Neuroplasticity and non-invasive brain stimulation in the developing brain

A network meta-analysis of non-invasive brain stimulation interventions for autism spectrum disorder: Evidence from randomized controlled trials

The efficacy and acceptability of various non-invasive brain stimulation (NIBS) interventions for autism spectrum disorder remain unclear. We carried out a systematic review for randomized controlled trials (RCTs) regarding NIBS for reducing autistic symptoms (INPLASY202370003). Sixteen articles (N = 709) met the inclusion criteria for network meta-analysis. Effect sizes were reported as standardized mean differences (SMDs) or odds ratios with 95 % confidence intervals (CIs). Fourteen active NIBS interventions, including transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation, and transcranial pulse stimulation were analyzed. Only anodal tDCS over the left dorsolateral prefrontal cortex paired with cathodal tDCS over an extracephalic location (atDCS_F3 + ctDCS_E) significantly improved autistic symptoms compared to sham controls (SMD = - 1.40, 95 %CIs = - 2.67 to - 0.14). None of the NIBS interventions markedly improved social-communication symptoms or restricted/repetitive behaviors in autistic participants. Moreover, no active NIBS interventions exhibited significant dropout rate differences compared to sham controls, and no serious adverse events were reported for any intervention.

Maintaining a Dynamic Brain: A Review of Empirical Findings Describing the Roles of Exercise, Learning, and Environmental Enrichment in Neuroplasticity from 2017-2023

Brain plasticity, also termed neuroplasticity, refers to the brain's life-long ability to reorganize itself in response to various changes in the environment, experiences, and learning. The brain is a dynamic organ capable of responding to stimulating or depriving environments, activities, and circumstances from changes in gene expression, release of neurotransmitters and neurotrophic factors, to cellular reorganization and reprogrammed functional connectivity. The rate of neuroplastic alteration varies across the lifespan, creating further challenges for understanding and manipulating these processes to benefit motor control, learning, memory, and neural remodeling after injury. Neuroplasticity-related research spans several decades, and hundreds of reviews have been written and published since its inception. Here we present an overview of the empirical papers published between 2017 and 2023 that address the unique effects of exercise, plasticity-stimulating activities, and the depriving effect of social isolation on brain plasticity and behavior.

Non-invasive brain stimulation for treating catatonia: a systematic review

Background

Non-invasive brain stimulation (NIBS) techniques offer new therapeutic options for modifying pathological neuroplasticity and have been proven to be beneficial in the treatment of neuropsychiatric disorders.

Objective

This study aimed to investigate the role of NIBS in treating catatonia.

Materials and methods

We conducted a systematic search to identify meta-analyses or systematic reviews on electroconvulsive therapy (ECT) and studies on the effects of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) on patients with catatonia from the PubMed, Web of Science, Embase, China National Knowledge Internet, Wanfang, and China Science and Technology Journal databases from inception until 31 July 2022. The methodological quality of the included studies was assessed with the AMSTAR2 or Joanna Briggs Institute Critical Appraisal tools. Paired t-tests and Wilcoxon signed-rank tests were used to compare changes in catatonia symptom scores after rTMS or tDCS.

Results

A total of 13 systematic reviews and one meta-analysis on ECT, two systematic reviews and 12 case reports on rTMS, and seven studies of 14 cases applying tDCS were identified. Systematic reviews of ECT consistently described improvement in catatonia symptoms across catatonia types and patient age groups. After treatment with rTMS (t = 4.489, p = 0.006) and tDCS (z = -3.065, p = 0.002), patients exhibited significant improvement.

Conclusion

ECT, rTMS, and tDCS were effective in treating catatonia. Early intervention with NIBS techniques may help improve catatonia symptoms in patients with schizophrenia. It may be advantageous to use rTMS or tDCS to maintain this improvement. NIBS techniques may thus represent a promising treatment for catatonia, but additional high-quality randomized controlled trials are needed.

Non-invasive brain stimulation for limb motor function and daily living activity improvement in acute stroke: A meta-analysis

OBJECTIVE

To evaluate the effect of non-invasive brain stimulation (NIBS) in improving limb motor dysfunction and daily living activity during at the phase of acute stroke.

MATERIALS AND METHODS

Randomized controlled trials about the effect of NIBS on hemiparesis in acute stroke were retrieved from databases of China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), Wanfang Data, CBM, PubMed, Embase, Cochrane Library, and Web of Science from inception until January 3rd 2022. The quality of the trials was assessed, and the data were extracted according to the Cochrane Handbook for Systematic Reviews of Interventions. A statistical analysis was carried out using Review Manager 5.3 and STATA 14. The effect size was evaluated by using the weighed mean difference (WMD) and a 95% confidence interval (CI). The stability and sensitivity of the results and sources of heterogeneity were also analyzed.

RESULTS

12 studies involving 639 patients were included. Our meta-analysis showed that NIBS could improve the Fugl-Meyer Assessment (weighed mean difference = 3.96, 95% confidence interval = 3.45 to 4.48) and Barthel Index (weighed mean difference = 12.29, 95% confidence interval = 4.93 to 19.66), while reducing the National Institutes of Health Stroke Scale (weighed mean difference = -2.37, 95% confidence interval = -3.43 to -1.31).

CONCLUSION

NIBS is effective in improving paretic limb motor function and activities of daily living in patients during at the phase of acute stroke.

Dosage consideration for transcranial direct current stimulation in post-stroke dysphagia: A systematic review and network meta-analysis

Objective

This systematic review and network meta-analysis sought to determine the efficacy of different intensities of transcranial direct current stimulation (tDCS) in patients with dysphagia after stroke to improve swallowing function.

Methods

Randomized-controlled trials (RCTs) of tDCS in post-stroke dysphagia were searched from Pubmed, EMBASE, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Service System (SinoMed), Wanfang database, and Chinese Scientific Journals Database (VIP) from databases' inception to June 22, 2022. Article screening, data extraction, and article quality evaluation were completed by 2 independent researchers. Network meta-analysis was performed using Stata.

Results

A final total of 20 studies involving 838 stroke patients were included. The included control interventions were sham tDCS and conventional therapy (CT). Network meta-analysis showed that 20 min of 1.2, 1.4, 1.5, 1.6, and 2 mA anodal tDCS and 30 min of 2 mA anodal tDCS significantly improved post-stroke dysphagia compared with CT (all P < 0.05). In addition, 20 min of 1, 1.4, 1.6, and 2 mA anodal tDCS also significantly improved post-stroke dysphagia compared with sham tDCS (all P < 0.05). Our results demonstrated that 20 min of stimulation at 1.4 mA was the optimal parameters for anodal tDCS and exhibited superior efficacy to CT [SMD = 1.08, 95% CI (0.46, 1.69)] and sham tDCS [SMD = 1.45, 95% CI (0.54, 2.36)].

Conclusion

Different durations and intensities of anodal tDCS are effective in improving post-stroke dysphagia. However, 20 min of tDCS at 1.4 mA may be the optimal regimen.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/#recordDetails, identifier CRD42022342506.

The effects of aerobic exercise and transcranial direct current stimulation on cognitive function in older adults with and without cognitive impairment: A systematic review and meta-analysis

BACKGROUND

Aerobic exercise (AE) may slow age-related cognitive decline. However, such cognition-sparing effects are not uniform across cognitive domains and studies. Transcranial direct current stimulation (tDCS) is a form of non-invasive brain stimulation and is also emerging as a potential alternative to pharmaceutical therapies. Like AE, the effectiveness of tDCS is also inconsistent for reducing cognitive impairment in ageing. The unexplored possibility exists that pairing AE and tDCS could produce synergistic effects and reciprocally augment cognition-improving effects in older individuals with and without cognitive impairments. Previous research found such synergistic effects on cognition when cognitive training is paired with tDCS in older individuals with and without mild cognitive impairment (MCI) or dementia.

AIM

The purpose of this systematic review with meta-analysis was to explore if pairing AE with tDCS could augment singular effects of AE and tDCS on global cognition (GC), working memory (WM) and executive function (EF) in older individuals with or without MCI and dementia.

METHODS

Using a PRISMA-based systematic review, we compiled studies that examined the effects of AE alone, tDCS alone, and AE and tDCS combined on cognitive function in older individuals with and without mild cognitive impairment (MCI) or dementia. Using a PICOS approach, we systematically searched PubMed, Scopus and Web of Science searches up to December 2021, we focused on 'MoCA', 'MMSE', 'Mini-Cog' (measures) and 'cognition', 'cognitive function', 'cognitive', 'cognitive performance', 'executive function', 'executive process', 'attention', 'memory', 'memory performance' (outcome terms). We included only randomized controlled trials (RTC) in humans if available in English full text over the past 20 years, with participants' age over 60. We assessed the methodological quality of the included studies (RTC) by the Physiotherapy Evidence Database (PEDro) scale.

RESULTS

Overall, 68 studies were included in the meta-analyses. AE (ES = 0.56 [95% CI: 0.28-0.83], p = 0.01) and tDCS (ES = 0.69 [95% CI: 0.12-1.26], p = 0.02) improved GC in all three groups of older adults combined (healthy, MCI, demented). In healthy population, AE improved GC (ES = 0.46 [95% CI: 0.22-0.69], p = 0.01) and EF (ES = 0.27 [95% CI: 0.05-0.49], p = 0.02). AE improved GC in older adults with MCI (ES = 0.76 [95% CI: 0.21-1.32], p = 0.01). tDCS improved GC (ES = 0.69 [90% CI: 0.12-1.26], p = 0.02), all three cognitive function (GC, WM and EF) combined in older adults with dementia (ES = 1.12 [95% CI: 0.04-2.19], p = 0.04) and improved cognitive function in older adults overall (ES = 0.69 [95% CI: 0.20-1,18], p = 0.01).

CONCLUSION

Our systematic review with meta-analysis provided evidence that beyond the cardiovascular and fitness benefits of AE, pairing AE with tDCS may have the potential to slow symptom progression of cognitive decline in MCI and dementia. Future studies will examine the hypothesis of this present review that a potentiating effect would incrementally improve cognition with increasing severity of cognitive impairment.

Noninvasive neuromodulation for unilateral neglect after stroke: a systematic review and network meta-analysis

OBJECTIVE

To systematically evaluate the effect of noninvasive neuromodulation (NINM) on unilateral neglect (UN) after stroke and compare the effects of different NINMs.

METHODS

Randomized controlled trials (RCTs) on the effect of NINM on UN after stroke were retrieved from the PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang Data, VIP, and CBM databases from inception to January 2022. The risk of bias and quality of the trials were assessed following the Cochrane Handbook of Systematic Reviews and the physiotherapy evidence database PEDro Scale. Statistical analysis was conducted with Stata 16.0 and R 4.0.2. This study was registered on PROSPERO (No. CRD42021295336).

RESULTS

A total of 12 RCTs involving 291 patients were included. Meta-analysis showed that NINM could reduce the line bisection test (LBT) score (SMD =  - 1.56, 95% CI - 2.10 ~  - 1.03, P < 0.05), the line cancellation test score (SMD =  - 1.83, 95% CI - 2.39 ~  - 1.27, P < 0.05), and the star cancellation test score (SMD =  - 2.85, 95% CI - 4.93 ~  - 0.76, P < 0.05). Network meta-analysis showed that the best probabilistic ranking of the effects of different NINMs on the LBT score was theta-burst stimulation (TBS) (P = 0.915) > repetitive transcranial magnetic stimulation (P = 0.068) > transcranial direct current stimulation (P = 0.018).

CONCLUSION

Existing evidence showed that NINM could improve UN after stroke and that TBS was best. Due to the number of included studies and sample size, more large-sample, multicenter, double-blinded, high-quality clinical RCTs are still needed in the future to further confirm the results of this research.

Effects of robot-assisted task-oriented upper limb motor training on neuroplasticity in stroke patients with different degrees of motor dysfunction: A neuroimaging motor evaluation index

Introduction

Although robot-assisted task-oriented upper limb (UL) motor training had been shown to be effective for UL functional rehabilitation after stroke, it did not improve UL motor function more than conventional therapy. Due to the lack of evaluation of neurological indicators, it was difficult to confirm the robot treatment parameters and clinical efficacy in a timely manner. This study aimed to explore the changes in neuroplasticity induced by robot-assisted task-oriented UL motor training in different degrees of dysfunction patients and extract neurological evaluation indicators to provide the robot with additional parameter information.

Materials and methods

A total of 33 adult patients with hemiplegic motor impairment after stroke were recruited as participants in this study, and a manual muscle test divided patients into muscle strength 0–1 level (severe group, n = 10), 2–3 level (moderate group, n = 14), and 4 or above level (mild group, n = 9). Tissue concentration of oxyhemoglobin and deoxyhemoglobin oscillations in the bilateral prefrontal cortex, dorsolateral prefrontal cortex (DLPFC), superior frontal cortex (SFC), premotor cortex, primary motor cortex (M1), primary somatosensory cortex (S1), and occipital cortex were measured by functional near-infrared spectroscopy (fNIRS) in resting and motor training state. The phase information of a 0.01 −0.08 Hz signal was identified by the wavelet transform method. The wavelet amplitude, lateralization index, and wavelet phase coherence (WPCO) were calculated to describe the frequency-specific cortical changes.

Results

Compared with the resting state, significant increased cortical activation was observed in ipsilesional SFC in the mild group and bilateral SFC in the moderate group during UL motor training. Patients in the mild group demonstrated significantly decreased lateralization of activation in motor training than resting state. Moreover, the WPCO value of motor training between contralesional DLPFC and ipsilesional SFC, bilateral SFC, contralesional, S1, and ipsilesional M1 showed a significant decrease compared with the resting state in the mild group.

Conclusion

Robot-assisted task-oriented UL motor training could modify the neuroplasticity of SFC and contribute to control movements and continuous learning motor regularity for patients. fNIRS could provide a variety of real-time sensitive neural evaluation indicators for the robot, which was beneficial to formulating more reasonable and effective personalized prescriptions during motor training.

Effects of a short and intensive transcranial direct current stimulation treatment in children and adolescents with developmental dyslexia: A crossover clinical trial

Developmental Dyslexia (DD) significantly interferes with children’s academic, personal, social, and emotional functioning. Nevertheless, therapeutic options need to be further validated and tested in randomized controlled clinical trials. The use of transcranial direct current stimulation (tDCS) has been gaining ground in recent years as a new intervention option for DD. However, there are still open questions regarding the most suitable tDCS protocol for young people with DD. The current crossover study tested the effectiveness of a short and intensive tDCS protocol, including the long-term effects, as well as the influence of age and neuropsychological processes at baseline on reading improvements. Twenty-four children and adolescents with DD were randomly assigned to receive active tDCS during the first slot and sham tDCS during the second slot or vice versa. Five consecutive daily sessions of left anodal/right cathodal tDCS set at 1 mA for 20 min were administered over the parieto-occipital regions. Reading measures (text, high frequency word, low frequency word, and non-word lists) and neuropsychological measures (visual-spatial and verbal working memory, phoneme blending, and rapid automatized naming tasks) were collected before, immediately after, 1 week and 1 month later the treatment. Our results showed that only the active tDCS condition improved non-word reading speed immediately after and 1 month later the end of the treatment compared with baseline. In addition, the improvement in non-word reading speed was significantly correlated with age and with neuropsychological measures (verbal working memory and phoneme blending) at baseline but only in the active tDCS condition. The current crossover study contributed to enforce previous effects of tDCS, including long-term effects, on non-word reading speed and to understand the effect of age and neuropsychological processes on reading outcomes. Our findings showed that tDCS could be a low-cost and easy-to-implement treatment option with long-term effects for children and adolescents with DD.

Non-invasive brain stimulation and neuroenhancement

•

The available data frame with a wide parameter space of tES does not allow an overarching protocol recommendation.

•

Established engineering risk-management procedures with regard to manufacturing should be followed.

•

Consensus among experts is that tES for neuroenhancement is safe as long as tested protocols are followed.

Attempts to enhance human memory and learning ability have a long tradition in science. This topic has recently gained substantial attention because of the increasing percentage of older individuals worldwide and the predicted rise of age-associated cognitive decline in brain functions. Transcranial brain stimulation methods, such as transcranial magnetic (TMS) and transcranial electric (tES) stimulation, have been extensively used in an effort to improve cognitive functions in humans.

Here we summarize the available data on low-intensity tES for this purpose, in comparison to repetitive TMS and some pharmacological agents, such as caffeine and nicotine. There is no single area in the brain stimulation field in which only positive outcomes have been reported. For self-directed tES devices, how to restrict variability with regard to efficacy is an essential aspect of device design and function. As with any technique, reproducible outcomes depend on the equipment and how well this is matched to the experience and skill of the operator. For self-administered non-invasive brain stimulation, this requires device designs that rigorously incorporate human operator factors. The wide parameter space of non-invasive brain stimulation, including dose (e.g., duration, intensity (current density), number of repetitions), inclusion/exclusion (e.g., subject’s age), and homeostatic effects, administration of tasks before and during stimulation, and, most importantly, placebo or nocebo effects, have to be taken into account. The outcomes of stimulation are expected to depend on these parameters and should be strictly controlled. The consensus among experts is that low-intensity tES is safe as long as tested and accepted protocols (including, for example, dose, inclusion/exclusion) are followed and devices are used which follow established engineering risk-management procedures. Devices and protocols that allow stimulation outside these parameters cannot claim to be “safe” where they are applying stimulation beyond that examined in published studies that also investigated potential side effects.

Brain stimulation devices marketed for consumer use are distinct from medical devices because they do not make medical claims and are therefore not necessarily subject to the same level of regulation as medical devices (i.e., by government agencies tasked with regulating medical devices). Manufacturers must follow ethical and best practices in marketing tES stimulators, including not misleading users by referencing effects from human trials using devices and protocols not similar to theirs.

Botulinum Toxin Type A in the Spasticity of Cerebral Palsy Related to Congenital Zika Syndrome: An Observational Study

PURPOSE

Investigate the effect of botulinum toxin type-A (BoNT-A) on spasticity and motor performance in children with Cerebral Palsy (CP) related to Congenital Zika Syndrome (CZS).

METHODS

Prospective longitudinal observational study of 34 children with CP referred for BoNT-A treatment. Outcomes were evaluated with a muscle tone assessment scale (Modified Ashworth Scale - MAS) and the Patients' Global Impression of Improvement (PGI-I) scale.

RESULTS

Mean age was 32.06 ± 3.07 months and 85% were classified as Gross Motor Function Classification System (GMFCS) V. Primitive reflexes were present in 56% of the sample. The majority of the parents (97.9%) reported improvement in range of motion or reduction in spasticity after treatment with botulinum toxin. No side effects were recorded. When compared to the baseline, median reduction in the MAS was 0.5 (IQR = 0).

CONCLUSIONS

The findings of this study suggest that BoNT-A may effectively promote functional improvements and reduce muscle tone, improving the child's and family's quality of life.

Non-invasive Brain Stimulation for Neuropathic Pain After Spinal Cord Injury: A Systematic Review and Network Meta-Analysis

Objective

This study aims to systematically evaluate the effect of non-invasive brain stimulation (NIBS) on neuropathic pain (NP) after spinal cord injury and compare the effects of two different NIBS.

Methods

Randomized controlled trials (RCTs) about the effect of NIBS on NP after spinal cord injury (SCI) were retrieved from the databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang Data, VIP, and CBM from inception to September 2021. The quality of the trials was assessed, and the data were extracted according to the Cochrane handbook of systematic review. Statistical analysis was conducted with Stata (version 16) and R software (version 4.0.2).

Results

A total of 17 studies involving 507 patients were included. The meta-analysis showed that NIBS could reduce the pain score (SMD = −0.84, 95% CI −1.27 −0.40, P = 0.00) and the pain score during follow-up (SMD = −0.32, 95%CI −0.57 −0.07, P = 0.02), and the depression score of the NIBS group was not statistically significant than that of the control group (SMD = −0.43, 95%CI −0.89–0.02, P = 0.06). The network meta-analysis showed that the best probabilistic ranking of the effects of two different NIBS on the pain score was repetitive transcranial magnetic stimulation (rTMS) (P = 0.62) > transcranial direct current stimulation (tDCS) (P = 0.38).

Conclusion

NIBS can relieve NP after SCI. The effect of rTMS on NP is superior to that of tDCS. We suggest that the rTMS parameters are 80–120% resting motion threshold and 5–20 Hz, while the tDCS parameters are 2 mA and 20 min. However, it is necessary to carry out more large-scale, multicenter, double-blind, high-quality RCT to explore the efficacy and mechanism of NIBS for NP after SCI.

Systematic Review and Network Meta-Analysis of Noninvasive Brain Stimulation on Dysphagia after Stroke

Background

Dysphagia is a common sequelae after stroke. Noninvasive brain stimulation (NIBS) is a tool that has been used in the rehabilitation process to modify cortical excitability and improve dysphagia.

Objective

To systematically evaluate the effect of NIBS on dysphagia after stroke and compare the effects of two different NIBS.

Methods

Randomized controlled trials about the effect of NIBS on dysphagia after stroke were retrieved from databases of PubMed, Embase, Cochrane Library, Web of Science, CNKI, Wanfang Data, VIP, and CBM, from inception to June 2021. The quality of the trials was assessed, and the data were extracted according to the Cochrane Handbook for Systematic Reviews of Interventions. A statistical analysis was carried out using RevMan 5.3 and ADDIS 1.16.8. The effect size was evaluated by using the standardized mean difference (SMD) and a 95% confidence interval (CI).

Results

Ultimately, 18 studies involving 738 patients were included. Meta-analysis showed that NIBS could improve the dysphagia outcome and severity scale (DOSS) score (standard mean difference (SMD) = 1.44, 95% CI 0.80 to 2.08, P < 0.05) and the water swallow test score (SMD = 6.23, 95% CI 5.44 to 7.03, P < 0.05). NIBS could reduce the standardized swallowing assessment (SSA) score (SMD = −1.04, 95% CI -1.50 to -0.58, P < 0.05), the penetration-aspiration scale (PAS) score (SMD = −0.85, 95% CI -1.33 to -0.36, P < 0.05), and the functional dysphagia scale score (SMD = −1.05, 95% CI -1.48 to -0.62, P < 0.05). Network meta-analysis showed that the best probabilistic ranking of the effects of two different NIBS on the DOSS score is rTMS (P = 0.52) > tDCS (P = 0.48), the best probabilistic ranking of the SSA score is rTMS (P = 0.72) > tDCS (P = 0.28), and the best probabilistic ranking of the PAS score is rTMS (P = 0.68) > tDCS (P = 0.32).

Conclusion

Existing evidence showed that NIBS could improve swallowing dysfunction and reduce the occurrence of aspiration after stroke, and that rTMS is better than tDCS. Limited by the number of included studies, more large-sample, multicenter, double-blind, high-quality clinical randomized controlled trials are still needed in the future to further confirm the results of this research.