title: Critical decline in fine motor hand movements in human aging.
abstract: BACKGROUND
  Slowing of motor movements in human aging is a well-known occurrence, but its biologic basis is poorly understood. Reliable quantitation may refine observations of this phenomenon to better aid research on this entity.
  
  
  METHODS
  A panel equipped with timing sensors under computer control was used to measure upper extremity movement times in two groups of healthy individuals: adults younger than 60 years of age (n = 56; range, 18-58 years) and adults older than 60 years of age (n = 38; range, 61-94 years).
  
  
  RESULTS
  Fine motor performance was better in the dominant hand (p = 0.0007) regardless of age. Adult and aged groups differed on two basic timing measures, which reflect coarse motor and fine motor performance (p < 0.0001). There were no gender differences on either measure. There was a strong effect of task difficulty with age on coarse motor (p < 0.01) and fine motor (p < 0.0001) measures. The fine motor measure of hand performance in healthy individuals correlated in a nonlinear fashion with age for more difficult tasks (r2 = 0.63) but showed a simple linear relation for less-demanding tasks (r2 = 0.5).
  
  
  CONCLUSIONS
  This technique sensitively detects age-related motor performance decline in humans. There may be a critical period in late midlife when fine motor performance decline either begins or abruptly worsens.
authors.affiliation: Department of Neurology, Sanders-Brown Center on Aging, University of Kentucky College of Medicine, Lexington, USA. csmith@mri.uky.edu
authors.forename: C D
authors.initials: CD
authors.lastname: Smith
authors.forename: G H
authors.initials: GH
authors.lastname: Umberger
authors.forename: E L
authors.initials: EL
authors.lastname: Manning
authors.forename: J T
authors.initials: JT
authors.lastname: Slevin
authors.forename: D R
authors.initials: DR
authors.lastname: Wekstein
authors.forename: F A
authors.initials: FA
authors.lastname: Schmitt
authors.forename: W R
authors.initials: WR
authors.lastname: Markesbery
authors.forename: Z
authors.initials: Z
authors.lastname: Zhang
authors.forename: G A
authors.initials: GA
authors.lastname: Gerhardt
authors.forename: R J
authors.initials: RJ
authors.lastname: Kryscio
authors.forename: D M
authors.initials: DM
authors.lastname: Gash
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006225:Hand / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009068:Movement / Q000502:physiology*; D012044:Regression Analysis