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Impaired gait dynamics are associated with increased falls risk, and are worse in cognitively impaired older adults. Dual-tasking is the performance of a second task, cognitive or physical, while walking. Dual-tasking impairs gait in individuals with deficits in cognitive function. The aims of this thesis were to review the literature on dual-task costs on gait dynamics in adults with cognitive impairment, and to identify clinical characteristics associated with this cost in older adults with Mild Cognitive Impairment (MCI) or dementia. First, a systematic review of 25 articles that measured single- and dual-task walking in adults with MCI or dementia was conducted. Findings suggested dual-task cost is higher in individuals with cognitive impairment compared to cognitively healthy older adults, and similarly, higher in adults with dementia compared to adults with MCI. Research is lacking into nonlinear gait dynamics, the relationship to fall risk, and other characteristics which may be associated dual-task gait dynamics. Next, data from an acute exposure to dual-tasking in 93 adults with MCI were used to explore linear and nonlinear effects of dual tasking on gait dynamics. Cognitive, physical and psychosocial function and brain morphology were assessed to identify any associations with gait dynamics. Gait dynamics worsened significantly during dual-tasking, while cognitive performance was preserved. Additionally, a higher dual-task cost of gait dynamics was associated with lower aerobic fitness, poorer balance, reduced psychological well- being, and reductions in brain thickness and volume in the posterior cingulate and hippocampus respectively. Observed associations with physical fitness, psychological well-being and brain volumes suggest that interventions targeting these modifiable characteristics could potentially improve dual-task performance, and ultimately falls risk, in adults with cognitive impairment. |
