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Stephanie Pietrangelo, Caitlin Murphy, Sophie Hallot, Ross Clark, Karen Li, Judith Renaud, Aaron Johnson; The impact of a cognitive task and vision impairment on the postural control of older adults. Invest. Ophthalmol. Vis. Sci. 2022;63(7):2260 – F0468.
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© ARVO (1962-2015); The Authors (2016-present)
Older adults, especially those with visual impairments are at risk of falls. Executive functions decline with age and dual-task studies have demonstrated an increase in the postural instability of older adults when performing a cognitive task. However, less is known about the role of cognitive load on the postural stability in visually impaired older adults. The current study examines the separate and combined role of cognitive load and visual impairment on postural stability in older adults.
A total of 57 normally sighted participants (NSP; Mage = 69.7), and 31 visually impaired participants (VIP; Mage = 82.5) were included. Measures of postural control (total displacement and mediolateral [ML] movement) were obtained during a static balance task using a Wii Balance Board under normal vision conditions, and by 17 VIP (Mage = 80.7), and all 57 NSP while performing a cognitive task (serial-3 subtraction). In addition, the NSP performed all tasks under simulated visual impairment with a visual acuity simulated to either 20/80 (n = 27) or 20/200 (n = 30).
The VIP had greater ML movement compared to NSP under normal vision conditions (t(39.1) = 3.78, p = <.001, d = 0.91) and this difference remained even under simulated impairment conditions (20/80: p = .001; 20/200: p = .002). With the cognitive task introduced, VIP increased in total displacement (t(16), p = 0.01, d = -0.63) and NSP increased in both total displacement (W = 47, p = <.001, r = -0.94) and ML movement (W = 140, p = .001, r = -0.46). With the introduction of the cognitive task, the difference in ML movement between VIP and NSP was no longer found regardless of the visual condition NSP were in.
Visually impaired participants had greater ML movement compared to NSP. Movement in the ML direction indicates the use of a hip strategy, which has been associated with increased fall risk. This may point to additional factors contributing to differences in postural control in VIP besides decreased visual function. Given that the NSP experienced a similar increase in ML movement once a cognitive task was introduced, these factors in question may be related to changes in task prioritization and sensory reweighting that the VIP have adopted over time. This can have implications in the type and timing of mobility interventions used for the visually impaired.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.
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