Relationship between Motor Estimation Error and Physical Function in Patients with Parkinson's Disease.

: Motor estimation error is an index of how accurately one's body movement is recognized. This study determines whether motor estimation error distance is a Parkinson's disease (PD)- or age-related disability using a two-step task. : The participants were 19 PD patients and 58 elderly people with disabilities. A two-step prediction test and an actual two-step test were performed. The motor estimation error distance (prediction of two-step distance minus actual two-step distance) and error rate between the two groups were compared. We conducted a correlation analysis between the motor estimation error and clinical factor (e.g., Hoehn and Yahr stage (H & Y), Unified Parkinson's Disease Rating Scale (UPDRS)) related to PD. : The motor estimation error distance was not significantly different between the PD patient group and the elderly group with disabilities. However, significant correlations between motor estimation error and H & Y, and between motor estimation error and UPDRS part II, were observed. The error rate was significantly correlated with the Fall Efficacy Scale. : The motor estimation error distance is influenced by both aging and PD.