Overview

This study aims to evaluate the feasibility, acceptability, and preliminary effects of a home-based, remotely supervised intervention combining transcranial direct current stimulation (tDCS) and online chair yoga (OCY) to manage chronic knee pain in older adults with Alzheimer's Disease and Related Dementias (ADRD). Chronic knee pain is prevalent among individuals with ADRD and is often underdiagnosed and undertreated, contributing to neuropsychiatric symptoms, reduced quality of life, and increased caregiver burden. Current pharmacological options, such as opioids, pose risks of adverse events in this population.

tDCS is a safe, noninvasive technique that uses low-intensity electrical current to modulate brain activity and may improve pain perception by targeting central mechanisms. Chair yoga is a mind-body intervention shown to improve pain and mood in older adults, including those with dementia. This study proposes that combining tDCS and OCY may have synergistic benefits in reducing pain and enhancing function.

Participants will include older adults aged 60+ with mild to moderate ADRD and chronic knee pain, along with their caregivers. Over four weeks, participants will complete 14 supervised sessions of combined tDCS and OCY at home. Outcomes include feasibility, satisfaction, pain intensity, pain interference, neuropsychiatric symptoms, sleep disturbance, cognitive function, mobility, and quality of life. Neurophysiological measures (e.g., fNIRS, EEG, HF-HRV) will also be assessed to explore underlying mechanisms.

This study seeks to lay the foundation for future large-scale randomized controlled trials of home-based nonpharmacological interventions for chronic pain in ADRD.

Eligibility

Inclusion Criteria (participants):

• Live in the community (not institutionalized).
• Have a diagnosis of Alzheimer's disease and related dementias (ADRD), including Alzheimer's disease, Lewy Body Dementia, Vascular Dementia, or Multiple Etiology Dementias (MED) diagnosed by a neurologist or other healthcare provider.
• Be in mild to moderate ADRD, as indicated by a Quick Dementia Rating Scale (QDRS) score between 6 and 20.5.
• Score above 10 on the Montreal Cognitive Assessment (MoCA).
• Experience chronic knee pain (caregiver-reported average pain in the past 3 months \> 40 out of 100).
• Have no planned changes to their medication regimen or other interventions for knee pain during the trial.
• Agree to participate in both transcranial direct current stimulation (tDCS) and online chair yoga (OCY).
• Be able to ambulate independently with minimal assistance (e.g., using a cane or walker) for participation in OCY and the Timed Up and Go (TUG) test. - -- Be English-speaking and able to understand verbal instructions (literacy not required).
• Be able to consent for themselves or identify a legally authorized representative who can provide written informed consent.
• Exhibit neuropsychiatric symptoms (e.g., apathy, agitation).
• Be naïve to yoga and tDCS.

Exclusion Criteria (participants):

• a history of brain surgery, brain tumor, head trauma, seizure/epilepsy, stroke, cancer affecting the head, or intracranial metal implantation;
• systemic rheumatic disorders, including rheumatoid arthritis, systemic lupus erythematosus, or fibromyalgia;
• prosthetic knee replacement or non-arthroscopic surgery to the affected knee;
• compromised skin integrity on the head in the area where electrodes will be placed;
• serious comorbidities that preclude participation in tDCS or OCY (e.g., heart failure \[level IV\] causing shortness of breath on exertion);
• hospitalization within the preceding year for neuropsychiatric illness that would impact knee pain or interfere with study procedures;
• use of another neurostimulation device (e.g., spinal cord stimulator, cardio-stimulator, or implanted cardioverter-defibrillator).

Inclusion Criteria (caregivers):

A caregiver is defined in this study as the person who provides care and assistance to a patient with ADRD (e.g., helping with daily activities, managing medications, ensuring safety).

• Caregivers must be at least 18 years old
• have provided care and assistance to the patient for at least 10 hours per week at the time of enrollment
• anticipate continuing to provide care and assistance for the next 4 months (until the study ends)
• be willing to receive tDCS training, administer home-based tDCS sessions, and assist the patient in attending OCY sessions
• have access to a reliable Internet connec¬tion for secure videoconferencing for real-time remote supervision
• English-speaking caregivers who can understand verbal instructions.

Exclusion Criteria (caregivers):

• alcohol/substance use disorder
• inability to understand English
• disability that would prevent assisting patients with ADRD from participating in tDCS and OCY (e.g., blindness, deafness)
• unwillingness to provide care and assistance to patients until the study is completed.
• If caregiver does not meet the inclusion/exclusion criteria, the participant will not be accepted into the study.