Loss of fractal gait harmony in Parkinson's Disease

Objective: Recently, an intrinsic fractal harmonic structure was found underlying the rhythm of physiological walking, but it has not yet been investigated in subjects with a neurological disease. The aim of this study was to determine if and how this harmonic structure is altered in patients with Parkinson's Disease. Methods: Gait analysis of 70 patients with Parkinson's Disease in pharmacological phase on was performed, the findings of which we compared with reference data of age-matched healthy subjects. Fifteen patients were retested after a washout period of 12 h. Results: Alterations in all spatio-temporal gait parameters and gait indices with regard to symmetry, coordination, and harmony were noted, but after correction for multicollinearity bias, only the latter correlated significantly with Unified Parkinson's Disease Rating Scale motor score (= 0.001). The fractal gait structure underwent even more extensive alterations in pharmacological off phase (<0.05). Conclusions: The intrinsic gait harmony was altered in patients with Parkinson's Disease and significantly correlated to motor severity. It could be partially recovered by assumption of L-dopa. Significance: Loss of harmony is a quantitatively assessable gait benchmark in Parkinson's Disease. It seems to be dependent on dopaminergic but also on non-dopaminergic networks.