Overload of anxiety on postural control impairments in chronic stroke survivors: The role of external focus and cognitive task on the automaticity of postural control.

Zahra Ghorbanpour,Seyed Ali Hosseini,Farhad Tabatabai Ghomsheh,Ebrahim Pishyareh,Enayatollah Bakhshi,Hajar Mehdizadeh,Ghorban Taghizadeh,Yumeng Li

doi:10.1371/journal.pone.0252131

Abstract

BackgroundDespite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.MethodsPostural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).ResultsStroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.ConclusionsThe results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.

Highlights

Postural control of standing is critical for doing functional activities, which underlie many activities of daily living [1]
As opposed to baseline and internal focus (IF) conditions, postural instability and neuromuscular stiffening significantly reduced in external focus (EF) condition and decreased more in cognitive task conditions, hard cognitive task (HC) condition
The results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks

Summary

Introduction

Postural control of standing is critical for doing functional activities, which underlie many activities of daily living [1]. Stroke survivors experience different sensory and motor impairments (e.g. decreased proprioception, over-reliance on visual inputs, muscle activation deficits, etc.), leading to impairments of postural control [2]. As a consequence of impaired postural control, about 40–70% of stroke survivors experience a fall each year, leading to fear of falling [3], which hampers activities of daily living and social participation and decreases the quality of life [3, 4]. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. The current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation

Objectives

Methods

Results

Conclusion