title: Hair loss among elderly men: etiology and impact on perceived age.
abstract: BACKGROUND
  Androgenetic alopecia is the most common type of hair loss in men, but little is known about the etiology of androgenetic alopecia in elderly men and its impact on perceived age. Here we used a population-based twin study of men aged 70+ to assess the magnitude of the genetic component affecting hair loss and to examine the association between baldness and perceived age.
  
  
  METHODS
  In the fourth wave of The Longitudinal Study of Aging Danish Twins we obtained digital photos of the face and photos of the vertex area of 739 elderly male twins, including 148 intact twin pairs. The degree of baldness and perceived age were assessed in each twin by five and nine nurses, respectively. The heritability of balding was estimated using structural-equation analysis, and it was tested whether baldness was associated with estimations of age.
  
  
  RESULTS
  The intrapair correlation of degree of balding was consistently higher for monozygotic than for dizygotic twin pairs regardless of the baldness categorization used, and structural-equation analysis revealed a heritability of 79% (95% confidence interval, 0.40--0.85) for the mean baldness index. The remaining variation could be attributed to non-shared environmental effects. There was only a very weak and statistically nonsignificant association between baldness and overestimation of age.
  
  
  CONCLUSIONS
  The majority of the variation in baldness in elderly men can be explained by genetic factors, and hair quantity has little impact on perceived age in elderly men.
authors.affiliation: The Danish Twin Registry, Epidemiology Unit, Institute of Public Health, University of Southern Denmark, Odense C, Denmark.
authors.forename: Helle
authors.initials: H
authors.lastname: Rexbye
authors.forename: Inge
authors.initials: I
authors.lastname: Petersen
authors.forename: Maria
authors.initials: M
authors.lastname: Iachina
authors.forename: Jakob
authors.initials: J
authors.lastname: Mortensen
authors.forename: Matt
authors.initials: M
authors.lastname: McGue
authors.forename: James W
authors.initials: JW
authors.lastname: Vaupel
authors.forename: Kaare
authors.initials: K
authors.lastname: Christensen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000473:pathology*; D000505:Alopecia / Q000235:genetics / Q000473:pathology* / Q000523:psychology*; D003718:Denmark; D004200:Diseases in Twins / Q000235:genetics / Q000473:pathology / Q000523:psychology; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010465:Perception; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic