Linking executive dysfunction to gait initiation deficits in Parkinson's disease with freezing of gait

INTRODUCTION: Freezing of gait (FoG) is a disabling symptom of Parkinson's disease (PD) that often emerges during gait initiation and is linked to executive dysfunction. We investigated whether cognitive inhibition and processing speed are associated with gait initiation deficits in people with PD with and without FoG. METHODS: Seventy-nine individuals with PD (50 PD + FoG, 29 PD-FoG) and 37 healthy older adults were evaluated. Executive functions were assessed using the Victoria Stroop test and the Trail Making Test, with scores converted to age- and education-adjusted z-scores. Gait initiation was elicited during a cognitive-motor conflict stepping task. Anticipatory postural adjustments (APA) delay, APA duration, APA amplitude, and normalized step amplitude were extracted. Group differences were assessed using Mann-Whitney tests; associations between cognitive and biomechanical variables were examined using Spearman's rank correlation. RESULTS: PD + FoG showed poorer executive performance than PD-FoG on Stroop-III and TMT-B, while the pooled PD group performed worse than healthy controls on all Stroop and TMT measures. Longer APA duration correlated with poorer TMT-B and Stroop-III performance in PD + FoG. Larger amplitudes of mediolateral APA correlate with lower values in nFoGq in PD + FoG. In healthy controls, longer APA delay was associated with poorer TMT-B performance. DISCUSSION: Executive dysfunction-particularly impaired inhibition and slowed cognitive flexibility-is selectively related to prolonged APA duration during gait initiation, especially in PD + FoG. These findings support a model in which FoG arises from the interaction between vulnerable postural preparation and limited executive control, highlighting APA duration as a potential biomechanical marker and therapeutic target.