Exploring cognitive motor interference in multiple sclerosis by the visual Stroop test

Background The dual task paradigm (the simultaneous performance of motor and cognitive task) is used in a laboratory setting to evaluate walking impairments that affect patients’ daily lives. Although promising, it is poorly standardized and neither the cognitive task nor the motor task have been validated in a matched healthy control group (HC) for multiple sclerosis (MS). Objective Our aim was to set up a standardized instrument to evaluate cognitive motor interference in MS using the interference test par excellence: the stroop colour word test (SCWT). Methods Patients with MS and HC underwent 3D gait analysis with a dual task protocol, using the SCWT as a cognitive task. Gait performance impairment during the dual task was evaluated by dual task cost (DTC). A MANOVA was used to verify the effect of status (MS, HC) on DTC, calculated for the spatiotemporal parameter of the gait. Results In MS, the DTC was higher for the following gait parameters: speed (p= 0.013), cadence (p= 0.004), stride time (p= 0.005) stance phase (p<0.001), and swing phase duration (p=0.032). Conclusion DTC is present in MS and HC, but the motor cost in MS is higher. The present work provides a useful and validated basis for future studies about cognitive motor interference in MS.