predictive of and progressed into persistent wrinkles visible without expression in 2008.
African Americans showed the least change in both persistent and temporary wrinkling from 1999 to 2008, significantly less than that of Caucasians
Conclusions:
- Persistent wrinkles evolve from temporary wrinkles.
- The pattern of expression lines predicts the pattern of future persistent wrinkles.
- While skin wrinkling progressively increases over one’s lifetime, the most significant period of change was in the 40s.
- Certain intrinsic and extrinsic factors are not causative, but influence the rate, of facial wrinkling
- Lighter and/or dryer skin individuals are more prone to skin wrinkling than their darker and more hydrated counterparts.
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