Critical decline in fine motor hand movements in human aging

Background: Slowing of motor movements in human aging is a well-known occur rence, but its biologic basis is poorly understood. Reliable quantitation m ay refine observations of this phenomenon to better aid research on this en tity. 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 yea rs) and adults older than 60 years of age (n = 38; range, 61-94 years). Res ults: Fine motor performance was better in the dominant hand (p = 0.0007) r egardless of age. Adult and aged groups differed on two basic timing measur es,which reflect coarse motor and fine motor performance (p < 0.0001). Ther e were no gender differences on either measure; There was a strong effect o f 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 indi viduals correlated in a nonlinear fashion with age for more difficult tasks (r(2) = 0.63) but showed a simple linear relation for less-demanding tasks (r(2) = 0.5). Conclusion: This technique sensitively detects age-related m otor performance decline in humans. There may be a critical period in late midlife when fine motor performance decline either begins or abruptly worse ns.