title: New wrinkles on wrinkling: an 8-year longitudinal study on the progression of expression lines into persistent wrinkles.
abstract: BACKGROUND
  While cumulative lifetime sun exposure is well recognized as having an important role in the progression of facial wrinkling, the role of facial expression has largely been overlooked, in part due to the lack of comprehensive longitudinal data on the change in both expression lines and persistent wrinkles with age.
  
  
  OBJECTIVE
  To track the detailed pattern of facial wrinkling in the same group of people over several years and to verify that expression lines evolve into persistent wrinkles. In addition, to identify factors predictive of a faster or slower rate of wrinkling.
  
  
  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.
  
  
  CONCLUSIONS
  Repeated skin flexure during facial expression causes persistent wrinkles. The pattern of expression lines predicts the pattern of future persistent wrinkles. Certain intrinsic and extrinsic factors are not causative, but influence the rate, of facial wrinkling.
authors.affiliation: The Procter & Gamble Company, Cincinnati, OH 45241, USA. hillebrand.gg@pg.com
authors.forename: G G
authors.initials: GG
authors.lastname: Hillebrand
authors.forename: Z
authors.initials: Z
authors.lastname: Liang
authors.forename: X
authors.initials: X
authors.lastname: Yan
authors.forename: T
authors.initials: T
authors.lastname: Yoshii
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D005145:Face; D005149:Facial Expression; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007091:Image Processing, Computer-Assisted; D008019:Life Style; D008137:Longitudinal Studies; D008875:Middle Aged; D012629:Sebum / Q000378:metabolism; D012867:Skin / Q000737:chemistry / Q000378:metabolism; D015595:Skin Aging / Q000473:pathology* / Q000502:physiology; D011795:Surveys and Questionnaires; D055815:Young Adult