Investigating reach and grasp in Parkinson's disease cognitive impairment

Cosgrove, Jeremy

January 2016

Thesis or dissertation

© 2016 Jeremy Cosgrove. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright holder.

Reach and grasp are evolutionary conserved motor actions controlled by highly specialised neural pathways that have major nodes in the posterior parietal and premotor frontal cortices. Mild cognitive impairment is an important non-motor symptom of Parkinson’s disease (PD) and there is evidence that the risk of transition between PD mild cognitive impairment (PD-MCI) and Parkinson’s disease dementia (PDD) is dependent on which neurotransmitter systems within the brain are most dysfunctional. Studies of reach and grasp in PD subjects with normal cognition (PD-NC) suggest a greater dependence on visual feedback to guide reach and grasp compared with controls.

The primary aim of this thesis is to explore how cognitive impairment influences reach and grasp in PD. Twenty two PD-NC, 23 PD-MCI, ten PDD and 19 controls reached and grasped for a target whilst wearing movement sensing equipment in four conditions: full vision, a darkened room with an illuminated target, with eyes closed at a natural speed and as quickly as possible in full vision. All PD subjects were tested whilst on. Kinematic parameters of reach and grasp were extracted from the movement data and analysed using standard statistical methods.

Our results show a spectrum of change to kinematic reach parameters when reaching and grasping with eyes closed: PD-NC are disproportionately affected compared to controls and PDD are disproportionately affected compared to PD-NC. Parameters of reach and grasp were similar between PD-NC and PD-MCI in all conditions. These results have been discussed in the context of abnormal integration of sensorimotor functions and impaired spatial working memory in PD. Reaction time when reaching and grasping as quickly as possible is significantly associated with global cognition in the PD subjects after controlling for age, motor signs and disease duration. This supports a role for reaction time as a potential biomarker for cognitive impairment in PD.

Hull York Medical School, The University of Hull and the University of York
Alty, Jane; Jamieson, Stuart; Smith, Stephen W., 1973-
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