Anxiety Independently Contributes to Severity of Freezing of Gait in People With Parkinson's Disease.

Freezing of gait is a disabling feature of Parkinson's disease, and it has been shown that nonmotor symptoms, such as anxiety and cognitive impairment, may be involved in the pathophysiology of the phenomenon. However, the association between freezing of gait severity and nonmotor symptoms is yet to be determined. Therefore, the overall aim of this study was to determine factors that contribute to severity of freezing of gait in people with Parkinson's disease. Participants (N=78) were assessed by disease-specific and self-report measures, including the Hospital Anxiety and Depression Scale (HADS), the Montreal Cognitive Assessment, and the Freezing of Gait Questionnaire (FOG-Q). Participants were classified as "freezers" if they scored ≥1 on item 3 of the FOG-Q; the sum of items 3-6 was used to determine freezing of gait severity. Freezers (N=27) showed higher scores on the HADS anxiety (p=0.002) and HADS depression (p=0.006) subscales. A multivariate linear model showed that disease severity (as measured by using the modified Hoehn and Yahr scale) accounted for 31% of the variance in FOG-Q severity scores (p<0.001). The presence of HADS anxiety ≥8 points increased the explained variance to 38% (p=0.010), and the full model (reached by adding the levodopa equivalent dose) explained 42% of the variance in freezing of gait severity (p=0.026). The findings provide additional support for the contribution of anxiety to greater freezing of gait severity, taking into account not only the frequency but the duration of the episodes, and suggest that anxiety should be routinely evaluated in people with Parkinson's disease who present with freezing of gait.