Differential Effects of Cognitive Load and Deep Brain Stimulation on Dual-Task Performance in Parkinson’s Patients

Many situations in daily life require the simultaneous performance of motor and cognitive tasks, such as reaching for items in the supermarket while recalling a shopping list. For patients with Parkinson’s Disease (PwPD), who already suffer from distinct motor and cognitive symptoms, these situations can be even more challenging. While deep brain stimulation (DBS) provides a promising option for symptom management in the advanced stages of the disease, its effect on everyday life situations has not been explored as much. Thus, using a dual-task paradigm, this study aimed to address this gap by investigating the effects of varying levels of cognitive load and DBS on motor and cognitive performance in PwPD. Eight PwPD with DBS were tested twice: once with DBS turned on and once off. Motor performance was assessed with a custom-designed motor task that required the patients to perform consecutive goal-directed reaching movements. These movements were recorded with a markerless hand...Show moreMany situations in daily life require the simultaneous performance of motor and cognitive tasks, such as reaching for items in the supermarket while recalling a shopping list. For patients with Parkinson’s Disease (PwPD), who already suffer from distinct motor and cognitive symptoms, these situations can be even more challenging. While deep brain stimulation (DBS) provides a promising option for symptom management in the advanced stages of the disease, its effect on everyday life situations has not been explored as much. Thus, using a dual-task paradigm, this study aimed to address this gap by investigating the effects of varying levels of cognitive load and DBS on motor and cognitive performance in PwPD. Eight PwPD with DBS were tested twice: once with DBS turned on and once off. Motor performance was assessed with a custom-designed motor task that required the patients to perform consecutive goal-directed reaching movements. These movements were recorded with a markerless hand-tracking module to capture broad motor performance measures and detailed kinematic data. Cognitive performance was assessed with a serial subtraction task, including high and low levels of cognitive load (subtracting by seven and one, respectively). Finally, linear mixed-effect models were used to statistically compare the effects of DBS, high, and low cognitive load on overall motor and cognitive performance and relevant kinematic features. The results show that high cognitive load negatively affected overall motor and cognitive performance, while low cognitive load only affected cognitive performance. On the other hand, DBS improved overall motor performance while not affecting cognitive performance. Furthermore, high cognitive load and DBS had a significant, yet opposite, effect on the same kinematic features: deceleration time, movement time, reaction time, peak velocity, and coefficient of variation of trajectory error. In conclusion, this study highlights the feasibility of administering more naturalistic experimental designs with a dual-task paradigm and detailed kinematic analyses in PwPD. We show that the dual-task effect is dependent on the amount of cognitive load and that Deep Brain Stimulation can significantly improve motor performance in dual-tasking scenarios. Finally, our detailed kinematic analyses reveal specific components of a reaching movement responsible for changes in motor performance, providing valuable insights for future research and clinical practice.Show less

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Differential Effects of Cognitive Load and Deep Brain Stimulation on Dual-Task Performance in Parkinson’s Patients