The "posture second" strategy: A review of wrong priorities in Parkinson's disease

Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
Journal of the Neurological Sciences (Impact Factor: 2.47). 11/2006; 248(1-2):196-204. DOI: 10.1016/j.jns.2006.05.010
Source: PubMed


Falls are common in Parkinson's disease. It remains difficult to predict these falls, presumably because clinical balance tests assess single components of postural control, whereas everyday fall mechanisms are typically more complicated. A substantial proportion of everyday falls appears to occur while Parkinson patients attempt to perform multiple tasks at the same time. Furthermore, little attention is generally paid to the possible contribution of cognitive impairments to falls. The importance of mental dysfunction is supported by the fact that cognitive loading while walking or balancing can lead to marked deteriorations in postural performance, and there is some evidence to suggest that such "dual tasking" is particularly difficult for elderly persons with dementia or depression. We examined what strategies Parkinson patients used when a basic walking task became increasingly challenging by adding additional tasks (both motor and cognitive). Most patients could perform a simple "dual task" test: simultaneously walking and answering simple questions. However, as the walking task became more complex, patients' performance began to deteriorate. Interestingly, this was reflected not only by failure to answer questions, but also by an increasing number of blocks in motor performance (walking and balancing). This behaviour was different from that of both young and elderly controls, who appeared to sacrifice performance on the cognitive task in order to optimise their gait and balance ("posture first" strategy). Preliminary evidence suggest that impaired multiple task performance is associated with a two-fold increased risk of sustaining falls in daily life. We conclude that Parkinson patients are less inclined than healthy persons to maintain a safe gait. Instead, Parkinson patients use a "posture second" strategy and treat all elements of a complex task with equal priority, which in daily life may go at the expense of maintaining balance and lead to falls.

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    • "They sacrificed their performance on the walking task in order to improve their cognitive task performance. The decline of this 'posture-first' strategy may pose aging populations at a greater risk of falling in complex multitask environments (Bloem et al. 2006; Schaefer et al. 2015). Although this result seems to contradict previous work on obstacle avoidance (Potocanac et al. 2015), it is useful to note that the cost of failing to avoid an obstacle (possibly resulting in tripping and falling) is much higher than the cost of missing a shifted stepping target during visually cued treadmill walking. "
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    ABSTRACT: Making step adjustments is an essential component of walking. However, the ability to make step adjustments may be compromised when the walker’s attentional capacity is limited. This study compared the effects of ageing and dual tasking on step adjustments in response to stepping target perturbations during visually cued treadmill walking. Fifteen older adults (69.4±5.0 yrs; mean±SD) and fifteen young adults (25.4±3.0 yrs) walked at a speed of 3 km/h on a treadmill. Both groups performed visually cued step adjustments in response to unpredictable shifts of projected stepping targets in forward (FW), backward (BW), or sideward (SW) directions, at different levels of task difficulty (which increased as the available response distance [ARD] decreased), and with and without dual tasking (auditory Stroop task). RESULTS: In both groups, step adjustments were smaller than required. For FW and BW shifts, older adults undershot more under dual-task conditions. For these shifts, ARD affected the age groups differentially. For SW shifts, larger errors were found for older adults, dual tasking and the most difficult ARD. Stroop task performance did not differ between groups in all conditions. Older adults have more difficulty than young adults to make corrective step adjustments while walking, especially under dual-tasking conditions. Furthermore, they seemed to prioritize the cognitive task over the step adjustment task, a strategy that may pose ageing populations at a greater fall risk. For comparable task difficulty the older adults performed considerably worse than the young adults, indicating a decreased ability to adjust steps under time pressure.
    Experimental Brain Research 08/2015; DOI:10.1007/s00221-015-4407-5 · 2.04 Impact Factor
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    • "So far, either immediate effects of random WBV or training with steady WBV lasting several weeks has been evaluated , but not whether there are higher effects of a random WBV training lasting several weeks in comparison to a placebo treatment. Quantitative differences in the performance of tasks with potential fall risk [16] [17] (bending forward , climbing steps) have been shown between participants with PD and healthy controls [18]. Therefore, in this study, "
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    ABSTRACT: Background. Random whole body vibration (WBV) training leads to beneficial short-term effects in patients with Parkinson's disease (PD). However, the effect of WBV lasting several weeks is not clear. Objectives. The aim of this study was to assess a random WBV training over 5 weeks in PD. Methods. Twenty-one participants with PD were allocated to either an experimental or a placebo group matched by age, gender, and Hoehn&Yahr stage. The WBV training consisted of 5 series, 60 s each. In the placebo group, vibration was simulated. The primary outcome was the change of performance in Functional reach test (FRT), step-walk-turn task, biomechanical Gait Analysis, Timed up and go test (TUG), and one leg stance. Findings. In most of the parameters, there was no significant interaction of "time∗group." Both groups improved significantly in Gait parameters, TUG, and one leg stance. Only in the FRT [F(1,15) = 8.397; P < 0.05] and in the TUG [F(1,15) = 4.971; P < 0.05] the experimental group performed significantly better than the placebo group. Conclusions. Random WBV training over 5 weeks seems to be less effective than reported in previous studies performing short-term training. The slight improvements in the FRT and TUG are not clinically relevant.
    Parkinson's Disease 10/2014; 2014:386495. DOI:10.1155/2014/386495 · 2.01 Impact Factor
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    • "Since gait speed and functional balance performance have been shown to correlate to FOF in bivariate analyses [23,24], these aspects may tentatively be of importance when investigating contributing factors to FOF. Dual-tasking might also be of interest since it worsens gait impairments in PD and may lead to wrong prioritization, i.e. the “posture second” strategy [9,25]. There is thus a need for a more thorough understanding of contributing factors to FOF in PD in order to address this efficiently in clinical practice and research. "
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    ABSTRACT: This study aimed to comprehensibly investigate potential contributing factors to fear of falling (FOF) among people with idiopathic Parkinson's disease (PD). The study included 104 people with PD. Mean (SD) age and PD-duration were 68 (9.4) and 5 (4.2) years, respectively, and the participants' PD-symptoms were relatively mild. FOF (the dependent variable) was investigated with the Swedish version of the Falls Efficacy Scale, i.e. FES(S). The first multiple linear regression model replicated a previous study and independent variables targeted: walking difficulties in daily life; freezing of gait; dyskinesia; fatigue; need of help in daily activities; age; PD-duration; history of falls / near falls and pain. Model II included also the following clinically assessed variables: motor symptoms, cognitive functions, gait speed, dual-task difficulties and functional balance performance as well as reactive postural responses. Both regression models showed that the strongest contributing factor to FOF was walking difficulties, i.e. explaining 60% and 64% of the variance in FOF-scores, respectively. Other significant independent variables in both models were needing help from others in daily activities and fatigue. Functional balance was the only clinical variable contributing additional significant information to model I, increasing the explained variance from 66% to 73%. The results imply that one should primarily target walking difficulties in daily life in order to reduce FOF in people mildly affected by PD. This finding applies even when considering a broad variety of aspects not previously considered in PD-studies targeting FOF. Functional balance performance, dependence in daily activities, and fatigue were also independently associated with FOF, but to a lesser extent. Longitudinal studies are warranted to gain an increased understanding of predictors of FOF in PD and who is at risk of developing a FOF.
    BMC Neurology 01/2014; 14(1):19. DOI:10.1186/1471-2377-14-19 · 2.04 Impact Factor
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