Difficulties in the integration of visual, vestibular, and somatosensory information in individuals with Parkinson’s disease (PD) may alter perception of verticality. Accordingly, in this cross-sectional study, we analyzed PD patients’ ( n = 13) subjective visual vertical (SVV) and subjective haptic vertical (SHV) perceptions and compared them to those of healthy controls ( n = 14). We compared SVV and SHV findings among participants with PD, healthy controls, and cutoff points of normality based on prior research literature, using the parametric nonpaired t test (at p < .05) and Cohen’s d (at d > 0.8) to determine clinical relevance. We analyzed SVV with the bucket test and SHV with the rod rotations task in clockwise and counterclockwise directions. We calculated Pearson correlations to analyze the association between verticality tests and the most clinically affected body side. We calculated both the percentage of A-effect (expression of body tilt underestimation to the midline) and E-effect (expression of body tilt overestimation in the upright position). Individuals with PD showed greater variability in right SHV supination compared to the healthy control participants ( p = .002). There was greater clinical relevance in right (as opposed to left) SVV ( d = 0.83), right (as opposed to left) SHV pronation ( d = 0.91), and left (as opposed to right) SHV pronation ( d = 0.88). We observed a higher proportion of E-effect in individuals with PD. A significantly higher proportion of patients with PD, compared to patients in past literature, had right SHV pronation ( p = .001), left SHV pronation ( p = .023), right SHV supination ( p = .001), left SHV supination ( p = .046), and left SHV pronation ( p = .046). Thus, subjective visual and proprioceptive perception of verticality is altered in patients with PD, compared to individuals without PD.

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Some investigators have demonstrated that an anchor system can improve postural control in elderly persons during balance tasks, but none have reported on the use of this approach in individuals with Parkinson’s disease (PD). Therefore, we aimed to evaluate the effect of an anchor system on postural sway in elderly individuals with ( n = 13) and without ( n = 14) PD. In this cross-sectional study, we measured postural sway with a force platform based on the Clinical Test of Sensory Interaction of Balance (CTSIB). We calculated center of pressure (COP) parameters, as a function of time, based on the ellipse sway area (cm2) and evaluated self-efficacy for postural control based on the degree of difficulty in each task. With the anchor system (i.e., handheld ropes attached to weights on the floor), we observed a significant reduction in the ellipse sway area in the semi-tandem position among individuals with PD ( p = .04). For participants without PD, there was no significant difference in sway with or without the anchor system in all positions. Also, for participants with PD, there was an improvement in self-efficacy for postural control associated with the anchor system in several positions while there was only a self-efficacy improvement with the anchor system in the semi-tandem position for those without PD. Acute use of a haptic anchor system reduced postural sway in the semi-tandem position in individuals with PD, and the anchor system generally improved postural control self-efficacy for body sway in individuals with PD.