The impact of distinct cognitive dual-tasks on gait in Parkinson's disease and the associations with the clinical features of Parkinson's disease

Aims To investigate the impact of distinct cognitive dual-task abilities in patients with Parkinson's disease (PD) and compare the impact of these dual-tasks in association with the severity of PD and its clinical features. Materials and methods Modified Hoehn and Yahr Scale, UPDRS, and Standardized Mini-Mental State Examination (SMMSE) were evaluated in all PD patients. The subtype of PD and the presence of freezing of gait (FOG) were also evaluated. The Timed Up and Go (TUG) test was applied under single- and dual-task conditions including the digit span-forwards, digit span-backwards, delayed recall memory, counting down the days, counting backwards from 20, and animal fluency tests. Results Most of the cognitive dual-tasks resulted in deterioration in gait performance in our PD subjects. Remarkably, the completion time of TUG duration under single- and dual-task of counting down days was higher in the FOG (+) PD subjects (p = 0.008, p = 0.050, respectively). Besides, the TUG duration under the dual-task of counting down days was found to be positively correlated with the UPDRS-motor scores and FOG scores. Conclusion We think that the concurrent execution of the dual-task of counting down days, which requires complex attentional skills, may disturb gait via a mechanism of overloading of the attentional reserves proceeding gait which is already defective in PD subjects. The neural correlate of this domain and its significance in performing dual-tasks in PD should be investigated in future large-scale studies. The results of these studies may provide substantial perspectives regarding the pathophysiology of gait disturbance in PD.