Impact of depression on gait variability in Parkinson’s disease

•Depression is associated with gait variability especially in a dual-task condition.•Swing time variability might be particularly sensitive to an impact of depression.•Treating depression is important for improvement of gait and reduction of falls. The goal of this study was to analyze how depression associated with Parkinson’s disease (PD) affected gait variability in these patients using a dual-task paradigm. Additionally, the dependency of the executive functions and the impact of depression on gait variability were analyzed. Three subject groups were included: patients with PD, but no depression (PD-NonDep; 14 patients), patients with both PD and depression (PD-Dep; 16 patients) and healthy controls (HC; 15 subjects). Gait was recorded using the wireless sensors. The participants walked under four conditions: single-task, motor dual- task, cognitive dual-task, and combined dual-task. Variability of stride length, stride duration, and swing time was calculated and analyzed using the statistical methods. Variability of stride duration and stride length were not significantly different between PD-Dep and PD-NonDep patients. The linear mixed model showed that swing time variability was statistically significantly higher in PD-Dep patients compared to controls (p = 0.001). Hamilton Disease Rating Scale scores were significantly correlated with the swing time variability (p = 0.01). Variability of all three parameters of gait was significantly higher while performing combined or cognitive task and this effect was more pronounced in PD-Dep group of patients. Depression in PD was associated with swing time variability, and this effect was more prominent while performing a dual-task. Diagnosing and treating depression might be important for gait improvement and fall reduction in PD patients.