Background: Day-to-day reliability and cut-off values to detect abnormal walking fatigability (WF) remain to be investigated in persons with multiple sclerosis (pwMS). Methods: In all, 49 pwMS (mean Expanded Disability Status Scale (EDSS) ± standard deviation (SD): 3.3 ± 1.9) and 28 matched healthy controls (HC) performed the six-minute walking test (6MWT) on two different days to determine day-to-day reliability (intraclass correlation coefficient (ICC)) and limits of agreement (LOA) for five different equations of WF. Objective: To examine day-to-day reliability, agreement and discriminative validity for measuring WF. Results and conclusion: WF expressed as the ratio between the first and sixth minute had the best day-to-day reliability (ICC’s range of 0.76–0.95 and 0.60–0.86, respectively) in both pwMS and HC, while LOA were 15% and 7%, respectively. Ecological validity and clinical importance should be further investigated.

Background: Simultaneous execution of motor and cognitive tasks can result in worsened performance on one or both tasks, indicating cognitive motor interference (CMI). A growing amount of research on CMI in persons with Multiple Sclerosis (pwMS) is observed. However, psychometric properties of dual-task outcomes have been scarcely reported.Objective: To investigate the between-day test-retest reliability of the motor and cognitive dual-task costs (DTC) during multiple CMI test conditions with various task complexity in pwMS and matched healthy controls (HC).Methods: 34 pwMS (Expanded Disability Status Scale score 3.0±0.8) and 31 HCs were tested and retested on three single cognitive, four single motor and twelve cognitivemotor dual-tasks. Cognitive tasks included serial subtraction by seven, titrated digit span backwards and auditory vigilance. Motor tasks were walking: at self-selected speed, over obstacles, crisscross and while carrying a water-filled cup. Outcome measures were cognitive and motor DTC, calculated as percentage change of dualtask performance compared to single-task performance. Intraclass correlations (ICCs) and Spearman correlation coefficients were calculated as appropriate.Results: For DTCmotor of gait speed, ICCs ranged from 0.45 to 0.81 and Spearman correlations from 0.74 to 0.82. For DTCcognitive, ICCs ranged from -0.18 to 0.49 and Spearman correlations from -0.28 to 0.26. Reliability depended on the type of motor and cognitive task.Conclusion: Reliability of the DTCmotor was, overall, good, while that of the DTCcognitive was poor. The 'walking' and 'cup' dual-task conditions were the most reliable regardless of the integrated cognitive task.3

The aim was to compare the effectiveness of dual-task training (DTT) compared to single mobility training (SMT) on dual-task walking, mobility and cognition, in persons with Multiple Sclerosis (pwMS). Forty pwMS were randomly assigned to the DTT or SMT groups. The DTT-group performed dual-task exercises using an interactive tablet-based application, while the SMT-group received conventional walking and balance exercises. Both interventions were supervised and identical in weeks (8) and sessions (20). Nine cognitive-motor dual-task conditions were assessed at baseline, after intervention and at 4-weeks follow-up (FU). The dual-task cost (DTC), percentage change of dual-task performance compared to single-task performance, was the primary outcome. Mobility and cognition were secondarily assessed. Mixed model analyses were done with group, time and the interaction between group and time as fixed factors and participants as random factors. Significant time by group interactions were found for the digit-span walk and subtraction walk dual-task conditions, with a reduction in DTC (gait speed) for the DTT maintained at FU. Further, absolute dual-task gait speed during walking over obstacles only improved after the DTT. Significant improvements were found for both groups in various motor and cognitive measures. However, the DTT led to better dual-task walking compared to the SMT.

Background: Performing a cognitive task and a motor task simultaneously is an everyday act that can lead to decreased performance on both tasks.Objective: To provide insight into the neural correlates associated with cognitive-motor dual tasking in individuals with a neurologic disorder. Method:We searched the PubMed and Web of Science databases for studies that had been published up to January 16 th , 2019. Studies investigating the neural correlates of cognitivemotor dual task performance in individuals with a variety of neurologic disorders were included, independently from whether the study included healthy controls. Clinical and imaging data were abstracted for the comparison between single tasks and a dual task in the individuals with a neurologic disorder and for the comparison between the healthy controls and the individuals with a neurologic disorder. Results: Eighteen studies met the inclusion criteria. Study populations included individuals with Parkinson disease, multiple sclerosis, mild cognitive impairment, Alzheimer disease, CBN-20-51 Veldkamp 3 traumatic brain injury, and stroke. Neuroimaging types used to study the neural correlates of cognitive-motor dual tasking during upper limb or gait tasks included fMRI, functional nearinfrared spectroscopy, EEG, and PET. Conclusion:Despite large heterogeneity in study methodologies, some recurrent patterns were noted. Particularly, in neurologic patients, an already higher brain activation during single tasks was seen compared with healthy controls, thereby compromising the patients' ability to further adapt brain activation with increasing load during dual tasking and resulting in reduced behavioral dual task performance.Systematic Review Registration: Prospero (Identifier CRD42019129975).

Background: Cognitive–motor interference (CMI) is measured by dual-tasking (DT), which involves motor and cognitive tasks. There is no consensus as to whether CMI is present in multiple sclerosis (MS). Objectives: We investigated the effects of 16 DT conditions by measuring motor complexity, cognitive domain, and task difficulty. Method: In total, 40 persons with MS (pwMSs) with Expanded Disease Status Scale (EDSS) 3.2 ± 1.7 and 31 age- and sex-matched healthy controls (HCs) completed 2 single walking, 8 single cognitive, and 2 complex walking tasks and 16 cognitive–motor DT. The main outcomes were mean values of gait velocity and the percentage change from single to DT (motor DT costs, mDTCs) and mean values of cognitive task accuracy and the percentage changes (cognitive DTC, cDTC). Results: Two-way analyses of variance showed the main effect of cognitive task yielded an F ratio of F (4, 268) = 72.35, p < 0.01, for mean gait velocity, and an F ratio of F (4, 304) = 17.12, p < 0.001, for mDTC, indicating that the mean velocity was significantly lower and the mDTC significantly higher for DS_B (mean = 1.27, SD = 0.03, and mean = 13.52, SD = 1.28, respectively). The main effect of cognitive task yielded an F ratio of F (4, 116) = 84.32, p < 0.001, with the lowest average accuracy for DS_B (mean = 43.95, SD = 3.33); no effect was found for cDTC. In pwMSs, the EDSS accounted for 28% ( F = 13.65, p = 0.001) of variance in a model predicting the highest mDTC. Conclusions: Overall, among different cognitive tasks added, the Digit Span backward was the most interfering cognitive task over gait velocity and accuracy. The effect was similar independently from the motor complexity and the group. PwMSs and HCs behaved in a similar manner at all motor complexity levels and during all cognitive task.