Self-administered transcranial direct current stimulation treatment of knee osteoarthritis alters pain-related fNIRS connectivity networks.

Significance: Knee osteoarthritis (OA) is a disease that causes chronic pain in the elderly population. Currently, OA is mainly treated pharmacologically with analgesics, although research has shown that neuromodulation via transcranial direct current stimulation (tDCS) may be beneficial in reducing pain in clinical settings. However, no studies have reported the effects of home-based self-administered tDCS on functional brain networks in older adults with knee OA. Aim: We used functional near-infrared spectroscopy (fNIRS) to investigate the functional connectivity effects of tDCS on underlying pain processing mechanisms at the central nervous level in older adults with knee OA. Approach: Pain-related brain connectivity networks were extracted using fNIRS at baseline and for three consecutive weeks of treatment from 120 subjects randomly assigned to two groups undergoing active tDCS and sham tDCS. Results: Our results showed that the tDCS intervention significantly modulated pain-related connectivity correlation only in the group receiving active treatment. We also found that only the active treatment group showed a significantly reduced number and strength of functional connections evoked during nociception in the prefrontal cortex, primary motor (M1), and primary somatosensory (S1) cortices. To our knowledge, this is the first study in which the effect of tDCS on pain-related connectivity networks is investigated using fNIRS. Conclusions: fNIRS-based functional connectivity can be effectively used to investigate neural circuits of pain at the cortical level in association with nonpharmacological, self-administered tDCS treatment.

Feasibility, Acceptability, and Efficacy of Home-Based Transcranial Direct Current Stimulation on Pain in Older Adults with Alzheimer's Disease and Related Dementias: A Randomized Sham-Controlled Pilot Clinical Trial.

Although transcranial direct current stimulation (tDCS) is emerging as a convenient pain relief modality for several chronic pain conditions, its feasibility, acceptability, and preliminary efficacy on pain in patients with Alzheimer's disease and related dementias (ADRD) have not been investigated. The purpose of this pilot study was to assess the feasibility, acceptability, and preliminary efficacy of 5, 20-min home-based tDCS sessions on chronic pain in older adults with ADRD. We randomly assigned 40 participants to active (n = 20) or sham (n = 20) tDCS. Clinical pain intensity was assessed using a numeric rating scale (NRS) with patients and a proxy measure (MOBID-2) with caregivers. We observed significant reductions of pain intensity for patients in the active tDCS group as reflected by both pain measures (NRS: Cohen's d = 0.69, p-value = 0.02); MOBID-2: Cohen's d = 1.12, p-value = 0.001). Moreover, we found home-based tDCS was feasible and acceptable intervention approach for pain in ADRD. These findings suggest the need for large-scale randomized controlled studies with larger samples and extended versions of tDCS to relieve chronic pain on the long-term for individuals with ADRD.

Efficacy of Home-Based Transcranial Direct Current Stimulation on Experimental Pain Sensitivity in Older Adults with Knee Osteoarthritis: A Randomized, Sham-Controlled Clinical Trial.

Although transcranial direct current stimulation (tDCS) is encouraging regarding clinical pain intensity for individuals with knee osteoarthritis, very few studies have explored its impact on experimental pain sensitivity, which may hinder our understanding of underlying therapeutic mechanisms. The purpose of this study was to assess the efficacy of 15 home-based tDCS sessions on experimental pain sensitivity and explore its relationships with clinical pain intensity. We randomly assigned 120 participants to active tDCS (n = 60) and sham tDCS (n = 60). Quantitative sensory testing (QST) was used, including heat pain threshold and tolerance, pressure pain threshold, and conditioned pain modulation. Patients in the active tDCS group exhibited reduced experimental pain sensitivity as reflected by all QST measures at the end of treatment. Furthermore, correlations were observed between changes in clinical pain intensity and experimental pain sensitivity. These findings warrant further studies on tDCS and experimental pain sensitivity in patients with knee osteoarthritis and exploring the magnitude and sustainability of effects on a longer term.

Self-administered transcranial direct current stimulation for pain in older adults with knee osteoarthritis: A randomized controlled study.

BACKGROUND: Knee osteoarthritis (OA) is a leading cause of pain in older adults. Previous studies indicated clinic-based transcranial direct current stimulation (tDCS) was effective to reduce pain in various populations, but no published studies have reported the efficacy of home-based self-administered tDCS in older adults with knee OA using a randomized clinical study. OBJECTIVE: The purpose of this study was to evaluate the efficacy and feasibility of tDCS on clinical pain intensity in adults with knee OA pain. METHODS: One hundred twenty participants aged 50-85 years with knee OA pain were randomly assigned to receive fifteen daily sessions of 2 mA tDCS for 20 min (n = 60) or sham tDCS (n = 60) over 3 weeks with remote supervision via telehealth. Clinical pain intensity was measured by the Numeric Rating Scale and Western Ontario and McMaster Universities Osteoarthritis Index. Also, we collected data on the tDCS experience via a questionnaire. RESULTS: Participants (68% female) had a mean age of 66 years. Active tDCS significantly reduced pain intensity compared to sham tDCS after completion of the fifteen daily sessions (Cohen's d = 1.20; p-value < 0.0001). Participants showed high levels of satisfaction with their tDCS experience, and there have been no adverse events. CONCLUSION: We demonstrated that home-based self-administered tDCS was feasible and reduced clinical pain intensity in older adults with knee OA, which can increase its accessibility. Future studies with multi-site randomized controlled trials are needed to validate our findings. TRIAL REGISTRATION: ClinicalTrials.gov Identifier NCT04016272.

Functional Near-Infrared Spectroscopy to Assess Central Pain Responses in a Nonpharmacologic Treatment Trial of Osteoarthritis.

BACKGROUND AND PURPOSE: Knee osteoarthritis (OA) is a common source of pain in older adults. Although OA-induced pain can be relieved with analgesics and anti-inflammatory drugs, the current opioid epidemic is fostering the exploration of nonpharmacologic strategies for pain mitigation. Amongs these, transcranial direct current stimulation (tDCS) and mindfulness-based meditation (MBM) hold potential for pain-relief efficacy due to their neuromodulatory effects of the central nervous system, which is known to play a fundamental role in pain perception and processing. METHODS: In this double-blind study, we used functional near-infrared spectroscopy (fNIRS) to investigate the effects of tDCS combined with MBM on underlying pain processing mechanisms at the central nervous level in older adults with knee OA. Nineteen subjects were randomly assigned to two groups undergoing a 10-day active tDCS and MBM regimen and a sham tDCS and MBM regimen, respectively. RESULTS: Our results showed that the neuromodulatory intervention significantly relieved pain only in the group receiving active treatment. We also found that only the active treatment group showed a significant increase in oxyhemoglobin activation of the superior motor and somatosensory cortices colocated to the placement of the tDCS anodal electrode. To our knowledge, this is the first study in which the combined effect of tDCS and MBM is investigated using fNIRS. CONCLUSION: In conclusion, fNIRS can be effectively used to investigate neural mechanisms of pain at the cortical level in association with nonpharmacological, self-administered treatments.

Feasibility and efficacy of remotely supervised cranial electrical stimulation for pain in older adults with knee osteoarthritis: A randomized controlled pilot study.

Cranial electrical stimulation (CES) is a noninvasive brain stimulation technique that has been shown to improve pain. However, few studies have investigated the potential benefits associated with remotely supervised CES in older adults with knee osteoarthritis (OA). The aim of this study was to examine the feasibility and preliminary efficacy of remotely supervised CES via secure videoconferencing software on clinical pain severity, experimental pain sensitivity, and pain-related cortical response in older adults with knee OA. Thirty participants with symptomatic knee OA pain were randomly assigned to receive 10 daily sessions (60 min each) of remotely supervised CES (n = 15) or sham CES (n = 15) over two weeks. We measured clinical pain severity via a Numeric Rating Scale, experimental pain sensitivity (e.g., heat pain sensitivity, pressure pain sensitivity, and conditioned pain modulation) using quantitative sensory testing, and pain-related cortical response via functional near-infrared spectroscopy imaging. We also measured participant satisfaction with treatment using the Client Satisfaction Questionnaire. Active CES significantly reduced scores on the Numeric Rating Scale and increased heat pain threshold, pressure pain thresholds, and conditioned pain modulation. We also found significant changes in pain-related cortical hemodynamic activity after CES. Participants tolerated CES well without serious adverse effects and were satisfied with the treatment. Our findings demonstrate promising clinical efficacy of remotely supervised CES for older adults with knee OA.

Home-based self-administered transcranial direct current stimulation in older adults with knee osteoarthritis pain: An open-label study.

Clinic-based transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation technique that has been shown to improve pain. However, no published studies have reported using home-based self-administered tDCS in older adults with knee osteoarthritis (OA). The present study aimed to evaluate the preliminary efficacy and feasibility of home-based self-administered tDCS with real-time remote supervision on clinical pain, anxiety, depression, and sleep disturbances in older adults with knee OA. Twenty 50- to 85-year-old community-dwelling participants with knee OA received 10 daily home-based sessions of 2 mA tDCS for 20 min with real-time remote supervision. We measured clinical pain severity via the Visual Analog Scale, Western Ontario and McMaster Universities Osteoarthritis Index, and Short-Form McGill Pain Questionnaire. We assessed anxiety, depression, and sleep disturbances using the Patient-Reported Outcomes Measurement Information System (PROMIS) anxiety-short form, depression-short form, and sleep disturbance-short form, respectively. All 20 participants completed all 10 home-based tDCS sessions without serious adverse effects. Both clinical pain severity and sleep disturbances were improved after completion of the 10 tDCS sessions. Anxiety and depression scores were not significantly improved. We demonstrated that home-based self-administered tDCS with real-time remote supervision was feasible and beneficial in alleviating clinical pain in older adults with knee OA. These findings support future studies with larger samples and longer-term follow-up evaluations.

Efficacy of combining home-based transcranial direct current stimulation with mindfulness-based meditation for pain in older adults with knee osteoarthritis: A randomized controlled pilot study.

Transcranial direct current stimulation (tDCS) has been shown to be effective for reducing pain, and a growing body of literature shows the potential analgesic effects of mindfulness-based meditation (MBM). However, few studies have investigated the potential benefits associated with combining tDCS and MBM in older adults with knee osteoarthritis (OA). Therefore, the aim of this study was to examine the feasibility and preliminary efficacy of home-based tDCS paired with MBM in older adults with knee OA. Thirty participants 50-85 years old with symptomatic knee OA were randomly assigned to receive 10 daily sessions of home-based 2 mA tDCS paired with active MBM for 20 min (n = 15) or sham tDCS paired with sham MBM (n = 15). We measured clinical pain and OA symptoms via a Numeric Rating Scale and the Western Ontario and McMaster Universities Osteoarthritis Index. Pressure pain sensitivity and conditioned pain modulation were measured using quantitative sensory testing. Participant satisfaction and side effects were assessed via a questionnaire. Active tDCS paired with active MBM significantly reduced scores on the Numeric Rating Scale and Western Ontario and McMaster Universities Osteoarthritis Index and increased pressure pain thresholds and conditioned pain modulation. Participants tolerated tDCS paired with MBM well without serious adverse effects and were satisfied with the treatment. Our findings demonstrate promising clinical efficacy of home-based tDCS paired with MBM for older adults with knee OA.