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Parkinson’s Disease
Volume 2016 (2016), Article ID 6827085, 8 pages
Research Article

The Cognition of Maximal Reach Distance in Parkinson’s Disease

1Department of Rehabilitation, Juntendo University Nerima Hospital, 3-1-10 Takanodai, Nerima-ku, Tokyo 177-8521, Japan
2Department of Rehabilitation Medicine, Juntendo University Graduate School, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan

Received 13 May 2016; Revised 10 July 2016; Accepted 20 July 2016

Academic Editor: Cristine Alves da Costa

Copyright © 2016 Satoru Otsuki and Masanori Nagaoka. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study aimed to investigate whether the cognition of spatial distance in reaching movements was decreased in patients with Parkinson’s disease (PD) and whether this cognition was associated with various symptoms of PD. Estimated and actual maximal reaching distances were measured in three directions in PD patients and healthy elderly volunteers. Differences between estimated and actual measurements were compared within each group. In the PD patients, the associations between “error in cognition” of reaching distance and “clinical findings” were also examined. The results showed that no differences were observed in any values regardless of dominance of hand and severity of symptoms. The differences between the estimated and actual measurements were negatively deviated in the PD patients, indicating that they tended to underestimate reaching distance. “Error in cognition” of reaching distance correlated with the items of posture in the motor section of the Unified Parkinson’s Disease Rating Scale. This suggests that, in PD patients, postural deviation and postural instability might affect the cognition of the distance from a target object.