Attentional set-shifting deficits correlate with the severity of freezing of gait in Parkinson's disease.

Freezing of gait (FOG) is a poorly understood symptom of Parkinson’s disease (PD) during which a patient suffers an abrupt cessation of walking [1]. Whilst little consensus exists regarding the mechanisms underlying FOG [2], there is considerable evidence that additional cognitive demand whilst walking represents a significant trigger in the pathophysiology of FOG [2]. In addition, the severity of self-reported FOG has been correlated with a selective deficit in attentional set-shifting [3]. Taken together, these findings suggest a degree of commonality between corticostriatal networks serving attention and the pathophysiology of FOG. However, no study has directly linked clinical measures of FOG severity during walking with diminished executive function, in particular the ability to rapidly switch between tasks. In this study we hypothesized that impaired behavioral performance on cognitive testing should correlate with objective measures of actual freezing events whilst walking.