Six-Spot Step Test Under Three Different Task Conditions To Assess Dual-Task Ability in People With Multiple Sclerosis

Abstract

Background: The Six-Spot Step Test (SSST) is a valid measure to assess the ability of people with multiple sclerosis (pwMS) to maintain balance whilst challenging stability during walking. This study aimed to compare the performance of three different SSST conditions in pwMS and healthy controls (HC) and to explore whether incorporating cognitive tasks into the SSST improves its discriminative capacity by increasing cognitive load. Methods: Fifty-two pwMS (median EDSS = 1.75) and 19 HC were recruited. Participants performed the SSST under three different task conditions: conventional SSST, SSST with word-list generation task (WLG), and SSST with the serial-7 backward task. The dual-task cost (DTC) was calculated for two cognitive task conditions. Results: There was a significant difference across different SSST conditions in both groups. There was also significant condition*group interaction [F (2,132) = 3.69, p = 0.028, eta(2) = 0.053]. PwMS completed all SSST conditions in a longer duration compared to HC. The DTC of SSST with backward and WLG tasks was greater in the MS group than in HC. However, there was no significant differences in the number of correct answers during the dual-task conditions between pwMS and HC. All three conditions showed excellent discriminative ability between pwMS and HC (Area Under Curve value > 0.8). Significance: The SSST had the ability to discriminate between pwMS and HC in both conventional method and with secondary cognitive task. The SSST could be used to evaluate early walking and dual-task deficits even in pwMS with mild disability for future research and clinical practice.