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J Neurol Neurosurg Psychiatry 83:1149-1154 doi:10.1136/jnnp-2012-303056
  • Movement disorders
  • Research paper

Differential susceptibility to motor impulsivity among functional subtypes of Parkinson's disease

  1. Carol A Manning3
  1. 1Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  2. 2Amsterdam Center for the Study of Adaptive Control in Brain and Behaviour (Acacia), Psychology Department, University of Amsterdam, Amsterdam, The Netherlands
  3. 3Neurology Department, University of Virginia Health Systems, Charlottesville, Virginia, USA
  1. Correspondence to Dr Scott A Wylie, 1161 21st Avenue South, A-0118 Medical Center North, Department of Neurology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; scott.a.wylie{at}vanderbilt.edu
  1. Contributors SAW made the following contributions: drafting and revising manuscript, study concept and design, analysis and interpretation of data, acquisition of data, statistical analysis and study supervision. WvdW made the following contributions: drafting and revising manuscript, study concept and design, analysis and interpretation of data, and statistical analysis. KRR made the following contributions: drafting and revising manuscript, study concept and design, and analysis and interpretation of data. DOC contributed by drafting and revising the manuscript. GFW made the following contributions: drafting and revising the manuscript, study concept and design, and acquisition of data. CAM made the following contributions: drafting and revising manuscript, and study concept and design.

  • Received 23 April 2012
  • Revised 19 July 2012
  • Accepted 1 August 2012
  • Published Online First 23 August 2012

Abstract

Background and objectives Parkinson's disease patients with predominant postural instability and gait difficulties (PIGD) may experience unique cognitive difficulties compared to patients with tremor predominant (TD) symptoms. PIGD patients are also at high risk for falling, and some of the worst fallers seem to react impulsively to their environment. We tested the hypothesis that PIGD patients show poorer control over motor impulses compared to TD patients.

Methods 34 PD participants were divided into predominant PIGD (n=17) or TD (n=17) functional subtypes based on their presenting symptoms in their optimally treated motor state. All participants performed a speeded reaction task that quantified motor impulsivity and the proficiency of inhibiting prepotent motor impulses.

Results The groups showed similar reaction times, but compared to TD patients, PIGD patients made significantly more impulsive motor errors. Notably, when the initial impulsive erroneous response was avoided, PIGD and TD groups were similar in their ability to suppress the incorrect motor impulse from further interfering with the selection of a correct action.

Conclusions PD patients with PIGD predominant symptoms show greater susceptibility to acting on prepotent motor impulses compared to TD patients. This finding may have direct implications for fall risk and also points to dissociable neurocognitive pathologies in TD and PIGD subtypes. Clinically, the use of specific cognitive instruments to assess the expression and inhibition of motor impulses may help identify PD patients who have difficulty ‘thinking before they leap’ and are at high risk of falling.

Footnotes

  • Funding National Institute on Ageing (the content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institute on Ageing or the National Institutes of Health) grant (K23AG028750 to SAW).

  • Competing interests None.

  • Ethics approval Ethics approval was provided by University of Virginia Institutional Review Board/Human Investigation Committee.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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