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 = .013), cadence (p = .004), stride time (p = .005) stance phase (p < .001), and swing phase duration (p = .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.