Objective: To compare task-related brain activity during a touchscreen task in Parkinson’s disease (PD) patients and healthy controls (HC) in single (ST) and dual task (DT) condition.

Background: The loss of motor automaticity in PD increases attentional processing possible leading to overload during DT. However, the impact of adding cognitive distractions to a touchscreen task, and its neural correlates have not yet been examined.

Method: Thirty-eight HC (age 68±8) and 39 cognition-matched PD patients (age 69±9, HYII-III), off medication, were randomized to perform the Swipe-Slide Pattern task in either ST or DT conditions in the MRI scanner. The secondary task consisted of counting red or green lights presented in the periphery. We calculated the movement time (MT, s) to complete a pattern and the Euclidean distance (ED) for the target path as an accuracy measure. We estimated task-related brain activity using a general linear model with the BOLD timeseries for each ROI (400 cortical, 28 cerebellar, 54 subcortical). A two-way ANOVA examined the influence of GROUP (PD vs HC) and TASK (ST vs DT).

Results: Behaviourally, we found a GROUP x TASK interaction for MT (F=4.374; p=0.04) and main effects of GROUP and TASK for ED (F>5.6; p<0.05), indicating faster and more accurate performance in DT vs ST. The faster performance in DT vs ST was driven by PD. At the neural level, we found lower activity in 6 regions of the default mode network (DMN), and more activity in the primary visual cortex in PD vs HC (F>7.1; p<0.01). Across groups, 21 regions from cognitive control and visual networks showed more activity in DT vs ST (F>7.1; p<0.01). Finally, we found a significant GROUP x TASK interaction for 8 regions of the somatomotor and ventral attention networks (F>7.5; p<0.01), indicating less activity in PD than in HC in DT vs ST.

Conclusion: Unexpectedly, PD performed faster and more accurate during DT vs ST, whereas HC showed a consistent performance. Overall, PD showed higher engagement (i.e., less active DMN) and higher visual guidance compared to HC. Both groups were able to increase cognitive control and visual processing required by the DT. However, PD recruited less somatomotor and ventral attention networks during DT, suggestive of an overload. Nevertheless, these results suggest that adding cognitive distractions to a touchscreen task caused limited behavioural interference in PD, due to intact cognitive control and visual recruitment.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/neural-correlates-of-dual-task-touchscreen-performance-in-parkinsons-disease/