Objective: The main objective of this study was to evaluate: (i)whether highly anxious PD (HA-PD) have a reduced capacity for information processing compared to PD with low anxiety (LA-PD); (ii)whether anxiety acts as a load (i.e. increases processing demands) similar to a cognitive dual-task; and (iii)if dopamine modulates their ability to manage these increased processing loads.

Background: Anxiety in Parkinson’s disease (PD) has become increasingly recognized as a common debilitating non-motor symptom that may exacerbate motor symptoms in PD, especially in those who are highly anxious. Interestingly, motor impairments that result from anxiety often resemble those produced from a cognitive dual-task. Thus, it has been speculated that anxiety may reduce one’s capacity for processing.

Methods: Forty-four participants (10 HA-PD, 11 LA-PD, 23 HC) stood quietly on a force platform for 30 seconds in 3 randomized virtual reality conditions: i)Baseline (BL): ground plank, ii)Dual-task (DT): ground plank while simultaneously counting backwards by sevens, iii) Anxiety (ANX): elevated plank. Participants rated their feelings of stress and anxiety after every trial using self-assessment manikins. All PD participants were asked to complete the study in both their ON and OFF dopaminergic state.

Results: Overall, HA-PD demonstrated significantly greater AP displacement (p=0.021), and greater variability in both the AP (p=0.049) and ML directions (p=0.048) compared to LA-PD. Additionally, the HA-PD group had significantly greater ML sway displacement during DT compared to BL and ANX conditions whereas, LA-PD and HC did not. HA-PD also demonstrated significantly greater AP sway variability compared to LA-PD and HC specifically during the ANX condition (p=0.048). Finally, all PD in the ON state had significantly greater AP displacement during DT compared to the ANX condition (p=0.022), however this difference was not found in the OFF state.

Conclusions: Anxiety appears to have a negative effect on PD patients’ capacity for processing information since HA-PD demonstrated greater sway variability during BL which was exacerbated with a DT. Likewise, anxiety may act similar to a cognitive load, by demanding processing resources since ML sway was also increased during the ANX condition in HA-PD compared to LA-PD and HC. However, further research is needed to understand dopaminergic and non-dopaminergic contributions to limbic and cognitive processing in PD.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/are-limbic-and-cognitive-effects-on-balance-in-parkinsons-disease-equal/