Patients affected by functional movement disorders (FMD) have abnormal processing of stress responses. Until now, little was known on the influence of f this abnormal stress processing on automatic motor defense behavior, such as freeze response. The aim of this study was to investigate stress-induced postural motor responses in FMD on a population made of nine FMD patients and thirteen healthy controls.
For the purpose of this study, our inertial sensors (Physilog®) were attached to the thorax of the participants.
A significant interaction effect was found, showing that healthy controls reduced their thorax sway over time during exposure to stress whereas patients with FMD did not.
Patients with FMD failed to show a reduction of body sway over time, i.e., freeze response observed in the controls, thus suggesting an impairment in the automatic defense behavior. In addition, a lower complexity of movement (HFD) was found in FMD, which deserves future research in order to verify whether this could represent a characteristic trait of the disorder.
This study was jointly conducted by G.A.Zito (Department of Neurology, Inselspital, Bern University Hospital), K. Apazoglou and S. Aybek (Department of Neuroscience, Faculty of Medicine, University of Geneva), A. Paraschiv-Ionescu and K. Aminian (Laboratory of Movement Analysis and Measurement, EPFL, Lausanne).
Keywords: Functional movement disorders, Motor behavior, Stress Freeze response