Critical decline in fine motor hand movements in human aging

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). Conclusion: 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.