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Abstract
Objective: To investigate which concurrent cognitive task (if any) had the most detrimental effect on balance control of patients with multiple sclerosis (MS).
Methods: In a dual-task experiment, we evaluated the reciprocal effect of simultaneously performing a postural and a cognitive task on balance and cognition in 52 patients and 26 sex- and age-matched controls. Balance was assessed by static posturography, while cognition was scored as number of correct items at 3 different neuropsychological tests, i.e., the Symbol Digit Modalities Test (SDMT), word list generation (WLG), and Stroop Color-Word Test (SCWT).
Results: In both single and dual-task conditions, the patients had larger postural sway and worse scores at SDMT, WLG, and SCWT than the controls (p < 0.05). Test-retest reliability was excellent for all dual-task metrics (85%–94%). By means of 2-way analyses of the variance, we found significant main effects of dual task on balance, regardless of the concurrent cognitive task (p < 0.001). There was no main effect of dual task on cognitive performance across all the 3 task conditions (p ≥ 0.1). We observed a significant condition-by-group interaction effect on balance only when the SCWT was administered as concurrent task (p = 0.01), indicating a greater dual-task cost of balance for the patients than controls (53% vs 28%, p = 0.04).
Conclusions: We suggest that tasks exploring executive functions involved in discriminating conflicting stimuli may be the most suitable to unmask the cognitive-postural interference phenomenon in patients with MS. This may support the hypothesis that MS-related damage constrains brain networks to subserve both postural control and executive functions.
GLOSSARY
- ANOVA=
- analysis of variance;
- CMI=
- cognitive-motor interference;
- CPI=
- cognitive-postural interference;
- DT=
- dual-task;
- DTC=
- dual-task cost;
- HC=
- healthy controls;
- MS=
- multiple sclerosis;
- NPS=
- neuropsychological;
- SCWT=
- Stroop Color-Word Test;
- SDMT=
- Symbol Digit Modalities Test;
- ST=
- single-task;
- WLG=
- Word List Generation
Footnotes
Go to Neurology.org for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
Supplemental data at Neurology.org
- Received December 23, 2015.
- Accepted in final form April 6, 2016.
- © 2016 American Academy of Neurology
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