Medication and trial duration influence postural and pointing parameters during a standing repetitive pointing task in individuals with Parkinson’s disease
Deborah A. Jehu 
Hiram Cantú
Allen Hill
Caroline Paquette
Julie N. Côté
Julie Nantel
We aimed to determine the effects of levodopa medication on the performance of a repetitive pointing task while standing, and to investigate the optimal trial duration in individuals with Parkinson’s disease, and older adults. Seventeen individuals with Parkinson’s disease (5 freezers) and 9 older adults stood on force platforms for 30 s and 120 s while performing a bilateral repetitive pointing task, tracked by motion capture. Participants with Parkinson’s disease were assessed on and off medication and older adults were also assessed on separate days. The main findings were that: 1) on medication, participants with Parkinson’s exhibited greater center of pressure root mean square in the medial-lateral direction, greater velocity in the medial-lateral and anterior-posterior directions, and greater range in the medial-lateral direction than off medication; 2) longer trial durations resulted in greater center of pressure range in the medial-lateral and anterior-posterior directions and greater coefficient of variation in finger pointing on the least affected side; 3) Parkinson’s participants exhibited larger range in the medial-lateral direction compared to older adults; 4) off medication, freezers presented with less range and root mean square in the anterior-posterior direction than non-freezers; and 5) a correlation emerged between the freezing of gait questionnaire and pointing asymmetry and the coefficient of variation of pointing on the most affected side. Therefore, Parkinson’s medication may increase instability during a repetitive pointing task. Longer trials may provide a better depiction of sway by discriminating between those with and without neurological impairment. Individuals with Parkinson’s were less stable than older adults, supporting that they are at a greater risk for falls. The greater restrictive postural strategy in freezers compared to non-freezers is likely a factor that augments fall-risk. Lastly, the link between freezing of gait and upper-limb movement indicates that freezing may manifest first in the lower-limbs.
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Citation
@article{jehu2018,
author = {Jehu, Deborah A. and Cantú, Hiram and Hill, Allen and
Paquette, Caroline and Côté, Julie N. and Nantel, Julie},
title = {Medication and Trial Duration Influence Postural and Pointing
Parameters During a Standing Repetitive Pointing Task in Individuals
with {Parkinson’s} Disease},
journal = {PLOS ONE},
volume = {13},
number = {4},
pages = {e0195322},
date = {2018-04-05},
url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0195322},
doi = {10.1371/journal.pone.0195322},
langid = {en},
abstract = {We aimed to determine the effects of levodopa medication
on the performance of a repetitive pointing task while standing, and
to investigate the optimal trial duration in individuals with
Parkinson’s disease, and older adults. Seventeen individuals with
Parkinson’s disease (5 freezers) and 9 older adults stood on force
platforms for 30 s and 120 s while performing a bilateral repetitive
pointing task, tracked by motion capture. Participants with
Parkinson’s disease were assessed on and off medication and older
adults were also assessed on separate days. The main findings were
that: 1) on medication, participants with Parkinson’s exhibited
greater center of pressure root mean square in the medial-lateral
direction, greater velocity in the medial-lateral and
anterior-posterior directions, and greater range in the
medial-lateral direction than off medication; 2) longer trial
durations resulted in greater center of pressure range in the
medial-lateral and anterior-posterior directions and greater
coefficient of variation in finger pointing on the least affected
side; 3) Parkinson’s participants exhibited larger range in the
medial-lateral direction compared to older adults; 4) off
medication, freezers presented with less range and root mean square
in the anterior-posterior direction than non-freezers; and 5) a
correlation emerged between the freezing of gait questionnaire and
pointing asymmetry and the coefficient of variation of pointing on
the most affected side. Therefore, Parkinson’s medication may
increase instability during a repetitive pointing task. Longer
trials may provide a better depiction of sway by discriminating
between those with and without neurological impairment. Individuals
with Parkinson’s were less stable than older adults, supporting that
they are at a greater risk for falls. The greater restrictive
postural strategy in freezers compared to non-freezers is likely a
factor that augments fall-risk. Lastly, the link between freezing of
gait and upper-limb movement indicates that freezing may manifest
first in the lower-limbs.}
}