Project 5

Shifting the gear on shifting weight: an analysis of freezing-related balance deficits in advanced PD

State-of-the-Art: In a systematic review, we recently confirmed that a very prominent risk factor for falling is gait freezing, which is defined by brief episodes of absence or marked reduction of forward progression of the feet despite the intention to walk. As freezers develop balance deficits earlier than non-freezers, it is probable that postural instability and gait freezing interact and/or have similar causative mechanisms. So far, it has been revealed that freezers produce inadequate voluntary mediolateral weight shifts, a surrogate marker for balance deficit, associated with the severity of gait freezing.

Approach: We will investigate in patients with advanced PD whether mediolateral control of the CoM in response to the already validated Melba task is different in freezers and non-freezers and determine its association with falling, cognition and freezing. CoM parameters will be obtained from force plates embedded in the CAREN platform. We expect that performance on the MELBA will be particularly sensitive to difficulties with mediolateral postural control and may even provoke freezing. Also, we will investigate the effects of practicing mediolateral weight-shifting using a similar set-up as the MELBA in the same groups of subjects (WASP-task) and test immediate learning and retention tests. We will use Transcranial Magnetic Stimulation to measure learning-induced changes in motor cortex excitability. These novel insights are essential for implementing technology-based motor learning to improve specific problems of postural instability.