The Effect of Adult Aging on the Vestibular Control of Standing Balance Under Increased Cognitive Demand
Datum
2016-06
Autor:innen
Peters, Wendy
Zeitschriftentitel
ISSN der Zeitschrift
Bandtitel
Verlag
University of Oregon
Zusammenfassung
Postural control is an essential aspect of everyday life, but it can be
compromised while multi-tasking or with altered attention, particularly among older
adults. Age-related decrements within the sensorimotor system put older adults at
greater risk of sustaining falls, however the effect of adult aging on the vestibular
control of balance remains unclear. Purpose: The present study aimed to investigate the
vestibular control of standing balance in old women under increased cognitive demand.
Methods: Eight old (-70 years) and eight young (-23 years) recreationally active,
healthy women stood on a force-plate with arms relaxed at their sides and head turned
to the left for four 90-s trials while exposed to continuous electrical vestibular
stimulation (EVS). Participants stood quietly with or without performing a cognitive
task (mental arithmetic). The vestibular-evoked balance response was derived via
anterior-posterior (AP) ground forces acting on the body and analyzed in the time
(cumulant density) and frequency (coherence) domains. Total AP center of pressure
(COP) displacement was measured as a means of quantifying balance stability. Results:
Cumulant density peak medium latency amplitude was 42% larger in older women compared to the young for the single tasks (p < 0.05). Additionally, the medium latency
peak amplitude increased by 13% from the single to dual task for the young (p < 0.05)
but did not change for the old (p = 0.700). Coherence was elevated in older females
compared to young at frequencies < 4 Hz during quiet standing. With the addition of a
cognitive task, coherence was larger than the single task for the young women at
frequencies < 2 Hz, but coherence did not change in the older females. Total AP COP
displacement was not significantly different among age groups or tasks (p > 0.05).
Conclusion: The present findings in young adults likely resulted from the vestibular
system acting as a compensatory mechanism to modulate balance control when
cognitive resources are reallocated to a dual-task. Older females exhibit a greater
vestibular-evoked balance response than young during single-task conditions, likely due
to an increased sensitivity of the vestibular nuclei. While there was an increase in the
vestibular-evoked balance response for the young during the single task as compared to
the dual, the response in older females was not further elevated under the dual-task
paradigm. Additionally, a lack of difference in total AP COP displacement among age
groups or tasks suggests the possible involvement of additional compensatory
mechanisms controlling for postural sway in old women under conditions of increased
cognitive demand.
Beschreibung
50 pages. A thesis presented to the Department of Human Physiology and the Clark Honors College of the University of Oregon in partial fulfillment of the requirements for degree of Bachelor of Science, Spring 2016.
Schlagwörter
Standing balance, Human physiology, Vestibular system, Aging, Dual-task, Cognitive task, EVS, Human physiology