Dopaminergic interactions between anxiety and processing of the environment in PD


Recent research has suggested that anxiety influences gait in PD, with an identified dopa-sensitive gait response in highly anxious PD. Sensory-perceptual deficits have been suggested to underlie gait impairments in PD, thus, it may be that in threatening situations anxiety acts like a dual task limiting one's ability to process information about the environment. The current study aimed to (i)evaluate whether anxiety influences information (visual) processing in PD while walking in threatening situations, and (ii)examine whether dopaminergic medication modulates anxiety's influence on information processing. Forty-eight participants (24 HC; 12 Low Anxious [LA-PD], 12 Highly Anxious [HA-PD]) were asked to walk across a plank in virtual reality that was either located: on the ground (LOW) or above a deep pit (HIGH). The plank varied in size from 60-100 cm, and after participants crossed the plank they were asked to judge the width of the plank they had just walked across. Both ON and OFF medication states were evaluated in PD, and judgment error as well as self-reported anxiety levels were measured. Overall PD had similar judgment error as HC. However, when examining the PD groups across both medication states, a condition x plank size interaction was found for constant error (p=0.011), revealing that all PD participants judged the narrowest plank more accurately when walking across the HIGH plank (compared to LOW). The opposite was observed when PD participants walked across the widest plank, that is, participants overestimated the plank size after they had walked across the HIGH plank (compared to the LOW). Finally, medication state did not influence judgment error. In conclusion, the current study did not find evidence that dopamine modulates the influence of anxiety on processing aspects of the environment, nor was there evidence to suggest that anxiety interferes with accurate perception of the plank size in PD. Instead the current findings suggest that anxiety enhances threat-relevant processing when walking in extremely threatening situations.