Dementia, tDCS, Physical Exercise, Neuromodulation, Fall Prevention
Conditions
Brief summary
Falls and mobility decline are major health concerns among older adults with dementia, often linked to deterioration in executive function and cognitive-motor control. Step training interventions that challenge both cognitive and motor faculties have shown promise in enhancing balance and motor reaction to reduce fall risk. However, long-term retention of training gains remains limited, largely constrained by reduced neuroplasticity and underlying neurodegeneration in this population. The primary objective of this study is to investigate the efficacy of high-definition transcranial direct current stimulation (HD-tDCS), a form of wearable non-invasive brain stimulation, combined with step training in community-dwelling older adults with mild dementia. Participants will be randomly allocated to either an active HD-tDCS plus step training group or a sham stimulation plus step training control group. Assessments will be conducted at baseline, immediately post-intervention, and at a 3-month follow-up to evaluate changes in cognitive and physical function (including choice stepping reaction time (CSRT), executive function, and dual-task ability) as well as cortical activity during stepping. In addition, a mid-point assessment will be conducted for the primary outcome (i.e., CSRT). An embedded qualitative evaluation will be conducted with participant-caregiver dyads and healthcare professionals/staff to evaluate implementation outcomes and feasibility (including perceived acceptability, user experience, and practical facilitators and barriers to adoption). Findings from this trial will help optimize neuromodulation-augmented rehabilitation strategies and inform community-based fall prevention programs.
Interventions
BEHAVIORALStep training
A structured stepping exercise program will be delivered on a designated stepping mat. The intervention incorporates progressive cognitive tasks (including mental arithmetic, working memory, and executive function challenges) combined with directional volitional stepping. Training difficulty is progressively adapted based on individual performance, with physical and cognitive exertion monitored to maintain a moderate intensity level.
DEVICEsham HD-tDCS
The sham HD-tDCS targets the prefrontal cortex via a 4×1 multi-electrode montage during training. The sham HD-tDCS delivers brief current stimulation to simulate scalp sensations without inducing neuroplastic effects to maintain blinding. All sessions are delivered by trained research personnel following standardized safety guidelines.
DEVICEactive HD-tDCS
The active HD-tDCS targets the prefrontal cortex via a 4×1 multi-electrode montage during training. The active HD-tDCS delivers 2 mA current for 20 minutes with ramp-up and ramp-down phases. All sessions are delivered by trained research personnel following standardized safety guidelines.
Sponsors
The Hong Kong Polytechnic University
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
TRIPLE (Subject, Caregiver, Outcomes Assessor)
Eligibility
Sex/Gender
ALL
Age
65 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Interested persons will be included if they are (1) aged 65 years or older; (2) able to walk 10 m without assistance; (3) can communicate in Chinese; and (4) clinically diagnosed with dementia, with mild-stage severity evidenced by a total score of 10 to 18 (inclusive) on the Hong Kong version of the Montreal Cognitive Assessment (HK-MoCA) \[21\].
Exclusion criteria
* Individuals will be excluded if they, or their caregivers, report: (1) severe cardiopulmonary diseases, severe musculoskeletal disorders, or severe visual or hearing impairments; (2) any neurological conditions other than dementia; (3) contraindications to tDCS, including metallic head implants (excluding dental fillings), cardiac pacemakers, skull defects, a history of unprovoked seizures, or skin/scalp lesions at electrode sites; or (4) concurrent or recent physical therapy or non-invasive brain stimulation within the past 3 months.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Choice Stepping Reaction Time (CSRT) Test Completion Time | Baseline, mid-point of intervention (Week 6), immediate post-intervention (Week 12), and 3-month follow-up (Week 24) | The clinical Choice Stepping Reaction Time (CSRT) test evaluates goal-directed volitional stepping speed and accuracy. Participants stand on a designated mat and step onto indicated target panels as quickly and accurately as possible in response to standardized verbal cues across 12 test trials. Performance is recorded as the total time (in seconds) required to successfully complete all 12 correct steps using a stopwatch. Shorter completion times indicate faster reaction and better stepping performance. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Dorsolateral Prefrontal Cortex (DLPFC) Hemodynamic Response During Choice Stepping | Baseline, immediate post-intervention, and 3-month follow-up | Cortical activity in the bilateral dorsolateral prefrontal cortex (DLPFC) is assessed during the choice stepping task using functional near-infrared spectroscopy (fNIRS). Performance is quantified by task-evoked changes in oxygenated hemoglobin concentration (ΔHbO) relative to baseline. Greater increases in ΔHbO reflect higher cortical activation and neural recruitment during task execution. |
| Berg Balance Scale (BBS) Score | Baseline, immediate post-intervention, and 3-month follow-up | Balance will be measured using the Berg Balance Scale (BBS). Participants' ability to maintain an upright posture during 14 functional activities (e.g., sitting, rising from a seated position, transfer between two chairs, reaching while standing) will be rated on a scale ranging from 0 to 4, with higher scores reflecting greater balance. |
| Maximum Step Length | Baseline, immediate post-intervention, and 3-month follow-up | The Maximum Step Length test (MSLT) assesses an individual's ability to step as far as possible in a given direction (forward, backward, or sideways) and then return to the starting position without losing balance. An average of three attempts for each direction will be recorded. |
| Single- and Dual-Task TUG Speed | Baseline, immediate post-intervention, and 3-month follow-up | Cognitive-motor dual-tasking ability will be assessed using the single-task and dual-task of the Timed Up and Go (TUG) test. This dual-task TUG combines the standard mobility assessment with a simultaneous verbal fluency task. Under the instruction of a trained assessor, participants will be asked to rise from a standard chair, walk 3 meters, turn around, return to the chair, and sit down as quickly and safely as possible, while simultaneously naming items randomly chosen from a pool of topics (e.g., animals, fruits, or modes of transportation). The total time to complete the task will be recorded. Verbal responses will be monitored to ensure task engagement. |
| Trail Making Test (TMT) Score | Baseline, immediate post-intervention, and 3-month follow-up | Executive function including attention shift and processing speed will be measured using the Trail Making Test (TMT), an education-fair alternative to the traditional Trail Making Test validated in older adults. The TMT consists of two parts: TMT-A (evaluates visuospatial scanning and perceptual tracking) and TMT-B (evaluates executive divided attention and mental set-shifting). TMT-A requires participants to connect numbers in an ascending sequence (i.e., numbers 1-25) enclosed in uniform circles. TMT-B requires participants to connect numbers in an ascending sequence while alternating between two distinct geometric shapes (circles and squares, e.g., 1-circle to 2-square to 3-circle). Shorter completion times indicated better performance. |
Countries
Hong Kong
Contacts
CONTACTJae QJ LIU, PhD Student
PRINCIPAL_INVESTIGATORMarco YC Pang, Chair professor
The Hong Kong Polytechnic University
Outcome results
None listed