Anxiety is among the most debilitating nonmotor symptoms of Parkinson's disease (PD). This study aimed to determine how PD patients with low and high levels of anxiety (LA‐PD and HA‐PD, respectively) compare with age‐ and sex‐matched controls at the level of motor control of reach‐to‐grasp movements during single‐ and dual‐task conditions with varying complexity. Reach‐to‐grasp movement kinematics were assessed in 20 LA‐PD, 20 HA‐PD, and 20 sex‐ and age‐matched healthy controls under single‐ as well as easy and difficult dual‐task conditions. Assessment of PD patients was performed during both the on‐ and off‐drug phases. The results obtained during dual‐task conditions reveal deficits in both reach and grasp components for all three groups (e.g., decreased peak velocity and delayed maximum hand opening). However, these deficits were significantly greater in the PD groups, especially in the HA‐PD group. Although dopaminergic medication improved reach kinematics, it had no effect on grasp kinematics. The results of our study indicated that high levels of anxiety may enhance the inefficiency of upper limb motor control in PD patients, especially during high demanding cognitive conditions, and should, therefore, be considered in the assessment and planning of interventions for upper limb function in these patients.

Background and Objectives: To investigate the correlation between reach and grasp kinematic measures and clinical measures of gross and fine manual dexterity in patients with idiopathic Parkinson Disease (PD). Methods: Sixty patients (44 men, 16 women) with idiopathic PD (Mean±SD of age: 59.85±11.89 years) were recruited in this non-experimental cross-sectional study using a non-probability sampling method. Their gross and fine manual dexterity were assessed using the Box and Block Test (BBT) and Nine Hole Peg Test (NHPT), respectively. Also, reach and grasp kinematic measures (including normalized movement time, peak velocity, Maximum Grip Aperture [MGA], and percentage of movement time in which MGA occurred [PMGA]) were measured in the more affected hand. Results: The results showed a significant and moderate correlation between reach kinematic measures (i.e. normalized movement time and peak velocity) and both gross and fine manual dexterity assessed by BBT (P=0.000) and NHPT (P=0.000), respectively. However, there was not a significant correlation between grasp kinematic measures (i.e. MGA and PMGA) and gross manual dexterity measured by BBT (P>0.05) as well as fine manual dexterity assessed by NHPT (P>0.05). Conclusion: This study showed no to moderate correlation between reach and grasp kinematic measures and clinical measures of gross and fine manual dexterity in patients with PD, supporting the significance of multi-level evaluation using both clinical and kinematic measures in the evaluation of upper limb function in patients with PD.

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