Walking is a complex and continuous task that entails repetitive motions of the body. Relatively high gait variability sensitively predicts falls and cognitive decline in older adults. Previous work has identified an unique brain network relationship linked to gait variability and its relevant cognitive function (i.e., sustained attention). This project aims to develop a non-invasive brain stimulation montage designed to modulate the shared brain networks dynamics and to demonstrate its effects on resting state functional connectivity, gait and cognitive performance in older adults at risk for falls.

This is a randomized controlled trial to examine the efficacy of a non-invasive brain stimulation intervention of tDCS to improve unsteady gait in older adults. The investigators will enroll 30 older adults with elevated gait variability. Participants will be randomized into one of two arms: a) 10 sessions of tDCS and b) 5 sessions of sham stimulation followed by 5 sessions of tDCS. Participants will engage in a set of pre-intervention assessments, the brain stimulation intervention - consisting of 10, once-daily, 20-min stimulation sessions over a 2-week period, and a set of post-intervention assessments. This project is expected to demonstrate that tDCS can be used to reduce gait variability in older adults.

Inclusion Criteria:

• Aged 65 and above.
• Ability to speak and read English.
• Ability to walk independently and continuously for at least 1 minute.
• Elevated gait variability as defined by a coefficient of variation (CoV) about average stride time larger and equal to 0.025 during straight-line walking at preferred speed.

Exclusion Criteria:

• More than mild cognitive impairment defined by a Montreal Cognitive Assessment (MoCA) score less than 18.
• Parkinson's disease, multiple sclerosis, stroke, active brain tumor, or other neurological disorders.
• Self-reported pain or lower extremity deformity that significantly disrupts walking.
• Contraindications to MRI or tDCS.
• An episode of acute illness or exacerbation of a diagnosis that requires hospitalization or active treatment within the past 3 months.
• Current treatment for congestive heart failure, angina, uncontrolled arrythmia, deep vein thrombosis, or other uncontrolled cardiovascular events.
• Myocardial infarction, coronary artery bypass grafting, angioplasty, or other cardiac conditions within the past 3 months,
• Active cancer for which chemo/radiation therapy is being received.
• Psychiatric co-morbidity including major depressive disorder, schizophrenia, psychosis, or other psychiatric illness.
• Recent use of any sedating medications (sedatives, anti-psychotics, hypnotics, anti-depressants) or change in medication within the previous month.
• Chronic vertigo or other diagnosed vestibular disorders.
• Legal blindness, visual impairments that cannot be corrected with glasses, contact lenses, medicine, or surgery.
• Those without WiFi access
• Those who do not plan to live in their current homes for the duration of the study

The prospective plan is to have data available in a data repository.

The data will be available when the data are unblinded.

Depending on the repositories in which the data is held. Use of the data will be restricted by permission and appropriate human subjects review of the prospective project.