Age-Related Attenuation of Dominant Hand Superiority

The decline of motor performance of the human hand-arm system with age is well-documented. While dominant hand performance is superior to that of the non-dominant hand in young individuals, little is known of possible age-related changes in hand dominance. We investigated age-related alterations of hand dominance in 20 to 90 year old subjects. All subjects were unambiguously right-handed according to the Edinburgh Handedness Inventory. In Experiment 1, motor performance for aiming, postural tremor, precision of arm-hand movement, speed of arm-hand movement, and wrist-finger speed tasks were tested. In Experiment 2, accelerometer-sensors were used to obtain objective records of hand use in everyday activities

Age-related change of performance in fine motor tasks

<div><p>Group data illustrating right and left hand performance (±SEM) in “steadiness”, “line tracing”, “aiming” and “tapping” tasks.</p> <p>Linear Pearson's correlations revealed a significant influence of age on almost all parameters: steadiness (number of errors, <b>a</b>), line tracing (number of errors, <b>b</b>, total time right hand, <b>c</b>), aiming (total time, <b>d</b>) and tapping (number of hits, <b>f</b>) (p≤0.001).</p> <p>Only for line tracing (total time for the left hand, <b>c</b>), and aiming (number of errors, <b>e</b>) were a lack of age related influences found (p≥0.069).</p></div

Examination of fine motor performance

<div><p>A commercial test-series was used to measure the fine motor performance of both hands.</p> <p>The “steadiness” task describes the ability to maintain prescribed arm-hand positions (<b>a</b>).</p> <p>“Line tracing” describes the ability to fulfil precise arm-hand movements (<b>b</b>).</p> <p>“Aiming” describes the ability to accomplish fast movements directed at small targets (<b>c</b>).</p> <p>Finally, “tapping” describes the ability to perform very fast, repetitive hand movements (<b>d</b>).</p></div

Changing hand use over the lifespan

<div><p>Illustration of age-dependent changes in the laterality indices (±SEM) obtained from acceleration measurements used to objectively assess the frequency of hand use (+1 for right hand superiority to –1 for left hand superiority) for all subjects tested (n = 36).</p> <p>There is a significant linear correlation of individual laterality indices with age (Pearson, r = −0.447, p = 0.007) indicative of a loss of right (dominant) hand advantage with age.</p></div

Contradictory results of questionnaires and practical tasks

<div><p>Three dimensional plot illustrating the age-dependence of the sensitivity of the EHI-scores obtained from the Edinburgh Handedness Inventory, and the laterality indices averaged over all motor tasks and parameters (laterality of motor performance) for the 4 age groups investigated.</p> <p>While subjects of all age groups are characterized by approximately the same handedness score (EHI ≥ 70), there is a distinct reduction in laterality, indicating that the age-related loss of dominant hand advantage remains largely unrealized by the subjects.</p></div

Laterality indices for fine motor performance

<p>Averaged laterality indices (±SEM) for the total time in the aiming task (a), number of errors in the steadiness task (b), the line tracing task (c), and the total time needed for the line tracing task (d).</p

Age-related attenuation of dominant hand superiority

$\textit {Background.}$ The decline of motor performance of the human hand-arm system with age is well-documented. While dominant hand performance is superior to that of the non-dominant hand in young individuals, little is known of possible age-related changes in hand dominance. We investigated age-related alterations of hand dominance in 20 to 90 year old subjects. All subjects were unambiguously right-handed according to the Edinburgh Handedness Inventory. In Experiment 1, motor performance for aiming, postural tremor, precision of arm-hand movement, speed of arm-hand movement, and wrist-finger speed tasks were tested. In Experiment 2, accelerometer-sensors were used to obtain objective records of hand use in everyday activities. $\textit {Principal Findings.}$ Our data confirm previous findings of a general task-dependent decline in motor performance with age. Analysis of the relationship between right/left-hand performances using a laterality index showed a loss of right hand dominance with advancing age. The clear right-hand advantage present at younger ages changed to a more balanced performance in advanced age. This shift was due to a more pronounced age-related decline of right hand performance. Accelerometer-sensor measurements supported these findings by demonstrating that the frequency of hand use also shifted from a clear right hand preference in young adults to a more balanced usage of both hands in old age. Despite these age-related changes in the relative level of performance in defined motor tasks and in the frequency of hand use, elderly subjects continued to rate themselves as unambiguous right-handers. $\textit {Conclusion.}$ The discrepancy between hand-specific practical performance in controlled motor tests as well as under everyday conditions and the results of questionnaires concerning hand use and hand dominance suggests that most elderly subjects are unaware of the changes in hand dominance that occur over their lifespan, i.e., a shift to ambidexterity