Simultaneous performance of motor and cognitive tasks in persons with multiple sclerosis: dual task assessment

Abstract

People with multiple sclerosis (MS) suffer from motor and cognitive impairments. In recent years, some studies investigated the impact of performing both cognitive and motor task simultaneously compared to singular. A decreased velocity by taking fewer and shorter steps was found. So far, cognitive-motor testing was mostly only executed once, with a current lack of knowledge on its reliability limiting its use as an experimental outcome measure. For this reason, we wanted to investigate the between-day reliability of dual task costs (on cognition and mobility) during diverse cognitive-motor interference test conditions in 22 persons with MS (pwMS) and 22 age-gender matched healthy controls. Cognitive tasks were: counting backwards by seven, titrated digit span backwards and auditory vigilance with alphabet. Motor tasks were: walking at a self-selected speed, walking while stepping over low obstacles, walking crisscross and walking while carrying a cup filled with water. Experimental outcome measure was the cognitive-motor interference (CMI), expressed in cognitive, motor and combined dual task cost (DTC). Reliability of the motor DTC was better than cognitive DTC. The most reliable test of all dual task conditions was the 'vigilance walk', who showed the highest correlation in both groups for combined (and motor) DTC, but not for cognitive DTC. There were no clear and systematic differences on reliability between the MS and HC group.