Improved Dual-Task Interference in Parkinson’s Disease Following Deep Brain Stimulation

This work aims to evaluate how Deep Brain Stimulation (DBS) impacts the motor-cognitive dual-task performance of Parkinson's Disease (PD) patients. We analyzed the muscle synergies of 27 PD patients at T0 (pre-surgery), T1 (3 months post-surgery), and T2 (12 months post-surgery), compared to a control group of 30 age-matched individuals, during a walking task and a motor-cognitive dual task (walking while performing a phonemic fluency task). To evaluate dual-task interference, the Dual Task Effect (DTE) of both motor and cognitive metrics was analyzed. Our findings demonstrate that DBS significantly enhances dual-task capacity, with PD patients transitioning from a detrimental "posture-second"strategy at T0 to a more efficient attentional allocation pattern post-surgery. More specifically, the average motor metric mDTEFWHM (DTE of the Full-Width-at-Half-Maximum of the muscle synergy activation coefficients) of PD patients changed from -12.5 ± 11.5 % (T0) to -3.7 ± 10.2 % (T1) and -4.5 ± 8 % (T2), becoming not different from that of controls (-1.1 ± 12.7 %). On the other hand, the PD cognitive DTE (cDTE) at T0 was -12.4 ± 23.2 %, not significantly different from that of controls (-23.0 ± 21.0 %), and remained unchanged 1 year after the DBS implant (T2: -11.2 ± 25.9). The reduced impact of cognitive loading on motor function without compromising cognitive performance suggests enhanced attentional resource management of PD patients after DBS that may translate to improved dynamic balance and reduced fall risk in daily activities.