Cognitive assessment for fall groups.

<p>Mean (sd) values for performance on cognitive tests assessing attention, working memory and fluency are compared between fall groups.</p><p>IDED: Intra- and extradimensional set shift test.</p><p>SWM: Spatial working memory.</p

Output parameters of multivariate logistic regression models assessing the association between total impulsivity and fall risk.

<p>Output of logistic regression models controlling for gender, disease severity, dopaminergic medication, and cognitive function. H&Y: Hoehn and Yahr stages. PIGD: Postural instability and gait disability. MMSE: Mini-Mental State Examination. LED: levodopa dose equivalent. ^a LED values were divided by 1000 for these analyses.</p

Demographic and clinical measures for fall groups.

<p>P values of independent t-tests and chi-square are presented to compare fall groups.</p><p>UPDRS-III: Unified Parkinson’s Disease Rating Scale motor examination; PIGD: Postural Instability and Gait Disability; MMSE: Mini-Mental State Examination; LED: Levodopa Equivalent Dose. DA: dopamine.</p

Self-reported impulsivity scores (BIS-11) for fall groups.

<p>P values are presented for comparisons between fall groups using the independent samples t-test.</p><p>Cohen’s d indicates effect size (0.2: small effect; 0.5: medium effect; 0.8: large effect).</p

Output parameters of multivariate logistic regression models assessing the association between attentional impulsivity and fall risk.

<p>Output of logistic regression models controlling for gender, disease severity, dopaminergic medication, and cognitive function. H&Y: Hoehn and Yahr stages. PIGD: Postural instability and gait disability. MMSE: Mini-Mental State Examination. LED: levodopa dose equivalent. ^a LED values were divided by 1000 for these analyses.</p

Subject characteristics.

<p>Data is shown as mean ± standard deviation. Clinical characterization using the Tinetti mobility index <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086650#pone.0086650-Tinetti1" target="_blank">[18]</a>; ABC-6 = Short Activities-specific Balance Confidence <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086650#pone.0086650-OudeNijhuis1" target="_blank">[20]</a>; H&Y = Hoehn & Yahr, range 0 (no signs of disease) to 5 (wheelchair bound/bedridden) <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086650#pone.0086650-Goetz1" target="_blank">[37]</a>; UPDRS = Unified Parkinson’s Disease Rating Scale <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0086650#pone.0086650-FahnS1" target="_blank">[17]</a>.</p

Participant characteristics.

<p>Data reflect means (standard deviation between brackets). N; number of subjects, NS; not significant, UPDRS; Unified Parkinson’s Disease Rating Scale, L: Left side most affected H&Y Hoehn & Yahr, FAB; Frontal Assessment Battery. NFoG-Q; new freezing of gait questionnaire.</p>†<p>Mann-Whitney U test.</p><p>Patients were assessed during the OFF state. There were no significant differences between patients and controls, or between freezers and non-freezers.</p

Experimental set-up.

<p>Participants stood on the dual forceplate (A), with their arms crossed over their chest, embedded in the movable platform (B). Two independent perturbations in the forward-backward direction were applied simultaneously using both the movable platform (B) and the pusher (C). Interaction forces between the pusher (C) and the participant were measured with a force sensor (D). Actual falls were prevented by the safety harness (E), which did not provide any support or directional cues. Reflective spherical markers (F) measured movements of the participant.</p

Single subject ankle torque.

<p>(A) Anterior-posterior ankle torque traces to FAST, MEDIUM and SLOW perturbations on the most affected side of a PD patient with eyes open. (B) Traces as in A, for the least affected side of a PD patient with eyes open. (C) Average traces of anterior-posterior ankle torque on the left and right side of a control with eyes open. In the lower panels traces of the platform velocities (deg/s) for FAST, MEDIUM and SLOW rotations are shown. The vertical lines at 0 ms represent the onset of the platform rotation.</p

Population average centre of mass (COM) displacements.

<p>(A) Traces of the anterior-posterior displacement of the COM (mm) to FAST, MEDIUM, and SLOW rotations in PD patients with eyes open. (B) Traces as in A, for PD with eyes closed. (C) Traces as in A for controls with eyes open. (D) Traces as in C for controls with eyes closed. In the lower panels traces of the platform velocities (deg/s) for FAST, MEDIUM and SLOW rotations are shown. The vertical lines at 0 ms represent the onset of the platform rotation.</p