Analyzing gait variability and dual-task interference in patients with Parkinson's disease and freezing by means of the word-color Stroop test.

The ability to carry out two tasks at once is critical to effective functioning in the real world and deficits are termed Dual-task interference or effect-DTE. DTE substantially compromised the gait of subjects with Parkinson's disease and freezing of gait (PD + FOG), leading to exaggerated slowing, increasing gait dysrhythmicity, and inducing FOG episodes. This study aimed to investigate the DTE in gait variability of subjects with PD and freezing of gait (PD + FOG). Thirty-three patients with PD + FOG and 14 healthy individuals (REFERENCE) took part at this study. Two gait conditions were analyzed: usual walking (single task) and walking while taking the word-color Stroop test (dual task). The computed variables were as follows: gait velocity, step length, step timing, gait asymmetry, variability measures and DTE of each variable. The PD + FOG group has presented negative DTE values for all analyzed variables, indicating dual task cost. The REFERENCE group has presented dual-task benefits for step length standard deviation and step time. Differences between both groups and conditions were found for all variables, except for step time. Taking the word-color Stroop test while walking led to a larger dual-task cost in subjects with PD + FOG.