Abstract
The TUG test is a reliable and valid test for quantifying functional mobility (Podsiadlo & Richardson, 1991). Parkinson's disease (PD) patients face many mobility challenges as well as attention deficits. In order to test both mobility and attention, the current study had both PD patients (N=10, 62.8 + 10.5 yrs) and healthy age-matched adults (N=12, 65.7 + 6.3 yrs) perform the TUG test with a dual task. Dual task paradigms determine the amount of interference a secondary task has on the performance of a primary task. The participants were instructed to rise from a chair and walk towards a counter three metres away. Hidden behind a curtain on the counter was either: 1) nothing, 2) an empty tray, or 3) a tray with glasses (TWG). After reaching and grabbing the item located behind the curtain, the participants were ask to turn around and walk back. Kinematic data was collected using an Optotrak system and gaze behaviours (fixations) were collected using an ASL Mobile Eye Tracker. Results showed that during the approach and return, both velocity and step length were significantly lower (p<0.05) in PDs compared to the healthy participants, independent of the condition. Gaze behaviours showed that PDs took more time to process visual information; they had fewer fixations but longer fixation durations than the healthy participants. Although both groups of participants directed more attention (total fixation duration) towards the tray during the TWG condition than other conditions, only the PDs demonstrated a significant (p<0.05) decrease in stability. This decrease in stability was due to the PDs inability to properly re-direct sufficient amounts of attention towards task-relevant objects, which may be the reason for mobility challenges within this population.