Repetitive transcranial magnetic stimulation (rTMS) fails to improve cognition in patients with parkinson's disease: a Meta-analysis of randomized controlled trials

Transcranial Magnetic Stimulation Applications in the Study of Executive Functions: A Review

PURPOSE

Executive functions (EFs) are a set of advanced cognitive functions essential for human survival and behavioral regulation. Understanding neurophysiological mechanisms of EFs as well as exploring methods to enhance them are still challenging problems in cognitive neuroscience. In recent years, transcranial magnetic stimulation (TMS) has been widely used in the field of EF research and has made notable progress. This article aimed to discuss the impact of TMS technology on EF research from both basic and applied research perspectives.

METHODS

We searched for literature on TMS and EFs published in the last decade (2013-2023) and reviewed how TMS has been applied in the field of EF.

FINDINGS

We found that the combination of TMS with neuroimaging techniques was helpful in exploring the brain mechanisms of EFs and investigating the executive dysfunctions caused by other neuropsychiatric disorders. Moreover, TMS could be considered as one of the most important techniques to enhance EFs among patient populations, even healthy people, with high safety and credibility. Meanwhile, we discussed the application of TMS in the research of EFs and made suggestions for future research directions. We suggested that a multidisciplinary structure of methods such as epigenetics and endocrinology could be integrated with TMS for investigating deeper in EF domains, and a substantial number of high-quality clinical studies are required to further elucidate the effects of TMS on EFs.

CONCLUSIONS

TMS holds great promise for gaining insight into investigating the neural mechanisms of EFs and improving executive functions among different populations.

Basal forebrain integrity, cholinergic innervation and cognition in idiopathic Parkinson's disease

Most individuals with Parkinson's disease experience cognitive decline. Mounting evidence suggests this is partially caused by cholinergic denervation due to α-synuclein pathology in the cholinergic basal forebrain. Alpha-synuclein deposition causes inflammation, which can be measured with free water fraction, a diffusion MRI-derived metric of extracellular water. Prior studies have shown an association between basal forebrain integrity and cognition, cholinergic levels and cognition, and basal forebrain volume and acetylcholine, but no study has directly investigated whether basal forebrain physiology mediates the relationship between acetylcholine and cognition in Parkinson's disease. We investigated the relationship between these variables in a cross-sectional analysis of 101 individuals with Parkinson's disease. Cholinergic levels were measured using fluorine-18 fluoroethoxybenzovesamicol (18F-FEOBV) PET imaging. Cholinergic innervation regions of interest included the medial, lateral capsular and lateral perisylvian regions and the hippocampus. Brain volume and free water fraction were quantified using T1 and diffusion MRI, respectively. Cognitive measures included composites of attention/working memory, executive function, immediate memory and delayed memory. Data were entered into parallel mediation analyses with the cholinergic projection areas as predictors, cholinergic basal forebrain volume and free water fraction as mediators and each cognitive domain as outcomes. All mediation analyses controlled for age, years of education, levodopa equivalency dose and systolic blood pressure. The basal forebrain integrity metrics fully mediated the relationship between lateral capsular and lateral perisylvian acetylcholine and attention/working memory, and partially mediated the relationship between medial acetylcholine and attention/working memory. Basal forebrain integrity metrics fully mediated the relationship between medial, lateral capsular and lateral perisylvian acetylcholine and free water fraction. For all mediations in attention/working memory and executive function, the free water mediation was significant, while the volume mediation was not. The basal forebrain integrity metrics fully mediated the relationship between hippocampal acetylcholine and delayed memory and partially mediated the relationship between lateral capsular and lateral perisylvian acetylcholine and delayed memory. The volume mediation was significant for the hippocampal and lateral perisylvian models, while free water fraction was not. Free water fraction in the cholinergic basal forebrain mediated the relationship between acetylcholine and attention/working memory and executive function, while cholinergic basal forebrain volume mediated the relationship between acetylcholine in temporal regions in memory. These findings suggest that these two metrics reflect different stages of neurodegenerative processes and add additional evidence for a relationship between pathology in the basal forebrain, acetylcholine denervation and cognitive decline in Parkinson's disease.

Effect of different modalities of transcranial magnetic stimulation on Parkinson's patients cognitive impairment and long-term effectiveness: a systematic review and network meta-analysis

Objective

This study used network Meta-analysis to compare the effects of different transcranial magnetic stimulation (TMS) modalities on the effectiveness and long-term validity of improving cognitive function in Parkinson's patients.

Methods

Computer searches of the Cochrane Library, PubMed, Web of Science, Embass, CNKI and Wanfang Data were conducted to collect randomized controlled clinical studies on TMS to improve cognitive function in Parkinson's patients published from the time of library construction to December 2023.

Results

A total of 22 studies and 1,473 patients were included, comprising 5 interventions: high frequency repetitive transcranial magnetic stimulation (HF-rTMS), low frequency repetitive transcranial magnetic stimulation (LF-rTMS), intermittent theta burst stimulation (iTBS), sham stimulation and conventional rehabilitation therapy (CRT). Network Meta-analysis showed that the ranking results of different TMS intervention modalities in terms of MoCA scores were: HF-rTMS > LF-rTMS > iTBS > sham > CRT, the ranking results of different TMS intervention modalities in terms of MMSE scores were: HF-rTMS > LF-rTMS > sham > CRT. The effect of TMS on improving Parkinsonian cognitive function lasted for 1 month compared to the no-stimulation group.

Conclusion

TMS has some long-term sustained effects on improving cognitive function in Parkinson's patients. HF-rTMS is more effective in improving cognitive function in Parkinson's patients.Systematic review registration: https://www.crd.york.ac.uk/PROSPERO, identifier: CRD42023463958.

After-effects of repetitive transcranial magnetic stimulation with parameter dependence on long-term potentiation-like plasticity and object recognition memory in rats

Objective

To investigate the after-effects of 25-Hz repetitive transcranial magnetic stimulation (rTMS) at 60, 100, and 120% resting motor threshold (rMT) on long-term potentiation (LTP) in the rat hippocampus, to clarify the intensity dependence of rTMS, and to determine whether it simultaneously affects learning and memory ability.

Methods

Five rats were randomly selected from 70 male Wistar rats, and evoked rMT potentials were recorded in response to magnetic stimulation. The remaining 65 rats were randomly assigned to five groups (n = 13), including sham rTMS, 1 Hz 100% rMT, and 25 Hz rTMS groups with 3 subgroups of 60% rMT, 100% rMT, and 120% rMT. Five rats in each group were anesthetized and induced by a priming TMS-test design for population spike (PS) response of the perforant path-dentate gyrus in the hippocampus; the remaining eight rats in each group were evaluated for object recognition memory in the novel object recognition (NOR) task after the different rTMS protocols.

Results

Forty-five percent (approximately 1.03 T) of the magnetic stimulator output was confirmed as rMT in the biceps femoris muscle. The PS ratio was ranked as follows: 25 Hz 100% rMT (267.78 ± 25.71%) > sham rTMS (182 ± 9.4%) >1 Hz 100% rMT (102.69 ± 6.64%) > 25 Hz 120% rMT (98 ± 11.3%) > 25 Hz 60% rMT (36 ± 8.5%). Significant differences were observed between the groups, except for the difference between the 25 Hz 120% rMT and the 1 Hz 100% rMT groups (p = 0.446). LTP was successfully induced over the 60-min recording period only in the sham rTMS and 25 Hz 100% rMT groups. Moreover, these two groups spent more time exploring a novel object than a familiar object during the NOR task (p < 0.001), suggesting long-term recognition memory retention. In the between-group analysis of the discrimination index, the following ranking was observed: 25 Hz 100% rMT (0.812 ± 0.158) > sham rTMS (0.653 ± 0.111) > 25 Hz 120% rMT (0.583 ± 0.216) >1 Hz 100% rMT (0.581 ± 0.145) > 25 Hz 60% rMT (0.532 ± 0.220).

Conclusion

The after-effect of 25-Hz rTMS was dependent on stimulus intensity and provided an inverted (V-shaped) bidirectional modulation on hippocampal plasticity that involved two forms of metaplasticity. Furthermore, the effects on the recognition memory ability were positively correlated with those on LTP induction in the hippocampus in vivo.

Neuronavigated repetitive transcranial magnetic stimulation improves depression, anxiety and motor symptoms in Parkinson's disease

Background

Repetitive transcranial magnetic stimulation (rTMS) is a potential treatment option for Parkinson's disease patients with depression (DPD), but conflicting results in previous studies have questioned its efficacy.

Method

To investigate the safety and efficacy of neuronavigated high-frequency rTMS at the left DLPFC in DPD patients, we conducted a randomized, double-blind, sham-controlled study (NCT04707378). Sixty patients were randomly assigned to either a sham or active stimulation group and received rTMS for ten consecutive days. The primary outcome was HAMD, while secondary outcomes included HAMA, MMSE, MoCA and MDS-UPDRS-III. Assessments were performed at baseline, immediately after treatment, 2 weeks, and 4 weeks post-treatment.

Results

The GEE analysis showed that the active stimulation group had significant improvements in depression, anxiety, and motor symptoms at various time points. Specifically, there were significant time-by-group interaction effects in depression immediately after treatment (β, -4.34 [95% CI, -6.90 to -1.74; P = 0.001]), at 2 weeks post-treatment (β, -3.66 [95% CI, -6.43 to -0.90; P = 0.010]), and at 4 weeks post-treatment (β, -4.94 [95% CI, -7.60 to -2.29; P < 0.001]). Similarly, there were significant time-by-group interaction effects in anxiety at 4 weeks post-treatment (β, -2.65 [95% CI, -4.96 to -0.34; P = 0.024]) and in motor symptoms immediately after treatment (β, -5.72 [95% CI, -9.10 to -2.34; P = 0.001] and at 4 weeks post-treatment (β, -5.43 [95% CI, -10.24 to -0.61; P = 0.027]).

Conclusion

The study suggested that neuronavigated high-frequency rTMS at left DLPFC is effective for depression, anxiety, and motor symptoms in PD patients.

Effects of repetitive transcranial magnetic stimulation on gait disorders and cognitive dysfunction in Parkinson's disease: A systematic review with meta-analysis

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is acknowledged to be crucial to manage freezing of gait (FOG) and cognitive impairment for patients with Parkinson's disease (PD), but its effectiveness is unclear.

OBJECTIVE

To determine the effects of rTMS on FOG and cognitive function in people with PD and to investigate potential factors that modulate the rTMS effects.

METHODS

Databases searched included PubMed, Web of Science, EMBASE, and the Cochrane Library from inception to December 31, 2021. Eligible studies include a controlled randomized clinical trial of rTMS intervention for FOG and cognitive dysfunction in PD patients. The weighted mean difference (WMD) with 95% confidence intervals (CI) were calculated with fixed-effects models. The outcome of the study included gait and cognitive assessments.

RESULTS

Sixteen studies with a total of 419 patients were included. Fixed-effects analysis revealed that rTMS was effective in improving freezing of gait questionnaire scores (short-term effect: WMD = -0.925, 95% CI: -1.642 to -0.209, p = .011; long-term effect: WMD = -2.120, 95% CI: -2.751 to -1.489, p = .000), 10-m walking time (short-term effect: WMD = -0.456, 95% CI: -0.793 to -0.119, p = .008; long-term effect: WMD = -0.526, 95% CI: -0.885 to -0.167, p = .004), Timed Up-and-Go scores (short-term effect: WMD = -1.064, 95% CI: -1.555 to -0.572, p = .000; long-term effect: WMD = -1.097, 95% CI: -1.422 to -0.772, p = .000), Montreal cognitive assessment (WMD = 3.714, 95% CI: 2.567 to 4.861, p = .000), and frontal assessment battery (WMD = -0.584, 95% CI: -0.934 to -0.234, p = .001).

CONCLUSIONS

RTMS showed a beneficial effect on FOG and cognitive dysfunction in parkinsonism. However, the optimal rTMS protocol has not been determined and further high-quality studies are needed.

Autophagy and apoptosis cascade: which is more prominent in neuronal death?

Autophagy and apoptosis are two crucial self-destructive processes that maintain cellular homeostasis, which are characterized by their morphology and regulated through signal transduction mechanisms. These pathways determine the fate of cellular organelle and protein involved in human health and disease such as neurodegeneration, cancer, and cardiovascular disease. Cell death pathways share common molecular mechanisms, such as mitochondrial dysfunction, oxidative stress, calcium ion concentration, reactive oxygen species, and endoplasmic reticulum stress. Some key signaling molecules such as p53 and VEGF mediated angiogenic pathway exhibit cellular and molecular responses resulting in the triggering of apoptotic and autophagic pathways. Herein, based on previous studies, we describe the intricate relation between cell death pathways through their common genes and the role of various stress-causing agents. Further, extensive research on autophagy and apoptotic machinery excavates the implementation of selective biomarkers, for instance, mTOR, Bcl-2, BH3 family members, caspases, AMPK, PI3K/Akt/GSK3β, and p38/JNK/MAPK, in the pathogenesis and progression of neurodegenerative diseases. This molecular phenomenon will lead to the discovery of possible therapeutic biomolecules as a pharmacological intervention that are involved in the modulation of apoptosis and autophagy pathways. Moreover, we describe the potential role of micro-RNAs, long non-coding RNAs, and biomolecules as therapeutic agents that regulate cell death machinery to treat neurodegenerative diseases. Mounting evidence demonstrated that under stress conditions, such as calcium efflux, endoplasmic reticulum stress, the ubiquitin-proteasome system, and oxidative stress intermediate molecules, namely p53 and VEGF, activate and cause cell death. Further, activation of p53 and VEGF cause alteration in gene expression and dysregulated signaling pathways through the involvement of signaling molecules, namely mTOR, Bcl-2, BH3, AMPK, MAPK, JNK, and PI3K/Akt, and caspases. Alteration in gene expression and signaling cascades cause neurotoxicity and misfolded protein aggregates, which are characteristics features of neurodegenerative diseases. Excessive neurotoxicity and misfolded protein aggregates lead to neuronal cell death by activating death pathways like autophagy and apoptosis. However, autophagy has a dual role in the apoptosis pathways, i.e., activation and inhibition of the apoptosis signaling. Further, micro-RNAs and LncRNAs act as pharmacological regulators of autophagy and apoptosis cascade, whereas, natural compounds and chemical compounds act as pharmacological inhibitors that rescue neuronal cell death through inhibition of apoptosis and autophagic cell death.

MicroRNA-135b-5p Downregulation Causes Antidepressant Effects by Regulating SIRT1 Expression

Depression is a serious and potentially life-threatening mental illness. Recently, the role of sirtuin 1 (SIRT1) in chronic unpredictable mild stress (CUMS) management has been examined. The present study explored and clarified whether microRNA (miR)-135b-5p could play a role in depression by regulating the expression of SIRT1. SIRT1 was identified as the target gene of miR-135b-5p using TargetScan and the dual luciferase reporter assay. In addition, the expression levels of SIRT1 were significantly reduced in mouse peripheral blood and hippocampal tissue samples, while the expression of miR-135b-5p exhibited the opposite effects. Subsequently, the effects of miR-135b-5p inhibition were investigated in mice with depression. The results indicated that the miR-135b-5p inhibitor significantly increased the weight loss induced by CUMS compared with the model group, while reducing the expression levels of miR-135b-5p and further alleviating the depression-like behavior induced by CUMS. Concomitantly, the results indicated that the miR-135b-5p inhibitor inhibited CUMS-induced hippocampal cell apoptosis and significantly reduced the expression levels of cleaved caspase-3 and the ratio of cleaved caspase-3/caspase-3. Moreover, the miR-135b-5p inhibitor significantly reduced the CUMS-induced increase of the inflammatory factors IL-1β, IL-6 and TNF-α in the hippocampal mouse samples, while significantly increasing the expression levels of SIRT1. Finally, the results demonstrated that all the effects of the miR-135b-5p inhibitor on CUMS-induced mice were significantly reversed by SIRT1 silencing. In conclusion, the present study indicated that the miR-135b-5p/SIRT1 pathway was a key mediator of antidepressant effects induced in depressed mice. Therefore, it could be considered a potential therapeutic target for the treatment of CUMS-induced depression.