Elsevier

Physiotherapy

Volume 91, Issue 3, September 2005, Pages 152-158
Physiotherapy

An external focus of attention attenuates balance impairment in patients with Parkinson's disease who have a fall history

https://doi.org/10.1016/j.physio.2004.11.010Get rights and content

Abstract

Objectives

Studies using young, non-impaired adults have shown that by directing attention to the outcome of movements (external focus) rather than directing attention to the movements involved in a specific skill (internal focus), motor skill acquisition is enhanced. The purpose of this study was to investigate the generalisability of these attentional focus findings to balance in subjects with Parkinson's disease.

Design

Experimental, repeated measures design.

Setting

Physiotherapy research facility.

Participants

Twenty-two subjects diagnosed with idiopathic Parkinson's disease.

Interventions

Subjects were tested under three attentional focus conditions; no instruction, internal focus and external focus.

Main outcome measure

Balance equilibrium scores from three computerised dynamic posturography conditions.

Results

A significant condition x attentional focus interaction was found (F [4, 84] = 2.86, P < 0.05), indicating increased sway with internal focus relative to no focus instructions (control) under the eyes-open condition. More importantly, when only subjects with a history of falls were considered, there was a significant interaction between condition and attentional focus (F [4, 36] = 4.40, P < 0.01). Post hoc tests revealed that the external focus instructions resulted in less sway than both internal focus and no attentional focus instructions under sway-referenced conditions.

Conclusion

These findings support previous research studies on attentional focus. In particular, it was demonstrated that the balance of subjects with Parkinson's disease and a fall history can be enhanced by instructing subjects to adopt an external focus.

Introduction

Parkinson's disease is a progressive neurodegenerative disease that characteristically produces a variety of motor control problems and movement disorders including bradykinesia, rigidity, resting tremor, and deterioration in balance and postural control. The cumulative effects of these impairments often result in considerable disability, thereby predisposing the individual to falling. Whereas associated motor deficits are not usually directly life threatening, they can contribute to falling, which in turn can lead to severe injuries (e.g. head injuries, fractures, etc.). These injuries may ultimately lead to hospitalisation and/or confinement to a wheelchair. Falling can also lead to fearfulness about walking, which may result in social isolation.

Koller et al. [1] reported that 10% of patients with Parkinson's disease fall more than once per week. In addition, patients are five times more likely to suffer fall-related fractures [2]. Johnell et al. [2] reported that by 10 years after diagnosis, an estimated 27% of a Parkinsonism cohort had experienced a new hip fracture, which was a 20-fold increase in risk compared with an age- and sex-matched control group. Clearly, such statistics highlight that a primary focus in physiotherapy intervention of patients with Parkinson's disease is the prevention of falls [3]. Interestingly, postural instability, which is implicated as a causative factor of falls in this group, is the only major motor sign that appears to be resistant to dopaminergic therapy [1]. This further illustrates the need for developing physiotherapy interventions that effectively enhance balance in those with Parkinson's disease.

One potential way to improve physiotherapy balance training in Parkinson's disease comes from motor learning research, which suggests that performance on a variety of motor skills, such as balance, can be enhanced in young, healthy adults by giving them attentional focus instructions [4], [5], [6], [7], [8], [9], [10], [11], [12]. Specifically, it has been demonstrated that directing the performer's attention to the effects that his or her movements have on the environment (external focus) is more effective than directing attention to the movements themselves (internal focus). For example, using a balance task, Wulf et al. [5] compared the effectiveness of instructions that directed the performers’ attention to their feet (internal focus) with those of instructions that directed attention to markers on the balance platform (external focus). Compared with an internal focus, the adoption of an external focus resulted in enhanced balance learning. It has also been shown that the focus of attention adopted on a suprapostural task (e.g. pointing) can affect postural control, with an external focus resulting in greater postural stability than an internal focus [13]. Taken together, these results suggest that external focus instructions can enhance the learning of balance tasks in subjects without pathology. If these results could be replicated in subjects with Parkinson's disease, this could lead to more effective physiotherapy intervention directed at improving balance.

Importantly, external focus advantages have also been found in comparison to control conditions without attentional focus instructions [5], [14], [15]. That is, while internal focus and control groups often show similar performances, an external focus generally results in enhanced performance and learning. This seems to hold true for the learning of new skills [5], [14], as well as for the performance of well-practiced skills (e.g. standing still) [13]. This finding is important as it suggests that if subjects are given external focus instructions, motor performance can be enhanced above and beyond their normal level of performance. This might, therefore, have important implications for training procedures used in physiotherapy settings.

Wulf et al. [7], [8], [10], [16] proposed a ‘constrained action hypothesis’ to account for these external focus benefits. According to this view, subjects focusing on their body movements tend to actively intervene in the control of their movements, which interferes with automatic motor control processes. In contrast, focusing attention on the movement effect (i.e. the outcome of the movement) allows unconscious processes to control the movements required to achieve this effect. That is, an external focus promotes the utilisation of automatic control processes, resulting in enhanced performance and learning. In fact, the benefits of an external focus appear to increase with task complexity [17], [18]. If the task is relatively simple and already controlled relatively automatically, an external focus might not provide additional advantages. However, if the task is relatively complex and challenging for the individual, an external focus typically results in enhanced performance.

Section snippets

Aim of the study

The purpose of this study was to explore the generalisability of the attentional focus advantages outlined by Wulf and co-workers [4], [5], [6], [7], [8], [9], [10], [11], [12] in a population of subjects with Parkinson's disease. Specifically, we wanted to determine whether balance in subjects with Parkinson's disease could be improved by giving them external focus instructions, relative to internal focus or no attentional focus instructions (control condition). In addition and perhaps most

Subjects

A convenience sample using disproportional stratified sampling (1:1 ratio of faller to non-faller) of 22 subjects (five females, 17 males) was recruited from the local American Parkinson's Disease Association. Diagnosis of idiopathic Parkinson's disease was made by a neurologist. Subjects were all Hoehn and Yahr Stage II or III [19], and were aged 61–86 years (mean age: 72.7 years, mean onset: 6.7 years). Ten of the 22 subjects reported at least one unexplained fall within the last year (mean:

Fallers and non-fallers

Equilibrium scores There was a main effect of condition (F [2, 42] = 41.30, P < 0.001, Eta2 = 0.66) indicating increasingly lower equilibrium scores with increasing task difficulty (eyes open, eyes closed, sway referenced/eyes open). The main effect of attentional focus was not significant (F [2, 42] = 2.22, P > 0.05), but the interaction of condition and attentional focus was significant (F [4, 84] = 2.86, P < 0.05, Eta2 = 0.12) Follow-up ANOVAs and post hoc tests (LSD) revealed that the only significant

Discussion

The present study examined the influence of different types of attentional strategies for balance in subjects with idiopathic Parkinson's disease. Specifically, we wanted to examine whether previously found benefits of adopting an external focus of attention would be observed for this population. While there were no significant external focus advantages for the combined group of subjects (with and without a history of falls), benefits of an external focus emerged for the fallers under

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