The Potential of Transcranial Alternating Current Stimulation to Alleviate Dual-Task Gait Costs in Older Adults: Insights from a Double-Blinded Pilot Study.

BACKGROUND: The performance of an attention-demanding task while walking, i.e., dual-tasking, leads to dual-task costs (e.g., reduced gait speed) in older adults. Previous studies have shown that dual-task costs in gait are associated with future falls and cognitive decline. According to the communication through coherence hypothesis, transcranial alternating current stimulation (tACS) might help alleviate this problem. OBJECTIVE: The aim of this study was to examine the effects of a single session of theta-tACS targeting the left fronto-parietal network (L-FPN) on dual-task walking and cognitive function compared to sham stimulation and transcranial direct current stimulation (tDCS) targeting the left dorsolateral prefrontal cortex, a node within the L-FPN. METHODS: Twenty older adults completed a four-visit, double-blinded, within-subject, cross-over study in which usual-walking, dual-task walking, and cognitive function were evaluated before and immediately after 20 min of tACS, tDCS, or sham (order randomized) stimulation. Dual-task costs to gait speed (primary outcome) and other measures were analyzed. RESULTS: The dual-task cost to gait speed tended to be lower (i.e., better) after tACS (p = 0.067, Cohen's d = 0.433∼small); tDCS significantly reduced this dual-task cost (p = 0.012, Cohen's d = 0.618∼medium), and sham stimulation had no effect (p = 0.467). tACS significantly reduced the dual-task cost to step length (p = 0.037, Cohen's d = 0.502∼medium); a trend was seen after tDCS (p = 0.069, Cohen's d = 0.443∼small). No statistical differences were found for other measures of gait or cognitive function. CONCLUSIONS: The positive effects of tACS on dual-task gait speed and step length were roughly similar to those seen with tDCS. These results suggest that tACS affects the fronto-parietal network and, similar to tDCS, tACS may improve dual-tasking. Nonetheless, to achieve larger benefits and differentiate the effects of tACS and tDCS on brain function and dual-task walking in older adults, other stimulation montages and protocols should be tested.

Targeted tDCS Mitigates Dual-Task Costs to Gait and Balance in Older Adults.

OBJECTIVE: Among older adults, the ability to stand or walk while performing cognitive tasks (ie, dual-tasking) requires coordinated activation of several brain networks. In this multicenter, double-blinded, randomized, and sham-controlled study, we examined the effects of modulating the excitability of the left dorsolateral prefrontal cortex (L-DLPFC) and the primary sensorimotor cortex (SM1) on dual-task performance "costs" to standing and walking. METHODS: Fifty-seven older adults without overt illness or disease completed 4 separate study visits during which they received 20 minutes of transcranial direct current stimulation (tDCS) optimized to facilitate the excitability of the L-DLPFC and SM1 simultaneously, or each region separately, or neither region (sham). Before and immediately after stimulation, participants completed a dual-task paradigm in which they were asked to stand and walk with and without concurrent performance of a serial-subtraction task. RESULTS: tDCS simultaneously targeting the L-DLPFC and SM1, as well as tDCS targeting the L-DLPFC alone, mitigated dual-task costs to standing and walking to a greater extent than tDCS targeting SM1 alone or sham (p < 0.02). Blinding efficacy was excellent and participant subjective belief in the type of stimulation received (real or sham) did not contribute to the observed functional benefits of tDCS. INTERPRETATION: These results demonstrate that in older adults, dual-task decrements may be amenable to change and implicate L-DPFC excitability as a modifiable component of the control system that enables dual-task standing and walking. tDCS may be used to improve resilience and the ability of older results to walk and stand under challenging conditions, potentially enhancing everyday functioning and reducing fall risks. ANN NEUROL 2021;90:428-439.

Treadmill training with virtual reality to enhance gait and cognitive function among people with multiple sclerosis: a randomized controlled trial.

BACKGROUND: Motor and cognitive impairments impact the everyday functioning of people with MS (pwMS). The present randomized controlled trial (RCT) evaluated the benefits of a combined motor-cognitive virtual reality training program on key motor and cognitive symptoms and related outcomes in pwMS. METHODS: In a single-blinded, two-arm RCT, 124 pwMS were randomized into a treadmill training with virtual reality (TT + VR) group or a treadmill training alone (TT) (active-control) group. Both groups received three training sessions per week for 6 weeks. Dual-tasking gait speed and cognitive processing speed (Symbol Digit Modalities Test, SDMT, score) were the primary outcomes. Secondary outcomes included additional tests of cognitive function, mobility, and patient-reported questionnaires. These were measured before, after, and 3 months after training. RESULTS: Gait speed improved (p < 0.005) in both groups, similarly, by about 10 cm/s. The TT + VR group (n = 53 analyzed per-protocol) showed a clinically meaningful improvement of 4.4 points (95% CI 1.9-6.8, p = 0.001) in SDMT, compared to an improvement of only 0.8 points in the TT (n = 51 analyzed per-protocol) group (95% CI 0.9-2.5 points, p = 0.358) (group X time interaction effect p = 0.027). Furthermore, TT + VR group-specific improvements were seen in depressive symptoms (lowered by 31%, p = 0.003), attention (17%, p < 0.001), and verbal fluency (11.6% increase, p = 0.002). DISCUSSION: These findings suggest that both TT and TT + VR improve usual and dual-task gait in pwMS. Nonetheless, a multi-modal approach based on VR positively impacts multiple aspects of cognitive function and mental health, more than seen after treadmill-treading alone. Trial registered at ClinicalTrials.Gov NCT02427997.

Daily-Living Freezing of Gait as Quantified Using Wearables in People With Parkinson Disease: Comparison With Self-Report and Provocation Tests.

OBJECTIVE: Freezing of gait (FOG) is an episodic, debilitating phenomenon that is common among people with Parkinson disease. Multiple approaches have been used to quantify FOG, but the relationships among them have not been well studied. In this cross-sectional study, we evaluated the associations among FOG measured during unsupervised daily-living monitoring, structured in-home FOG-provoking tests, and self-report. METHODS: Twenty-eight people with Parkinson disease and FOG were assessed using self-report questionnaires, percentage of time spent frozen (%TF) during supervised FOG-provoking tasks in the home while off and on dopaminergic medication, and %TF evaluated using wearable sensors during 1 week of unsupervised daily-living monitoring. Correlations between those 3 assessment approaches were analyzed to quantify associations. Further, based on the %TF difference between in-home off-medication testing and in-home on-medication testing, the participants were divided into those responding to Parkinson disease medication (responders) and those not responding to Parkinson disease medication (nonresponders) in order to evaluate the differences in the other FOG measures. RESULTS: The %TF during unsupervised daily living was mild to moderately correlated with the %TF during a subset of the tasks of the in-home off-medication testing but not the on-medication testing or self-report. Responders and nonresponders differed in the %TF during the personal "hot spot" task of the provoking protocol while off medication (but not while on medication) but not in the total scores of the self-report questionnaires or the measures of FOG evaluated during unsupervised daily living. CONCLUSION: The %TF during daily living was moderately related to FOG during certain in-home FOG-provoking tests in the off-medication state. However, this measure of FOG was not associated with self-report or FOG provoked in the on-medication state. These findings suggest that to fully capture FOG severity, it is best to assess FOG using a combination of all 3 approaches. IMPACT: These findings suggest that several complementary approaches are needed to provide a complete assessment of FOG severity.

Tele-Rehabilitation with Virtual Reality: A Case Report on the Simultaneous, Remote Training of Two Patients with Parkinson Disease.

ABSTRACT: Physical training in Parkinson disease improves motor performance, alleviates nonmotor symptoms, and enhances cognition and quality of life. Nonetheless, adherence to exercise is low and travel costs and time may limit participation and compliance. Training at home can help avoid these burdens and, as needed during the recent global pandemic (COVID-19), reinforce social distancing and reduce the risk of infection. However, training at home requires motivation and self-control and telerehabilitation is time-consuming for both patient and therapist. In recent years, there is growing use of virtual reality and exergaming to increase motivation and adherence for exercising with evidence of improvements in mobility and balance after using virtual reality in the clinic. Here, a novel telerehabilitation training program using a treadmill-virtual reality system for simultaneous training of two patients with Parkinson disease in their homes is described. Remote monitoring software enabled visual and auditory communication with the two patients, allowing the trainer to adapt the settings remotely and provide feedback. Participants received weekly training sessions over 1 yr. The findings show high adherence to training, increased walking duration throughout the sessions, and increased patient confidence, gait speed, and mobility. Training multiple participants simultaneously was feasible, enabling an individualized treatment approach while conserving therapist time.

Virtual reality training to enhance behavior and cognitive function among children with attention-deficit/hyperactivity disorder: brief report.

Purpose: To examine the feasibility and efficacy of a combined motor-cognitive training using virtual reality to enhance behavior, cognitive function and dual-tasking in children with Attention-Deficit/Hyperactivity Disorder (ADHD). Methods: Fourteen non-medicated school-aged children with ADHD, received 18 training sessions during 6 weeks. Training included walking on a treadmill while negotiating virtual obstacles. Behavioral symptoms, cognition and gait were tested before and after the training and at 6-weeks follow-up. Results: Based on parental report, there was a significant improvement in children's social problems and psychosomatic behavior after the training. Executive function and memory were improved post-training while attention was unchanged. Gait regularity significantly increased during dual-task walking. Long-term training effects were maintained in memory and executive function. Conclusion: Treadmill-training augmented with virtual-reality is feasible and may be an effective treatment to enhance behavior, cognitive function and dual-tasking in children with ADHD.