Modulating brain networks to reduce gait variability in older adults at risk of falling - PROJECT SUMMARY My career goal is to lead efforts to improve gait rehabilitation and mitigate falls risk in older adults by conducting innovative research focused on the neural control and enhancement of gait and mobility. I am particularly interested in developing individualized, multi-modal, and patient-centered interventions that can both stand alone and be combined with current evidenced-based geriatrics rehabilitation programming. Though walking is a repetitive task, one’s temporospatial patterns of movement during walking vary from stride to stride. This gait variability, if sufficiently high, is predictive of both falls and cognitive decline in older adults. Still, the neural mechanisms that give rise to gait variability are not completely understood. We thus lack effective interventions to minimize gait variability in older adults. However, our team has demonstrated that in older adults, those with elevated gait variability exhibit worse ability to sustain performance on a continuous cognitive task over time (i.e., sustained attention). My work has also linked gait variability to the functional connectivity between the two large-scale brain networks believed to underserve sustained attention—namely, the dorsal attention network (DAN) and the default network (DN)—in multiple cohorts of older adults. Based upon these discoveries, we designed a novel multi-channel transcranial direct current stimulation (tDCS) intervention to simultaneously facilitate the excitability of the DAN and inhibit the excitability of the DN. Our preliminary data suggests that a single exposure to this tDCS, as compared to sham, reduces gait variability when tested just following stimulation. My overarching hypothesis is that this form of tDCS can modulate the functional connectivity between the DAN and DN and thus reduce gait variability in older adults. In this project, we will test this hypothesis by examining the acute after-effects of a single session of tDCS on resting-state functional connectivity (Aim 1), as well as determining the effects of a multi-session tDCS intervention on gait variability and related outcomes (Aim 2). We will recruit 30 older adults free of major disease that exhibit higher-than-typical gait variability. Participants will first complete a baseline assessment and two fMRI visits. The same participants will then be randomized to a tDCS intervention arm (ten, once-daily, 20-min sessions) or a ShamàtDCS intervention arm (five, once-daily, 20-min sessions of sham in week one followed by five, once- daily, 20-min sessions of tDCS in week 2). The primary outcome of gait variability will be assessed daily using a validated smartphone app for the entire study period. We expect to demonstrate that tDCS can modulate functional connectivity and reduce gait variability in older adults. The results from this project are expected to inform the design of a larger, more definitive trial of tDCS designed to optimize brain connectivity as it relates to gait variability in older adults. This research, combined with specific training in advanced neuroimaging and neuromodulation, cognitive neuroscience in aging, and the conduct a clinical research in vulnerable older adults, will greatly facilitate my efforts to transition into an independence clinician scientist.
