Cognitive effects and acceptability of non-invasive brain stimulation on Alzheimer's disease and mild cognitive impairment: a component network meta-analysis

Cortical plasticity, therapeutic effects, and neural circuit activity of angular gyrus rTMS in amnestic mild cognitive impairment

OBJECTIVE

This study aimed to explore the neurophysiological mechanisms behind the improvement of cognitive functions through angular gyrus repetitive transcranial magnetic stimulation (rTMS) in patients with amnestic mild cognitive impairment (aMCI) by assessing cortical plasticity, underscoring the predictive value of cortical plasticity for clinical outcomes.

METHODS

Twenty-seven aMCI patients were allocated to the intervention and control groups for 4 weeks of 20 Hz rTMS of the angular gyrus. Long-term potentiation (LTP)-like cortical plasticity in the motor M1 area, in conjunction with neuropsychological tests and resting-state brain imaging, was used to investigate the mechanism behind angular gyrus rTMS.

RESULTS

At baseline, aMCI patients presented impaired LTP-like motor cortical plasticity related to cognitive damage. Following treatment with angular gyrus rTMS, a reversal in the impairment of this plasticity was observed. This improvement was associated with clinical efficacy in terms of cognitive function and changes in the resting-state brain network activities of the sensorimotor, default mode, and frontoparietal networks.

CONCLUSIONS

Clinical symptoms are alleviated by angular gyrus rTMS, and damaged cortex plasticity also shows signs of improvement, potentially linked to transcortical neural activity across multiple brain regions in aMCI patients. Cortical plasticity induced by transcranial magnetic stimulation has potential value in predicting the clinical outcomes of neuromodulation.

SIGNIFICANCE

Motor cortex plasticity may be related to cognitive function and therapeutic effects in aMCI patients and may be modulated by angular gyrus transcranial magnetic stimulation.

Potential scalp acupuncture and brain stimulation targets for common neurological disorders: evidence from neuroimaging studies

BACKGROUND

Scalp acupuncture is a promising potential therapy for neurological disorders. However, the development of its stimulation targets-both in identifying novel targets and refining the precision of their localization-has advanced slowly, largely due to the inadequate integration of brain science findings. This study leverages advances in brain neuroimaging to identify evidence-based cortical targets, enhancing the potential of scalp acupuncture and other brain stimulation techniques.

METHODS

Using the Neurosynth Compose platform, systematic meta-analyses of neuroimaging studies were conducted to identify potential surface cortical targets for ten neurological conditions: Subjective Cognitive Decline (SCD), Mild Cognitive Impairment (MCI), Alzheimer's Disease (AD), Parkinson's Disease (PD), Multiple System Atrophy (MSA), Post-Stroke Aphasia (PSA), Primary Progressive Aphasia (PPA), Dyslexia, Chronic Pain, and Disorders of Consciousness (DoC). These targets were projected onto the scalp, further localized using scalp acupuncture lines, traditional acupoints and EEG 10-20 system.

RESULTS

We have identified specific cortical targets for scalp acupuncture associated with ten neurological disorders. Our findings are broadly consistent with current scalp acupuncture protocols while introducing additional new stimulation targets, such as the inferior temporal gyrus for memory processing and the angular gyrus for visuospatial attention. Additionally, the identified targets align with evidence from non-invasive brain stimulation, supporting therapeutic strategies for conditions such as movement disorders and cognitive impairments by targeting areas like the dorsolateral prefrontal cortex and primary motor cortex.

CONCLUSION

Our findings provide a foundation for developing a brain imaging-based scalp acupuncture protocol for neurological disorders. The identified targets may also be used as brain stimulation targets for these disorders.

The effects of transcranial magnetic stimulation on cognitive flexibility among undergraduates with insomnia symptoms: A prospective, single-blind, randomized control trial

Backgrounds

Repetitive transcranial magnetic stimulation(rTMS) has been widely used in the treatment of insomnia, but there is a lack of research on whether this method could enhance the cognitive flexibility(CF) of individuals with insomnia symptoms.

Objectives

To investigate the effects of rTMS on the CF of undergraduates with insomnia symptoms.

Methods

29 participants were randomly assigned into Active group(n = 15) and Sham group(n = 14), receiving 1 Hz rTMS interventions targeting the left dorsolateral prefrontal cortex for 2 weeks, comprising 10 sessions (active vs sham stimulation). Sleep quality and CF were assessed using the Pittsburgh Sleep Quality Index(PSQI), Insomnia Severity Index(ISI), Cognitive Flexibility Inventory(CFI), and the Number-Letter Task (N-L task) at baseline(T0), post-intervention(T1), and 8 weeks' follow-up(T2), and event-related potential(ERP) data during the N-L task were recorded.

Results

Following the intervention, compared to the Sham group, the ISI and PSQI scores in the Active group were significantly decreased, and the CFI score was significantly increased (P < 0.01); the results of the N-L task indicated that at T1, the switch cost of reaction time and accuracy for the Sham group were significantly higher than those for the Active group(P < 0.05). ERP analysis indicated that at T2, under switch conditions, the amplitude of the frontal area P2 in the Active group was significantly greater than that in the Sham group, and the beta-band ERD at parietal region in the Active group was significantly lower than that in the Sham group (P < 0.05).

Conclusions

rTMS could improve sleep quality and enhance the CF of undergraduates with insomnia symptoms.

Clinical Trials Registration

The effect of transcranial magnetic stimulation on cognitive flexibility in college students with insomnia (ChiCTR2400081263) URL: https://www.chictr.org.cn/showproj.html?proj=202951.

The Efficacy and Acceptability of Non-Invasive Brain Stimulation Interventions for Obsessive-Compulsive Disorder Management: A Network Meta-Analysis Based on 24 Stimulation Methods

INTRODUCTION

Despite the high lifetime prevalence and elevated disability rates, treatments for obsessive-compulsive disorder (OCD) have limited efficacy. Considering the abnormal connectivity in the cortical-striatal-thalamic-cortical loop circuits in OCD, several randomized controlled trials (RCTs) have addressed the efficacy of different non-invasive brain stimulation (NIBS) modalities for the management of OCD. However, these RCTs yielded inconclusive results.

METHODS

This network meta-analysis (NMA) included RCTs of NIBS interventions, such as transcranial direct current stimulation (tDCS) and various repetitive transcranial magnetic stimulation (rTMS), in OCD patients. The primary outcomes were changes in the overall severity of OCD and acceptability (i.e., dropout rates).

RESULTS

This NMA of 34 eligible RCTs (1089 participants) and 24 different NIBS interventions revealed that three NIBS interventions significantly improved overall OCD severity compared with sham controls, which were high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) [mean difference (MD) = -10.81, 95% confidence intervals (95% CIs) = -20.80 to -0.82], high-frequency deep TMS over the dorsal medial prefrontal cortex/anterior cingulate cortex (dmPFC/ACC) (MD = -9.74, 95% CIs = -16.42 to -3.06), and low-frequency rTMS over the right DLPFC (MD = -4.70, 95% CIs = -8.84 to -0.57).

CONCLUSIONS

This study highlighted that excitatory stimulation over the dmPFC/ACC and bilateral DLPFC, or inhibitory stimulation over the right DLPFC, was associated with significant improvements in overall OCD severity. Further large-scale RCTs with longer follow-up periods are needed to investigate the true impact of NIBS-based intervention to manage OCD.

TRIAL REGISTRATION

PROSPERO: CRD42023394953.

Impact of effective connectivity within the Papez circuit on episodic memory: moderation by perivascular space function

BACKGROUND AND OBJECTIVES

The formation and retrieval of episodic memory is dependent on the coordinated activity of multiple brain regions and neural networks, with the Papez circuit playing a critical role in this process. Recently, the role of the perivascular space (PVS) in cognitive function has garnered increasing attention. However, the role of PVS function between neural circuits and cognitive function in amnestic mild cognitive impairment (aMCI) patients remains unknown. Therefore, this study aims to (1) investigate alterations in the effective connectivity of the Papez circuit and PVS function in patients with aMCI and (2) explore the role of PVS function between the effective connectivity of the Papez circuit and episodic memory.

METHODS

Sixty participants, all of whom underwent multimodal MRI (fMRI, dMRI, and sMRI) and neuropsychological testing, were recruited for this case‒control study. General linear models were used to compare the effective connectivity within the Papez circuit and PVS function between aMCI patients and healthy controls (HCs) and further explore the role of PVS function between the effective connectivity within the Papez circuit and episodic memory.

RESULTS

The effective connectivity between multiple critical regions within the Papez circuit, notably in the hippocampus, anterior cingulate cortex, and parahippocampal gyrus, was significantly weakened in aMCI patients. Moreover, a significant reduction in the along the perivascular space (ALPS) index was observed among aMCI patients, accompanied by a marked increase in PVS volume, indicating significant PVS dysfunction. Further moderation analysis revealed that PVS function moderated the relationship between effective connectivity within the Papez circuit and episodic memory.

CONCLUSIONS

The effective connectivity within the Papez circuit and PVS function are closely related to cognitive function, particularly episodic memory, and enhancing PVS function may serve as a novel therapeutic target for slowing cognitive decline.

Efficacy of Transcranial Direct Current Stimulation and Photobiomodulation in Improving Cognitive Abilities for Alzheimer's Disease: A Systematic Review

Background: Due to the increasing global prevalence of Alzheimer's dementia (AD), neuromodulation techniques such as transcranial direct current stimulation (tDCS) and photobiomodulation (PBM) are considered potential complementary therapies. Objective: We assessed the efficacy and safety of tDCS and PBM and their potential to enhance cognitive functions in individuals with AD. Methods: This review primarily examined studies designed to evaluate the efficacy, followed by an assessment of the safety of tDCS and PBM for people with AD. The databases searched were PubMed, Scopus, and Web of Science Core Collection, resulting in 17 published randomized and controlled trials. References were screened over 5 years (2020-2024). The research design used PRISMA guidelines. Results: Fourteen studies were considered for tDCS, and the current literature supports efficacy and safety at an amperage of 2 mA, with electrodes placed on the dorsolateral prefrontal cortex (DLPFC). Three studies were included for PBM. The heterogeneity of these study measures made them unsuitable for combined efficacy analysis, and they did not provide a safety evaluation. Conclusions: Despite differences in efficacy assessments, tDCS and PBM improved cognitive abilities. There is an urgent need to standardize metrics for evaluating efficacy and safety, particularly for PBM. Future research is encouraged.

A retrospective analysis of ultrasound neuromodulation therapy using transcranial pulse stimulation in 58 dementia patients

BACKGROUND

Novel ultrasound neuromodulation techniques allow therapeutic brain stimulation with unmet precision and non-invasive targeting of deep brain areas. Transcranial pulse stimulation (TPS), a multifrequency sonication technique, is approved for the clinical treatment of Alzheimer's disease (AD). Here, we present the largest real-world retrospective analysis of ultrasound neuromodulation therapy in dementia (AD, vascular, mixed) and mild cognitive impairment (MCI).

METHODS

The consecutive sample involved 58 patients already receiving state-of-the-art treatment in an open-label, uncontrolled, retrospective study. TPS therapy typically comprises 10 sessions (range 8-12) with individualized MRI-based target areas defined according to brain pathology and individual pathophysiology. We compared the CERAD-Plus neuropsychological test battery results before and after treatment, with the CERAD Corrected Total Score ( CTS) as the primary outcome. Furthermore, we analyzed side effects reported by patients during the treatment period.

RESULTS

CERAD Corrected Total Score (CTS) significantly improved (p = .017, d = .32) after treatment (Baseline: M = 56.56, SD = 18.56; Post-treatment: M = 58.65, SD = 19.44). The group of top-responders (top quartile) improved even by 9.8 points. Fewer than one-third of all patients reported any sensation during treatment. Fatigue and transient headaches were the most common, with no severe adverse events.

CONCLUSIONS

The findings implicate TPS as a novel and safe add-on therapy for patients with dementia or MCI with the potential to further improve current state-of-the-art treatment results. Despite the individual benefits, further randomized, sham-controlled, longitudinal clinical trials are needed to differentiate the effects of verum and placebo.

Predicting the Beneficial Effects of Cognitive Stimulation and Transcranial Direct Current Stimulation in Amnestic Mild Cognitive Impairment with Clinical, Inflammation, and Human Microglia Exposed to Serum as Potential Markers: A Double-Blind Placebo-Controlled Randomized Clinical Trial

In amnestic mild cognitive impairment (aMCI), neuroinflammation evolves during disease progression, affecting microglial function and potentially accelerating the pathological process. Currently, no effective treatment exists, leading to explorations of various symptomatic approaches, though few target the underlying physiological mechanisms. Modulating inflammatory processes may be critical in slowing disease progression. Cognitive stimulation (CS) and transcranial direct current stimulation (tDCS) applied to the left dorsolateral prefrontal cortex (l-DLPFC) show promise, but the results are heterogeneous. Thus, a randomized, double-blind, placebo-controlled clinical trial is currently underway. The first-stage results were examined after three weeks of intervention in two groups: active tDCS combined with CS and sham tDCS combined with CS. Twenty-two participants underwent two assessments: T0 (baseline) and T1 (after 15 sessions of tDCS, active or sham, and 9 sessions of CS). The results demonstrated that CS improved cognition, increased brain-derived neurotrophic factor (BDNF) levels, and reduced peripheral proinflammatory cytokine levels (interleukin IL-6 and chemokine CX3CL1) in serum. This decrease in IL-6 may promote microglial proliferation and survival as a modulatory effect response, while the increase in BDNF might suggest a regulatory mechanism in microglia-neuron interaction responses. However, tDCS did not enhance the cognitive or modulatory effects of CS, suggesting that longer interventions might be required to achieve substantial benefits.

Efficacy of non-invasive brain stimulation interventions on cognitive impairment: an umbrella review of meta-analyses of randomized controlled trials

BACKGROUND

The impact of noninvasive brain stimulation (NIBS) on cognitive and mental outcomes in Alzheimer's disease (AD) and mild cognitive impairment (MCI) remains under debate due to contradictory findings from systematic reviews and meta-analyses (SRMAs). To synthesize evidence from SRMAs assessing the effectiveness of NIBS techniques on cognitive and mental outcomes in AD and MCI populations. By comparing our findings to recent reviews and clinical guidelines, we highlight how this study addresses current limitations in the literature, provides a more holistic perspective on NIBS interventions, and guides future research and clinical practice.

METHODS

We searched four databases from inception to May 15, 2024, reviewing SRMAs that analyzed the effects of NIBS. Effect sizes, 95% confidence intervals (CIs), and prediction intervals were computed for each meta-analysis. The methodological quality of the SRMAs was evaluated using the Measurement Tool to Assess Systematic Reviews 2, and the quality of evidence was assessed through the Grading of Recommendations, Assessment, Development, and Evaluation criteria.

FINDINGS

Ten SRMAs detailing 22 associations were analyzed, focusing on two NIBS techniques across 12 unique outcomes. Significant improvements were observed in global cognition, language, executive function, and memory. Repetitive transcranial magnetic stimulation (rTMS) significantly enhanced short-term global cognition (standardized mean difference [SMD], 0.44; 95% CI 0.02-0.86), language (SMD, 1.64; 95% CI 1.22-2.06), executive function (SMD, 1.64; 95% CI 0.18-0.83), and long-term global cognition (SMD, 0.29; 95% CI 0.07-0.50). Transcranial direct current stimulation (tDCS) was effective in improving memory (SMD, 0.60; 95% CI 0.32-0.89) and executive function (SMD, 0.39; 95% CI 0.08-0.71). NIBS interventions showed no significant correlation with neuropsychiatric symptoms but demonstrated good tolerability in terms of safety and acceptability.

INTERPRETATION

This umbrella review indicates that NIBS techniques, particularly rTMS and tDCS, can significantly improve cognitive functions such as global cognition, language, executive functions, and memory in patients with AD and MCI. Despite potential benefits, results should be interpreted cautiously due to study heterogeneity and methodological limitations. Future studies should investigate their long-term effects and applicability across dementia types.

A systematic review and meta-analysis of the impact of transcranial direct current stimulation on cognitive function in older adults with cognitive impairments: the influence of dosage parameters

INTRODUCTION

Numerous studies have demonstrated the effects of transcranial direct current stimulation (tDCS) on cognitive function in the older people. This study further explores the impact of tDCS and its dosage parameters on cognitive enhancement in older people with cognitive impairments.

METHODS

Randomized controlled trials (RCTs) published through November 2023 were retrieved from databases including PubMed, Scopus, EMBASE, EBSCO, and the Cochrane Library. Participants were older adults with cognitive impairments, including Alzheimer's disease (AD), mild cognitive impairment (MCI), and dementia. AD was diagnosed based on the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), or the National Institute of Neurological and Communicative Disorders and Stroke - Alzheimer' Disease and Related Disorders Association (NINCDS-ADRDA) criteria. Dementia was diagnosed using the DSM-V or NINCDS-ADRDA criteria, while MCI was diagnosed using the DSM-V, the Petersen criteria, or assessments such as Montreal Cognitive Assessment (MoCA) and Clinical Dementia Rating (CDR). Standardized mean difference (SMD) values were analyzed to assess the effects.

RESULTS

A total of 19 RCTs were included. tDCS significantly improved the Mini-Mental State Examination score both immediately post-intervention (SMD = 0.51, p = 0.005) and at follow-up (SMD = 2.29, p = 0.0003). Significant effects were observed when tDCS was used alone (SMD = 0.39, p = 0.04), at current densities ≤ 0.06 mA/cm2 (SMD = 0.25, p = 0.04), session durations exceeding 20 min (SMD = 0.89, p = 0.01), up to 15 sessions (SMD = 0.28, p = 0.009), and when an active electrode was placed over the temporal area (SMD = 0.33, p = 0.02). People with AD showed greater improvements compared to those with MCI or dementia (SMD = 0.91, p = 0.02). However, tDCS did not significantly improve memory or executive function.

CONCLUSION

tDCS demonstrated efficacy in enhancing global cognition in older people with cognitive impairments, providing insight into optimal parameters for clinical application. However, no improvement were observed in memory or executive function.

Efficacy of brain stimulation therapies across psychiatric, movement, and cognitive disorders: an umbrella review synthesizing meta-analyses of randomized controlled trials

BACKGROUND

Brain stimulation therapy (BST) has significant potential in treating psychiatric, movement, and cognitive disorders. Given the high prevalence of comorbidities among these disorders, we conducted an umbrella review to comprehensively assess the efficacy of BSTs in treating the core symptoms across these three categories of disorders.

METHODS

We systematically searched for meta-analyses and network meta-analyses of randomized controlled trials with sham controls up to September 25, 2024, from databases including PubMed, PsycINFO, Embase, and the Cochrane Library. Our primary outcome was improvements in core symptoms. We evaluated quality using 11 criteria. We calculated pooled effect estimates for core symptoms based on the largest meta-analyses, then conducted sensitivity and subgroup analyses, and assessed heterogeneity, publication bias, and small-study effects. Finally, we synthesized effect sizes from all meta-analyses to provide a comprehensive overview of BSTs' efficacy. PROSPERO registration: CRD42023439090.

FINDINGS

We included 198 articles with 108,377 patients evaluating 14 BSTs across 21 disorders. The largest meta-analysis showed a moderate standardized mean difference (SMD) of 0.56 (95% CI: 0.49, 0.64; I2 = 70%). Subgroup analyses revealed significant SMDs for psychiatric disorders (0.60; 95% CI: 0.49, 0.71; I2 = 66%), movement disorders (0.56; 95% CI: 0.42, 0.69; I2 = 79%), and cognitive disorders (0.46; 95% CI: 0.32, 0.61; I2 = 48%). SMDs were 0.44 (95% CI: 0.23, 0.65; I2 = 70%) for follow-up ≤1 month and 0.69 (95% CI: 0.43, 0.94; I2 = 84%) for follow-up >1 month. Compared to other conditions, BSTs show better therapeutic effects in treating depression, post-traumatic stress disorder, obsessive-compulsive disorder, pain, fibromyalgia, and post-stroke motor recovery.

INTERPRETATION

This review explored the potential of BSTs for comorbidities of the three disorders from a disorder-specific perspective, providing a roadmap for their clinical application and future research.

FUNDING

This work was supported by the Anhui Natural Science Foundation (2023AH040086), Key Laboratory of Philosophy and Social Science of Anhui Province on Adolescent Mental Health and Crisis Intelligence Intervention (SYS2023B08), and the Joint Funds of the National Natural Science Foundation of China (U23A20424).

Optimal dose and type of non-pharmacological treatments to improve cognitive function in people with Alzheimer's disease: a systematic review and network meta-analysis

OBJECTIVES

To evaluate and rank the effectiveness of specific non-pharmacological treatments (NPTs) in improving the global cognitive function in individuals with Alzheimer's disease (AD) and to examine the dose-response relationship.

METHOD

We conducted a systematic search in PubMed, MEDLINE, Embase, PsycINFO, CENTRAL, WOS, and CNKI from their inception to 15 February 2023. Standardized mean differences (SMD) and 95% confidence intervals (CI) were calculated for outcomes using random effects models.

RESULTS

We included 68 studies involving 5053 participants in this meta-analysis. The treatments with the highest cumulative probabilities for improving global cognitive function were transcranial direct current stimulation (tDCS), followed by physical exercise (PE), and repetitive transcranial magnetic stimulation (rTMS). Additionally, cognitive stimulation (CS), cognitive training CT), multidisciplinary program (MD), and reminiscence treatment (RT) also significantly improve the global cognitive function of people with AD. A non-linear dose-response association was observed for tDCS, PE, rTMS, CS, and CT with global cognitive improvement. Notably, no minimal threshold was identified for the beneficial effects of PE on cognition. The estimated minimal doses for clinically relevant changes in cognition were 33 min per week for tDCS, 330 MET-min per week for PE, and 8000 pulses per week for rTMS.

CONCLUSION

tDCS, PE, and rTMS are the better effective NPTs for enhancing global cognitive function in individuals with AD. Properly dosing these treatments can yield significant clinical benefits. Our findings support the clinical utility of low-dose exercise in improving cognition in people with AD.

Comparison of different surgical strategies for cervical dystonia: Evidence from Bayesian network analysis

BACKGROUND AND PURPOSE

Several surgical techniques have been used to treat cervical dystonia (CD), however, to date, the optimal surgical technique for CD remains controversial. We therefore conducted the first network meta-analysis to compare different surgical strategies for CD to inform clinical practice.

METHODS

Electronic databases were searched for surgical strategies for treating CD. The primary outcome was improvement in total Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) score. Subgroup analysis was performed to compare short-term (< 1 year) and long-term (≥ 1 year) outcomes. Safety outcomes included surgery-related adverse events (AEs).

RESULTS

A total of 55 trials with 2032 patients employing five surgical strategies were identified, including globus pallidus internus (GPi)/subthalamic nucleus (STN)-deep brain stimulation (DBS), selective peripheral denervation (SPD), microvascular decompression (MVD) and pallidotomy. All strategies led to significant improvement in total TWSTRS score (mean improvement range 18.65-28.22). GPi-DBS showed significantly greater enhancement than SPD for the whole dataset (mean difference [MD] 7.03, 95% credible interval [Crl] 1.53-12.56), while both GPi-DBS (MD 8.05, 95% Crl 2.35-13.80) and STN-DBS (MD 10.71, 95% Crl 2.22-19.20) exhibited more long-term improvement than SPD. Regarding safety outcomes, GPi/STN-DBS and MVD were associated with fewer surgery-related AEs than SPD (ln odds ratio range -1.68 to -1.41).

CONCLUSION

We conclude that DBS should be the preferred surgical option for CD, and the STN is a promising alternative target choice due to its comparable efficacy with the GPi. However, more direct evidence is still required.

Transcranial Direct Current Stimulation for Global Cognition in Mild Cognitive Impairment

Mild cognitive impairment (MCI) is a condition characterized by noticeable deficits in memory retrieval or other cognitive domains than the individuals with the same age but do not significantly interfere with daily functioning. It represents an intermediate stage between normal aging and dementia, and a crucial opportunity for intervention prior to extensive cognitive decline. Transcranial direct current stimulation (tDCS), a non-invasive neuromodulation technique, has shown promise in enhancing global cognition in MCI. Current evidence suggests that tDCS provides short-term cognitive benefits, particularly in memory and attention, with moderate effects observed in processing speed. However, its impact on executive function and language remains inconsistent, highlighting variability in individual responses and study methodologies. While long-term efficacy remains uncertain due to limited longitudinal research and short follow-up periods, safety concerns, especially with self-administered tDCS such as in home-based tDCS, underscore the need for proper training and device innovation. Despite this, tDCS is a promising, portable tool for cognitive enhancement in MCI, with potential to delay progression to dementia. Addressing challenges such as optimizing stimulation protocols, accounting for individual neuroanatomical variability, and establishing long-term effectiveness will be essential for its broader clinical adoption. Future research should focus on standardizing methodologies, incorporating biomarkers to predict treatment response, and conducting large-scale, longitudinal studies to refine its therapeutic application.

ABC Family Gene Polymorphisms and Cognitive Functions Interact to Influence Antidepressant Efficacy

INTRODUCTION

The importance of identifying relevant indicators of antidepressant efficacy is highlighted by the low response rates to antidepressant treatment for depression. The ABC gene family, encoding ATP-dependent transport proteins facilitating the transport of psychotropic drugs, has drawn attention. This study delved into the relationship between antidepressant efficacy and seven single nucleotide polymorphisms of ABCB1 and ABCB6 genes.

METHODS

A total of 549 depressed patients participated in the study, and all completed a 6-week course of antidepressant treatment. Cognitive function was assessed at baseline and post-treatment. Patients were categorized based on post-treatment HAMD-17 scores (with HAMD≤7 indicating remission), and comparisons were made between different groups in terms of allelic gene frequencies and genotypes. Logistic regression was used to explore the interaction between cognitive function and genotype on efficacy. Dual-luciferase reporter assays were performed to compare the regulatory effects of rs1109866 allele variants on the ABCB6 promoter.

RESULTS

There were no notable differences in allelic gene frequencies and genotypes between the remission and non-remission groups. Nonetheless, a significant interaction was identified between the rs1109866 genotype and language fluency-related indicators concerning efficacy (p=0.029) before correction. The dual-luciferase reporter assays demonstrated markedly higher fluorescence intensity of rs1109866-C compared to that of rs1109866-T (p<0.001).

DISCUSSION

Relying solely on genetic polymorphisms of ABC family genes as predictors of antidepressant treatment response may not be sufficient. However, the interaction between the rs1109866 and cognition plays a pivotal role. The potentially enhanced transcriptional activity of rs1109866-C might offer insight into its impact on antidepressant efficacy.

Impaired network organization in mild age-related hearing loss

Age-related hearing loss (ARHL) is considered one of the most common neurodegenerative disorders in the elderly; however, how it contributes to cognitive decline is poorly understood. With resting-state functional magnetic resonance imaging from 66 individuals with ARHL and 54 healthy controls, group spatial independent component analyses, sliding window analyses, graph-theory methods, multilayer networks, and correlation analyses were used to identify ARHL-induced disturbances in static and dynamic functional network connectivity (sFNC/dFNC), alterations in global network switching and their links to cognitive performances. ARHL was associated with decreased sFNC/dFNC within the default mode network (DMN) and increased sFNC/dFNC between the DMN and central executive, salience (SN), and visual networks. The variability in dFNC between the DMN and auditory network (AUN) and between the SN and AUN was decreased in ARHL. The individuals with ARHL had lower network switching rates than controls among global network nodes, especially in the DMN. Some disturbances within DMN were associated with disrupted executive and memory performance. The prolonged loss of sensory information associated with ARHL-induced compensatory within-network segregations and between-network integrations in the DMN might reduce network information processing and accelerate brain aging and cognitive decline.

The emerging field of non-invasive brain stimulation in Alzheimer's disease

Treating cognitive impairment is a holy grail of modern clinical neuroscience. In the past few years, non-invasive brain stimulation is increasingly emerging as a therapeutic approach to ameliorate performance in patients with cognitive impairment and as an augmentation approach in persons whose cognitive performance is within normal limits. In patients with Alzheimer's disease, better understanding of brain connectivity and function has allowed for the development of different non-invasive brain stimulation protocols. Recent studies have shown that transcranial stimulation methods enhancing brain plasticity with several modalities have beneficial effects on cognitive functions. Amelioration has been shown in preclinical studies on behaviour of transgenic mouse models for Alzheimer's pathology and in clinical studies with variable severity of cognitive impairment. While the field is still grappling with issues related to the standardization of target population, frequency, intensity, treatment duration and stimulated region, positive outcomes have been reported on cognitive functions and on markers of brain pathology. Here we review the most encouraging protocols based on repetitive transcranial magnetic stimulation, transcranial direct current stimulation, transcranial alternating current stimulation, visual-auditory stimulation, photobiomodulation and transcranial focused ultrasound, which have demonstrated efficacy to enhance cognitive functions or slow cognitive decline in patients with Alzheimer's disease. Beneficial non-invasive brain stimulation effects on cognitive functions are associated with the modulation of specific brain networks. The most promising results have been obtained targeting key hubs of higher-level cognitive networks, such as the frontal-parietal network and the default mode network. The personalization of stimulation parameters according to individual brain features sheds new light on optimizing non-invasive brain stimulation protocols for future applications.

Effects and safety of transcranial direct current stimulation on multiple health outcomes: an umbrella review of randomized clinical trials

Transcranial direct current stimulation (tDCS), which delivers a direct current to the brain, emerged as a non-invasive potential therapeutic in treating a range of neurological and neuropsychiatric disorders. However, a comprehensive quantitative evidence synthesis on the effects of tDCS on a broad range of mental illnesses is lacking. Here, we systematically assess the certainty of the effects and safety of tDCS on several health outcomes using an umbrella review of randomized controlled trials (RCTs). The methodological quality of each included original meta-analysis was assessed by the A Measurement Tool for Assessing Systematic Reviews 2 (AMSTAR2), and the certainty of the evidence for each effect was evaluated with Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). We followed an a priori protocol (PROSPERO CRD42023458700). We identified 15 meta-analyses of RCTs (AMSTAR 2; high 3, moderate 3, and low 9) that included 282 original articles, covering 22 unique health endpoints across 22 countries and six continents. From meta-analyses of RCTs supported by very low to high certainty of evidence, it was found that tDCS improved symptoms related to post-stroke, including post-stroke depression scale score (equivalent standardized mean difference [eSMD], 1.61 [95% confidence level, 0.72-2.50]; GRADE=moderate), activities of daily living independence (7.04 [3.41-10.67]; GRADE=high), motor recovery of upper and lower extremity (upper extremity: 0.15 [0.06-0.24], GRADE=high; lower extremity: 0.10 [0.03-0.16], GRADE=high), swallowing performance (GRADE=low), and spasticity (GRADE=moderate). In addition, tDCS had treatment effects on symptoms of several neurological and neuropsychiatric disorders, including obsessive-compulsive disorder (0.81 [0.44-1.18]; GRADE=high), pain in fibromyalgia (GRADE=low), disease of consciousness (GRADE=low), insight score (GRADE=moderate) and working memory (0.34 [0.01-0.67]; GRADE=high) in schizophrenia, migraine-related pain (-1.52 [-2.91 to -0.13]; GRADE=high), attention-deficit/hyperactivity disorder (reduction in overall symptom severity: 0.24 [0.04-0.45], GRADE=low; reduction in inattention: 0.56 [0.02-1.11], GRADE=low; reduction in impulsivity: 0.28 [0.04-0.51], GRADE=low), depression (GRADE=low), cerebellar ataxia (GRADE=low), and pain (GRADE=very low). Importantly, tDCS induced an increased number of reported cases of treatment-emergent mania or hypomania (0.88 [0.62-1.13]; GRADE=moderate). We found varied levels of evidence for the effects of tDCS with multiple neurological and neuropsychiatric conditions, from very low to high certainty of evidence. tDCS was effective for people with stroke, obsessive-compulsive disorder, fibromyalgia, disease of consciousness, schizophrenia, migraine, attention-deficit/hyperactivity disorder, depression, cerebellar ataxia, and pain. Therefore, these findings suggest the benefit of tDCS for several neurological and neuropsychiatric disorders; however, further studies are needed to understand the underlying mechanism and optimize its therapeutic potential.

Combined Catalpol and Tetramethylpyrazine Promote Axonal Plasticity in Alzheimer's Disease by Inducing Astrocytes to Secrete Exosomes Carrying CDK5 mRNA and Regulating STAT3 Phosphorylation

Alzheimer's disease (AD) is a common progressive degenerative disease of the central nervous system in aging populations. This study aimed to investigate the effects of combined catalpol and tetramethylpyrazine (CT) in promoting axonal plasticity in AD and the potential underlying mechanism. Astrocytes were treated with different concentrations of compatible CT. Exosomes were collected and subjected to sequencing analysis, which was followed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis of differentially expressed genes. Amyloid precursor protein/presenilin 1 (APP/PS1) double-transfected male mice were used as the in vivo AD models. Astrocyte-derived exosomes that were transfected with cyclin-dependent kinase 5 (CDK5) or CT treatment were injected into the tail vein of mice. The levels of CDK5, synaptic plasticity marker protein neurofilament 200 (NF200), and growth-associated protein 43 (GAP-43) in the hippocampus of mice were compared in each group. Immunofluorescence staining was used to detect the localization of STAT3 and to visualize synaptic morphology via β-tubulin-III (TUBB3). Astrocyte-derived exosomes transfected with siCDK5 or treated with CT were co-cultured with HT-22 cells, which were untransfected or silenced for signal transducer and activator of transcription 3 (STAT3). Amyloid β-protein (Aβ)1-42 was induced in the in vitro AD models. The viability, apoptosis, and expression levels of NF200 and GAP-43 proteins in the hippocampal neurons of each group were compared. In total, 166 differentially expressed genes in CT-induced astrocyte-derived exosomes were included in the KEGG analysis, and they were found to be enriched in 12 pathways, mainly in axon guidance. CT treatment significantly increased the level of CDK5 mRNA in astrocyte-derived exosomes-these exosomes restored CDK5 mRNA and protein levels in the hippocampus of the in vivo AD model mice and the in vitro AD model; promoted p-STAT3 (Ser727), NF200 and GAP-43 proteins; and promoted the regeneration and extension of neuronal synapses. Silencing of CDK5 blocked both neuronal protection as well as induction of axonal plasticity in AD by CT-treated exosomes in vitro and in vivo. Moreover, silencing of STAT3 blocked both neuronal protection as well as induction of axonal plasticity in AD caused by CDK5 overexpression or CT-treated astrocyte-induced exosomes. CT promotes axonal plasticity in AD by inducing astrocytes to secrete exosomes carrying CDK5 mRNA and regulating STAT3 (Ser727) phosphorylation.

Comparative efficacy of non-invasive brain stimulation on cognition function in patients with mild cognitive impairment: A systematic review and network meta-analysis

BACKGROUND

Mild cognitive impairment (MCI) is a critical time window for implementing prevention strategies to attenuate or delay cognitive decline. Non-invasive brain stimulation (NIBS) techniques are promising non-pharmacological therapies for improving the cognitive function of MCI, but it is unclear which type of NIBS protocol is most effective. This study aimed to compare and rank the beneficial effect of different NIBS methods/protocols on cognitive function and examine the acceptability of NIBS in patients with MCI.

METHODS

Electronic search of PubMed, Cochrane Library, EMBASE, China National Knowledge Infrastructure, Wanfang Database, and Chongqing VIP Database up to November 2023. Patients with diagnosis of MCI were included. The primary outcomes were acceptability and pre-post treatment changes in global cognitive function, and the secondary outcomes were specific cognitive domains (language and executive function). All network meta‑analysis procedures were performed under the frequentist model. A protocol for this systematic review was registered in PROSPERO (Registration number: CRD42023441448).

RESULTS

A network meta-analysis was conducted on 19 eligible RCTs consisting of 599 subjects. Compared with the sham stimulation, Repetitive Transcranial Magnetic Stimulation over the Bilateral dorsolateral prefrontal cortex (rTMS-F3F4) showed the strongest improvement in global cognitive function in MCI patients (SMD =1.52[95 %CIs =0.49-2.56]), followed by rTMS over the left dorsolateral prefrontal cortex (rTMS-F3) (SMD =1.25[95 %CIs =0.57-1.93]); Moreover, rTMS-F3F4 showed more significant efficacy in language function (SMD =0.96[95 %CIs = 0.20-1.72]); No statistically significant differences were found among the other cognitive domains. Compared with the rTMS-F4, rTMS-F3F4 showed a stronger improvement in global cognitive function in MCI patients (SMD =1.80[95 %CIs =0.02-3.59]). Similar results were obtained in subgroup analyses of cognitive function. All the methods were well-tolerated with an acceptable safety profile.

CONCLUSION

The present findings provide evidence of the benefits of NIBS, especially TMS stimulating the bilateral dorsolateral prefrontal cortex, for the beneficial effect on cognitive and language function in patients with MCI. However, because few studies were available for inclusion, additional well-designed, large-scale RCTs are warranted to support exploring longer-term dynamic effects.

Efficacy and acceptability of noninvasive brain stimulation for treating posttraumatic stress disorder symptoms: A network meta-analysis of randomized controlled trials

INTRODUCTION

Despite its high lifetime prevalence rate and the elevated disability caused by posttraumatic stress disorder (PTSD), treatments exhibit modest efficacy. In consideration of the abnormal connectivity between the dorsolateral prefrontal cortex (DLPFC) and amygdala in PTSD, several randomized controlled trials (RCTs) addressing the efficacy of different noninvasive brain stimulation (NIBS) modalities for PTSD management have been undertaken. However, previous RCTs have reported inconsistent results. The current network meta-analysis (NMA) aimed to compare the efficacy and acceptability of various NIBS protocols in PTSD management.

METHODS

We systematically searched ClinicalKey, Cochrane Central Register of Controlled Trials, Embase, ProQuest, PubMed, ScienceDirect, Web of Science, and ClinicalTrials.gov to identify relevant RCTs. The targeted RCTs was those comparing the efficacy of NIBS interventions, such as transcranial direct current stimulation (tDCS), repetitive transcranial magnetic stimulation (rTMS), and transcutaneous cervical vagal nerve stimulation, in patients with PTSD. The NMA was conducted using a frequentist model. The primary outcomes were changes in the overall severity of PTSD and acceptability (to be specific, rates of dropouts for any reason).

RESULTS

We identified 14 RCTs that enrolled 686 participants. The NMA demonstrated that among the investigated NIBS types, high-frequency rTMS over bilateral DLPFCs was associated with the greatest reduction in overall PTSD severity. Further, in comparison with the sham controls, excitatory stimulation over the right DLPFC with/without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms, including depression and anxiety symptoms, and overall PTSD severity.

CONCLUSIONS

This NMA demonstrated that excitatory stimulation over the right DLPFC with or without excitatory stimulation over left DLPFC were associated with significant reductions in PTSD-related symptoms.

TRIAL REGISTRATION

PROSPERO CRD42023391562.

Effect of cranial electrotherapy stimulation as an add-on therapy on late-life generalized anxiety disorder: An open-label study

INTRODUCTION

Cranial electrotherapy stimulation (CES) is beneficial in reducing anxiety in psychiatric patients. However, no studies have reported on elderly patients with generalized anxiety disorders (GAD). This study aimed to determine the efficacy and safety of a 6-week CES intervention for late-life GAD.

MATERIALS AND METHODS

This single-arm pilot study assessed 6-week CES treatment (Alpha-Stim AID) for late-life GAD and 4-week follow-up post intervention. The Hamilton Rating Scale for Anxiety (HAMA) and Beck Anxiety Inventory (BAI) were used as baseline and outcome measures at weeks 4, 6, and 10, respectively. Treatment response was defined as 50 % or more reduction of the HAMA score and remission was defined as a of score ≤7 on the HAMA. Other measures included depression, sleep quality, and quality of life assessment.

RESULTS

We included participants (n = 27) aged 68.0 ± 5.0 years, 81.5 % of whom were female. Fifteen (55.6 %), 18 (66.7 %), and 15 (55.6 %) patients were concurrently treated with antidepressants, BZDs, and antipsychotics, respectively. Intention-to-treat (ITT) analysis revealed a significant decrease in HAMA scores from baseline (20.96 ± 3.30) to week 6 (12.26 ± 7.09) and one-month (12.85 ± 7.08) follow-up at W10 (all p < 0.001). The response and remission rates were 33.3 %, 40.7 %, and 48.1 % and 25.9 %, 29.6 %, and 25.9 % at W4, W6, and W10, respectively. The CES improved depression and sleep conditions as measured by the Beck Depression Inventory-II and Pittsburgh Sleep Quality Index.

CONCLUSION

CES clinically reduces symptoms of anxiety and depression and may improve sleep quality in late-life GAD. Future randomized controlled study is needed.

The cognitive effect of non-invasive brain stimulation combined with cognitive training in Alzheimer's disease and mild cognitive impairment: a systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS) combined with cognitive training (CT) may have shown some prospects on improving cognitive function in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, data from clinical trials or meta-analysis involving NIBS combined with CT have shown controversial results. The aim of this systematic review and meta-analysis was to evaluate short-term and long-term effects of NIBS combined with CT on improving global cognition and other specific cognitive domains in patients with AD and MCI.

METHODS

This systematic review and meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Five electronic databases including PubMed, Web of Science, EBSCO, Cochrane Library and Embase were searched up from inception to 20 November 2023. The PEDro scale and the Cochrane's risk of bias assessment were used to evaluate risk of bias and methodological quality of included studies. All statistical analyses were conducted with Review Manager 5.3.

RESULTS

We included 15 studies with 685 patients. The PEDro scale was used to assess methodological quality with a mean score of 7.9. The results of meta-analysis showed that NIBS combined with CT was effective on improving global cognition in AD and MCI (SMD = 0.52, 95% CI (0.18, 0.87), p = 0.003), especially for patients accepting repetitive transcranial magnetic stimulation (rTMS) combined with CT (SMD = 0.46, 95% CI (0.14, 0.78), p = 0.005). AD could achieve global cognition improvement from NIBS combined with CT group (SMD = 0.77, 95% CI (0.19, 1.35), p = 0.01). Transcranial direct current stimulation (tDCS) combined with CT could improve language function in AD and MCI (SMD = 0.29, 95% CI (0.03, 0.55), p = 0.03). At evaluation follow-up, rTMS combined with CT exhibited larger therapeutic responses to AD and MCI in global cognition (SMD = 0.55, 95% CI (0.09, 1.02), p = 0.02). AD could achieve global cognition (SMD = 0.40, 95% CI (0.03, 0.77), p = 0.03) and attention/working memory (SMD = 0.72, 95% CI (0.23, 1.20), p = 0.004) improvement after evaluation follow-up from NIBS combined with CT group.

CONCLUSIONS

Overall, NIBS combined with CT, particularly rTMS combined with CT, has both short-term and follow-up effects on improving global cognition, mainly in patients with AD. tDCS combined with CT has advantages on improving language function in AD and MCI. Future more studies need evaluate cognitive effects of NIBS combined with CT on other specific cognitive domain in patients with cognitive deterioration.

Studying the Alzheimer's disease continuum using EEG and fMRI in single-modality and multi-modality settings

Alzheimer's disease (AD) is a biological, clinical continuum that covers the preclinical, prodromal, and clinical phases of the disease. Early diagnosis and identification of the stages of Alzheimer's disease (AD) are crucial in clinical practice. Ideally, biomarkers should reflect the underlying process (pathological or otherwise), be reproducible and non-invasive, and allow repeated measurements over time. However, the currently known biomarkers for AD are not suitable for differentiating the stages and predicting the trajectory of disease progression. Some objective parameters extracted using electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are widely applied to diagnose the stages of the AD continuum. While electroencephalography (EEG) has a high temporal resolution, fMRI has a high spatial resolution. Combined EEG and fMRI (EEG-fMRI) can overcome single-modality drawbacks and obtain multi-dimensional information simultaneously, and it can help explore the hemodynamic changes associated with the neural oscillations that occur during information processing. This technique has been used in the cognitive field in recent years. This review focuses on the different techniques available for studying the AD continuum, including EEG and fMRI in single-modality and multi-modality settings, and the possible future directions of AD diagnosis using EEG-fMRI.

Mechanistic insights and emerging therapeutic stratagems for Alzheimer's disease

Alzheimer's disease (AD), a multi-factorial neurodegenerative disorder has affected over 30 million individuals globally and these numbers are expected to increase in the coming decades. Current therapeutic interventions are largely ineffective as they focus on a single target. Development of an effective drug therapy requires a deep understanding of the various factors influencing the onset and progression of the disease. Aging and genetic factors exert a major influence on the development of AD. Other factors like post-viral infections, iron overload, gut dysbiosis, and vascular dysfunction also exacerbate the onset and progression of AD. Further, post-translational modifications in tau, DRP1, CREB, and p65 proteins increase the disease severity through triggering mitochondrial dysfunction, synaptic loss, and differential interaction of amyloid beta with different receptors leading to impaired intracellular signalling. With advancements in neuroscience tools, new inter-relations that aggravate AD are being discovered including pre-existing diseases and exposure to other pathogens. Simultaneously, new therapeutic strategies involving modulation of gene expression through targeted delivery or modulation with light, harnessing the immune response to promote clearance of amyloid deposits, introduction of stem cells and extracellular vesicles to replace the destroyed neurons, exploring new therapeutic molecules from plant, marine and biological sources delivered in the free state or through nanoparticles and use of non-pharmacological interventions like music, transcranial stimulation and yoga. Polypharmacology approaches involving combination of therapeutic agents are also under active investigation for superior therapeutic outcomes. This review elaborates on various disease-causing factors, their underlying mechanisms, the inter-play between different disease-causing players, and emerging therapeutic options including those under clinical trials, for treatment of AD. The challenges involved in AD therapy and the way forward have also been discussed.

Neuromodulation and the Gut-Brain Axis: Therapeutic Mechanisms and Implications for Gastrointestinal and Neurological Disorders

The gut-brain axis (GBA) represents a complex, bidirectional communication network that intricately connects the gastrointestinal tract with the central nervous system (CNS). Understanding and intervening in this axis opens a pathway for therapeutic advancements for neurological and gastrointestinal diseases where the GBA has been proposed to play a role in the pathophysiology. In light of this, the current review assesses the effectiveness of neuromodulation techniques in treating neurological and gastrointestinal disorders by modulating the GBA, involving key elements such as gut microbiota, neurotrophic factors, and proinflammatory cytokines. Through a comprehensive literature review encompassing PubMed, Google Scholar, Web of Science, and the Cochrane Library, this research highlights the role played by the GBA in neurological and gastrointestinal diseases, in addition to the impact of neuromodulation on the management of these conditions which include both gastrointestinal (irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and gastroesophageal reflux disease (GERD)) and neurological disorders (Parkinson's disease (PD), Alzheimer's disease (AD), autism spectrum disorder (ASD), and neuropsychiatric disorders). Despite existing challenges, the ability of neuromodulation to adjust disrupted neural pathways, alleviate pain, and mitigate inflammation is significant in improving the quality of life for patients, thereby offering exciting prospects for future advancements in patient care.

Comparative efficacy of seven nonpharmacological interventions on global cognition in older adults with and without mild cognitive impairment: a network meta-analysis of randomized controlled trials

To maintain current cognitive function and access greater cognitive reserves, nonpharmacological interventions may be a viable alternative for older adults with or without cognitive impairment. This study aimed to compare different nonpharmacological interventions for enhancing global cognition, including mind-body exercise, physical exercise, non-invasive brain stimulation, cognitive training intervention (CTI), acutherapy (ACU), meditation, and music therapy, by applying a network meta-analysis (NMA). Sixty-one randomized controlled trials evaluating the efficacy of interventions on global cognition in older adults with or without mild cognitive decline were selected. An NMA was conducted to compare the efficacy of different nonpharmacological interventions. The NMA revealed that mind-body exercise (standardized mean difference, 1.384; 95% confidence interval, 0.777-1.992); ACU (1.283; 0.478-2.088); meditation (0.910; 0.097-1.724); non-invasive brain stimulation (1.242; 0.254-2.230); CTI (1.269; 0.736-1.802); and physical exercise (0.977; 0.212-1.742), showed positive effects compared to passive controls. There were no significant differences between the efficacies of other interventions. Nonpharmacological interventions may potentially enhance and maintain global cognition through various pathways, such as memorizing movements and enhancing brain plasticity by reducing stress in the older adult population. Additional studies are needed to clarify the impact of other variables, including intervention methods or psychological variables.

Neuroprotective effects of repetitive transcranial magnetic stimulation on Alzheimer's disease: Undetermined therapeutic protocols and mechanisms

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by gradual deterioration of cognitive functions, for which an effective treatment is currently unavailable. Repetitive transcranial magnetic stimulation (rTMS), a well‐established noninvasive brain stimulation method, is utilized in clinical settings to address various neuropsychiatric conditions, such as depression, neuropathic pain, and poststroke dysfunction. Increasing evidence suggests that rTMS may enhance cognitive abilities in individuals with AD. However, its optimal therapeutic protocols and precise mechanisms are currently unknown, impeding its clinical implementation. In the present review, we aimed to summarize and discuss the efficacy‐related parameters in rTMS treatment, encompassing stimulus frequency, stimulus pattern, stimulus intensity, and the configuration of the stimulus coil. Furthermore, we reviewed promising rTMS therapeutic protocols involving various combinations of these factors, that were examined in clinical studies. Based on our analysis, we propose that a multisite high‐frequency rTMS (HF‐rTMS) regimen has value in AD therapy, and that promising single‐site protocols, such as HF‐rTMS, applied over the left dorsolateral prefrontal cortex, precuneus, or cerebellum are required to be validated in larger clinical studies. Lastly, we provide a comprehensive review of the potential mechanisms underlying the neuroprotective effects of rTMS on cognition in AD in terms of brain network modulation as well as cellular and molecular reactions. In conclusion, the interaction of diverse mechanisms may be responsible for the total therapeutic effect of rTMS on AD. This review provides theoretical and practical evidence for the future clinical application and scientific research of rTMS in AD.

Nonmedication Devices in Development for the Treatment of Alzheimer's Disease

 Huge investments continue to be made in treatment for Alzheimer's disease (AD), with more than one hundred drugs currently in development. Pharmacological approaches and drug development, particularly those targeting amyloid-β, have dominated the therapeutic landscape. At the same time, there is also a growing interest in devices for treating AD. This review aimed to identify and describe devices under development for AD treatment. In this review, we queried the devices that are in development for the treatment of AD. PubMed was searched through the end of 2021 using the terms "device," "therapeutics," and "Alzheimer's" for articles that report on devices to treat AD. Ten devices with 31 references were identified as actively being developed for the treatment of AD. Many of these devices are far along in development. Device-based therapies are often overlooked when evaluating treatment approaches to AD. However, many devices for treating AD are in development and some show promising results.

Transcranial pulse stimulation in Alzheimer's disease

BACKGROUND

Transcranial pulse stimulation (TPS) is a novel noninvasive ultrasonic brain stimulation that can increase cortical and corticospinal excitability, induce neuroplasticity, and increase functional connectivity within the brain. Several trials have confirmed its potential in treating Alzheimer's disease (AD).

OBJECTIVE

To investigate the effect and safety of TPS on AD.

DESIGN

A systematic review.

METHODS

PubMed, Embase via Ovid, Web of Science, Cochrane Library, CNKI (China National Knowledge Infrastructure), VIP (China Science and Technology Journal Database), and WanFang were searched from inception to April 1, 2023. Study selection, data extraction, and quality evaluation of the studies were conducted by two reviewers independently, with any controversy resolved by consensus. The Methodological Index for Nonrandomized Studies was used to assess the risk of bias.

RESULTS

Five studies were included in this review, with a total of 99 patients with AD. For cognitive performance, TPS significantly improved the scores of the CERAD (Consortium to Establish a Registry for Alzheimer's Disease) test battery, Alzheimer's Disease Assessment Scale (cognitive), Montreal Cognitive Assessment, and Mini-Mental Status Examination. For depressive symptoms, TPS significantly reduced the scores of the Alzheimer's Disease Assessment Scale (affective), Geriatric Depression Score, and Beck Depression Inventory. By functional magnetic resonance imaging, studies have shown that TPS improved cognitive performance in AD patients by increasing functional connectivity in the hippocampus, parahippocampal cortex, precuneus, and parietal cortex, and activating cortical activity in the bilateral hippocampus. TPS alleviated depressive symptoms in AD patients by decreasing functional connectivity between the ventromedial network (left frontal orbital cortex) and the salience network (right anterior insula). Adverse events in this review, including headache, worsening mood, jaw pain, nausea, and drowsiness, were reversible and lasted no longer than 1 day. No serious adverse events or complications were observed.

CONCLUSIONS

TPS is promising in improving cognitive performance and reducing depressive symptoms in patients with AD. TPS may be a safe adjunct therapy in the treatment of AD. However, these findings lacked a sham control and were limited by the small sample size of the included studies. Further research may be needed to better explore the potential of TPS.

PATIENT AND PUBLIC INVOLVEMENT

Patients and the public were not involved in this study.

A meta-analysis of non-invasive brain stimulation (NIBS) effects on cerebellar-associated cognitive processes

Non-invasive brain stimulation (NIBS) techniques, including transcranial magnetic stimulation (TMS) and transcranial electrical stimulation (tES), have provided valuable insights into the role of the cerebellum in cognitive processes. However, replicating findings from studies involving cerebellar stimulation poses challenges. This meta-analysis investigates the impact of NIBS on cognitive processes associated with the cerebellum. We conducted a systematic search and analyzed 66 studies and 91 experiments involving healthy adults who underwent either TMS or transcranial direct current stimulation (tDCS) targeting the cerebellum. The results indicate that anodal tDCS applied to the medial cerebellum enhances cognitive performance. In contrast, high-frequency TMS disrupts cognitive performance when targeting the lateral cerebellar hemispheres or when employed in online protocols. Similarly, low-frequency TMS and continuous theta burst stimulation (cTBS) diminish performance in offline protocols. Moreover, high-frequency TMS impairs accuracy. By identifying consistent effects and moderators of modulation, this meta-analysis contributes to improving the replicability of studies using NIBS on the cerebellum and provides guidance for future research aimed at developing effective NIBS interventions targeting the cerebellum.

Effects of repetitive transcranial magnetic stimulation combined with cognitive training on cognitive function in patients with Alzheimer's disease: a systematic review and meta-analysis

Purpose

To evaluate the effect of repetitive transcranial magnetic stimulation (rTMS) paired with cognitive training on cognitive function in Alzheimer's Disease (AD) patients.

Methods

PubMed, The Cochrane Library, Embase, CINAHL Complete (EBSCO), China National Knowledge Infrastructure (CNKI) and WanFang Database were searched. The risk of bias was appraised through the Cochrane collaboration tool. A meta-analysis was conducted, including an assessment of heterogeneity.

Results

Ten studies comprising 408 participants were included. The addition of rTMS significantly improved overall cognition in patients compared with cognitive intervention alone (p < 0.05 for all tests). The treatment also had some continuity, with significant improvements in cognitive function within weeks after the treatment ended (p < 0.05 for all tests).

Conclusion

Repetitive transcranial magnetic stimulation combined with cognitive training (rTMS-CT) is a valuable technique for the cognitive rehabilitation of AD patients. It is beneficial to improve the cognitive ability of patients and restore their overall functional state. The results of the study may provide a basis for clinical providers to implement interventions that facilitate the design of more rigorous and high-quality interventions.

Limitations

The number of studies and sample size in our study were small. We did not explore possible interactions between rTMS and medications and mood improvement after rTMS due to inadequate data.

Systematic review registration

This study was registered on PROSPERO with registration number CRD42023405615.

Exploring the impact of intensified multiple session tDCS over the left DLPFC on brain function in MCI: a randomized control trial

Transcranial direct current stimulation combined with cognitive training (tDCS-cog) represents a promising approach to combat cognitive decline among healthy older adults and patients with mild cognitive impairment (MCI). In this 5-day-long double-blinded randomized trial, we investigated the impact of intensified tDCS-cog protocol involving two trains of stimulation per day on working memory (WM) enhancement in 35 amnestic and multidomain amnestic MCI patients. Specifically, we focused to improve WM tasks relying on top-down attentional control and hypothesized that intensified tDCS would enhance performance of visual object matching task (VOMT) immediately after the stimulation regimen and at a 1-month follow-up. Secondarily, we explored whether the stimulation would augment online visual working memory training. Using fMRI, we aimed to elucidate the neural mechanisms underlying the intervention effects by analyzing BOLD activations during VOMT. Our main finding revealed no superior after-effects of tDCS-cog over the sham on VOMT among individuals with MCI as indicated by insignificant immediate and long-lasting after-effects. Additionally, the tDCS-cog did not enhance online training as predicted. The fMRI analysis revealed brain activity alterations in right insula that may be linked to tDCS-cog intervention. In the study we discuss the insignificant behavioral results in the context of the current evidence in tDCS parameter space and opening the discussion of possible interference between trained cognitive tasks.

Effects of a periodic intermittent theta burst stimulation in Alzheimer's disease

BACKGROUND

Previous studies have demonstrated that excitatory repetitive transcranial magnetic stimulation (rTMS) can improve the cognitive function of patients with Alzheimer's disease (AD). Intermittent theta burst stimulation (iTBS) is a novel excitatory rTMS protocol for brain activity stimulation with the ability to induce long-term potentiation-like plasticity and represents a promising treatment for AD. However, the long-term effects of iTBS on cognitive decline and brain structure in patients with AD are unknown.

AIMS

We aimed to explore whether repeating accelerated iTBS every three months could slow down the cognitive decline in patients with AD.

METHODS

In this randomised, assessor-blinded, controlled trial, iTBS was administered to the left dorsolateral prefrontal cortex (DLPFC) of 42 patients with AD for 14 days every 13 weeks. Measurements included the Montreal Cognitive Assessment (MoCA), a comprehensive neuropsychological battery, and the grey matter volume (GMV) of the hippocampus. Patients were evaluated at baseline and after follow-up. The longitudinal pipeline of the Computational Anatomy Toolbox for SPM was used to detect significant treatment-related changes over time.

RESULTS

The iTBS group maintained MoCA scores relative to the control group (t=3.26, p=0.013) and reduced hippocampal atrophy, which was significantly correlated with global degeneration scale changes. The baseline Mini-Mental State Examination (MMSE) score, apolipoprotein E genotype and Clinical Dementia Rating were indicative of MoCA scores at follow-up. Moreover, the GMV of the left (t=0.08, p=0.996) and right (t=0.19, p=0.977) hippocampus were maintained in the active group but significantly declined in the control group (left: t=4.13, p<0.001; right: t=5.31, p<0.001). GMV change in the left (r=0.35, p=0.023) and right (r=0.36, p=0.021) hippocampus across the intervention positively correlated with MoCA changes; left hippocampal GMV change was negatively correlated with global degeneration scale (r=-0.32, p=0.041) changes.

CONCLUSIONS

DLPFC-iTBS may be a feasible and easy-to-implement non-pharmacological intervention to slow down the progressive decline of overall cognition and quality of life in patients with AD, providing a new AD treatment option.

TRIAL REGISTRATION NUMBER

NCT04754152.

Effect of non-invasive neuromodulation techniques on vascular cognitive impairment: A Bayesian network meta-analysis protocol

BACKGROUND

VCI is a severe public health problem facing the world today. In addition to pharmacological treatment, non-invasive neuromodulation techniques have also been effective. At this stage, non-invasive neuromodulation techniques combined with pharmacological treatment are the mainstay of clinical treatment, and clinical trials are continuing to be conducted, which is becoming the direction of treatment for VCI. Therefore, we outline this systematic review and network meta-analysis protocol to evaluate and rank clinical data in future studies which can develop optimal protocols for the clinical treatment of VCI with non-invasive neuromodulation techniques in combination with drugs.

METHODS

The network meta-analysis will search eight databases, including PubMed, Embase, Cochrane Library, Web of Science, China Knowledge Infrastructure Library (CNKI), China Biology Medicine disc (CBM)), Wanfang Data Knowledge Service Platform and Vipshop Journal Service Platform (VIP), for a period of from the establishment of the library to January 30 2022. The quality of the studies will be evaluated using the Cochrane Review's Handbook 5.1 and the PEDro scale to assess the evidence and quality of the included randomised controlled trials. Risk of bias assessment and heterogeneity tests will be performed using the Review Manager 5.4 program, and Bayesian network meta-analysis will be performed using the Stata 16.0 and WinBUGS 1.4.3 program.

RESULTS

The results of the network meta-analysis will be published in a peer-reviewed journal.

CONCLUSIONS

Our study is expected to provide high quality evidence-based medical evidence for the treatment of VCI by clinicians.

TRIAL REGISTRATION

PROSPERO: CRD42022308580.

Unlocking the Potential of Repetitive Transcranial Magnetic Stimulation in Alzheimer's Disease: A Meta-Analysis of Randomized Clinical Trials to Optimize Intervention Strategies

Background

Repetitive transcranial magnetic stimulation (rTMS) is an advanced and noninvasive technology that uses pulse stimulation to treat cognitive impairment. However, its specific effects have always been mixed with those of cognitive training, and the optimal parameter for Alzheimer's disease (AD) intervention is still ambiguous.

Objective

This study aimed to summarize the therapeutic effects of pure rTMS on AD, excluding the influence of cognitive training, and to develop a preliminary rTMS treatment plan.

Methods

Between 1 January 2010 and 28 February 2023, we screened randomized controlled clinical trials from five databases (PubMed, Web of Science, Embase, Cochrane, and ClinicalTrials. gov). We conducted a meta-analysis and systematic review of treatment outcomes and rTMS treatment parameters.

Result

A total of 4,606 articles were retrieved. After applying the inclusion and exclusion criteria, 16 articles, comprising 655 participants (308 males and 337 females), were included in the final analysis. The findings revealed that rTMS significantly enhances both global cognitive ability (p = 0.0002, SMD = 0.43, 95% CI = 0.20-0.66) and memory (p = 0.009, SMD = 0.37, 95% CI = 0.09-0.65). Based on follow-up periods of at least 6 weeks, the following stimulation protocols have demonstrated efficacy for AD: stimulation sites (single or multiple targets), frequency (20 Hz), stimulation time (1-2 s), interval (20-30 s), single pulses (≤2500), total pulses (>20000), duration (≥3 weeks), and sessions (≥20).

Conclusions

This study suggests that rTMS may be an effective treatment option for patients with AD, and its potential therapeutic capabilities should be further developed in the future.

A Critical Review of Noninvasive Brain Stimulation Technologies in Alzheimer's Dementia and Primary Progressive Aphasia

Multiple pharmacologic agents now have been approved in the United States and other countries as treatment to slow disease and clinical progression for Alzheimer's disease. Given these treatments have not been proven to lessen the cognitive deficits already manifested in the Alzheimer's Clinical Syndrome (ACS), and none are aimed for another debilitating dementia syndrome identified as primary progressive aphasia (PPA), there is an urgent need for new, safe, tolerable, and efficacious treatments to mitigate the cognitive deficits experienced in ACS and PPA. Noninvasive brain stimulation has shown promise for enhancing cognitive functioning, and there has been interest in its potential therapeutic value in ACS and PPA. This review critically examines the evidence of five technologies in ACS and PPA: transcranial direct current stimulation (tDCS), transcranial alternating current stimulation (tACS), transcranial random noise stimulation (tRNS), repetitive transcranial magnetic stimulation (rTMS), and noninvasive vagus nerve stimulation (nVNS). Many randomized controlled trials of tDCS and rTMS report positive treatment effects on cognition in ACS and PPA that persist out to at least 8 weeks, whereas there are few trials for tACS and none for tRNS and nVNS. However, most positive trials did not identify clinically meaningful changes, underscoring that clinical efficacy has yet to be established in ACS and PPA. Much is still to be learned about noninvasive brain stimulation in ACS and PPA, and shifting the focus to prioritize clinical significance in addition to statistical significance in trials could yield greater success in understanding its potential cognitive effects and optimal parameters.

Activation changes in patients with post-stroke cognitive impairment receiving intermittent theta burst stimulation: A functional near-infrared spectroscopy study

BACKGROUND

Intermittent theta burst stimulation (iTBS) has demonstrated efficacy in patients with cognitive impairment. However, activation patterns and mechanisms of iTBS for post-stroke cognitive impairment (PSCI) remain insufficiently understood.

OBJECTIVE

To investigate the activation patterns and potential benefits of using iTBS in patients with PSCI.

METHODS

A total of forty-four patients with PSCI were enrolled and divided into an iTBS group (iTBS and cognitive training) or a control group (cognitive training alone). Outcomes were assessed based on the activation in functional near-infrared spectroscopy (fNIRS), as well as Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) and the modified Barthel Index (MBI).

RESULTS

Thirty-eight patients completed the interventions and assessments. Increased cortical activation was observed in the iTBS group after the interventions, including the right superior temporal gyrus (STG), left frontopolar cortex (FPC) and left orbitofrontal cortex (OFC). Both groups showed significant improvements in LOTCA and MBI after the interventions (p < 0.05). Furthermore, the iTBS group augmented superior improvement in the total score of MBI and LOTCA compared to the control group, especially in visuomotor organization and thinking operations (p < 0.05).

CONCLUSION

iTBS altered activation patterns and improved cognitive function in patients with PSCI. The activation induced by iTBS may contribute to the improvement of cognitive function.

Efficacy analysis of three brain stimulation techniques for Alzheimer's disease: a meta-analysis of repeated transcranial magnetic stimulation, transcranial direct current stimulation, and deep brain stimulation

INTRODUCTION

This systematic review and meta-analysis study investigates the efficacy of repeated transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and deep brain stimulation (DBS) using neuropsychological assessments as a potential treatment option for Alzheimer's disease (AD).

METHODS

PubMed, Embase, and the Cochrane Library were searched for studies on rTMS, tDCS, and DBS for the treatment of patients with AD between April 1970 and October 2022. The mini-Mental State Examination (MMSE) and AD Assessment Scale - Cognitive Subscale (ADAS-Cog) were adopted as the efficacy index.

RESULTS

The analysis yielded 17 eligible studies. rTMS greatly improved the cognition of patients with AD (immediate post-treatment WMD of MMSE score: 2.06, p < 0.00001; short-term follow-up WMD of MMSE score: 2.12, p = 0.006; WMD of ADAS-Cog score in single-arm studies: -4.97, p = 0.001). DBS did not reverse the progression of cognitive decline (WMD of ADAS-Cog score in single-arm studies: 7.40, p < 0.00001). Furthermore, tDCS demonstrated no significant efficacy in improving cognition in random clinical trials or single-arm studies.

CONCLUSION

rTMS is a promising non-medicinal alternative for cognitive improvement inpatients with AD.

Transcranial burst electrical stimulation contributes to neuromodulatory effects in the rat motor cortex

Background and objective

Transcranial Burst Electrical Stimulation (tBES) is an innovative non-invasive brain stimulation technique that combines direct current (DC) and theta burst stimulation (TBS) for brain neuromodulation. It has been suggested that the tBES protocol may efficiently induce neuroplasticity. However, few studies have systematically tested neuromodulatory effects and underlying neurophysiological mechanisms by manipulating the polarity of DC and TBS patterns. This study aimed to develop the platform and assess neuromodulatory effects and neuronal activity changes following tBES.

Methods

Five groups of rats were exposed to anodal DC combined with intermittent TBS (tBES+), cathodal DC combined with continuous TBS (tBES-), anodal and cathodal transcranial direct current stimulation (tDCS+ and tDCS-), and sham groups. The neuromodulatory effects of each stimulation on motor cortical excitability were analyzed by motor-evoked potentials (MEPs) changes. We also investigated the effects of tBES on both excitatory and inhibitory neural biomarkers. We specifically examined c-Fos and glutamic acid decarboxylase (GAD-65) using immunohistochemistry staining techniques. Additionally, we evaluated the safety of tBES by analyzing glial fibrillary acidic protein (GFAP) expression.

Results

Our findings demonstrated significant impacts of tBES on motor cortical excitability up to 30 min post-stimulation. Specifically, MEPs significantly increased after tBES (+) compared to pre-stimulation (p = 0.026) and sham condition (p = 0.025). Conversely, tBES (-) led to a notable decrease in MEPs relative to baseline (p = 0.04) and sham condition (p = 0.048). Although tBES showed a more favorable neuromodulatory effect than tDCS, statistical analysis revealed no significant differences between these two groups (p > 0.05). Additionally, tBES (+) exhibited a significant activation of excitatory neurons, indicated by increased c-Fos expression (p < 0.05), and a reduction in GAD-65 density (p < 0.05). tBES (-) promoted GAD-65 expression (p < 0.05) while inhibiting c-Fos activation (p < 0.05), suggesting the involvement of cortical inhibition with tBES (-). The expression of GFAP showed no significant difference between tBES and sham conditions (p > 0.05), indicating that tBES did not induce neural injury in the stimulated regions.

Conclusion

Our study indicates that tBES effectively modulates motor cortical excitability. This research significantly contributes to a better understanding of the neuromodulatory effects of tBES, and could provide valuable evidence for its potential clinical applications in treating neurological disorders.

Gamma connectivity predicts response to intermittent theta burst stimulation in Alzheimer's disease: a randomized controlled trial

There is growing evidence that neural network dysfunction is a likely proximate cause of cognitive impairment in Alzheimer's disease and may represent a promising therapeutic target. Here, we investigated whether a course of intermittent theta burst stimulation (iTBS) could modulate functional connectivity and cognition in mild to moderate Alzheimer's. In a double-blind parallel randomized sham-controlled trial, 58 participants were randomized to either active or sham iTBS. Stimulation was applied to the left dorsolateral prefrontal cortex, right dorsolateral prefrontal cortex, left posterior parietal cortex, and right posterior parietal cortex in every treatment session. Neurobiological (electroencephalography), cognitive, and behavioral functional assessments were undertaken at baseline and end of treatment. Cognitive and functional assessments were also conducted at 3 (blinded) and 6 month (active group only) follow-ups. Active iTBS increased resting-state gamma connectivity and improved delayed recall on an episodic memory task. Both baseline gamma connectivity and change in gamma connectivity predicted improved delayed recall following active treatment. These findings support future research into iTBS for Alzheimer's focusing on protocol optimization.

Improvement of working memory in older adults with mild cognitive impairment after repetitive transcranial magnetic stimulation - a randomized controlled pilot study

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique that could improve cognitive function. It is being developed as a non-pharmacological intervention to alleviate symptoms of cognitive deterioration. We assessed the efficacy of rTMS in improving cognitive functioning among people with Mild Cognitive Impairment (MCI) in a partially-blinded, sham-controlled randomized trial. Out of 91 subjects screened, 31 participants with MCI (mean age 70.73; SD = 4.47), were randomly assigned to one of three groups: (A) Active rTMS; (B) Active rTMS with Computerized Cognitive Training RehaCom; and (C) Sham control. The study evaluated cognitive function using the DemTect, FAS, and CANTAB tests before and after the stimulation. The following treatment protocol was applied: 2000 pulses at 10 Hz, 5-s train duration, and 25-s intervals at 110% of resting MT delivered over the left Dorsolateral Prefrontal Cortex (DLPFC) five times a week for 2 weeks. After 10 sessions of high-frequency rTMS, there was an improvement in overall cognitive function and memory, assessed by the DemTect evaluation, with no serious adverse effects. Analysis of differences in time (after 10 sessions) between studied groups showed statistically significant improvement in DemTect total score (time by group interaction p = 0.026) in favor of rTMS+RehaCom. The linear regression of CANTAB Paired Associates Learning revealed significant differences in favor of rTMS+RehaCom in three subtests. Our study shows that 10 sessions of rTMS over the left DLPFC (alone as well as combined with Computerized Cognitive Training) can have a positive impact on cognitive function in people with MCI. Further research should investigate the underlying mechanism and determine the optimal parameters for rTMS, which will be important for its efficacy in clinical settings.

The effects of transcranial direct current stimulation on cognitive function for mild cognitive impairment: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Transcranial direct current stimulation (tDCS) emerged as a potential modality for enhancing cognitive functions in patients with cognitive decline, including mild cognitive impairment (MCI). Our systematic review and meta-analysis aim to synthesize the available randomized controlled trials (RCTs) on the effects of tDCS on cognitive functions in patients with MCI.

METHODS

Our review protocol was registered on PROSPERO with ID: CRD42022360587. We conducted a systematic database search until September 2022. Standardized mean difference (SMD) and pooled effect size (ES) for robust variance estimation (RVE) method were used as effect estimates for our meta-analysis.

RESULTS

We included 11 RCTs with a total of 429 participants. The meta-analysis showed that, compared to sham groups, tDCS did not improve global functioning (measured by MOCA) (SMD = 0.02, CI =  - 0.30 to 0.35; p = 0.88), memory domain (ES = 0.681, CI =  - 2.15 to 3.51, p = 0.576), sustained attention (measured by TMT-A) (SMD =  - 0.21, CI =  - 0.52 to 0.10, p = 0.19), and executive function (measured by TMT-B) (SMD =  - 0.53, CI =  - 1.56 to 0.50, p = 0.20).

CONCLUSION

Our meta-analysis found no significant effect of tDCS on cognitive functions in MCI patients, including effects on global functioning, memory, sustained attention, and executive function. Therefore, an important change to be tested in future studies is to look for a better combination with tDCS for patients with MCI.

Repetitive transcranial magnetic stimulation may be superior to drug therapy in the treatment of Alzheimer's disease: A systematic review and Bayesian network meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive brain stimulation therapy that is primarily used to treat a variety of neuropsychiatric conditions. Recently, previous research reports stated that rTMS have the characteristics of neurorestorative in Alzheimer's disease (AD). However, the relevant clinical research evidence has not been fully summarized.

METHODS

This article performed a network meta-analysis of individual participant data from eligible studies searched in PubMed, Embase, and the Cochrane Library from inception to March 31, 2022. The drug treatments involved were acetylcholinesterase inhibitors (AChEIs), N-methyl-d-aspartate (NMDA), anti-amyloid-beta (Aβ), and some new targeted therapeutic drugs.

RESULTS

A total of 15, 548 individuals with AD disease in 57 randomized clinical trials (RCTs) were included in this meta-analysis. The results indicated that the patients who received rTMS treatment (standard mean difference [SMD]: 0.65; 95% confidence interval [CI]: 0.22-1.07) had a better MMSE score than placebo. Treatment outcome analysis showed that, compared with multiple pharmacological interventions, rTMS acquired the greatest probability rank with the best cognitive improvement in MMSE score [the surface under the cumulative ranking curve (SUCRA) 93.3%] and ADAS-cog score (SUCRA 86.7%). At the same time, rTMS treatment had the lowest rank in the adverse events (SUCRA 24.1%) except for the placebo group (SUCRA 19.1%).

CONCLUSION

Compared with the current clinical drug treatment, rTMS demonstrated better cognitive function improvement and fewer adverse events in AD patients. Therefore, rTMS shows broad prospects in the treatment of Alzheimer's disease, and it is worth being widely popularized in clinic.

DiscoverPath: A Knowledge Refinement and Retrieval System for Interdisciplinarity on Biomedical Research

The exponential growth in scholarly publications necessitates advanced tools for efficient article retrieval, especially in interdisciplinary fields where diverse terminologies are used to describe similar research. Traditional keyword-based search engines often fall short in assisting users who may not be familiar with specific terminologies. To address this, we present a knowledge graph based paper search engine for biomedical research to enhance the user experience in discovering relevant queries and articles. The system, dubbed DiscoverPath, employs Named Entity Recognition (NER) and part-of-speech (POS) tagging to extract terminologies and relationships from article abstracts to create a KG. To reduce information overload, DiscoverPath presents users with a focused subgraph containing the queried entity and its neighboring nodes and incorporates a query recommendation system enabling users to iteratively refine their queries. The system is equipped with an accessible Graphical User Interface that provides an intuitive visualization of the KG, query recommendations, and detailed article information, enabling efficient article retrieval, thus fostering interdisciplinary knowledge exploration. DiscoverPath is open-sourced at https://github.com/ynchuang/DiscoverPath with a demo video at Youtube.

Trajectory of changes in depressive symptoms after acute repetitive transcranial magnetic stimulation: A meta-analysis of follow-up effects

BACKGROUND

The follow-up effect after acute repetitive transcranial magnetic stimulation (rTMS) for major depressive episodes remains unclear. Furthermore, the benefits of maintenance rTMS are poorly understood.

AIM

To investigate the trajectory of changes in depressive symptoms after acute rTMS and effects of maintenance rTMS during this period.

METHOD

This meta-analysis (PROSPERO: CRD42022374077) searched major databases up to October 1, 2022. Treatment outcome was depressive scores collected at least 3 months after the end of an acute rTMS course for depression. We extracted data at different time points after acute rTMS and categorized by whether maintenance rTMS was performed. A single-stage random-effects dose-response meta-analysis was undertaken to model the nonlinear relationships. Effect sizes were calculated as standardized mean differences (SMDs) with 95% confidence intervals (CIs).

RESULTS

24 eligible studies comprising 911 total patients-225 of whom received maintenance rTMS-were included. Maintenance rTMS contributed to relative stability in patients' mood symptoms during the first 5 months (SMD [95% CI]: 3rd month, -0.10 [-0.30 to 0.10]; 5th month, 0.00 [-0.55 to 0.55]), with heterogeneity characterized as low to moderate. Further analysis revealed that maintenance rTMS performed monthly or more frequently provided sustained benefits for up to 6-12 months. Conversely, patients without maintenance rTMS had moderate to high heterogeneity, although the change in mean mood symptom scores during the 12-month follow-up was also minor (6th month, 0.03 [-0.51 to 0.56]; 12th month, 0.10 [-0.59 to 0.79]).

CONCLUSION

Maintenance rTMS might keep patients' mood relatively stable for up to 5 months after acute rTMS. Monthly or more frequent maintenance rTMS offers greater benefits.

Repetitive Transcranial Magnetic Stimulation (rTMS) in Mild Cognitive Impairment: Effects on Cognitive Functions-A Systematic Review

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique also used as a non-pharmacological intervention against cognitive impairment. The purpose of the present review was to summarize what is currently known about the effectiveness of rTMS intervention on different cognitive domains in patients with mild cognitive impairment (MCI) and to address potential neuromodulation approaches in combination with electroencephalography (EEG) and neuroimaging, especially functional magnetic resonance imaging (fMRI). In this systematic review, we consulted three main databases (PubMed, Science Direct, and Scopus), and Google Scholar was selected for the gray literature search. The PRISMA flowchart drove the studies' inclusion. The selection process ensured that only high-quality studies were included; after removing duplicate papers, explicit ratings were given based on the quality classification as high (A), moderate (B), or low (C), considering factors such as risks of bias, inaccuracies, inconsistencies, lack of direction, and publication bias. Seven full-text articles fulfilled the stated inclusion, reporting five double-blind, randomized, sham-controlled studies, a case study, and a randomized crossover trial. The results of the reviewed studies suggested that rTMS in MCI patients is safe and effective for enhancing cognitive functions, thus making it a potential therapeutic approach for MCI patients. Changes in functional connectivity within the default mode network (DMN) after targeted rTMS could represent a valuable indicator of treatment response. Finally, high-frequency rTMS over the dorsolateral prefrontal cortex (DLPFC) has been shown to significantly enhance cognitive functions, such as executive performance, together with the increase of functional connectivity within frontoparietal networks. The main limitations were the number of included studies and the exclusion of studies using intermittent theta-burst stimulation, used in studies on Alzheimer's disease. Therefore, neuroimaging techniques in combination with rTMS have been shown to be useful for future network-based, fMRI-guided therapeutic approaches.

A Systematic Review and Meta-Analysis of Cognitive Effects of rTMS in Caucasian Patients with Mild Cognitive Impairment

In recent years, repetitive transcranial magnetic stimulation (rTMS) has received much attention as a non-invasive, effective treatment modality for mild cognitive impairment (MCI). Although several meta-analyses have reported that rTMS can improve cognitive abilities, improvements in individual memory domains (speech, language, concentration, and memory) are poorly understood. In addition, stimulation parameters may be flawed in studies of global populations because of ethnic differences between Caucasians and Asians. This meta-analysis aimed to systematically characterize the efficacy of different combinations of rTMS parameters on different cognitive domains in Caucasian patients with MCI. We conducted a systematic literature search in Medline PubMed, Pubpsych, and Embase on the use of rTMS in MCI patients through November 2022. Randomized, double-blind, and sham-controlled trials (RCTs) from the Caucasian patient population were included. The studies reported outcome measures for different domains of cognition, such as language, concentration, or memory. Possible effects of covariates were examined using meta-regressions. The search yielded five publications. The analyses found that rTMS improved cognitive functions, memory, concentration, and language in patients with MCI and treatment with rTMS compared with the sham stimulation group. The statistical analysis results of the studies showed that rTMS could improve various cognitive functions, such as memory and concentration, in Caucasian MCI patients. A particular effect was found at a frequency of 10 Hz and stimulation of the LDLPFC. However, further studies are needed to validate these findings and explore more effective stimulation protocols and targets.

Transcranial direct current stimulation in combination with cognitive training in individuals with mild cognitive impairment: a controlled 3-parallel-arm study

OBJECTIVE

Several studies showed that transcranial direct current stimulation (tDCS) enhances cognition in patients with mild cognitive impairment (MCI), however, whether tDCS leads to additional gains when combined with cognitive training remains unclear. This study aims to compare the effects of a concurrent tDCS-cognitive training intervention with either tDCS or cognitive training alone on a group of patients with MCI.

METHODS

The study was a 3-parallel-arm study. The intervention consisted of 20 daily sessions of 20 minutes each. Patients (n = 62) received anodal tDCS to the left dorsolateral prefrontal cortex, cognitive training on 5 cognitive domains (orientation, attention, memory, language, and executive functions), or both. To examine intervention gains, we examined global cognitive functioning, verbal short-term memory, visuospatial memory, and verbal fluency pre- and post-intervention.

RESULTS

All outcome measures improved after the intervention in the 3 groups. The improvement in global cognitive functioning and verbal fluency was significantly larger in patients who received the combined intervention. Instead, the intervention gain in verbal short-term memory and visuospatial memory was similar across the 3 groups.

DISCUSSION

tDCS, regardless of the practicalities, could be an efficacious treatment in combination with cognitive training given the increased effectiveness of the combined treatment.

CONCLUSIONS

Future studies will need to consider individual differences at baseline, including genetic factors and anatomical differences that impact the electric field generated by tDCS and should also consider the feasibility of at-home treatments consisting of the application of tDCS with cognitive training.