Elsevier

Gait & Posture

Volume 40, Issue 3, July 2014, Pages 352-356
Gait & Posture

Correlates of dual task cost of standing balance in individuals with multiple sclerosis

https://doi.org/10.1016/j.gaitpost.2014.04.209Get rights and content

Highlights

  • Correlates of dual task cost of standing balance were examined in MS.

  • Individuals with MS have increases in sway with added cognitive task.

  • The amount of increase is unrelated to demographic, clinical and cognitive measures.

  • Individuals with low baseline sway have larger sway increases while dual tasking.

Abstract

Cognitive and balance dysfunction are common symptoms in individuals with multiple sclerosis (MS). Although traditionally seen as separate impairments, performing a concurrent cognitive task while maintaining an upright posture results in individuals with MS increasing their postural sway (i.e. dual task cost (DTC) of balance). However, the factors relating to this phenomenon are not clear. This investigation examined the demographic, clinical and cognitive correlates of DTC of balance in individuals with MS. Sixty-two persons with MS completed both quiet standing and dual task balance trials on a force platform. Additionally, they provided demographic information and performed clinical tests of balance, spasticity, fall risk and cognitive processing speed. Dual task cost was calculated as the percentage change in sway area from the baseline to dual task force platform conditions. Overall, there were no significant correlations between DTC of balance and any of the outcome measures in the entire sample. In contrast, postural sway in the baseline and dual task condition were found to correlate with disability, fall risk, balance performance, fatigue, cognitive processing speed and age. Secondary analysis revealed different correlates of DTC of balance in those with low versus high baseline sway. The results suggest that the change in standing balance with the simultaneous performance of cognitive task may only be informative in individuals with minimal balance dysfunction.

Introduction

Deficits in balance and cognition represent two prevalent impairments in individuals with multiple sclerosis (MS) [1], [2]. Balance dysfunction denotes one of the earliest reported symptoms in cases of MS and has been observed even in the absence of clinical disability [3], [4]. Similarly, cognitive impairments also arise early in the disease process and occur in approximately 50% of individuals with MS [5].

Traditionally, balance impairment in MS was believed to be influenced mainly by physiological factors including visual, somatosensory and vestibular impairments; muscle weakness; and spasticity [6], [7]. However, recent evidence suggests that balance in individuals with MS can also be negatively affected by the addition of a concurrent cognitive task (i.e. dual task) [4], [8], [9], [10]. These alterations in postural control while engaged in a cognitive task are indicative of cognitive–motor interference. Commonly, cognitive–motor interferences is quantified as dual task cost (DTC) by calculating the percentage change in outcome measures from single task performance to dual task performance.

Cognitive–motor interference, especially during balance tasks, represents an important topic of scientific inquiry as it has been linked to falls in clinical populations [11], [12]. Specific to MS, a recent study revealed that DTC of walking is associated with physiological fall risk [13]. Due to the potential link between cognitive–motor interaction and falls, DTCs of standing balance represent a potentially important rehabilitation target. In order to maximize the potential for successful rehabilitation, the underlying mechanisms of DTC in balance need to be identified.

The factors related to DTC in upright balance for individuals with MS are relatively unclear. One small study (n = 13) found evidence that DTCs during balance tasks were related to self-reported fatigue [14] while another [8] determined the DTC of standing balance in individuals with MS was not related to disability level. Additionally, walking function and cognitive processing speed are associated with DTC of walking in MS [15], [16]. Consequently, the purpose of the current study was to identify the correlates of DTC of standing balance in individuals with MS. We examined the relationship between demographic, cognitive and clinical balance measures to DTC of standing balance. Based on previous literature [14], [15], [16], [17] we hypothesized that the DTC of posture would be related to balance, cognitive function, fatigue and physiological fall risk.

Section snippets

Participants

This cross-sectional investigation utilized a convenience sample of 62 community-dwelling individuals with a neurologist confirmed diagnosis of MS who participated in an ongoing fall prevention program. Participants had to be over the age of forty, fallen in the previous year, be relapse free for 30 days and be able to stand independently for 30 s.

Procedures

All procedures were approved by the local Institutional Review Board. After arrival at the testing facility participants were informed of the testing

Results

Overall the sample consisted of 46 females and 16 males. Age ranged from 42 to 76 years with a mean of 60.9 years (SD = 7.2 years). Self-reported disability (SR-EDSS) ranged from 0 to 7 with a median value of 6 (IQR = 2). 25 participants required no assistive devices, 21 walked with a cane and 16 utilized a walker for community ambulation. The sample was relatively well educated with all participants having graduated from high school and 68% of participants having completed college degrees.

Discussion

This investigation is the most comprehensive examination of correlates of DTC of standing balance in individuals with MS to date. Despite the large range of disability, balance function, cognitive function, fatigue, and spasticity in the current sample, no correlates of DTC of standing balance were observed. However, postural sway in and of itself was found to relate to clinical balance assessments, fall risk, fatigue and disability level. Postural sway while engaged in a simultaneous cognitive

Conclusion

Overall the observations of this study suggest that the change in standing balance with the simultaneous performance of cognitive task offers minimal clinical information in individuals with MS. In contrast, static balance was found to relate to clinical measures of balance, physiological fall risk, and self-reports of fatigue and disability. Cognitive processing speed and age were only related to standing balance in the dual task condition, but not to the change in performance with the

Acknowledgements

This study was funded through grants from the Consortium of Multiple Sclerosis Centers and National Multiple Sclerosis Society (IL Lot NMSS 006), who took no role in experimental design or manuscript preparation.

References (31)

  • C.L. Martin et al.

    Gait and balance impairment in early multiple sclerosis in the absence of clinical disability

    Mult Scler

    (2006)
  • A. Kalron et al.

    Effect of a cognitive task on postural control in patients with a clinically isolated syndrome suggestive of multiple sclerosis

    Eur J Phys Rehab Med

    (2011)
  • R.H. Benedict et al.

    Risk factors for and management of cognitive dysfunction in multiple sclerosis

    Nat Rev Neurol

    (2011)
  • J.J. Sosnoff et al.

    Influence of spasticity on mobility and balance in persons with multiple sclerosis

    J Neurol Phys Ther

    (2011)
  • D.A. Wajda et al.

    Dual task cost of walking is related to fall risk in persons with multiple sclerosis

    J Neurol Sci

    (2013)
  • Cited by (0)

    View full text