Balance problems with Parkinson's disease: Are they anxiety-dependent?

School of Human Kinetics, The University of British Columbia, Osborne Centre Unit I, 6108 Thunderbird Boulevard, V6T 1Z3, Vancouver, BC, Canada.
Neuroscience (Impact Factor: 3.36). 03/2011; 177:283-91. DOI: 10.1016/j.neuroscience.2010.12.050
Source: PubMed


Non-motor symptoms, such as fear of falling and anxiety, are frequently reported in Parkinson's disease (PD). Recent evidence of anxiety and fear directly influencing balance control in healthy young and older adults, raises the question whether fear of falling and anxiety also directly contribute to the balance deficits observed in PD. The goal of the current study was to examine whether PD patients and controls responded similarly or differently to experimentally induced increases in anxiety. For this purpose, 14 PD patients (tested during a subjective optimal ON state) and 16 healthy age-matched control subjects stood in three conditions of different levels of postural threat: normal threat (quiet standing at ground level); medium threat (standing at the edge of a surface elevated to 80 cm); and high threat (same, but to 160 cm). Outcome measures included mean position, mean power of frequency (MPF) and root mean square (RMS) of centre of pressure (COP) displacements in the anterior-posterior (AP) and medial-lateral (ML) directions. Physiological and psychosocial measures of fear and anxiety were also recorded. Increased threat changed postural control similarly in PD patients and controls; MPF of AP and ML COP increased and the mean COP position was shifted backward in both groups. These results indicate that during the ON state, static balance in PD patients and controls is equally susceptible to the influence of anxiety. Significant correlations observed between COP changes and measures of fear and anxiety provide evidence to support the proposed neural links between structures controlling emotion and postural control. Future studies should further address this issue by including more severely affected patients, by testing the influence of dopaminergic medication, by including more anxious patients, and by using dynamic measures of balance.

Download full-text


Available from: Elizabeth Pasman, Sep 11, 2015
  • Source
    • "However, limited research has investigated how anxiety influences movement control in PD compared with healthy older adults. Studies of both gait and balance did not identify any unique relationship between anxiety and movement behaviors in PD (when compared with healthy controls), but it is important to recognize that participants with PD were only tested in their ON state and these studies excluded participants with PD who experienced high levels of anxiety (Caetano et al., 2009; Pasman et al., 2011). Given that dopaminergic replacement ameliorates basal ganglia-associated deficits , one might expect that testing patients with PD in the OFF state might reveal a different pattern of behavior in response to anxious stimuli. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In order to understand how dopamine modulates the effect of anxiety on gait, the goal of this study was to use virtual reality to provoke anxiety in PD (in both ON and OFF states) and quantify its effect on gait. Seventeen PD and 20 HC were instructed to walk in a virtual environment in two anxiety-provoking conditions: (i) across a plank that was located on the GROUND; (ii) across an ELEVATED plank. All PD participants completed this in both the ON and OFF states, and then were striated into groups based on baseline trait anxiety scores for further analyses. Anxiety (skin conductance and self-report) and spatiotemporal aspects of gait were measured. Overall, the ELEVATED condition resulted in greater skin conductance levels and self-reported anxiety levels. Additionally, all participants demonstrated slower gait with increased step-to-step variability when crossing the ELEVATED plank compared to the plank on the GROUND. Results showed that dopaminergic treatment selectively improved gait in only the highly anxious PD group, by significantly improving velocity, step length, step time and step-to-step variability specifically when walking across the ELEVATED plank (ON versus OFF comparison). In conclusion, only highly trait anxious PD benefitted from dopaminergic treatment, specifically when walking in the anxiety-provoking environment. Improvements to gait during anxious walking might be a result of dopaminergic medication acting in two ways: 1) improving the basal ganglia's capacity to process information and 2) by reducing the load from anxiety and subsequently making more resources available to effectively process other competing inputs. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
    European Journal of Neuroscience 04/2015; DOI:10.1111/ejn.12928 · 3.18 Impact Factor
  • Source
    • "Biological systems generally exploit redundancy to improve robustness and flexibility of control (Karniel, 2011). The exploitation of all available DOFs to maximize performance and flexibility is generally a sign of skill and learning (Bernstein, 1967, page 107–108), whereas the elimination of available DOFs is usually a symptom of declining ability through age (Hsu et al., 2012), disease (Oude Nijhuis et al., 2008; Pasman et al., 2011), or fear (Adkin et al., 2002). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Modular organization in control architecture may underlie the versatility of human motor control; but the nature of the interface relating sensory input through task-selection in the space of performance variables to control actions in the space of the elemental variables is currently unknown. Our central question is whether the control architecture converges to a serial process along a single channel? In discrete reaction time experiments, psychologists have firmly associated a serial single channel hypothesis with refractoriness and response selection [psychological refractory period (PRP)]. Recently, we developed a methodology and evidence identifying refractoriness in sustained control of an external single degree-of-freedom system. We hypothesize that multi-segmental whole-body control also shows refractoriness. Eight participants controlled their whole body to ensure a head marker tracked a target as fast and accurately as possible. Analysis showed enhanced delays in response to stimuli with close temporal proximity to the preceding stimulus. Consistent with our preceding work, this evidence is incompatible with control as a linear time invariant process. This evidence is consistent with a single-channel serial ballistic process within the intermittent control paradigm with an intermittent interval of around 0.5 s. A control architecture reproducing intentional human movement control must reproduce refractoriness. Intermittent control is designed to provide computational time for an online optimization process and is appropriate for flexible adaptive control. For human motor control we suggest that parallel sensory input converges to a serial, single channel process involving planning, selection, and temporal inhibition of alternative responses prior to low dimensional motor output. Such design could aid robots to reproduce the flexibility of human control.
    Frontiers in Computational Neuroscience 05/2013; 7:55. DOI:10.3389/fncom.2013.00055 · 2.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this article, we briefly summarize the incidence and significant consequences of falls among older adults, the insufficient effectiveness of commonly used multifactorial interventions and the evidence linking falls and cognitive function. Recent pharmacologic and nonpharmacologic studies that evaluated the effects of cognitive therapy on fall risk are reviewed. The results of this article illustrate the potential utility of multiple, diverse forms of cognitive therapy for reducing fall risk. The article also indicates that large-scale, randomized controlled trials are warranted and that additional research is needed to better understand the pathophysiologic mechanisms underlying the interplay between human mobility, fall risk and cognitive function. Nonetheless, we suggest that multimodality interventions that combine motor and cognitive therapy should, eventually, be incorporated into clinical practice to enable older adults and patients to move safer and with a reduced fall risk.
    Expert Review of Neurotherapeutics 07/2011; 11(7):1057-75. DOI:10.1586/ern.11.69 · 2.78 Impact Factor
Show more