The Effects of High-definition Transcranial Direct Current Stimulation on Balance Control in Older Adults With Chronic Low Back Pain

The Effects of High-definition Transcranial Direct Current Stimulation on Balance Control in Older Adults With Chronic Low Back Pain: a Randomized Controlled Trial

The goal of this clinical trial is to investigate the effects and mechanisms of high-definition transcranial direct current stimulation over left dorsolateral prefrontal cortex on chronic low back pain and balance in older adults. The main questions it aims to answer are:

Primary hypothesis 1: Active stimulation would have greater improvement in pain and balance, reduced left dorsolateral prefrontal cortex activation than sham stimulation.

Primary hypothesis 2: Active stimulation would have enhanced functional connectivity than sham stimulation.

Primary hypothesis 3: The balance improvement would be related to reduced pain, decreased left dorsolateral prefrontal cortex activation, enhanced functional connectivity, attention, and/or executive function.

Participants will be randomly received a single-session of high-definition transcranial direct current stimulation (active or sham stimulation). Before and immediately after the intervention, balance (semi-tandem stance and timed up-and-go test (TUG)) and cognitive (attention and executive function) tests will be assessed.

Inclusion Criteria:

• Aged 60-85 years;
• With non-specific chronic low back pain that has no definitive diagnosis but lasted for at least 3 months, typically occurs in the area between the lower rib margins and the buttock creases;
• With an average pain intensity over the last week to be ≥ 3 on an 11-point numerical rating scale (NRS) anchored with "no pain" at zero and "worst pain imaginable" at 10;
• Have normal cognitive function (Hong Kong Montreal Cognitive Assessment ≥ 22);
• Who agree to sign an informed consent form.

Exclusion Criteria:

• Inability to ambulate without assistance from another person or tools (e.g., canes or walkers);
• Having specific causes of low back pain (e.g., spinal stenosis, lumbar disc herniation, spondylolisthesis, recent vertebral fracture, spinal infection);
• Having other acute or overt musculoskeletal conditions in other parts of the body (e.g., fractures, severe pain, multiple joint pain (e.g., knee pain));
• History of lumbar or lower extremity surgery;
• Receiving LBP treatment within the past one month or at present;
• Have never received non-invasive brain stimulation (e.g., transcranial direct current stimulation, repetitive transcranial magnetic stimulation, and transcranial alternating current stimulation) before.