title: Age-dependent changes in damage processes of hair cuticle.
abstract: BACKGROUND
  Human hair cuticle is always exposed to various stresses and then gradually lost in daily life. There are two typical patterns of cuticle damage: type L, where the cell membrane complex, the structure located between cuticle cells, is split and the cuticle lifts up, and type E, where the fragile substructure of the cuticle cell (endocuticle) is damaged so that its rugged residue is exposed. We previously reported that type L damage preferentially occurs in the case of Japanese females in their 20s to 40s.
  
  
  OBJECTIVE
  This study aims to elucidate the age-dependent change of cuticle and its effect on hair properties.
  
  
  METHODS
  Hair fibers collected from Japanese females (ranging from 10 to 70 years old) were evaluated in the aspects of inclination for each type of damage, resistance of cuticle against grooming stresses and content of fatty acid 18-MEA on hair surface.
  
  
  RESULTS
  It was revealed that the dominant damage pattern shifts from type L to E with aging. Furthermore, the cuticle becomes gradually less resistant to daily grooming stress. The dominance of type E damage accelerates cuticle loss. Reduction of 18-MEA on weathered hair is accelerated with aging on elder hair.
  
  
  CONCLUSIONS
  It has been reported that various age-dependent changes of whole hair shaft, such as diameter, density, elasticity, etc., occur in the age range of 40s and 50s. In this study, it was revealed that cuticle becomes more fragile and the hair surface properties deteriorate in the same age range.
authors.affiliation: R&D - Development Research - Hair Care Products Research, Kao Corporation, Tokyo, Japan; The United Graduate School of Drug Discovery and Medical Information Sciences, Gifu University, Gifu, Japan.
authors.forename: Toshie
authors.initials: T
authors.lastname: Takahashi
authors.forename: Akira
authors.initials: A
authors.lastname: Mamada
authors.forename: Steven
authors.initials: S
authors.lastname: Breakspear
authors.forename: Takashi
authors.initials: T
authors.lastname: Itou
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Tanji
mesh_terms: D000375:Aging / Q000502:physiology*; D044466:Asian People; D004537:Eicosanoic Acids / Q000032:analysis; D004548:Elasticity; D005260:Female; D018859:Hair Follicle / Q000737:chemistry / Q000473:pathology* / Q000502:physiology; D006801:Humans; D006920:Hygiene; D013499:Surface Properties
chemical_list: D004537:Eicosanoic Acids; C111345:18-methyleicosanoic acid
keywords: age; cmc; cuticle; hair; weathering