Cognitive-Postural Interference in Multiple Sclerosis

SYSTEMATIC REVIEW published: 23 August 2019 doi: 10.3389/fneur.2019.00913 Cognitive-Postural Interference in Multiple Sclerosis Ludivine Chamard Witkowski 1,2,3*, Mathieu Mallet 1 , Mathieu Bélanger 1,2,3 , Alier Marrero 1,3 and Grant Handrigan 4 Vitality Health Network, Dr. Georges-L.-Dumont University Hospital Centre, Moncton, NB, Canada, 2 Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Sherbrooke, QC, Canada, 3 Centre de Formation Médicale du Nouveau-Brunswick, Moncton, NB, Canada, 4 École de Kinésiologie et de Loisir, Université de Moncton, Moncton, NB, Canada 1 Edited by: Brian M. Sandroff, University of Alabama at Birmingham, United States Reviewed by: Renee Veldkamp, University of Hasselt, Belgium Ricardo Constantino Ginestal, Hospital Clínico San Carlos, Spain *Correspondence: Ludivine Chamard Witkowski Specialty section: This article was submitted to Multiple Sclerosis and Neuroimmunology, a section of the journal Frontiers in Neurology Received: 04 June 2019 Accepted: 06 August 2019 Published: 23 August 2019 Citation: Chamard Witkowski L, Mallet M, Bélanger M, Marrero A and Handrigan G (2019) Cognitive-Postural Interference in Multiple Sclerosis. Front. Neurol. 10:913. doi: 10.3389/fneur.2019.00913 Frontiers in Neurology | www.frontiersin.org Multiple Sclerosis (MS) is a neurodegenerative disease associated with cognition and balance impairments, which can lead to accidental falls. Postural control requires cognitive resources. This interaction is quantifiable by using the dual-task paradigm. The cognitive-postural interference (CPI) is commonly evaluated through an assessment of the dual-task cost (DTC). The aim of this review was to summarize literature related to process, results and effects of CPI in MS patients. The Prisma statement was used to guide this systematic review. Eligible articles had to include participants with MS for whom CPI was assessed using the DTC. A total of 14 articles meeting inclusion criteria were retained. All studies used the double stance with eyes open for the postural task component. Three types of cognitive tasks were used: Stroop Color–Word Test (SCWT), Word List Generation and Backward Counting. However, cognitive task scores in single or dual task were unavailable in 11 studies, which prevented calculating the DTC for that task. Prioritization instructions were provided in seven studies. Mutual interference was shown in three studies, postural interference in nine and postural facilitation in two. This review highlights the presence of CPI among MS patients. Postural interference usually occurred during dual task while cognitive performance during dual task was rarely reported. Postural task performance does not appear to vary based on EDSS level. We advise authors of future studies to use the SCWT in combination with postural task measure (sway area and postural sway) for DT assessment, with explicit prioritization instructions. Further, the cognitive and postural tasks should be performed in ST and DT and all results should be presented. Keywords: dual-task, multiple sclerosis, cognition, postural control, balance, cognitive-postural interference INTRODUCTION Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease of the central nervous system affecting visual, cerebellar, sensory, and motor functions. MS is associated with executive dysfunction and postural impairments and affects quality of life in 85% of patients (1). Imbalance and risk of falling are reported in early MS patients with absence of clinical disability (2). Moreover, 65% of MS patients have some form of cognitive impairment (3). 1 August 2019 | Volume 10 | Article 913 Chamard Witkowski et al. Cognitive-Postural Interference in Multiple Sclerosis METHODS Postural control is defined as the body’s ability to maintain adequate gravity alignment when maintaining an upright posture with voluntary and involuntary movements (4). It is a complex task that requires integration of visual, vestibular, and somatosensory information by the central nervous system (5). Postural control involves specific cortical areas, and attentional and executive dysfunctions are associated with motor disorders (6). There is a physiological relationship between attention, cognition and balance; these functions are, respectively, treated by the frontal lobes, the thalami and the cerebellum, which are linked by a neuronal network (7). Postural and cognitive disorders were traditionally measured independently in MS patients; however, the simultaneous assessment of postural and cognitive performances demonstrated an interaction suggesting shared attentional resources (8, 9). The cognitive-postural interference (CPI) is measured by performing a dual task (DT) examination, which involves conducting a postural task along with a cognitive task and comparing performance with that of single-task conditions. The dual-task cost (DTC) is used to quantify the CPI, which represents the percent difference between DT and ST performance (10). Specifically, in cases where higher values indicate better performance, DTC (%) can be calculated as: DTC (%) = (DTC Score − ST Score) X 100% ST Score This review is based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations, and the search strategy—including keywords and choice of databases (13)—was developed in collaboration with an experienced librarian. Searches were conducted in PubMed, ScienceDirect and SPORTdiscus for potentially relevant studies without date restrictions (last updated in October 2018). The keywords applied for this search were {“Multiple Sclerosis”} AND {“Dual Task” OR “Dual Task Cost” OR Cognitive-Motor Interference”} AND {“Balance” OR “Posture”}. Previous reviews were excluded but examined to identify publications that may have been missed by our search strategy. Reference lists of eligible studies were also reviewed to ensure that all potentially eligible studies were retrieved. Eligible studies were peer-reviewed and original studies, published in either English or French, whose MS participants were performing postural (i.e., double stance, eyes open) and cognitive tasks at the same time. All types of quantitative study designs were eligible for this review. The exclusion criteria were: (1) studies concerning walking; (2) studies concerning effectiveness of rehabilitation process; and (3) studies concerning effectiveness of medications, unless the pre-treatment data were available. Once duplicates were removed, titles and abstracts were assessed independently by two reviewers (LCW and MM). The full texts of articles considered potentially eligible were then assessed. Any disagreement between the two reviewers led to a discussion and group-based decision about study inclusion. Results extraction was also conducted by two independent reviewers (LCW and MM). Quality assessment was performed with two tools, the National Servi (...truncated)