Repetitive Transcranial Magnetic Stimulation for Improving Cognitive Function in Patients With Mild Cognitive Impairment: A Systematic Review

Accelerated iTBS-Induced changes in resting-state functional connectivity correspond with cognitive improvement in amnestic MCI

BACKGROUND

Published results of our Phase I safety and feasibility trial of accelerated intermittent theta burst stimulation (a-iTBS) in mild cognitive impairment (MCI) due to Alzheimer's disease showed a large effect-size improvement in cognition.

OBJECTIVE

Further demonstrate target engagement by identifying whether changes in local and network-level functional connectivity relate to the observed cognitive improvement.

METHODS

Eighteen patients with MCI received 3-day a-iTBS (8 sessions/day) to the left dorsolateral prefrontal cortex at Beam F3 (14,400 total pulses) and completed MRI and cognitive testing at pre- and post-treatment. Based on electric field models, we selected 3 stimulated target regions of interest (ROIs) which belonged to the frontoparietal (FPN), default mode (DMN), and ventral attention (VAT) networks (3 target networks). Metrics of resting-state functional connectivity were computed at the ROI level (within-network degree: number of connections) and network level (segregation: strength of connectivity within-network relative to other networks). We correlated changes in cognition and connectivity of the target ROIs and networks; off-target ROI (primary visual) and networks served as negative controls.

RESULTS

Improvements in cognition were associated with connectivity changes in the target ROIs and networks, but not in off-target negative controls. Positive associations were observed for degree of the l-DMN and segregation of target networks overall, with significant effects for DMN and VAT.

CONCLUSION

Cognitive improvement following a-iTBS in MCI may be attributable to local and network-level reconfigurations in functional connectivity. These findings will inform larger trials designed to further evaluate the neural mechanisms of a-iTBS for cognition in MCI.

Repetitive transcranial magnetic stimulation may promote the reversion of mild cognitive impairment to normal cognition

Purpose

This study aimed to investigate the potential effects of repetitive transcranial magnetic stimulation (rTMS) on the reversion of mild cognitive impairment (MCI) to normal cognitive function and to elucidate the underlying mechanisms.

Methods

The study enrolled 25 MCI participants, who underwent a 10-day of rTMS treatment and an 18-month follow-up, along with 15 healthy subjects. Participants with MCI were categorized into MCI reverters (MCI-R) and MCI maintainers (MCI-M). We assessed differences in baseline cognitive performance, functional connectivity, and changes of cognitive functions after rTMS between MCI-R and MCI-M to identify possible predictors of reversion of MCI and explore the neural modulation mechanisms.

Results

MCI-M exhibited more severe cognitive impairments across more domains, particularly in language function (p < 0.05). Functional connectivity was more severely damaged in MCI-M participants, notably within the default mode network (DMN), executive control network (ECN), and frontoparietal network (FPN). After rTMS therapy, MCI-R participants demonstrated more significantly improved immediate and delayed recall memory scores (p < 0.05). These memory function changes and baseline functional connectivity of DMN, ECN, and FPN were predictive of the reversion of MCI.

Conclusions

The efficacy of rTMS in memory function may promote the reversion of MCI to normal cognition, with the functional connectivity of DMN, ECN, and FPN playing a crucial important role. The severity of cognitive impairment and functional connectivity damage correlated with the likelihood of the reversion of MCI to normal cognition, underscoring the importance of early rTMS intervention for dementia prevention.

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 randomized controlled trial of repetitive transcranial magnetic stimulation plus donepezil vs donepezil alone for mild to moderate cognitive impairment due to small vessel cerebrovascular disease

OBJECTIVES

Small vessel cerebrovascular disease (SVCVD) accounts for 35% to 67% of vascular dementias, and may be overlooked by healthcare providers due to its insidious onset. SVCVD involves chronic cerebral ischemia and hypoperfusion, endothelial dysfunction, blood-brain barrier disruption, and interstitial fluid reflux. The purpose of this study was to investigate the clinical efficacy of repetitive transcranial magnetic stimulation (rTMS) combined with donepezil hydrochloride compared to donepezil alone in the treatment of mild-to-moderate cognitive impairment in patients with SVCVD.

MATERIAL AND METHODS

A cohort of 115 individuals with mild-to-moderate cognitive impairment due to SVCVD was purposefully selected and randomized into two groups: a test group and a control group. The test group received a combination of repetitive transcranial magnetic stimulation (rTMS) and oral donepezil hydrochloride (10 mg/day), while the control group received oral donepezil alone (10 mg/day). The Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores were evaluated in both groups prior to and following the interventions.

RESULTS

Following 6 weeks of treatment, both groups demonstrated enhancement in cognitive function. However, a statistically significant difference was observed between the test group and the control group (p < .05 on both the MMSE and the MOCA), favoring the test group.

CONCLUSIONS

Compared to donepezil alone, the combination of repetitive transcranial magnetic stimulation (rTMS) and donepezil has a significantly greater effect on enhancing cognitive function among individuals experiencing mild-to-moderate cognitive impairment resulting from SVCVD.

Transcranial Magnetic Stimulation Combined with Auricular Point Pressure Bean on Emotional Disorders in Elderly Patients after Intracerebral Hemorrhage Surgery: A Retrospective Cohort Study

Objective

To investigate whether the combination of repetitive transcranial magnetic stimulation (rTMS) and auricular point pressure bean could effectively ameliorate postoperative affective disorder in elderly patients suffering from cerebral hemorrhage.

Methods

From June 2020 to September 2023, 116 elderly patients with depression after cerebral hemorrhage, who underwent surgical procedures were divided into the exposure group and the control group. The division was determined based on whether received rTMS and traditional Chinese medicine auricular point pressure bean therapy. Hamilton anxiety scale (HAMA), Hamilton Depression scale (HAMD), National Institutes of Health Stroke scale (NIHSS), Montreal Cognitive Assessment scale (MoCA) and Mini Mental State examination scale (MMSE) were collected and compared between before intervention and after intervention.

Results

In accordance with a 1 : 1 matching ratio, the patients in the study were paired using propensity score matching (PSM), with 53 patients in both the exposure group and the control group. There were no notable differences in baseline characteristics between the 2 groups (P > .05). Following the intervention, the HAMA score and the NIHSS score of the exposure group were markedly lower than those of the control group (P < .001). Additionally, theMoCA scores (P = .001) and MMSE scores (P < .001) in the exposure group were significantlyhigher. The difference score have a significant difference in HAMA score (P = .001), NIHSS score (P < .001), MoCA (P < .001) and MMSE scores (P < .001).

Conclusion

The combination of rTMS therapy and auricular point pressure bean therapy in traditional Chinese medicine demonstrates can effectively relieve the anxiety level, postoperative emotional and cognitive disorders of elderly patients after intracerebral hemorrhage, and provide certain ideas and support for clinical treatment.

Recent Research Progress on the Use of Transcranial Magnetic Stimulation in the Treatment of Vascular Cognitive Impairment

Vascular Cognitive Impairment (VCI) is a condition where problems with brain blood vessels lead to a decline in cognitive abilities, commonly affecting the elderly and placing a significant burden on both patients and their families. Compared to medication and surgery, Transcranial Magnetic Stimulation (TMS) is a non-invasive treatment option with fewer risks and side effects, making it particularly suitable for elderly patients. TMS not only assesses the excitability and plasticity of the cerebral cortex, but its effectiveness in treating Vascular Cognitive Impairment (VCI) and its subtypes has also been validated in numerous clinical trials worldwide. However, there is still a lack of review on the physiological mechanisms of TMS treatment for VCI and its specific clinical application parameters. Therefore, this article initially provided a brief overview of the risk factors, pathological mechanisms, and classification of VCI. Next, the article explained the potential physiological mechanisms of TMS in treating VCI, particularly its role in promoting synaptic plasticity, regulating neurotransmitter balance, and improving the function of the default mode network. Additionally, The article also summarizes the application of rTMS in treating VCI and its subtypes, VCI-related sleep disorders, and the use of TMS in follow-up studies of VCI patients, providing empirical evidence for the clinical application of TMS and rTMS technologies.

Effects of repetitive transcranial magnetic stimulation on episodic memory in patients with subjective cognitive decline: study protocol for a randomized clinical trial

Introduction

Early decline of episodic memory is detectable in subjective cognitive decline (SCD). The left dorsolateral prefrontal cortex (DLPFC) is associated with encoding episodic memories. Repetitive transcranial magnetic stimulation (rTMS) is a novel and viable tool to improve cognitive function in Alzheimer's disease (AD) and mild cognitive impairment, but the treatment effect in SCD has not been studied. We aim to investigate the efficacy of rTMS on episodic memory in individuals with SCD, and to explore the potential mechanisms of neural plasticity.

Methods

In our randomized, sham-controlled trial, patients (n = 60) with SCD will receive 20 sessions (5 consecutive days per week for 4 weeks) of real rTMS (n = 30) or sham rTMS (n = 30) over the left DLPFC. The primary outcome is the Auditory Verbal Learning Test-Huashan version (AVLT-H). Other neuropsychological examinations and the long-term potentiation (LTP)-like cortical plasticity evaluation serve as the secondary outcomes. These outcomes will be assessed before and at the end of the intervention.

Discussion

If the episodic memory of SCD improve after the intervention, the study will confirm that rTMS is a promising intervention for cognitive function improvement on the early stage of dementia. This study will also provide important clinical evidence for early intervention in AD and emphasizes the significance that impaired LTP-like cortical plasticity may be a potential biomarker of AD prognosis by demonstrating the predictive role of LTP on cognitive improvement in SCD.

Ethics and dissemination

The study was approved by the Human Research Ethics Committee of the hospital (No. 2023-002-01). The results will be published in peer-review publications.

Clinical trial registration

https://www.chictr.org.cn/, identifier ChiCTR2300075517.

High-Frequency rTMS Could Improve Impaired Memory in Mild Cognitive Impairment Patients in China: A Randomized Controlled Study

OBJECTIVE

The purpose of this study was to investigate the effects of repetitive transcranial magnetic stimulation (rTMS) on improving memory deficits in mild cognitive impairment (MCI), as well as to provide visualized evidence for neuronal specificity by using resting-state functional magnetic resonance imaging.

MATERIALS AND METHODS

Forty MCI patients were enrolled to receive 10-session and sham-controlled 10Hz-rTMS over the left dorsolateral prefrontal cortex. The resting-state functional magnetic resonance imaging combined with memory scales assessment were performed before and after the intervention. To elucidate the therapeutic mechanism of rTMS, amplitude of low-frequency fluctuations (ALFF) and functional connectivity were calculated. The Pearson correlation was used to measure the relationship between ALFF and memory performance.

RESULTS

Compared with the sham group, ALFF significantly increased in the right insula, right inferior frontal gyrus-opercular part, and decreased in the left middle occipital gyrus, left angular gyrus, and left lingual gyrus after rTMS. The change in Auditory Verbal Learning Test scores were negatively correlated with ALFF decreases in the left lingual gyrus. Functional connectivity significantly increased between the posterior cingulate cortex and right supramarginal gyrus, and decreased between the right frontoinsular cortex and right supramarginal gyrus after intervention.

CONCLUSION

High-frequency rTMS over the left dorsolateral prefrontal cortex could facilitate improvement on impaired memory in patients with MCI via modulating the neuronal activity and brain network.

Facilitated lexical processing accuracy and reaction times following repetitive Transcranial Magnetic Stimulation in dementia of the Alzheimer type: a case study

We investigated the potential effects of high-frequency (10 Hz) repetitive Transcranial Magnetic Stimulation (rTMS) of the bilateral Dorsolateral Prefrontal Cortex (DLPFC) (30-sessions; 2-sessions/day) on improving lexical processing in one participant with mild - Alzheimer's disease (hereafter dementia of the Alzheimer type-DAT). Increased accuracy and faster reaction times (RTs) were reported in a lexical-decision task (LDT) up to 2-months post-intervention. The current findings indicate that high-frequency stimulation of the DLPFC might be a potential therapeutic tool to improve lexical processing in mild-DAT.

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 magnetic stimulation effects on cognitive enhancement in mild cognitive impairment and Alzheimer's disease: a systematic review and meta-analysis

Introduction

Transcranial magnetic stimulation (TMS) is a non-invasive intervention that holds promise for improving cognitive function in individuals with Alzheimer's disease (AD). However, the effectiveness of this therapy and the optimal TMS parameters has not reached a consensus. The purpose of the meta-analysis was to systematically discern the effectiveness of different components of TMS protocols on cognitive improvement in patients with mild cognitive impairment (MCI) and AD.

Methods

The meta-analysis was preregistered on Prospero (registration number: CRD42022345482). PubMed, Web of Science, Science Direct, and Cochrane Library databases were used to search, screen and identify eligible studies with the following keywords: Transcranial Magnetic Stimulation OR TMS OR theta burst stimulation AND Alzheimer OR Alzheimers OR Alzheimer's OR mild cognitive impairment OR MCI. Randomized controlled trials (RCTs) of participants with accepted standardized diagnostic criteria were searched by two authors independently. The risk of bias was assessed using an adapted Cochrane Risk of Bias tool. Standardized mean difference (SMD) and 95% confidence interval (CI) were calculated using the random-effects models. Subgroup analyses were performed to investigate the influential factors.

Results

A total of 21 studies and 25 trials were included in this meta-analysis. The findings revealed a significant overall cognition improvement of real stimulation compared with sham stimulation (short-term effects: SMD, 0.91; 95% CI 0.44-1.38; P < 0.01; long-lasting effects: SMD, 0.91; 95% CI 0.27-1.55; P < 0.01). Subgroup analysis demonstrated that stimulation of the left dorsolateral prefrontal cortex and bilateral cerebellums, as well as moderate frequency stimulation (5 Hz and 10 Hz) on mild and moderate cognitive impairment patients, were more effective than other TMS protocols. However, the additional application of cognitive training showed no significant improvement.

Conclusion

Cognitive improvement effect of TMS was demonstrated in MCI and AD patients in both short-term assessment and long-lasting outcomes, and the efficiency of TMS is affected by the stimulation frequency, stimulation site, and participant characteristics. Further RCTs are needed to validate the findings of our subgroup analysis.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022345482, identifier: CRD42022345482.

A modified mouse model of perioperative neurocognitive disorders exacerbated by sleep fragmentation

Aging is one of the greatest risk factors for postoperative cognitive dysfunction (POCD), also known as perioperative neurocognitive disorder (PND). Animal models of PND are usually induced in mice over 18 months of age, which imposes expensive economic and time costs for PND-related studies. Sleep disorders, including sleep fragmentation, are reported to aggravate memory impairment in neurocognitive-related diseases such as Alzheimer's disease (AD). Therefore, the aim of the present study was to explore whether a PND model could be constructed in younger mice with the help of fragmented sleep. We found that fragmented sleep followed by laparotomy under isoflurane anesthesia could stably induce PND in 15-month-old mice. To determine whether the neurocognitive decline in this model could be salvaged by clinical treatments, we administered repetitive transcranial magnetic stimulation (rTMS) to the model mice before anesthesia and surgery. We found that 10 days of high-frequency rTMS (HF-rTMS) could improve spatial learning and memory deficits in this modified PND model. We are the first to successfully construct a PND model in younger mice,which is more economical, that can be used as an alternative model for future PND studies.

Effects of rTMS treatment on global cognitive function in Alzheimer's disease: A systematic review and meta-analysis

Background

Although repetitive transcranial magnetic stimulation (rTMS) has been extensively studied in patients with Alzheimer's disease (AD), the clinical evidence remains inconsistent. The purpose of this meta-analysis was to evaluate the effects of rTMS on global cognitive function in patients with AD.

Methods

An integrated literature search using 4 databases (PubMed, Web of Science, Embase, and Cochrane Library) was performed to identify English language articles published up to October 6, 2021. We pooled Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-Cog) scores using a random-effects model via RevMan 5.4 software. We calculated estimates of mean differences (MD) with 95% confidence intervals (CI). The primary outcomes were pre-post treatment changes in global cognition as measured using MMSE and ADAS-Cog immediately after rTMS treatment, and the secondary outcome was duration of cognitive improvement (1–1.5 and ≥3 months).

Results

Nine studies with 361 patients were included in this meta-analysis. The results showed that rTMS significantly improved global cognitive function immediately following rTMS treatment [(MD) 1.82, 95% confidence interval (CI) 1.41–2.22, p < 0.00001, MMSE; 2.72, 95% CI, 1.77–3.67, p < 0.00001, ADAS-Cog], and the therapeutic effects persisted for an extended duration (2.20, 95% CI, 0.93–3.47, p =0.0007, MMSE; 1.96, 95% CI, 0.96–2.95, p = 0.0001, ADAS-Cog). Subgroup analyses showed that high frequency rTMS targeted to the left dorsolateral prefrontal cortex (DLPFC) for over 20 sessions induced the greatest cognitive improvement, with effects lasting for more than 1 month after the final treatment. There were no significant differences in dropout rate (p > 0.05) or adverse effect rate (p > 0.05) between the rTMS and control groups.

Conclusions

Repetitive TMS is a potentially effective treatment for cognitive impairment in AD that is safe and can induce long-lasting effects. Our results also showed that ADAS-cog and MMSE differed in determination of global cognitive impairment.

Systematic review registration

http://www.crd.york.ac.uk/PROSPERO, PROSPERO CRD42022315545.

Strategies to Promote Cognitive Health in Aging: Recent Evidence and Innovations

PURPOSE OF REVIEW

We review recent work on applications of non-pharmacologic strategies to promote cognitive health in older adulthood and discuss potential network mechanisms, limitations, and considerations for improving intervention uptake and efficacy.

RECENT FINDINGS

In healthy older adults and patients with mild cognitive impairment, cognitive training produces global and domain-specific cognitive gains, though effect sizes tend to be modest and transfer is variable. Non-invasive brain stimulation has shown moderate success in enhancing cognitive function, though the optimum approach, parameters, and cortical targets require further investigation. Physical activity improves cognitive functions in late life, with emerging trials highlighting key intervention components that may maximize treatment outcomes. Multimodal interventions may be superior to single-component interventions in conferring cognitive gains, although interpretation is limited by modest sample sizes and variability in training components and parameters. Across modalities, individual differences in patient characteristics predict therapeutic response. These interventions may advance cognitive health by modulating functional networks that support core cognitive abilities including the default mode, executive control, and salience networks. Effectiveness of cognitive enhancement strategies may be increased with clinician-led coaching, booster sessions, gamification, integration of multiple intervention modalities, and concrete applications to everyday functioning. Future trials involving rigorous comparisons of training components, parameters, and delivery formats will be essential in establishing the precise approaches needed to maximize cognitive outcomes. Novel studies using patient-level clinical and neuroimaging features to predict individual differences in training gains may inform the development of personalized intervention prescriptions to optimize cognitive health in late life.

Repetitive Transcranial Magnetic Stimulation (rTMS) of Dorsolateral Prefrontal Cortex May Influence Semantic Fluency and Functional Connectivity in Fronto-Parietal Network in Mild Cognitive Impairment (MCI)

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive neuromodulation technique that is increasingly used as a nonpharmacological intervention against cognitive impairment in Alzheimer’s disease (AD) and other dementias. Although rTMS has been shown to modify cognitive performances and brain functional connectivity (FC) in many neurological and psychiatric diseases, there is still no evidence about the possible relationship between executive performances and resting-state brain FC following rTMS in patients with mild cognitive impairment (MCI). In this preliminary study, we aimed to evaluate the possible effects of rTMS of the bilateral dorsolateral prefrontal cortex (DLPFC) in 27 MCI patients randomly assigned to two groups: one group received high-frequency (10 Hz) rTMS (HF-rTMS) for four weeks (n = 11), and the other received sham stimulation (n = 16). Cognitive and psycho-behavior scores, based on the Repeatable Battery for the Assessment of Neuropsychological Status, Beck Depression Inventory-II, Beck Anxiety Inventory, Apathy Evaluation Scale, and brain FC, evaluated by independent component analysis of resting state functional MRI (RS-fMRI) networks, together with the assessment of regional atrophy measures, evaluated by whole-brain voxel-based morphometry (VBM), were measured at baseline, after five weeks, and six months after rTMS stimulation. Our results showed significantly increased semantic fluency (p = 0.026) and visuo-spatial (p = 0.014) performances and increased FC within the salience network (p ≤ 0.05, cluster-level corrected) at the short-term timepoint, and increased FC within the left fronto-parietal network (p ≤ 0.05, cluster-level corrected) at the long-term timepoint, in the treated group but not in the sham group. Conversely, regional atrophy measures did not show significant longitudinal changes between the two groups across six months. Our preliminary findings suggest that targeting DLPFC by rTMS application may lead to a significant long-term increase in FC in MCI patients in a RS network associated with executive functions, and this process might counteract the progressive cortical dysfunction affecting this domain.

Transcranial Magnetic Stimulation for Improving Dysphagia After Stroke: A Meta-Analysis of Randomized Controlled Trials

Background

Rehabilitation of post-stroke dysphagia is an urgent clinical problem, and repetitive transcranial magnetic stimulation (rTMS) has been widely used in the study of post-stroke function. However, there is no reliable evidence-based medicine to support the effect of rTMS on post-stroke dysphagia. This review aims to evaluate the effectiveness and safety of rTMS on post-stroke dysphagia.

Methods

English-language literature published before December 20, 2021, were searched in six electronic databases. Identified articles were screened, data were extracted, and the methodological quality of included trials was assessed. Meta-analysis was performed using RevMan 5.3 software. The GRADE method was used to assess the quality of the evidence.

Results

A total of 10 studies with 246 patients were included. Meta-analysis showed that rTMS significantly improved overall swallowing function (standardized mean difference [SMD]−0.76, 95% confidence interval (CI)−1.07 to−0.46, p < 0.0001, n = 206; moderate-quality evidence), Penetration Aspiration Scale (PAS) (mean difference [MD]−1.03, 95% CI−1.51 to−0.55, p < 0.0001, n = 161; low-quality evidence) and Barthel index scale (BI) (MD 23.86, 95% CI 12.73 to 34.99, p < 0.0001, n = 136; moderate-quality evidence). Subgroup analyses revealed that (1) rTMS targeting the affected hemisphere and targeting both hemispheres significantly enhanced overall swallowing function and reduced aspiration. (2) Low-frequency rTMS significantly enhanced overall swallowing function and reduced aspiration, and there was no significant difference between high-frequency rTMS and control group in reducing aspiration (p = 0.09). (3) There was no statistical difference in the dropout rate (low-quality evidence) and adverse effects (moderate-quality evidence) between the rTMS group and the control group.

Conclusion

rTMS improved overall swallowing function and activity of daily living ability and reduced aspiration in post-stroke patients with good acceptability and mild adverse effects.

Effects of Repetitive Transcranial Magnetic Stimulation in Patients With Mild Cognitive Impairment: A Meta-Analysis of Randomized Controlled Trials

Background: Mild cognitive impairment (MCI) is an intermediary state between normal aging and dementia. It has a high risk of progression in patients with Alzheimer's disease (AD). Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to improve cognitive deficits in patients with MCI and AD. Although previous meta-analyses included studies carried on patients with MCI and AD, few studies have analyzed patients with MCI independently. This meta-analysis aimed to evaluate the effects and safety of rTMS on cognition function in patients with MCI and factors that may influence such effects. Methods: Data used in this study were searched and screened from different databases, including PubMed, Web of Science, Embase, the Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Chinese Technical Periodicals (VIP), Wanfang Database, and China BioMedical Literature Database (SinoMed). The retrieved studies were carefully reviewed, data were extracted, and the quality of data was assessed. Results: A total of 12 studies involving 329 patients with MCI were included in the present meta-analysis. The analyses results revealed that rTMS improved cognitive function [standardized mean difference (SMD) = 0.83, 95% confidence interval (CI) = 0.44-1.22, p = 0.0009] and memory function (SMD = 0.73, 95% CI = 0.48-0.97, p < 0.00001) in the MCI + rTMS active group when compared to the sham stimulation group. The showed that: (1) cognitive improvement was more pronounced under high-frequency rTMS stimulation of multiple sites, such as the bilateral dorsolateral prefrontal cortex and (2) more than 10 rTMS stimulation sessions produced higher improvement on cognition function in patients with MCI. Conclusions: This study shows that rTMS can improve cognitive function in patients with MCI, especially when applied at high frequency, multi-site, and for a prolonged period. However, further studies are required to validate these findings and explore more effective stimulation protocols and targets. Systematic Review Registration: [http://www.crd.york.ac.uk/PROSPERO/], identifier: CRD 42021238708.

Cognitive Enhancement of Repetitive Transcranial Magnetic Stimulation in Patients With Mild Cognitive Impairment and Early Alzheimer's Disease: A Systematic Review and Meta-Analysis

Repetitive transcranial magnetic stimulation (rTMS), a non-invasive brain stimulation technique, has been considered as a potentially effective treatment for the cognitive impairment in patients with mild cognitive impairment (MCI) and Alzheimer’s Disease (AD). However, the effectiveness of this therapy is still under debate due to the variety of rTMS parameters and individual differences including distinctive stages of AD in the previous studies. The current meta-analysis is aiming to assess the cognitive enhancement of rTMS treatment on patients of MCI and early AD. Three datasets (PubMed, Web of Science and CKNI) were searched with relative terms and finally twelve studies with 438 participants (231 in the rTMS group and 207 in the control group) in thirteen randomized, double-blind and controlled trials were included. Random effects analysis revealed that rTMS stimulation significantly introduced cognitive benefits in patients of MCI and early AD compared with the control group (mean effect size, 1.17; 95% CI, 0.76 - 1.57). Most settings of rTMS parameters (frequency, session number, stimulation site number) significantly enhanced global cognitive function, and the results revealed that protocols with 10 Hz repetition frequency and DLPFC as the stimulation site for 20 sessions can already be able to produce cognitive improvement. The cognitive enhancement of rTMS could last for one month after the end of treatment and patients with MCI were likely to benefit more from the rTMS stimulation. Our meta-analysis added important evidence to the cognitive enhancement of rTMS in patients with MCI and early AD and discussed potential underlying mechanisms about the effect induced by rTMS.

Longitudinal relationships between cognitive domains and DEPRESSION and anxiety symptoms in systemic lupus erythematosus

OBJECTIVES

To examine i) the relationship between neuropsychological performance and depression and anxiety over time, and ii) the overlap between classification of cognitive dysfunction, anxiety, and depression in SLE.

METHODS

301 patients with SLE were included. Cognition was measured using a modified version of the ACR neuropsychological battery; cognitive dysfunction was defined as z-scores ≤-1.5 on ≥2 domains. Depression and anxiety were measured using the Beck Depression Inventory-II and the Beck Anxiety Inventory, respectively. All measures were assessed at baseline, 6, and 12 months. Their relationships were analyzed using Multiple Factor Analysis (MFA).

RESULTS

Anxiety and depression and neuropsychological performance were stable across time. Factor analysis identified two dimensions explaining 42.2% of the variance in neuropsychological performance. The first dimension (33.1% of the variance) included primarily complex cognitive tests measuring executive function; verbal, visual, and working memory; and complex processing speed. The second dimension (9.1% of the variance) included primarily measures of simple information processing speed or motor dexterity. Anxiety and depression scores were consistently related to the first cognitive dimension. There was substantial overlap in participants classified with cognitive dysfunction and anxiety and depression.

CONCLUSIONS

Depression and anxiety symptoms in SLE patients are related to a cognitive dimension incorporating memory, executive function and complex processing speed in a stable manner across one year. Many patients with cognitive dysfunction exhibit clinically significant anxiety and depression. Further research should examine whether cognition improves when anxiety and depression are treated and mechanistic links between anxiety and depression and cognitive dysfunction in SLE.

Transcranial Magnetic Stimulation as a Diagnostic and Therapeutic Tool in Various Types of Dementia

Dementia is recognized as a healthcare and social burden and remains challenging in terms of proper diagnosis and treatment. Transcranial magnetic stimulation (TMS) is a diagnostic and therapeutic tool in various neurological diseases that noninvasively investigates cortical excitability and connectivity and can induce brain plasticity. This article reviews findings on TMS in common dementia types as well as therapeutic results. Alzheimer’s disease (AD) is characterized by increased cortical excitability and reduced cortical inhibition, especially as mediated by cholinergic neurons and as documented by impairment of short latency inhibition (SAI). In vascular dementia, excitability is also increased. SAI may have various outcomes, which probably reflects its frequent overlap with AD. Dementia with Lewy bodies (DLB) is associated with SAI decrease. Motor cortical excitability is usually normal, reflecting the lack of corticospinal tract involvement. DLB and other dementia types are also characterized by impairment of short interval intracortical inhibition. In frontotemporal dementia, cortical excitability is increased, but SAI is normal. Repetitive transcranial magnetic stimulation has the potential to improve cognitive function. It has been extensively studied in AD, showing promising results after multisite stimulation. TMS with electroencephalography recording opens new possibilities for improving diagnostic accuracy; however, more studies are needed to support the existing data.

Repetitive transcranial magnetic stimulation increases the brain's drainage efficiency in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with high prevalence rate among the elderly population. A large number of clinical studies have suggested repetitive transcranial magnetic stimulation (rTMS) as a promising non-invasive treatment for patients with mild to moderate AD. However, the underlying cellular and molecular mechanisms remain largely uninvestigated. In the current study, we examined the effect of high frequency rTMS treatment on the cognitive functions and pathological changes in the brains of 4- to 5-month old 5xFAD mice, an early pathological stage with pronounced amyloidopathy and cognitive deficit. Our results showed that rTMS treatment effectively prevented the decline of long-term memories of the 5xFAD mice for novel objects and locations. Importantly, rTMS treatment significantly increased the drainage efficiency of brain clearance pathways, including the glymphatic system in brain parenchyma and the meningeal lymphatics, in the 5xFAD mouse model. Significant reduction of Aβ deposits, suppression of microglia and astrocyte activation, and prevention of decline of neuronal activity as indicated by the elevated c-FOS expression, were observed in the prefrontal cortex and hippocampus of the rTMS-treated 5xFAD mice. Collectively, these findings provide a novel mechanistic insight of rTMS in regulating brain drainage system and β-amyloid clearance in the 5xFAD mouse model, and suggest the potential use of the clearance rate of contrast tracer in cerebrospinal fluid as a prognostic biomarker for the effectiveness of rTMS treatment in AD patients.