Efficacy and safety of simultaneous rTMS-tDCS over bilateral angular gyrus on neuropsychiatric symptoms in patients with moderate Alzheimer's disease: A prospective, randomized, sham-controlled pilot study

Characteristic of motor-related cortical network during stimulating at the affected or bilateral limbs of stroke patients by acupuncture

BACKGROUND

The compensatory pattern between the two hemispheres after stroke has been the focus of research. Some evidence suggests bilateral stimulation more effectively engages networks across both hemispheres compared to the affected side only.

OBJECTIVES

To explore whether the stimulating at bilateral limbs of stroke patients by acupuncture may better engage compensatory reorganization between the hemispheres compared to stimulating at the hemiplegic limb.

METHODS

Conscious patients with hemiplegia were screened. Brain activity was assessed by the functional near-infrared spectroscopy(fNIRS) in three states: no treatment, acupuncture on the affected side, and then acupuncture on both sides. Brain activation and directed functional connectivity(FC) was analyzed between the two acupuncture strategies.

RESULTS

Acupuncture of bilateral limbs resulted in stronger activation in the primary motor cortex(M1) of the ipsilesional hemisphere than acupuncture of the affected side only. And no significantly enhanced activation of the contralesional hemisphere was observed after acupuncture on the healthy limb. Besides, the FCs from the ipsilesional premotor cortex to the contralesional sensory-related area were significantly enhanced, and the FCs from the sensory area to motor area within the ipsilesional hemisphere were also significantly enhanced. Additionally, FCs from contralesional M1 to ipsilesional motor area were attenuated.

CONCLUSION

Stimulating at bilateral limbs by acupuncture could lead to greater brain network remodeling in the motor-related areas compared to stimulating solely at the affected side, and not through more stimulation.

Network-targeted transcranial magnetic stimulation (TMS) for mild cognitive impairment (MCI)

BACKGROUND

Transcranial magnetic stimulation (TMS) is a promising non-pharmacological intervention for treatment of mild cognitive impairment (MCI) and early Alzheimer's disease (AD). Yet, we know little about precisely where stimulation would be ideal to improve cognitive function.

OBJECTIVE

To examine the network functional connectivity (fc) characteristics of prefrontal and parietal stimulation sites, given that these sites have led to improved cognitive function in TMS studies involving MCI-AD and unimpaired participants.

METHODS

Resting-state functional MRI data were acquired from 32 MCI participants at the baseline visit of an ongoing TMS trial and used to compute connectivity with prefrontal and parietal stimulation locations, selected on the basis of previous TMS studies. The TMS seed maps were examined for extent of spatial overlap with eight canonical networks. After identifying the network most likely to be targeted by TMS, we applied strategies that may provide purer targeting. Finally, we examined network connectivity in relation to participants' behavioral characteristics because of the potential for TMS treatment to be personalized.

RESULTS

The prefrontal TMS seed map overlapped primarily with the salience network. The prefrontal site is also notable for its anti-correlated connectivity with the AD-vulnerable posterior cingulate cortex (PCC). The parietal TMS seed map showed the expected strong positive connectivity with the PCC and other default network regions. Nonetheless, this particular parietal site may simultaneously modulate the fronto-parietal network. Strategies to improve network targeting and to personalize TMS are reported as secondary findings.

CONCLUSION

These results can be applied to network-targeted brain stimulation for MCI and early AD treatment. Greater precision and personalization of TMS offer the promise of achieving better outcomes for individuals with MCI or mild AD dementia.

A systematic review and meta-analysis on the characteristics of transcranial magnetic stimulation treatment protocols for patients with Alzheimer's disease

BackgroundAlzheimer's disease (AD) is the most common neurodegenerative condition causing dementia. Currently, there has been no established non-pharmacological treatment for cognitive decline in patients with AD. Recent evidence suggests that repetitive transcranial magnetic stimulation (rTMS) may be effective as a non-invasive treatment for improving cognitive function in AD.ObjectiveThis study aimed to examine the characteristics of rTMS treatment protocols for patients with ADMethodsWe conducted a systematic literature search on clinical trials on rTMS for improving cognitive decline in patients with AD, using the PubMed, PsycINFO, and Scopus databases and performed a meta-analysis according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. To clarify which cognitive domains in AD are improved by rTMS, meta-analyses were conducted on both global cognitive function and on each cognitive domain including verbal memory, processing speed, and executive function. In addition, sub-analyses of the treatment details of rTMS parameters including stimulation sites, stimulation frequency, stimulation intensity, and with/without the neuro-navigation technique and meta-regression analyses adjusting for gender, education, and the number of rTMS pulses were performed.ResultsThe results showed significant improvements in global cognitive function, while no significant findings in verbal memory, processing speed and executive function. No significant results were found in subgroup analysis or meta-regression.ConclusionsTo enrich the evidence for cognitive enhancement in AD with rTMS, the randomized controlled trials using a unified rTMS protocol with a larger sample size are warranted.

Comparative efficacy of rTMS on different targets in Alzheimer's disease: a systematic review and meta-analysis

Background

Repetitive transcranial magnetic stimulation (rTMS) is emerging as a promising non-invasive intervention for Alzheimer's disease (AD), yet therapeutic outcomes remain inconsistent across studies. This meta-analysis aimed to evaluate the cognitive benefits of rTMS in AD patients, with a specific focus on stimulation targets and protocols variations.

Methods

A systematic literature search was conducted in PubMed, Web of Science, Embase, and Cochrane Library for relevant English-language studies published up to 31 May 2024. Cognitive outcomes were assessed using the Mini-Mental State Examination (MMSE) and Alzheimer's Disease Assessment Scale-Cognitive Section (ADAS-Cog). Data were pooled using a random-effects model, with standardized mean difference (SMD) or mean differences (MD) and 95% confidence intervals (CI) calculated. Subgroup analyses were performed to examine the effects of stimulation targets, protocol variations and population demographics on rTMS efficacy.

Results

Twenty-two studies involving 874 participants were included in this meta-analysis. Overall, rTMS significantly improved cognitive function (SMD = 0.27; 95% CI = 0.14-0.41; p < 0.0001), showing that the efficacy of rTMS varied by stimulation target and protocol. Stimulation of the dorsolateral prefrontal cortex (DLPFC) led to significant cognitive improvement (SMD = 0.49, 95% CI = -0.26 to 0.73; p < 0.0001), whereas bilateral DLPFC stimulation showed no significant improvement (SMD = 0.13; 95% CI = -0.40 to 0.66; p = 0.62). Stimulating the parietal lobe or associated regions produced moderate cognitive benefits (SMD = 0.29; 95% CI = 0.03-0.55; p = 0.03). Notably, multi-target stimulation over the bilateral DLPFC, parietal lobes, Wernicke's area, and Broca's area also showed substantial cognitive improvement (MD = 2.85; 95% CI = 1.69-4.00; p < 0.00001). Additionally, subgroup analysis based on geographical background revealed greater effects in studies conducted in Asia (SMD = 0.40, 95% CI = 0.14-0.65; p < 0.003).

Conclusion

rTMS is an effective intervention for cognitive enhancement in AD, with its efficacy significantly influenced by stimulation target and protocol. Notably, the greater cognitive benefits observed in Asian populations suggest a potential role of genetic and demographic factors that warrant further investigation. These findings contribute to the development of optimized, personalized rTMS protocols for AD treatment.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/recorddashboard, CRD42023434084.

Effects of 52 weeks of precuneus rTMS in Alzheimer's disease patients: a randomized trial

BACKGROUND

Personalized repetitive transcranial magnetic stimulation (rTMS) of the precuneus (PC) is emerging as a new non-invasive therapeutic approach in treating Alzheimer's disease (AD). Here we sought to investigate the effects of 52 weeks of rTMS applied over the PC on cognitive functions in patients with mild-to-moderate dementia due to AD.

METHODS

Forty-eight patients with mild-to-moderate dementia due to AD were enrolled for the study. Of those 31 patients were extended to 52 weeks after being included in a 24-week trial (NCT03778151) with the same experimental design. The trial included a 52-week treatment with a 2-week intensive course where rTMS (or sham) was applied over the PC daily (5 times per week, Monday to Friday), followed by a 50-week maintenance phase in which the same stimulation was applied once weekly. Personalization of rTMS treatment was established using neuronavigated TMS in combination with electroencephalography (TMS-EEG). The primary outcome measure was change from baseline to week 52 of the Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB). Secondary outcomes included score changes in the Alzheimer's Disease Assessment Scale- Cognitive Subscale (ADAS-Cog)11, Mini Mental State Examination (MMSE), Alzheimer's Disease Cooperative Study-Activities of Daily Living scale (ADCS-ADL) and Neuropsychiatric Inventory (NPI). Changes in cortical activity and connectivity were monitored by TMS-EEG.

RESULTS

Among 48 patients randomized (mean age 72.8 years; 56% women), 32 (68%) completed the study. Repetitive TMS of the PC (PC-rTMS) had a significant effect on the primary outcome measure. The estimated mean change in CDR-SB after 52 week was 1.36 for PC-rTMS (95% confidence interval (CI) [0.68, 2.04]) and 2.45 for sham-rTMS group (95%CI [1.85, 3.05]). There were also significant effects for the secondary outcomes ADAS-Cog11, ADCS-ADL and NPI scores. Stronger DMN connectivity at baseline was associated with favorable response to rTMS treatment.

CONCLUSIONS

Fifty-two weeks of PC-rTMS may slow down the impairment of cognitive functions, activities of daily living and behavioral disturbances in patients with mild-to-moderate AD. Further multicenter studies are needed to confirm the clinical potential of DMN personalized rTMS.

TRIAL REGISTRATION

The study was registered on the clinicaltrial.gov website on 07-07-2022 (NCT05454540).

Targeting Neural Oscillations for Cognitive Enhancement in Alzheimer's Disease

Alzheimer's disease (AD), the most prevalent form of dementia, is marked by progressive cognitive decline, affecting memory, language, orientation, and behavior. Pathological hallmarks include extracellular amyloid plaques and intracellular tau tangles, which disrupt synaptic function and connectivity. Neural oscillations, the rhythmic synchronization of neuronal activity across frequency bands, are integral to cognitive processes but become dysregulated in AD, contributing to network dysfunction and memory impairments. Targeting these oscillations has emerged as a promising therapeutic strategy. Preclinical studies have demonstrated that specific frequency modulations can restore oscillatory balance, improve synaptic plasticity, and reduce amyloid and tau pathology. In animal models, interventions, such as gamma entrainment using sensory stimulation and transcranial alternating current stimulation (tACS), have shown efficacy in enhancing memory function and modulating neuroinflammatory responses. Clinical trials have reported promising cognitive improvements with repetitive transcranial magnetic stimulation (rTMS) and deep brain stimulation (DBS), particularly when targeting key hubs in memory-related networks, such as the default mode network (DMN) and frontal-parietal network. Moreover, gamma-tACS has been linked to increased cholinergic activity and enhanced network connectivity, which are correlated with improved cognitive outcomes in AD patients. Despite these advancements, challenges remain in optimizing stimulation parameters, individualizing treatment protocols, and understanding long-term effects. Emerging approaches, including transcranial pulse stimulation (TPS) and closed-loop adaptive neuromodulation, hold promise for refining therapeutic strategies. Integrating neuromodulation with pharmacological and lifestyle interventions may maximize cognitive benefits. Continued interdisciplinary efforts are essential to refine these approaches and translate them into clinical practice, advancing the potential for neural oscillation-based therapies in AD.

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.

Transcranial electrical stimulation as a therapeutic strategy for Alzheimer's disease: Current uses and challenges

Alzheimer's disease (AD) is an age-related neurodegenerative disorder for which there are currently rarely effective drug treatments available to halt or slow down its progression. With the aging of the world population, AD as the primary cause of dementia, is rapidly becoming one of the most expensive, lethal, and burdening diseases of this century. In recent years, the new method used to treat nervous system diseases including AD is transcranial electrical stimulation (tES) with non-invasive and for regulating the flexibility of neural circuits operation and behaviors. The rationale of tES for AD neuromodulation is derived from research on animal and clinical trials. In the present paper, we review the current uses of the tES including transcranial direct current stimulation, transcranial alternating current stimulation, and transcranial pulsed electrical stimulation in rehabilitation for AD's core clinical symptom with cognitive dysfunctions, as well as the relevant data from AD animal models have also been discussed. Finally, the regarding applied challenges of tES in AD therapy have been referred for further improvement.

Effect of a single nonpharmacological intervention on cognitive functioning in older adults with mild-to-moderate Alzheimer's disease: A meta-analysis of randomized controlled trials

Most studies of nonpharmacological interventions have used a combination of medications in experimental and control groups to improve cognitive functioning or to control symptoms, but the results have been inconsistent with respect to the effects of single nonpharmacological interventions on cognitive functioning in older patients with Alzheimer's disease. The aim of this study was to assess the effect of a single nonpharmacological intervention on cognitive functioning in older adults with mild-to-moderate Alzheimer's disease. We conducted a systematic review and meta-analysis in the first week of January 2024, searching eight electronic databases for articles that reflect on non-pharmacological interventions in Alzheimer's disease published between January 1, 1986, and December 31, 2023. All included articles had to be randomized controlled trials. The primary measure was the change in cognitive function before and after the intervention. Data were extracted by two authors and quality was assessed using the Cochrane Handbook. With the exception of the Montreal Cognitive Assessment (MoCA) scale [MD=2.99, 95% CI (-0.66,6.63)], the differences between the intervention group and the control group were significant for all the remaining scales, namely, the Mini-Mental State Examination (MMSE) [SMD=0.65, 95% CI (0.15,1.15)], Activity of Daily Living Scale (ADL) [MD=-2.30, 95% CI (-3.63,0.97)], Quality of Life in Alzheimer's Disease Scale (QoL-AD) [MD=5.03, 95% CI (2.27,7.78)], Neuropsychiatric Inventory (NPI) [MD=-2.16, 95% CI (-3.86,0.46)], and Alzheimer's Disease Assessment Scale-cognitive score (ADAS-cog) [MD=-5.21, 95% CI (-7.89,2.54)]. Subgroup analysis revealed that the most effective intervention was exercise therapy, followed by repetitive transcranial magnetic stimulation. On the other hand, music therapy was not found to be effective. Current evidence suggests that nonpharmacological interventions can be used to improve cognitive functioning in older adults with mild-to-moderate Alzheimer's disease. This study was registered in PROSPERO (registration number: CRD42024497247).

Repetitive Transcranial Magnetic Stimulation-Mediated Neuroprotection in the 5xFAD Mouse Model of Alzheimer's Disease Through GABRG2 and SNAP25 Modulation

Alzheimer's disease (AD) is a leading neurodegenerative disorder with substantial impacts on cognition and behavior. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive neuromodulation technique, has been used to treat various neuropsychiatric disorders, but its efficacy in AD has not been thoroughly investigated. This study examines the neuroprotective effects of rTMS in the 5xFAD mouse model of AD, with a particular focus on its modulation of GABAergic neuronal activity via the GABRG2 and SNAP25 proteins. Transcriptomic sequencing of rTMS-treated 5xFAD mice revealed 32 genes influenced by the treatment, among which GABRG2 was identified as a critical modulatory target. Electrophysiological assessments, including whole-cell patch clamp recordings from frontal cortex neurons, demonstrated significant alterations in inhibitory synaptic currents following rTMS. Subsequent experiments involved sh-GABRG2 transduction combined with rTMS treatment (20Hz, 14 days), examining behavioral responses, GABAergic neuron functionality, cortical GABA expression, cerebrospinal fluid GABA concentrations, β-amyloid accumulation, and pro-inflammatory cytokine levels. The results indicated notable improvements in behavioral performance, enhanced functionality of GABAergic neurons, and reductions in β-amyloid deposition and neuroinflammation after rTMS treatment. Further analysis revealed that SNAP25 overexpression could counteract the negative effects of GABRG2 silencing, highlighting the crucial role of SNAP25 downstream of GABRG2 in mediating rTMS's therapeutic effects in AD. This research highlights rTMS's potential to modulate synaptic and vesicular transport mechanisms, offering a promising avenue for ameliorating symptoms of AD through neuroprotective pathways.

Role of BDNF-TrkB signaling in the improvement of motor function and neuroplasticity after ischemic stroke in rats by transcranial direct current stimulation

BACKGROUND

Transcranial direct current stimulation (tDCS) has an impact on improving cognitive and motor dysfunction induced by ischemia-reperfusion injury. However, to use this technology more rationally in clinical practice, a deepened understanding of the molecular mechanisms behind its therapeutic effects is needed. This study explored the role of the brain-derived neurotrophic factor(BDNF) and its associated receptor tropomyosin-receptor kinase B(TrkB) while deciphering the underlying mechanisms in transcranial direct current therapy to treat ischemic stroke.

METHODS

A middle cerebral artery occlusion-reperfusion(MCAO/R) model was established in rats to observe tDCS effects on brain damage. Behavioral tests, the modified neurologic severity score(mNSS), and the Hoffman reflex / the M wave(Hmax/Mmax) ratio helped assess motor function and neurologic deficits. HE and Nissl staining helped observe the morphological changes and count of nerve cells. We tested the expression of growth-associated protein-43(Gap-43) and microtubule-associated protein-2(Map-2), K+-Cl- co-transporter 2(KCC2), γ-aminobutyric acid(GABA), and key BDNF-TrkB downstream signaling, the phospholipase C gamma(PLCγ) / CaMK IV / cAMP response element binding protein(CREB), and extracellular signal-regulated protein kinase(ERK1/2) / ribosomal S6 kinase(RSK) using western blotting. Moreover, BDNF was analyzed in plasma using the enzyme-linked immunosorbent assay (ELISA) to investigate the tDCS effect on human BDNF expression levels. Finally, a BDNF receptor antagonist, ANA-12, was administered to explore the tDCS mechanism mediating BDNF-TrkB signaling.

RESULTS

After tDCS treatment, the mNSS was improved, and the motor function was restored. Moreover, tDCS decreased cell swelling after MCAO/R and enhanced the number of neurons. tDCS treatment increased: (1) BDNF, Gap-43, Map-2 expression, (2) KCC2, GABA, and (3) PLCγ, CaMK IV, CREB and ERK1/2, RSK. Furthermore, ELISA results indicate that tDCS elevated human plasma BDNF protein expression. However, the therapeutic effect of tDCS was suppressed to a certain extent by adding ANA-12.

CONCLUSION

Our findings indicate that tDCS may exert a neuroprotective effect by activating the downstream key molecules of BDNF-TrkB expression, for instance, PLCγ/ CaMK IV/ CREB and ERK/ RSK pathway. Moreover, tDCS can control neuronal excitability, promote axonal regeneration, and accelerate motor function recovery in ischemia reperfusion-injured rats.

The effects of transcranial direct current stimulation on global cognition in patients with Alzheimer's disease: An update meta-analysis

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease. At present, there are currently no drugs that can cure AD.

OBJECTIVE

A number of empirical studies have shown that transcranial direct current stimulation (tDCS) may be used to treat cognitive abnormalities in patients with AD. We will through meta-analysis reviews tDCS overall research on the effects of cognitive function in patients with AD.

METHODS

Systematic searches were performed in the PubMed, Embase, and Cochrane Library databases from their creation until 8 March 2024. Using a fixed effect model and random effect model to evaluate the average difference between the treatment group and control group (MD) and its 95% confidence interval (CI).

RESULTS

The study included 10 randomized controlled trials (Nactive = 165, Nsham = 167). The results of the overall analysis showed that tDCS did not significantly improve the overall cognitive function (SMD = 0.17; 95%CI = -0.05, 0.39; p = 0.14; I² = 51%). Quality of life of AD patients after treatment was also evaluated, but no improvement was seen. Subgroup analysis showed no significant improvement in global cognitive function after tDCS treatment. The sensitivity analysis to confirm the reliability of the data, risk assessment did not find any high-risk projects.

CONCLUSIONS

The tDCS treatment did not improve cognitive function in patients with AD. Further empirical research in the future will help to explore new schemes for tDCS to improve cognitive function of patients.

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.

Cognitive Remediation in Patients With Bipolar Disorder: A Randomized Trial by Sequential tDCS and Navigated rTMS Targeting the Primary Visual Cortex

BACKGROUND

Non-invasive brain stimulation (NIBS), such as transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), has emerged as a promising alternative in the precise treatment of clinical symptoms, such as the cognitive impairment of bipolar disorder (BD). Optimizing the neurocognitive effects by combining tDCS and rTMS to strengthen the clinical outcome is a challenging research issue.

OBJECTIVE

In this randomized, controlled trial, we first combined tDCS and neuronavigated rTMS targeting the V1 region to explore the efficacy on neurocognitive function in BD patients with depressive episodes.

METHODS

Eligible individuals (n = 105) were assigned into three groups, Group A (active tDCS-active rTMS), Group B (sham tDCS-active rTMS), and Group C (active tDCS-sham rTMS). All participants received 3-week treatment in which every participant received 15 sessions of stimulation through the study, 5 sessions every week, with tDCS treatment followed by neuronavigated rTMS every session. We evaluated the cognitive, emotional, and safety outcomes at week-0 (w0, baseline), week-3 (w3, immediately post-treatment), and week-8 (w8, follow-up period). The THINC-integrated tool (THINC-it), 17-item Hamilton Depression Rating Scale, and Young Mania Rating Scale were applied for evaluating the cognitive function and emotional state, respectively. Data were analyzed by repeated measure ANOVA and paired t-test.

RESULTS

Eventually, 32 patients in Group A, 27 in Group B, and 23 in Group C completed the entire treatment. Compared to Groups B and C, Group A showed greater improvement in Symbol Check items (Time and Accuracy) at W3 and Symbol Check Accuracy at W8 (p < 0.01). The W0-W3 analysis indicated a significant improvement in depressive symptoms in both Group A and Group B (p < 0.01). Additionally, neuroimaging data revealed increased activity in the calcarine sulcus in Group A, suggesting potential neuroplastic changes in the visual cortex following the electromagnetic stimulation.

CONCLUSIONS

These findings provide preliminary evidence that the combination of navigated rTMS with tDCS targeting V1 region may serve as a potential treatment strategy for improving cognitive impairment and depressive symptoms in BD patients.

TRIAL REGISTRATION

Clinical Trial Registry number: NCT05596461.

Effect of combined treatment with transcranial direct current stimulation and repetitive transcranial magnetic stimulation compared to monotherapy for the treatment of chronic insomnia: a randomised, double-blind, parallel-group, controlled trial

BACKGROUND

Chronic insomnia increases the risk of various health problems and mental illness. Existing research suggests promise for both transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS) in treating chronic insomnia individually. However, the combined effects of tDCS and rTMS on this condition remain unclear. This study aimed to verify the efficacy and safety of tDCS combined with rTMS for the treatment of adult patients with chronic insomnia.

METHODS

This was a randomised double-blind parallel-group controlled study. Overall, 157 participants with chronic insomnia were randomly assigned to one of three neurotherapy regimens: tDCS + rTMS, sham tDCS + rTMS, or tDCS + sham rTMS. All groups received 20 treatment sessions over 4 consecutive weeks. The primary outcome was the change in patients' sleep as assessed by the Pittsburgh Sleep Quality Index (PSQI) at 2 weeks, 4 weeks, and 3 months of follow-up. The secondary outcome was the assessment of different dimensions of depression and anxiety in patients through the Hamilton Depression Scale (HAMD) and Hamilton Anxiety Scale (HAMA), as well as the occurrence of adverse events.

RESULTS

Throughout the intervention and after the 3-month follow-up, the tDCS + rTMS group had significantly reduced total PSQI scores compared with the other two groups [tDCS + rTMS, 9.21 vs. sham tDCS + rTMS, 10.03; difference - 1.10; 95% confidence interval (CI), - 1.82 to - 0.38; p = 0.003; tDCS + rTMS, 9.21 vs. tDCS + sham rTMS, 10.76; difference - 2.14; 95% CI, - 2.90 to - 1.38; p < 0.001; sham tDCS + rTMS, 10.03 vs. tDCS + sham rTMS, 10.76; difference - 1.04; 95% CI, - 1.82 to - 0.26; p = 0.010), indicating improved overall sleep quality. Total HAMD and insomnia factor scores were significantly lower in the tDCS + rTMS group than in the other two groups after treatment (p < 0.05). Notably, no adverse events or serious adverse reactions were observed during the study period.

CONCLUSIONS

Combining tDCS with rTMS effectively relieved insomnia symptoms, achieving a significant therapeutic effect after 2-week of intervention, and demonstrating the persistence of treatment effects in later follow-up, emphasising the advantages of combination therapy in improving treatment stability and long-term benefits, reflecting the rapid and effective augmentation of combination therapy. This combined therapy may serve as a safe and effective treatment for adults with chronic insomnia.

TRIAL REGISTRATION

This study was registered as a clinical trial with the China Clinical Trial Registration Center (ChiCTR2100052681).

Synaptic Plasticity in the Injured Brain Depends on the Temporal Pattern of Stimulation

Neurostimulation protocols are increasingly used as therapeutic interventions, including for brain injury. In addition to the direct activation of neurons, these stimulation protocols are also likely to have downstream effects on those neurons' synaptic outputs. It is well known that alterations in the strength of synaptic connections (long-term potentiation, LTP; long-term depression, LTD) are sensitive to the frequency of stimulation used for induction; however, little is known about the contribution of the temporal pattern of stimulation to the downstream synaptic plasticity that may be induced by neurostimulation in the injured brain. We explored interactions of the temporal pattern and frequency of neurostimulation in the normal cerebral cortex and after mild traumatic brain injury (mTBI), to inform therapies to strengthen or weaken neural circuits in injured brains, as well as to better understand the role of these factors in normal brain plasticity. Whole-cell (WC) patch-clamp recordings of evoked postsynaptic potentials in individual neurons, as well as field potential (FP) recordings, were made from layer 2/3 of visual cortex in response to stimulation of layer 4, in acute slices from control (naive), sham operated, and mTBI rats. We compared synaptic plasticity induced by different stimulation protocols, each consisting of a specific frequency (1 Hz, 10 Hz, or 100 Hz), continuity (continuous or discontinuous), and temporal pattern (perfectly regular, slightly irregular, or highly irregular). At the individual neuron level, dramatic differences in plasticity outcome occurred when the highly irregular stimulation protocol was used at 1 Hz or 10 Hz, producing an overall LTD in controls and shams, but a robust overall LTP after mTBI. Consistent with the individual neuron results, the plasticity outcomes for simultaneous FP recordings were similar, indicative of our results generalizing to a larger scale synaptic network than can be sampled by individual WC recordings alone. In addition to the differences in plasticity outcome between control (naive or sham) and injured brains, the dynamics of the changes in synaptic responses that developed during stimulation were predictive of the final plasticity outcome. Our results demonstrate that the temporal pattern of stimulation plays a role in the polarity and magnitude of synaptic plasticity induced in the cerebral cortex while highlighting differences between normal and injured brain responses. Moreover, these results may be useful for optimization of neurostimulation therapies to treat mTBI and other brain disorders, in addition to providing new insights into downstream plasticity signaling mechanisms in the normal brain.

Associations between the multitrajectory neuroplasticity of neuronavigated rTMS-mediated angular gyrus networks and brain gene expression in AD spectrum patients with sleep disorders

INTRODUCTION

The multifactorial influence of repetitive transcranial magnetic stimulation (rTMS) on neuroplasticity in neural networks is associated with improvements in cognitive dysfunction and sleep disorders. The mechanisms of rTMS and the transcriptional-neuronal correlation in Alzheimer's disease (AD) patients with sleep disorders have not been fully elucidated.

METHODS

Forty-six elderly participants with cognitive impairment (23 patients with low sleep quality and 23 patients with high sleep quality) underwent 4-week periods of neuronavigated rTMS of the angular gyrus and neuroimaging tests, and gene expression data for six post mortem brains were collected from another database. Transcription-neuroimaging association analysis was used to evaluate the effects on cognitive dysfunction and the underlying biological mechanisms involved.

RESULTS

Distinct variable neuroplasticity in the anterior and posterior angular gyrus networks was detected in the low sleep quality group. These interactions were associated with multiple gene pathways, and the comprehensive effects were associated with improvements in episodic memory.

DISCUSSION

Multitrajectory neuroplasticity is associated with complex biological mechanisms in AD-spectrum patients with sleep disorders.

HIGHLIGHTS

This was the first transcription-neuroimaging study to demonstrate that multitrajectory neuroplasticity in neural circuits was induced via neuronavigated rTMS, which was associated with complex gene expression in AD-spectrum patients with sleep disorders. The interactions between sleep quality and neuronavigated rTMS were coupled with multiple gene pathways and improvements in episodic memory. The present strategy for integrating neuroimaging, rTMS intervention, and genetic data provide a new approach to comprehending the biological mechanisms involved in AD.

Efficacy and safety of transcranial magnetic stimulation on cognition in mild cognitive impairment, Alzheimer's disease, Alzheimer's disease-related dementias, and other cognitive disorders: a systematic review and meta-analysis

OBJECTIVE

We aim to analyze the efficacy and safety of TMS on cognition in mild cognitive impairment (MCI), Alzheimer's disease (AD), AD-related dementias, and nondementia conditions with comorbid cognitive impairment.

DESIGN

Systematic review, Meta-Analysis.

SETTING

We searched MEDLINE, Embase, Cochrane database, APA PsycINFO, Web of Science, and Scopus from January 1, 2000, to February 9, 2023.

PARTICIPANTS AND INTERVENTIONS

RCTs, open-label, and case series studies reporting cognitive outcomes following TMS intervention were included.

MEASUREMENT

Cognitive and safety outcomes were measured. Cochrane Risk of Bias for RCTs and MINORS (Methodological Index for Non-Randomized Studies) criteria were used to evaluate study quality. This study was registered with PROSPERO (CRD42022326423).

RESULTS

The systematic review included 143 studies (n = 5,800 participants) worldwide, encompassing 94 RCTs, 43 open-label prospective, 3 open-label retrospective, and 3 case series. The meta-analysis included 25 RCTs in MCI and AD. Collectively, these studies provide evidence of improved global and specific cognitive measures with TMS across diagnostic groups. Only 2 studies (among 143) reported 4 adverse events of seizures: 3 were deemed TMS unrelated and another resolved with coil repositioning. Meta-analysis showed large effect sizes on global cognition (Mini-Mental State Examination (SMD = 0.80 [0.26, 1.33], p = 0.003), Montreal Cognitive Assessment (SMD = 0.85 [0.26, 1.44], p = 0.005), Alzheimer's Disease Assessment Scale-Cognitive Subscale (SMD = -0.96 [-1.32, -0.60], p < 0.001)) in MCI and AD, although with significant heterogeneity.

CONCLUSION

The reviewed studies provide favorable evidence of improved cognition with TMS across all groups with cognitive impairment. TMS was safe and well tolerated with infrequent serious adverse events.

Effects of transcranial direct current stimulation on different cognitive domains in Alzheimer's disease: a meta-study

BACKGROUND

Numerous studies have investigated the potential effects of transcranial direct current stimulation (tDCS) on improving symptoms related to Alzheimer's disease (AD). However, these studies have produced inconsistent results, leading to a need for further investigation.

METHODS

A comprehensive search was conducted, including articles published from the initial availability date to 5 April 2024. The extracted study data were analyzed using STATA 12.0 software. The standard mean difference (SMD) and a 95% confidence interval (CI) were calculated to assess the effects of tDCS.

RESULTS

A total of 18 studies assessing the effects of tDCS on AD were included in the study. The study revealed that tDCS has an immediate positive impact on general cognitive, executive, language, and visuospatial function. However, the study did not observe any other significant effect of tDCS treatment on improvements in brain function, including long-term effects on general cognitive, attention, language, and memory function, as well as immediate effects on attention and memory function.

CONCLUSIONS

In conclusion, the study suggests that tDCS may be a promising intervention for improving the cognitive function of patients with AD. However, given the complex and multifactorial nature of AD, further well-designed studies with larger sample sizes are necessary to clarify the effectiveness of tDCS and determine the optimal combination of tDCS parameters.

Using Dual-Target rTMS, Single-Target rTMS, or Sham rTMS on Post-Stroke Cognitive Impairment

BACKGROUND

The clinical application of 10 Hz repetitive transcranil magnetic stimulation (rTMS) remains limited despite its demonstrated effectiveness in enhancing cortical excitability and improving cognitive function. The present study used a novel stimulus target [left dorsolateral prefrontal cortex + primary motor cortex] to facilitate the enhancement of cognitive function through the bidirectional promotion of cognitive and motor functions; Methods: Post-stroke cognitive impairment patients (n = 48) were randomly assigned to receive either dual-target, single-target, or sham rTMS for 4 weeks. Before and after 4 weeks of treatment, participants were asked to complete the Montreal Cognitive Assessment (MoCA) test, the Modified Barthel Index (MBI), the Trail-making Test (TMT), and the Digital Span Test (DST). In addition, the levels of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) in serum were also measured.

RESULTS

After adjusting for pre-intervention (baseline) MoCA scores, the post-intervention MoCA scores varied significantly. After post-hoc analysis, differences existed between the post-treatment scores of the dual-target rTMS group and the sham rTMS group (the experimental group scores were significantly higher), and between those of the dual-target rTMS group and the single-target rTMS group (the dual-target rTMS scores were significantly higher). The serum VEGF levels of the dual-target rTMS group were significantly higher those that of the sham rTMS group.

CONCLUSIONS

The present study presented data showing that a dual-target rTMS therapy is effective for Post-stroke cognitive impairment (PSCI). The stimulation exhibited remarkable efficacy, suggesting that dual-target stimulation (left dorsolateral prefrontal cortex+motor cortex (L-DLPFC+M1)) holds promise as a potential target for TMS therapy in individuals with cognitive impairment after stroke.

CLINICAL TRIAL REGISTRATION

No: ChiCTR220066184. Registered 26 November, 2022, https://www.chictr.org.cn.

Transcranial direct current stimulation over the right parietal cortex improves the depressive disorder: A preliminary study

OBJECTIVE

The right posterior parietal cortex is the core brain region of emotional processing and executive control network in the human brain, and the function of the right posterior parietal cortex is decreased in patients with major depressive disorder. This study aims to preliminarily investigate whether the excitation of the right posterior parietal cortex by transcranial direct current stimulation (tDCS) could improve their clinical symptoms.

METHODS

In this study, 12 patients with major depressive disorder were given tDCS treatment at Xuanwu Hospital of Capital Medical University and the First Hospital of Hebei Medical University. The stimulating electrode (anode) was placed on the patients' right parietal cortex, whereas the reference electrode (cathode) was placed on the patients' left mastoid. The stimulation intensity was set as 2.0 mA. The patients with depressive disorder were treated for 20 min at a time twice a day for 14 consecutive days. The severity of the clinical symptoms was evaluated using the Hamilton Depression Rating Scale-17 (HDRS-17) and the Hamilton Anxiety Rating Scale (HARS) at before and right after treatment.

RESULTS

The HDRS-17 scores of patients with depressive disorder decreased significantly following the tDCS treatment compared with those before treatment (p < .001). Further analysis revealed that the patients' anxiety/somatization, cognitive deficit, retardation, and sleep disorder scores all decreased significantly after the tDCS treatment (p < .05), although there was no significant change in their weight. Moreover, the patients' HARS scores decreased significantly after the tDCS treatment when compared with those before treatment (p < .01).

CONCLUSION

The right parietal cortex may be another key stimulation targets to improving the efficacy of tDCS treatment to the patients with major depressive disorder.

Effect of Inverse Solutions, Connectivity Measures, and Node Sizes on EEG Source Network: A Simultaneous EEG Study

Brain network provides an essential perspective for studying normal and pathological brain activities. Reconstructing the brain network in the source space becomes more needed, for example, as a target in non-invasive neuromodulation. Precise estimating source activities from the scalp EEG is still challenging because it is an ill-posed question and because of the volume conduction effect. There is no consensus on how to reconstruct the EEG source network. This study uses simultaneous scalp EEG and stereo-EEG to investigate the effect of inverse solutions, connectivity measures, and node sizes on the reconstruction of the source network. We evaluated the performance of different methods on both source activity and network. Numerical simulation was also carried out for comparison. The weighted phase-lag index (wPLI) method achieved significantly better performance on the reconstructed networks in source space than five other connectivity measures (directed transfer function (DTF), partial directed coherence (PDC), efficient effective connectivity (EEC), Pearson correlation coefficient (PCC), and amplitude envelope correlation (AEC)). There is no significant difference between the inverse solutions (standardized low-resolution brain electromagnetic tomography (sLORETA), weighted minimum norm estimate (wMNE), and linearly constrained minimum variance (LCMV) beamforming) on the reconstructed source networks. The source network based on signal phases can fit intracranial activities better than signal waveform properties or causality. Our study provides a basis for reconstructing source space networks from scalp EEG, especially for future neuromodulation research.

Distinguishable neural circuit mechanisms associated with the clinical efficacy of rTMS in aMCI patients

Repetitive transcranial magnetic stimulation is used in early-stage Alzheimer's disease to slow progression, but heterogeneity in response results in different treatment outcomes. The mechanisms underlying this heterogeneity are unclear. This study used resting-state neuroimaging to investigate the variability in episodic memory improvement from angular gyrus repetitive transcranial magnetic stimulation and tracked the neural circuits involved. Thirty-four amnestic mild cognitive impairment patients underwent angular gyrus repetitive transcranial magnetic stimulation (4 weeks, 20 Hz, 100% resting motor threshold) and were divided into high-response and low-response groups based on minimal clinically important differences in auditory verbal learning test scores. Baseline and pre/post-treatment neural circuit activities were compared. Results indicated that the orbital middle frontal gyrus in the orbitofrontal cortex network and the precuneus in the default mode network had higher local activity in the low-response group. After treatment, changes in local and remote connectivity within brain regions of the orbitofrontal cortex, default mode network, visual network, and sensorimotor network showed opposite trends and were related to treatment effects. This suggests that the activity states of brain regions within the orbitofrontal cortex and default mode network could serve as imaging markers for early cognitive compensation in amnestic mild cognitive impairment patients and predict the aftereffects of repetitive transcranial magnetic stimulation response.

Efficacy and safety of neuromodulation for apathy in patients with Alzheimer's disease: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Non-pharmacological interventions, including noninvasive neuromodulation, may alleviate apathy in individuals with Alzheimer's disease. This systematic review and meta-analysis investigated the efficacy and safety of neuromodulation for apathy in elderly patients with Alzheimer's disease (AD) or mild cognitive impairment (MCI).

METHODS

The Cochrane Central Register of Controlled Trials, EMBASE, and PubMed databases were searched for randomized controlled trials (RCTs) of neuromodulation for apathy in AD or MCI. The primary outcome was change in apathy based on the Apathy Evaluation Scale. Secondary outcomes were change in global cognition and trial discontinuation.

RESULTS

The meta-analysis included four RCTs involving 89 patients (aged 65.6-80.5 years) with apathy in AD or MCI. Findings showed no significant improvement in apathy (SMD = 0.57, 95% CI = -0.22-1.36; P = 0.16) or global cognition (SMD = 0.83, 95% CI = -0.11-1.78; P = 0.08) with neuromodulation compared to sham. Subgroup analyses showed significant improvement in apathy with high-frequency rTMS at 120% RMT compared to sham (SMD = 1.36, [95% CI = 0.61-2.12]; P = 0.0004), but not with rTMS at 80% RMT. For global cognition, high-frequency rTMS resulted in significant enhancement (SMD = 1.34 [95% CI = 0.59-2.10]; P = 0.0005), but no notable difference was observed with tDCS compared to sham. There was no significant difference in trial discontinuation in patients with AD or MCI treated with neuromodulation compared to sham.

CONCLUSION

High-frequency rTMS at 120% RMT for four weeks may be efficacious and safe for the treatment of apathy in elderly patients with AD or MCI. High-frequency rTMS may also improve global cognition in these patients. This implies rTMS has potential as an intervention for apathy in AD and MCI. Large well conducted RCTs are warranted to explore this effect further.

Transcranial direct current stimulation for global cognition in Alzheimer's disease: a systemic review and meta-analysis

This meta-analysis was to investigate the efficacy of transcranial direct current stimulation (tDCS) for general cognitive function in Alzheimer's disease (AD) and to investigate the potential influential factors. A systematic literature retrieval until August 2023 was performed by searching the PubMed, Embase, Web of Science, and Cochrane Library. Therapeutic effects of tDCS were evaluated using standardized mean difference (SMD) and 95% confidence interval (CI). Pooled effects of tDCS on AD patients were calculated immediately after treatment and at follow-up periods. Subgroup analyses were conducted to identify the potential prognostic factors. Eleven studies with 12 trials including 451 cases were included in our systemic review, in which 9 studies with 10 trials using Mini-Mental State Examination (MMSE) scales were included in the meta-analysis. tDCS significantly improved global cognition in AD immediately after the treatment (SMD, 0.46; 95% CI, 0.25-0.66; P<0.0001), but not at the shorter or longer follow-up period. Subgroup analyses suggested significant global cognitive improvement in patients receiving stimulation on temporal lobes instead of left dorsolateral prefrontal cortex, and in cases receiving tDCS with current density ≥ 0.08 mA/cm2 rather than <0.08 mA/cm2. Compared with tDCS plus cognitive training (CT), tDCS without CT produced obvious cognitive enhancement. In addition, patients with lower education were more likely to benefit from tDCS. tDCS was effective in improving general cognition in AD after treatment. However, further randomized trials are warranted to validate its longer-term effects as well as our subgroup analyses results.

Repetitive transcranial magnetic stimulation regulates effective connectivity patterns of brain networks in the spectrum of preclinical Alzheimer's disease

Objectives

Subjective cognitive decline (SCD) and amnestic mild cognitive impairment (aMCI) are considered as the spectrum of preclinical Alzheimer's disease (AD), with abnormal brain network connectivity as the main neuroimaging feature. Repetitive transcranial magnetic stimulation (rTMS) has been proven to be an effective non-invasive technique for addressing neuropsychiatric disorders. This study aims to explore the potential of targeted rTMS to regulate effective connectivity within the default mode network (DMN) and the executive control network (CEN), thereby improving cognitive function.

Methods

This study included 86 healthy controls (HCs), 72 SCDs, and 86 aMCIs. Among them, 10 SCDs and 11 aMCIs received a 2-week rTMS course of 5-day, once-daily. Cross-sectional analysis with the spectral dynamic causal model (spDCM) was used to analyze the DMN and CEN effective connectivity patterns of the three groups. Afterwards, longitudinal analysis was conducted on the changes in effective connectivity patterns and cognitive function before and after rTMS for SCD and aMCI, and the correlation between them was analyzed.

Results

Cross-sectional analysis showed different effective connectivity patterns in the DMN and CEN among the three groups. Longitudinal analysis showed that the effective connectivity pattern of the SCD had changed, accompanied by improvements in episodic memory. Correlation analysis indicated a negative relationship between effective connectivity from the left angular gyrus (ANG) to the anterior cingulate gyrus and the ANG.R to the right middle frontal gyrus, with visuospatial and executive function, respectively. In patients with aMCI, episodic memory and executive function improved, while the effective connectivity pattern remained unchanged.

Conclusion

This study demonstrates that PCUN-targeted rTMS in SCD regulates the abnormal effective connectivity patterns in DMN and CEN, thereby improving cognition function. Conversely, in aMCI, the mechanism of improvement may differ. Our findings further suggest that rTMS is more effective in preventing or delaying disease progression in the earlier stages of the AD spectrum.

Clinical Trial Registration

http://www.chictr.org.cn, ChiCTR2000034533.

Brain Stimulation in Alzheimer's Disease Trials

Alzheimer's disease (AD) continues to lack definitive curative therapies, necessitating an urgent exploration of innovative approaches. This review provides a comprehensive analysis of recent clinical trials focusing on invasive and non-invasive brain stimulation techniques as potential interventions for AD. Deep brain stimulation (DBS), repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), and transcranial alternating current stimulation (tACS) are evaluated for their therapeutic efficacy, safety, and applicability. DBS, though invasive, has shown promising results in mitigating cognitive decline, but concerns over surgical risks and long-term effects persist. On the other hand, non-invasive methods like rTMS, tDCS, and tACS have demonstrated potential in enhancing cognitive performance and delaying disease progression, with minimal side effects, but with varied consistency. The evidence hints towards an individualized, patient-centric approach to brain stimulation, considering factors such as disease stage, genetic traits, and stimulation parameters. The review also highlights emerging technologies and potential future directions, emphasizing the need for larger, multi-center trials to confirm preliminary findings and establish robust clinical guidelines. In conclusion, while brain stimulation techniques present a promising avenue in AD therapy, further research is imperative for more comprehensive understanding and successful clinical implementation. Through this review, we aim to catalyze the scientific discourse and stimulate further investigation into these novel interventions for AD.

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 Study on the Effect of Executive Control Network Functional Connection on the Therapeutic Efficacy of Repetitive Transcranial Magnetic Stimulation in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disease characterized by brain network dysfunction. Few studies have investigated whether the functional connections between executive control networks (ECN) and other brain regions can predict the therapeutic effect of repetitive transcranial magnetic stimulation (rTMS).

OBJECTIVE

The purpose of this study is to examine the relationship between the functional connectivity (FC) within ECN networks and the efficacy of rTMS.

METHODS

We recruited AD patients for rTMS treatment. We established an ECN using baseline period fMRI data and conducted an analysis of the ECN's FC throughout the brain. Concurrently, the support vector regression (SVR) method was employed to project post-rTMS cognitive scores, utilizing the connectional attributes of the ECN as predictive markers.

RESULTS

The average age of the patients was 66.86±8.44 years, with 8 males and 13 females. Significant improvement on most cognitive measures. We use ECN connectivity and brain region functions in baseline patients as features for SVR model training and fitting. The SVR model could demonstrate significant predictability for changes in Montreal Cognitive Assessment scores among AD patients after rTMS treatment. The brain regions that contributed most to the prediction of the model (the top 10% of weights) were located in the medial temporal lobe, middle temporal gyrus, frontal lobe, parietal lobe and occipital lobe.

CONCLUSIONS

The stronger the antagonism between ECN and parieto-occipital lobe function, the better the prediction of cognitive improvement; the stronger the synergy between ECN and fronto-temporal lobe function, the better the prediction of cognitive improvement.

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.

Cognitive Effect of Transcranial Direct Current Stimulation on Left Dorsolateral Prefrontal Cortex in Mild Alzheimer's Disease: A Randomized, Double-Blind, Cross-Over Small-Scale Exploratory Study

Background

Transcranial direct current stimulation (tDCS) is considered a potential therapeutic instrument for Alzheimer's disease (AD) because it affects long-term synaptic plasticity through the processes of long-term potentiation and long-term depression, thereby improving cognitive ability. Nevertheless, the efficacy of tDCS in treating AD is still debated. Dorsal lateral prefrontal cortex is the main role in executive functions.

Objective

We investigate the cognitive effects of tDCS on AD patients.

Methods

Thirty mild AD patients aged 66-86 years (mean = 75.6) were included in a double-blind, randomized, sham-controlled crossover study. They were randomly assigned to receive 10 consecutive daily sessions of active tDCS (2 mA for 30 min) or a sham intervention and switched conditions 3 months later. The anodal and cathodal electrodes were placed on the left dorsal lateral prefrontal cortex and the right supraorbital area, respectively. Subjects underwent various neuropsychological assessments before and after the interventions.

Results

The results showed that tDCS significantly improved Cognitive Abilities Screening Instrument scores, especially on the items of "concentration and calculation", "orientation", "language ability", and "categorical verbal fluency". Mini-Mental State Examination and Wisconsin Card Sorting Test scores in all domains of "concept formation", "abstract thinking", "cognitive flexibility", and "accuracy" also improved significantly after tDCS. For the sham condition, no difference was found between the baseline scores and the after-intervention scores on any of the neuropsychological tests.

Conclusion

>: Using tDCS improves the cognition of AD patients. Further large size clinical trials are necessary to validate the data.

Repetitive transcranial magnetic stimulation for apathy in patients with neurodegenerative conditions, cognitive impairment, stroke, and traumatic brain injury: a systematic review

Background

We aimed to determine the effects and tolerability of repetitive transcranial magnetic stimulation (rTMS) on apathy in patients with neurodegenerative conditions, mild cognitive impairment (MCI), stroke, and traumatic brain injury (TBI) via systematic review.

Methods

We conducted a systematic search in major electronic health databases, including PubMed, Scopus, and PsycINFO, covering the period from inception to June 2023. Comparative clinical trials and cohort studies, and studies with before-after designs were considered for inclusion. We used the Cochrane Risk of Bias and the National Institutes of Health (NIH) tools to assess methodological quality.

Results

Out of 258 records identified, 14 studies met our eligibility criteria (11 randomized controlled trials (RCT) and 3 studies utilized before-and-after designs) with a total of 418 patients (overall female-to-male ratio 1:1.17) included in the review. The overall methodological quality of the included studies was assessed to be fair to good. The stimulation parameters used varied considerably across the studies. The summary findings of our review indicate the following observations on the effects of rTMS on apathy: (1) the results of all included studies in Alzheimer's disease investigating the effects of rTMS on apathy have consistently shown a positive impact on apathy; (2) the majority of studies conducted in Parkinson's disease have not found statistically significant results; (3) a single study (RCT) on patients with primary progressive aphasia demonstrated significant beneficial effects of rTMS on apathy; (4) the trials conducted on individuals with MCI yielded varying conclusions; (5) one study (RCT) in chronic stroke suggested that rTMS might have the potential to improve apathy; (6) one study conducted on individuals with mild TBI did not find a significant favorable association on apathy; and (7) the use of different rTMS protocols on the populations described is generally safe.

Conclusion

The feasibility of utilizing rTMS as a treatment for apathy has been suggested in this review. Overall, limited evidence suggests that rTMS intervention may have the potential to modify apathy among patients with AD, PPA, MCI and chronic stroke, but less so in PD and mild TBI. These findings require confirmation by larger, well-designed clinical trials.

Low-frequency repetitive transcranial magnetic stimulation for children and adolescents with first-episode and drug-naïve major depressive disorder: A systematic review

OBJECTIVE

This systematic review of randomized controlled trials (RCTs) was conducted to explore the therapeutic effects and safety of active low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) versus sham LF-rTMS in children and adolescent patients with first-episode and drug-naïve (FEDN) major depressive disorder (MDD).

METHODS

A systematic literature search was performed, and data were extracted by two independent researchers. The coprimary outcomes were study-defined response and remission.

RESULTS

A systematic search of the literature yielded 442 references, of which 3 RCTs (130 children and adolescents with FEDN MDD, 50.8% male, and mean age range from 14.5 to 17.5 years) met the inclusion criteria. Among the two RCTs (66.7%, 2/3) examining the effects of LF-rTMS on study-defined response and remission and cognitive function, active LF-rTMS was more efficacious than sham LF-rTMS in terms of study-defined response rate and cognitive function (all p < 0.05) but not regarding study-defined remission rate (all p > 0.05). No significant group differences were found with regard to adverse reactions. None of the included RCTs reported the dropout rate.

CONCLUSION

These findings preliminarily found that LF-rTMS could benefit children and adolescents with FEDN MDD in a relatively safe manner, although further studies are warranted.