Abstract
This study examined the influence of motor symptom asymmetry in Parkinson's disease (PD) on Grooved Pegboard (GP) performance in right-handed participants. The Unified Parkinson's Disease Rating Scale was used to assess motor symptoms and separate participants with PD into two groups (right-arm affected, left-arm affected) for comparison with a group of healthy older adults. Participants completed the place and replace GP tasks two times with both hands. Laterality quotients were computed to quantify performance differences between the two hands. Comparisons among the three groups indicated that when the nonpreferred hand is affected by PD motor symptoms, superior preferred hand performance (as seen in healthy older adults) is further exaggerated in tasks that require precision (i.e., place task). Regardless of the task, when the preferred hand is affected, there is an evident shift to superior left-hand performance, which may inevitably manifest as a switch in hand preference. Results add to the discussion of the relationship between handedness and motor symptom asymmetry in PD.
Highlights
Parkinson’s disease (PD) is defined by asymmetric motor symptoms of tremor, rigidity, and bradykinesia [1, 2]
Acknowledging that a dearth of literature exists analyzing the relationship between functional laterality as reflected in relative hand performance on tests of motor function and asymmetry of motor symptoms associated with the disorder, recent publications have argued whether handedness can be used to predict side of onset of PD
A main effect of group (F(2, 248) = 32.256, p < .001, η2 = .206) revealed laterality quotients of all three groups differed. Both H-OA (M = 4.43, SD = 6.78) and LSA-PD (M = 7.64, SD = 13.33) groups had positive laterality quotients, indicative of superior right-hand performance; laterality quotients for the LSA-PD group were significantly greater than the H-OAs (p = .021)
Summary
Parkinson’s disease (PD) is defined by asymmetric motor symptoms of tremor, rigidity, and bradykinesia [1, 2]. This right-left asymmetry has been an influential factor when differentiating PD from other, similar movement disorders [3]. The reason for this symptom asymmetry is unknown; it may be influenced by handedness [4]. Acknowledging that a dearth of literature exists analyzing the relationship between functional laterality as reflected in relative hand performance on tests of motor function and asymmetry of motor symptoms associated with the disorder, recent publications have argued whether handedness can be used to predict side of onset of PD. Based on the hand used for writing [7], clinician
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