Remote tDCS and Chair Yoga for Chronic Knee Pain in Alzheimer's Patients

Older adults with ADRD frequently experience chronic pain, particularly knee pain, which is associated with worse behavioral symptoms and faster cognitive decline. Despite its impact, pain is often inadequately treated in this population due to communication difficulties and the risks associated with pharmacological treatments, especially opioids. Transcranial direct current stimulation (tDCS) is a promising nonpharmacological therapy that delivers low-intensity electrical current to modulate cortical excitability. Research suggests that tDCS can reduce clinical and experimental pain and improve pain processing, particularly when targeted to the motor cortex. Our group has demonstrated the safety and efficacy of home-based, remotely supervised tDCS in older adults, including those with ADRD. Chair yoga (CY), a modified yoga intervention involving seated or chair-supported postures, is also safe and effective for older adults with chronic pain and cognitive impairment. CY has demonstrated benefits in reducing pain, improving mood, and promoting physical activity with minimal risk of falls. Evidence suggests that yoga interventions may enhance central pain modulation and reduce neuropsychiatric symptoms. This pilot study tests a novel combination of tDCS and online CY (OCY) in a home-based setting. We hypothesize that combining tDCS and OCY will reduce chronic knee pain and improve related symptoms in older adults with ADRD. Participants will be recruited from geriatric outpatient clinics and community settings. Eligible participants will be 60 years or older, have mild to moderate ADRD, and experience chronic knee pain. The intervention will include 14 sessions over four weeks. All sessions will be supervised remotely via a secure videoconferencing platform. Primary outcomes are feasibility, acceptability, and satisfaction, assessed through recruitment, adherence, dropout rates, and participant feedback. Secondary outcomes include reductions in knee pain (measured by Numerical Rating Scale and MOBID-2), pain interference (PROMIS Pain Interference 4a), sleep disturbance (ActiGraph), neuropsychiatric symptoms (Neuropsychiatric Inventory Questionnaire), cognitive function (Montreal Cognitive Assessment and Cognivue), mobility (Timed Up and Go), and quality of life (QOL-AD). Exploratory neurophysiological outcomes will include functional near-infrared spectroscopy (fNIRS) to assess pain-related brain activity, EEG for neural pain signatures, and high-frequency heart rate variability (HF-HRV) for autonomic function. This study will help determine the feasibility and potential effects of a scalable, home-based tDCS+OCY protocol, with the goal of informing future large-scale trials and advancing personalized, nonpharmacological pain care in ADRD.