In Search of Manual Asymmetries in Aging during Performance of Activities of Daily Living: Does Upper Limb Performance Become More Symmetric with Age?
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Introduction: A common disorder arising most frequently after a left hemisphere stroke is limb apraxia. Limb apraxia is a deficit of skilled movement, such as performance of activities of daily living (ADLs), that is not a result of primary motor or sensory impairments, or deficits in motivation, memory, or comprehension (De Renzi, 1990). Currently, clinical neuropsychological assessment of apraxia relies largely on qualitative analyses of gross movements during the performance of activities of daily living in two task conditions (pantomime and tool). Further, apraxic patients often perform ADLs with their non-dominant limb to avoid often-present right-hand hemiparesis, but the assessment does not adequately account for this. Thus, it is unclear whether movement deficits are due to non-dominant limb use or limb apraxia. Moreover, it is not known how different task conditions and aging influence the performance of ADLs in healthy populations, as well as manual asymmetries. Purpose: The purpose of this thesis was to: 1. determine if age affects the magnitude of manual asymmetry in the performance of two ADLs (drinking water from a cup and slicing a loaf of bread with a knife); 2. determine if different task demands (pantomime and tool condition) affect magnitude of manual asymmetries during the performance of ADLs; and 3. determine if aging affects how task demands are expressed during the performance of ADLs. Methods: Fifty healthy right-hand dominant (as determined via Waterloo Handedness Questionnaire) younger and older adults participated in this study. A grooved pegboard task was completed by all participants prior to performance of the two ADLs using motion tracking. Upper limb movements (dominant and non-dominant limb) were captured at 60 Hz via a motion capture system (Vicon, Oxford, UK). Participants performed two task conditions: 1) pantomime (pretending to perform an ADL without holding the tool); and 2) tool (pretending to perform an ADL while holding the tool) in two ADLs: drinking water from a cup and slicing a loaf of bread with a knife. Each ADL was performed six times by both limbs. ADLs and limbs were randomized, while task conditions were blocked randomized between participants. Results: Overall, this study found that aging slows down motor performance on the Grooved Pegboard task, as well as the performance of both ADLs. Manual asymmetries were task dependent. The cup and knife ADL were both characterized by larger manual asymmetries in older adults relative to the younger adult group, particularly in terms of angular movement. Further, it was found that task demands were expressed differently in older adults relative to younger adults, with the tool condition yielding performance improvements in both groups. Conclusions: Despite the previous research, which has shown that manual asymmetries are reduced in older adults during the performance of motor tasks, this investigation points to the opposite during the performance of activities of daily living. Aging appears to increase the degree to which manual asymmetries are expressed. Further, aging also appears to play a role in the change in temporal and angular aspects of movement during the performance of ADLs in different task conditions. The degree to which task demands as reflected in the two task conditions improve or impair performance in healthy populations should be taken into consideration when evaluating ADL performance in patients with limb apraxia. In accordance with the previous research on aging, this study has shown that upper limb movements become slower as individuals age. Kinematic relationships presented in this study provide researchers and clinicians with an insight into how manual asymmetries, aging and different task demands come into play during the performance of one cyclical and non-cyclical task.