Effects of Transcranial Direct Current Stimulation on Information Processing Speed, Working Memory, Attention, and Social Cognition in Multiple Sclerosis

Electric vs. magnetic: Which brain stimulation wins for bothering symptoms in multiple sclerosis?

BACKGROUND

Multiple sclerosis (MS) is a chronic disease marked by fatigue, pain, cognitive impairment, and mood disorders. Pharmacological treatments often provide limited relief and have side effects, prompting interest in non-invasive neuromodulation techniques like transcranial direct current stimulation (tDCS) and transcranial magnetic stimulation (TMS). We aimed to compare the short-term efficacy of tDCS and TMS in alleviating fatigue, pain, depression, and cognitive impairment in MS patients.

METHODS

In a randomized, single-blinded, three-arm trial, 30 patients with relapsingremitting MS were assigned to active tDCS, active TMS, or placebo. The tDCS group received 2 mA anodal stimulation over the motor cortex for 20 min daily for five days, while the TMS group received 10 Hz stimulation at 80 % of the resting motor threshold for the same duration. The placebo group received sham stimulation. Outcomes were assessed using the Fatigue Severity Scale (FSS), Visual Analogue Scale (VAS) for pain, Beck Depression Inventory (BDI), and Brief International Cognitive Assessment for MS (BICAMS).

RESULTS

Both tDCS and TMS groups showed significant improvements in fatigue, pain, and depression compared to placebo (p < 0.05). No significant cognitive changes were observed in any group.

CONCLUSION

Short-term tDCS and TMS are effective for reducing fatigue, pain, and depression in MS patients, with tDCS showing potential for home use and TMS for clinical settings. Cognitive improvements may require longer treatment durations or combined therapies.

Enhancing the effect of rehabilitation on multiple sclerosis: A randomized clinical trial investigating the impact of remotely-supervised transcranial direct current stimulation and virtual reality telerehabilitation training

BACKGROUND

Multiple sclerosis (MS) is a demyelinating disease characterized by balance and gait impairment, fatigue, anxiety, depression, and diminished quality of life. Transcranial direct current stimulation (tDCS) has emerged as an effective intervention for managing these symptoms.

OBJECTIVE

This study aims to investigate the efficacy of remotely supervised tDCS (RS-tDCS) applied to the left dorsolateral prefrontal cortex, in conjunction with a telerehabilitation (TR) program, on motor (balance and gait), cognitive (executive functions), and participation outcomes (fatigue, anxiety, depression, and quality of life) in persons with MS (pwMS).

METHODS

In this multicenter interventional randomized controlled trial, pwMS were randomly assigned to: TR with active tDCS (TR RS-AtDCS, n = 20) or TR with sham tDCS (TR RS-StDCS, n = 21). Two additional groups of historical controls were represented by comparable TR (TR, n = 35) or usual care (UC, n = 35). The TR RS-tDCS program comprised a 6 weeks of rehabilitation intervention delivered through a hybrid mix model TR, five sessions a week each lasting 45 min with additional 20 min of tDCS during the first week.

RESULTS

The subjects underwent to TR treatments (TR; TR RS-AtDCS; TR RS-StDCS) exhibited post-treatment improvements compared to UC group in Mini-BESTest global score (p = 0.013, T0 vs T1 ̶ UC group: p = 0.429, TR groups: p < 0.001), anterior postural control (p = 0.028, T0 vs T1 ̶ UC group: p = 0.860, TR groups: p < 0.001), and dynamic walking (p = 0.010, T0 vs T1 ̶ UC group: p = 0.269, TR groups: p = 0.012). The TR RS-AtDCS group showed improvement in the 12-item MSWS (p = 0.006) and STAI-Y (p = 0.032) compared to UC, TR and TR RS-StDCS.

CONCLUSIONS

This study underscores the benefits of TR in addressing motor challenges (balance and gait) among pwMS. The incorporation of RS-tDCS positively impacted on participants' perceived walking difficulties and reduced anxiety. The novelty of this study lies in its comprehensive evaluation of motor, quality of life, and emotional outcomes within home-based interventions. These findings highlight the potential of combined interventions to enhance well-being in pwMS.

Neurophysiological methods for assessing and treating cognitive impairment in multiple sclerosis: A scoping review of the literature

In recent years, there has been a growing interest in exploring the non-classical symptoms of multiple sclerosis (MS), with a particular focus on cognitive impairments associated with the disease's progression. These cognitive symptoms are now recognized as crucial elements in the assessment of disease activity. In this context, neurophysiology has emerged as a valuable and accessible tool for studying and addressing cognitive decline in individuals with MS. This scoping literature review investigates the role of neurophysiology in assessing and treating cognitive impairment in MS patients. The review focuses on Electroencephalography (EEG), Non-Invasive Brain Stimulation (NIBS), and magnetoencephalography (MEG) to assess cognitive decline in MS patients. Moreover, we discuss all the papers that tried to treat this cognitive impairment with NIBS techniques. While several neurophysiological markers show potential, standardization of protocols is essential for enhancing the reliability and consistency of these approaches. Further research is warranted to explore other NIBS techniques and deepen our understanding of the neurophysiological underpinnings of cognitive deficits in MS.

Harnessing Brainwave Entrainment: A Non-invasive Strategy To Alleviate Neurological Disorder Symptoms

From 1990-2019, the burden of neurological disorders varied considerably across countries and regions. Psychiatric disorders, often emerging in early to mid-adulthood, are linked to late-life neurodegenerative diseases like Alzheimer's disease and Parkinson's disease. Individuals with conditions such as Major Depressive Disorder, Anxiety Disorder, Schizophrenia, and Bipolar Disorder face up to four times higher risk of developing neurodegenerative disorders. Contrarily, 65 % of those with neurodegenerative conditions experience severe psychiatric symptoms during their illness. Further, the limitation of medical resources continues to make this burden a significant global and local challenge. Therefore, brainwave entrainment provides therapeutic avenues for improving the symptoms of diseases. Brainwaves are rhythmic oscillations produced either spontaneously or in response to stimuli. Key brainwave patterns include gamma, beta, alpha, theta, and delta waves, yet the underlying physiological mechanisms and the brain's ability to shift between these dynamic states remain areas for further exploration. In neurological disorders, brainwaves are often disrupted, a phenomenon termed "oscillopathy". However, distinguishing these impaired oscillations from the natural variability in brainwave activity across different regions and functional states poses significant challenges. Brainwave-mediated therapeutics represents a promising research field aimed at correcting dysfunctional oscillations. Herein, we discuss a range of non-invasive techniques such as non-invasive brain stimulation (NIBS), neurologic music therapy (NMT), gamma stimulation, and somatosensory interventions using light, sound, and visual stimuli. These approaches, with their minimal side effects and cost-effectiveness, offer potential therapeutic benefits. When integrated, they may not only help in delaying disease progression but also contribute to the development of innovative medical devices for neurological care.

The effectiveness of transcranial direct current stimulation (tDCS) on information processing speed in children with intellectual disability

PURPOSE

The speed of information processing is known to play an important role in mental disorders; This study investigated the effect of the transcranial direct current stimulation on information processing speed in children with intellectual disabilities.

METHOD

An experimental design with a pretest- posttest control group was used. The study population consisted of 8- to 14-year-old children with intellectual disabilities attending special primary schools in Urmia, Iran. 36 children were randomly assigned to the experimental and control groups (18 for each group). The experimental group received 10 sessions of tDCS with anode positioned over the F3 electrode (left DLPFC) and cathode over F4 (right DLPFC) The control group did not receive any intervention. Trail Making Test (TMT) was used to assess information processing speed. Data were analyzed using MANCOVA.

RESULTS

The results revealed that tDCS led to a significant increase in information processing speed in the experimental group compared to the control group.

CONCLUSION

This study demonstrates that tDCS applied to the dorsolateral prefrontal cortex (DLPFC) is effective in enhancing information processing speed in children with intellectual disabilities. These finding have important implications for the development of interventions aimed at improving cognitive functioning in children with intellectual disabilities.

Effect of Aerobic Exercise versus Non-Invasive Brain Stimulation on Cognitive Function in Multiple Sclerosis: A Systematic Review and Meta-Analysis

OBJECTIVE

In this study, we investigated the effects of noninvasive brain stimulation (NIBS) and exercise on cognition in patients with multiple sclerosis (pwMS).

METHODS

A literature search was performed using the Cochrane Library, Scopus, PubMed and Web of Science. The time interval used for database construction was up to February 2024; the collected trials were subsequently screened, and the data were extracted.

RESULTS

We identified 12 studies with 208 pwMS treated with noninvasive brain stimulation. Seven of the twelve studies concluded that NIBS was effective in improving reaction time, attention and processing speed. Additionally, 26 articles investigated the effect of various types of exercise on cognition among 708 pwMS. Twelve studies used aerobic exercise only, three studies used resistance only, one used yoga, and ten studies used mixed forms of exercise, such as Pilates, resistance and Frenkel coordination. Aerobic exercise was effective in improving at least one cognitive domain in ten studies. Resistance exercise was found to improve cognition in three studies. Yoga failed to show any improvement in one study.

CONCLUSIONS

NIBS might be an effective intervention for cognition improvement among pwMS. Aerobic exercise and combined forms of exercise are the most frequently investigated and applied and found to be effective. Further studies are needed, especially for resistance, balance and stretching exercises.

Non-invasive brain stimulation on clinical symptoms in multiple sclerosis patients: A systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS) has demonstrated mixed effects on the clinical symptoms of multiple sclerosis. This systematic review and meta-analysis aimed to evaluate the effects of NIBS techniques on the most common symptoms of MS.

METHODS

A literature search was performed until October 2022 which included randomized controlled trials and quasi-experimental studies that used sham-controlled NIBS in patients with MS. We calculated the Hedge's effect sizes of each domain of interest and their 95% confidence intervals (95% CIs) and performed random effects meta-analyses.

RESULTS

A total of 49 studies were included in the systematic review (944 participants). Forty-four eligible studies were included for quantitative analysis, of which 33 applied transcranial direct current stimulation (tDCS), 9 transcranial magnetic stimulation (TMS), and 2 transcranial random noise stimulation (tRNS). We found a significant decrease in fatigue (ES:  - 0.86, 95% CI:  - 1.22 to - 0.51, p < 0.0001), pain (ES: - 1.91, 95% CI, - 3.64 to - 0.19, p=  0.03) and psychiatric symptoms (ES: - 1.44, 95% CI - 2.56 to - 0.32, p = 0.01) in favor of tDCS compared with the sham. On the other hand, there was no strong evidence showing tDCS effectiveness on motor performance and cognition (ES: - 0.03, 95% CI - 0.35 to 0.28, p = 0.83 and ES: 0.71, 95% CI, - 0.09 to 1.52, p = 0.08, respectively). Regarding TMS, we found a significant decrease in fatigue (ES: - 0.45, 95% CI: - 0.84 to -0.07, p = 0.02) and spasticity levels (ES: - 1.11, 95% CI: - 1.48 to - 0.75, p < 0.00001) compared to the sham. However, there was no strong evidence of the effectiveness of TMS on motor performance (ES: - 0.39, 95% CI - 0.95 to 0.16, p = 0.16). Finally, there was no significant evidence showing the effectiveness of tRNS on fatigue levels (ES: - 0.28, 95% CI: - 1.02 to 0.47, p = 0.46) and cognitive improvement (ES: - 0.04, 95% CI: - 0.6, 0.52, p = 0.88) compared with the sham.

CONCLUSIONS

Overall, most studies have investigated the effects of tDCS on MS symptoms, particularly fatigue. The symptom that most benefited from NIBS was fatigue, while the least to benefit was motor performance. In addition, we found that disability score was associated with fatigue improvement. Thus, these findings support the idea that NIBS could have some promising effects on specific MS symptoms. It is also important to underscore that studies are very heterogeneous regarding the parameters of stimulation, and this may also have influenced the effects on some specific behavioral domains.

Cognitive impairment and its treatment in patients with multiple sclerosis

Cognitive impairment (CI) is a relatively common manifestation of multiple sclerosis (MS), which can occur with any type of the disease course and activity. The largest CI prevalence and severity are observed in progressive MS. In relapsing-remitting MS the most prominent deterioration of cognitive functions is seen during relapses; however, in some patients it can continue also throughout remission. In a small number of patients CI can be the most significant symptom of the disease; in addition, it sometimes can be the only clinical feature of the relapse. Despite this, in clinical practice CI remains out of the focus of attention, and is not evaluated when assessing the disease severity and/or activity, while CI is not included into EDSS. Nonetheless, a number of specialized neuropsychological tests and batteries has been developed recently, which can be used for both screening and detailed assessment of CI in MS, as well as for assessment of its changes over time. CI has a negative impact on MS patients' quality of life, their social interactions, daily and occupational activities. The influence of disease-modifying agents on CI has been poorly investigated; however, there is evidence that they can reduce the degree of CI. The optimal choice of pathogenetic treatment in patients with CI remains understudied. There is no convincing evidence of the effectiveness of symptomatic pharmacological treatment of CI in MS, and cognitive rehabilitation is the only approach with confirmed effectiveness. Considering the limitations of this technique (its availability, quite a big number of sessions), there is a need to search for other methods to increase its efficacy, including non-invasive neuromodulation (in particular, transcranial direct current stimulation or transcranial magnetic stimulation). This article is focused on a brief review of the main diagnostic methods of CI in MS, its pathogenetic and symptomatic treatment, and cognitive rehabilitation techniques, as well as on the results of the studies on non-invasive neuromodulation.

Efficacy of non-invasive brain stimulation on cognitive and motor functions in multiple sclerosis: A systematic review and meta-analysis

OBJECTIVE

In this study, we aimed to investigate the effects of non-invasive brain stimulation (NIBS) on cognitive and motor functions in patients with multiple sclerosis (pwMS).

METHODS

A literature search was performed in the Cochrane Library, Embase, PubMed, Web of Science, Medline, CNKI, and Wan fang. The time interval used for database construction was up to December 2022, and the language was not limited. The collected trials were subsequently screened, the data were extracted, the quality was evaluated, and the effect sizes were computed using STATA/MP Version 13 for outcome analysis. Standard mean difference (SMD) and 95% confidence interval (CI) were calculated for domain of interest.

RESULTS

In total, 17 articles that examined 364 patients with multiple sclerosis were included in this analysis. Non-invasive brain stimulation did not improve the overall cognitive function [SMD = 0.18, 95% CI (-0.32, 0.69), P = 0.475] but helped improve motor function in patients [SMD = 0.52, 95% CI (0.19, 0.85), P = 0.002]. Moreover, this study specifically indicated that non-invasive brain stimulation improved alerting [SMD = 0.68, 95% CI (0.09, 1.26), P = 0.02], whereas non-invasive brain stimulation intervention improved motor function in patients aged <45 years [SMD = 0.67, 95% CI (0.23, 1.10), P = 0.003] and in patients with expanded disability status scale scores (EDSS) <3.5 [SMD = 0.82, 95% CI (0.22, 1.42), P = 0.007]. In particular, NIBS contributed to the improvement of spasticity in pwMS [SMD = 0.68, 95% CI (0.13, 1.23), P = 0.015].

CONCLUSION

These results of this present study provide evidence that non-invasive brain stimulation could improve alertness in pwMS. Furthermore, NIBS may help pwMS with motor function and those who are under 45 years of age or with EDSS < 3.5 improve their motor function. For the therapeutic use of NIBS, we recommend applying transcranial magnetic stimulation as an intervention and located on the motor cortex M1 according to the subgroup analysis of motor function. These findings warrant verification.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42022301012.

The effectiveness of anodal tDCS and cognitive training on cognitive functions in multiple sclerosis; a randomized, double-blind, parallel-group study

BACKGROUND

Forty to 70% of patients with multiple sclerosis (MS) suffer from cognitive impairment during their illness. Only a few studies have examined the effects of anodal transcranial direct current stimulation (a-tDCS) along with cognitive training on cognitive performance in MS patients. This study aims to determine whether multi-session a-tDCS with or without cognitive training impacts cognitive performance in MS.

METHODS

Eighty MS patients received a-tDCS, cognitive training, a-tDCS plus cognitive training, and sham for ten consecutive daily sessions. Cognitive function (including episodic memory, attention, and inhibitory control, working memory, and visuospatial skill) was measured at baseline, week 4, and week 12 after the intervention.

RESULTS

All cognitive functions significantly improved after the intervention compared to the sham condition. This effect also showed persistence during follow-up for some cognitive tasks in the a-tDCS and a-tDCS combined cognitive training groups. Although the cognitive training group experienced an immediate improvement in attention and inhibitory control, the difference was not significant at follow-up. Also, there were no significant differences between these three groups in cognitive scores after the intervention.

CONCLUSION

a-tDCS alone and a-tDCS paired with or without cognitive training as compared to sham appears to be a promising therapeutic option for cognitive performance in MS patients.

Evidence for modulation of planning and working memory capacities by transcranial direct current stimulation in a sample of adults with attention deficit hyperactivity disorder

BACKGROUND AND OBJECTIVE

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that affects up to 2.8% of the adult population. Albeit pharmacological and behavioral therapies alleviate some core symptoms of ADHD, they do not avail cognitive dysfunction adequately. Executive dysfunction has been considered to have a principal role in ADHD and has previously been linked to activity alterations in the prefrontal cortex. Transcranial Direct Current Stimulation (tDCS) is a noninvasive brain stimulation technique that may modulate prefrontal cortex activity and induce neuroplasticity, with preliminary results in ADHD. The aim of the present study is to assess the effect of repeated tDCS on measures of executive functions in adults with ADHD.

METHOD

In this randomized double-blind sham-controlled study, 22 adults with ADHD were allocated into two groups and were administered five consecutive sessions of 2 mA active/sham tDCS over the dorsolateral prefrontal cortex (right anodal/left cathodal). A neuropsychological test battery was administered before the first session and immediately after the last session.

RESULTS

The maximum number of digits and the total number of correct trials in the Digit Span Backward test increased in the active group (p = 0.017). The total move score in the Tower of London test decreased (p = 0.033), suggesting better planning ability. However, no significant differences were observed on Stroop Test and Trail Making Test after tDCS.

DISCUSSION

The present study corroborates the modulating effects of tDCS on planning and working memory in a small group of adults with ADHD. Our results highlighted that cognitive functions are modulable using tDCS in adults with ADHD.

Efficacy of transcranial direct current stimulation in people with multiple sclerosis: a review

BACKGROUND AND PURPOSE

Multiple sclerosis (MS) is a chronic inflammatory disease causing a wide range of symptoms including motor and cognitive impairment, fatigue and pain. Over the last two decades, non-invasive brain stimulation, especially transcranial direct current stimulation (tDCS), has increasingly been used to modulate brain function in various physiological and pathological conditions. However, its experimental applications for people with MS were noted only as recently as 2010 and have been growing since then. The efficacy for use in people with MS remains questionable with the results of existing studies being largely conflicting. Hence, the aim of this review is to paint a picture of the current state of tDCS in MS research grounded on studies applying tDCS that have been done to date.

METHODS

A keyword search was performed to retrieve articles from the earliest article identified until 14 February 2021 using a combination of the groups (1) 'multiple sclerosis', 'MS' and 'encephalomyelitis' and (2) 'tDCS' and 'transcranial direct current stimulation'.

RESULTS

The analysis of the 30 articles included in this review underlined inconsistent effects of tDCS on the motor symptoms of MS based on small sample sizes. However, tDCS showed promising benefits in ameliorating fatigue, pain and cognitive symptoms.

CONCLUSION

Transcranial direct current stimulation is attractive as a non-drug approach in ameliorating MS symptoms, where other treatment options remain limited. The development of protocols tailored to the individual's own neuroanatomy using high definition tDCS and the introduction of network mapping in the experimental designs might help to overcome the variability between studies.