Efficacy of transcranial direct current stimulation (tDCS) combined with complex (cognitively engaging) walking exercise in older adults. The primary outcome measures are executive function (computer-based assessment battery) and complex walking function (speed on an obstacle negotiation task). This will be a two-site trial conducted at the University of Florida (lead site) and Brooks Rehabilitation Hospital, which is necessary to achieve enrollment targets and will allow us to develop a multi-site research infrastructure for a future Phase 3 multi-site trial. The study will enroll up to 120 older adult women and men, who exhibit mild to moderate decline of executive function. All experimental groups will receive the same complex walking intervention, which will focus on use of cognitively engaging tasks such as obstacle crossing, accurate foot placement, and walking on complaint surfaces. Each session will consist of 30 minutes of walking. For tDCS, the active treatment group will receive 20 minutes of 2mA tDCS over prefrontal regions F3/F4 ("treatment group"). The second group is a sham control group. tDCS will be delivered simultaneously with complex walking exercise for 18 sessions over a 6-week period. Assessments will be conducted at baseline, post intervention (within one week), and 12 weeks post-intervention.
