Repetitive transcranial magnetic stimulation in the treatment of resistant depression: changes of specific neurotransmitter precursor amino acids

Metabolic features of adolescent major depressive disorder: A comparative study between treatment-resistant depression and first-episode drug-naive depression

Major depressive disorder (MDD) is a psychiatric illness that can jeopardize the normal growth and development of adolescents. Approximately 40% of adolescent patients with MDD exhibit resistance to conventional antidepressants, leading to the development of Treatment-Resistant Depression (TRD). TRD is associated with severe impairments in social functioning and learning ability and an elevated risk of suicide, thereby imposing an additional societal burden. In this study, we conducted plasma metabolomic analysis on 53 adolescents diagnosed with first-episode drug-naïve MDD (FEDN-MDD), 53 adolescents with TRD, and 56 healthy controls (HCs) using hydrophilic interaction liquid chromatography-mass spectrometry (HILIC-MS) and reversed-phase liquid chromatography-mass spectrometry (RPLC-MS). We established a diagnostic model by identifying differentially expressed metabolites and applying cluster analysis, metabolic pathway analysis, and multivariate linear support vector machine (SVM) algorithms. Our findings suggest that adolescent TRD shares similarities with FEDN-MDD in five amino acid metabolic pathways and exhibits distinct metabolic characteristics, particularly tyrosine and glycerophospholipid metabolism. Furthermore, through multivariate receiver operating characteristic (ROC) analysis, we optimized the area under the curve (AUC) and achieved the highest predictive accuracy, obtaining an AUC of 0.903 when comparing FEDN-MDD patients with HCs and an AUC of 0.968 when comparing TRD patients with HCs. This study provides new evidence for the identification of adolescent TRD and sheds light on different pathophysiologies by delineating the distinct plasma metabolic profiles of adolescent TRD and FEDN-MDD.

Combined repetitive transcranial magnetic stimulation and gut microbiota modulation through the gut-brain axis for prevention and treatment of autism spectrum disorder

Autism spectrum disorder (ASD) encompasses a range of neurodevelopmental conditions characterized by enduring impairments in social communication and interaction together with restricted repetitive behaviors, interests, and activities. No targeted pharmacological or physical interventions are currently available for ASD. However, emerging evidence has indicated a potential association between the development of ASD and dysregulation of the gut-brain axis. Repetitive transcranial magnetic stimulation (rTMS), a noninvasive diagnostic and therapeutic approach, has demonstrated positive outcomes in diverse psychiatric disorders; however, its efficacy in treating ASD and its accompanying gastrointestinal effects, particularly the effects on the gut-brain axis, remain unclear. Hence, this review aimed to thoroughly examine the existing research on the application of rTMS in the treatment of ASD. Additionally, the review explored the interplay between rTMS and the gut microbiota in children with ASD, focusing on the gut-brain axis. Furthermore, the review delved into the integration of rTMS and gut microbiota modulation as a targeted approach for ASD treatment based on recent literature. This review emphasizes the potential synergistic effects of rTMS and gut microbiota interventions, describes the underlying mechanisms, and proposes a potential therapeutic strategy for specific subsets of individuals with ASD.

Determining the Optimal Stimulation Sessions for TMS-Induced Recovery of Upper Extremity Motor Function Post Stroke: A Randomized Controlled Trial

To find out the optimal treatment sessions of repetitive transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) for upper extremity dysfunction after stroke during the 6-week treatment and to explore its mechanism using motor-evoked potentials (MEPs) and resting-state functional magnetic resonance imaging (rs-fMRI), 72 participants with upper extremity motor dysfunction after ischemic stroke were randomly divided into the control group, 10-session, 20-session, and 30-session rTMS groups. Low-frequency (1 Hz) rTMS over the contralesional M1 was applied in all rTMS groups. The motor function of the upper extremity was assessed before and after treatment. In addition, MEPs and rs-fMRI data were analyzed to detect its effect on brain reorganization. After 6 weeks of treatment, there were significant differences in the Fugl-Meyer Assessment of the upper extremity and the Wolf Motor Function Test scores between the 10-session group and the 30-session group and between the 20- and 30-session groups and the control group, while there was no significant difference between the 20-session group and the 30-session group. Meanwhile, no significant difference was found between the 10-session group and the control group. The 20-session group of rTMS decreased the excitability of the contralesional corticospinal tract represented by the amplitudes of MEPs and enhanced the functional connectivity of the ipsilesional M1 or premotor cortex with the the precentral gyrus, postcentral gyrus, and cingulate gyrus, etc. In conclusion, the 20-session of rTMS protocol is the optimal treatment sessions of TMS for upper extremity dysfunction after stroke during the 6-week treatment. The potential mechanism is related to its influence on the excitability of the corticospinal tract and the remodeling of corticomotor functional networks.

Metabolomic disorders: confirmed presence of potentially treatable abnormalities in patients with treatment refractory depression and suicidal behavior

BACKGROUND

Refractory depression is a devastating condition with significant morbidity, mortality, and societal cost. Approximately 15% of patients with major depressive disorder are refractory to currently available treatments. We hypothesized metabolic abnormalities contributing to treatment refractory depression are associated with distinct findings identifiable in the cerebrospinal fluid (CSF). Our hypothesis was confirmed by a previous small case-controlled study. Here we present a second, larger replication study.

METHODS

We conducted a case-controlled, targeted, metabolomic evaluation of 141 adolescent and adult patients with well-characterized history of depression refractory to three maximum-dose, adequate-duration medication treatments, and 36 healthy controls. Plasma, urine, and CSF metabolic profiling were performed by coupled gas chromatography/mass spectrometry, and high-performance liquid chromatography, electrospray ionization, tandem mass spectrometry.

RESULTS

Abnormalities were identified in 67 of 141 treatment refractory depression participants. The CSF abnormalities included: low cerebral folate (n = 20), low tetrahydrobiopterin intermediates (n = 11), and borderline low-tetrahydrobiopterin intermediates (n = 20). Serum abnormalities included abnormal acylcarnitine profile (n = 12) and abnormal serum amino acids (n = 20). Eighteen patients presented with two or more abnormal metabolic findings. Sixteen patients with cerebral folate deficiency and seven with low tetrahydrobiopterin intermediates in CSF showed improvement in depression symptom inventories after treatment with folinic acid and sapropterin, respectively. No healthy controls had a metabolite abnormality.

CONCLUSIONS

Examination of metabolic disorders in treatment refractory depression identified an unexpectedly large proportion of patients with potentially treatable abnormalities. The etiology of these abnormalities and their potential roles in pathogenesis remain to be determined.

Understanding ayahuasca effects in major depressive disorder treatment through in vitro metabolomics and bioinformatics

Emerging insights from metabolomic-based studies of major depression disorder (MDD) are mainly related to biochemical processes such as energy or oxidative stress, in addition to neurotransmission linked to specific metabolite intermediates. Hub metabolites represent nodes in the biochemical network playing a critical role in integrating the information flow in cells between metabolism and signaling pathways. Limited technical-scientific studies have been conducted to understand the effects of ayahuasca (Aya) administration in the metabolism considering MDD molecular context. Therefore, this work aims to investigate an in vitro primary astrocyte model by untargeted metabolomics of two cellular subfractions: secretome and intracellular content after pre-defined Aya treatments, based on DMT concentration. Mass spectrometry (MS)-based metabolomics data revealed significant hub metabolites, which were used to predict biochemical pathway alterations. Branched-chain amino acid (BCAA) metabolism, and vitamin B6 and B3 metabolism were associated to Aya treatment, as "housekeeping" pathways. Dopamine synthesis was overrepresented in the network results when considering the lowest tested DMT concentration (1 µmol L^-1). Building reaction networks containing significant and differential metabolites, such as nicotinamide, L-DOPA, and L-leucine, is a useful approach to guide on dose decision and pathway selection in further analytical and molecular studies.

A kynurenine pathway enzyme aminocarboxymuconate-semialdehyde decarboxylase may be involved in treatment-resistant depression, and baseline inflammation status of patients predicts treatment response: a pilot study

The kynurenine pathway (KP) and inflammation are substantial in depression pathogenesis. Although there is a crosstalk between the KP, inflammation, and neurotrophic factors, few studies examine these topics together. Novel medications may be developed by clarifying dysregulations related to inflammation, KP, and neurotrophic factors in treatment-resistant depression (TRD). We aimed to evaluate the serum levels of KP metabolites, proinflammatory biomarkers, and brain-derived neurotrophic factor (BDNF) in healthy controls (HC) and the patients with TRD whose followed up with three different treatments. Moreover, the effect of electroconvulsive therapy (ECT) and repetitive transcranial magnetic stimulation (rTMS) on biomarkers was investigated. Study groups comprised a total of 30 unipolar TRD patients consisting of three separate patient groups (ECT = 8, rTMS = 10, pharmacotherapy = 12), and 9 HC. The decision to administer only pharmacotherapy or ECT/rTMS besides pharmacotherapy was given independently of this research by psychiatrists. Blood samples and symptom scores were obtained three times for patients. At baseline, quinolinic acid (QUIN) was higher in the patients with TRD compared to HC, whereas picolinic acid (PIC), PIC/QUIN, and PIC/3-hydroxykynurenine were lower. Baseline interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) were higher in nonresponders and non-remitters. ECT had an acute effect on cytokines. In the rTMS group, tumor necrosis factor-α (TNF-α) decreased in time. PIC, QUIN, and aminocarboxymuconate-semialdehyde decarboxylase (ACMSD) enzyme may play a role in TRD pathogenesis, and have diagnostic potential. rTMS and ECT have modulatory effects on low-grade inflammation seen in TRD. Baseline inflammation severity is predictive in terms of response and remission in depression.

High frequency repetitive transcranial magnetic stimulation improves cognitive performance parameters in patients with Alzheimer's disease - an exploratory pilot study

BACKGROUND

Currently available medication for Alzheimer's disease (AD) may slows cognitive decline only transitory, but has failed to bring about long term positive effects. For this slowly progressive neurodegenerative disease so far no disease modifying therapy exists.

OBJECTIVE

To find out if non-pharmacologic non-ivasive neuromodulatory repetitive transcranial magnetic stimulation (rTMS) may offer a new alternative or an add on therapeutic strategy against loss of cognitive functions.

METHODS

In this exploratory intervention study safety and symptom development before and after frontopolar cortex stimulation (FPC) using intermittent theta burst stimulation (iTBS) at 10 subsequent working days was monitored as add-on treatment in 28 consecutive patients with AD. Out of these, 10 randomly selected patients received sham stimulation as a control. In addition, ​serum concentrations of neurotransmitter precursor amino acids, of immune activation and inflammation markers, of brain derived neurotrophic factor (BDNF) as well as of nitrite were measured.

RESULTS

Treatment was well tolerated, no serious adverse effects were observed. Improvement of cognition was detected by an increase of Mini Mental State Examination score (MMSE; p<0.01, paired rank test) and also by an increase in a modified repeat address phrase test, part of the 6-item cognitive ​impairment test (p < 0.01). A trend to an increase in the clock drawing test (CDT; p = 0.08) was also found in the verum treated group. Furtheron, in 10 of the AD patients with additional symptoms of depression treated with iTBS, a significant decrease in the HAMD-7 scale (p <0.01) and a trend to lower serum phenylalanine concentrations (p = 0.08) was seen. No changes of the parameters tested were found in the sham treated patients.

CONCLUSION

Our preliminary results may indicate that iTBS is effective in the treatment of AD. Also a slight influence of iTBS on the metabolism of phenylalanine was found after 10 iTBS sessions. An impact of iTBS to influence the enzyme phenylalanine hydroxylase (PAH), as found in previous series of treatment resistant depression, could not be seen in this our first observational trial in 10 AD patients with comorbidity of depression. Longer treatment periods for several weeks in a higher number of AD patients with depression could cause more intense and disease modifying effects visible in different neurotransmitter concentrations important in the pathogenesis of AD.

Devices and Technology in Transcranial Magnetic Stimulation: A Systematic Review

The technology for transcranial magnetic stimulation (TMS) has significantly changed over the years, with important improvements in the signal generators, the coils, the positioning systems, and the software for modeling, optimization, and therapy planning. In this systematic literature review (SLR), the evolution of each component of TMS technology is presented and analyzed to assess the limitations to overcome. This SLR was carried out following the PRISMA 2020 statement. Published articles of TMS were searched for in four databases (Web of Science, PubMed, Scopus, IEEE). Conference papers and other reviews were excluded. Records were filtered using terms about TMS technology with a semi-automatic software; articles that did not present new technology developments were excluded manually. After this screening, 101 records were included, with 19 articles proposing new stimulator designs (18.8%), 46 presenting or adapting coils (45.5%), 18 proposing systems for coil placement (17.8%), and 43 implementing algorithms for coil optimization (42.6%). The articles were blindly classified by the authors to reduce the risk of bias. However, our results could have been influenced by our research interests, which would affect conclusions for applications in psychiatric and neurological diseases. Our analysis indicates that more emphasis should be placed on optimizing the current technology with a special focus on the experimental validation of models. With this review, we expect to establish the base for future TMS technological developments.

Clinical application of transcranial magnetic stimulation in multiple sclerosis

Multiple sclerosis (MS) is a common chronic, autoimmune-mediated inflammatory and neurodegenerative disease of the central nervous system. The treatment of MS has enormous progress with disease-modifying drugs, but the complexity of the disease course and the clinical symptoms of MS requires personalized treatment and disease management, including non-pharmacological treatment. Transcranial magnetic stimulation (TMS) is a painless and non-invasive brain stimulation technique, which has been widely used in neurological diseases. In this review, we mainly focus on the progress of physiological assessment and treatment of TMS in MS.

Non-Invasive Brain Stimulation Effects on Biomarkers of Tryptophan Metabolism: A Scoping Review and Meta-Analysis

Abnormal activation of the kynurenine and serotonin pathways of tryptophan metabolism is linked to a host of neuropsychiatric disorders. Concurrently, noninvasive brain stimulation (NIBS) techniques demonstrate high therapeutic efficacy across neuropsychiatric disorders, with indications for modulated neuroplasticity underlying such effects. We therefore conducted a scoping review with meta-analysis of eligible studies, conforming with the PRISMA statement, by searching the PubMed and Web of Science databases for clinical and preclinical studies that report the effects of NIBS on biomarkers of tryptophan metabolism. NIBS techniques reviewed were electroconvulsive therapy (ECT), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS). Of the 564 search results, 65 studies were included with publications dating back to 1971 until 2022. The Robust Bayesian Meta-Analysis on clinical studies and qualitative analysis identified general null effects by NIBS on biomarkers of tryptophan metabolism, but moderate evidence for TMS effects on elevating serum serotonin levels. We cannot interpret this as evidence for or against the effects of NIBS on these biomarkers, as there exists several confounding methodological differences in this literature. Future controlled studies are needed to elucidate the effects of NIBS on biomarkers of tryptophan metabolism, an under-investigated question with substantial implications to clinical research and practice.

Repetitive Transcranial Magnetic Stimulation Improves Neuropathy and Oxidative Stress Levels in Rats with Experimental Cerebral Infarction through the Nrf2 Signaling Pathway

Ischemic stroke poses a serious threat to human health. Its high morbidity, disability, and lethality rates have led to it being a research hotspot. Cerebral ischemia reperfusion injury is a difficult point in the treatment of ischemic stroke. In recent years, studies have shown that repeated transcranial magnetic stimulation (rTMS) can enhance cerebral ischemic tolerance and have a significant protective effect on reperfusion injury after ischemia, but its specific mechanism is unknown. The Nrf2/pathway plays a vital role in ischemia-reperfusion injury in the body environment. Therefore, in this experiment, the middle cerebral artery occlusion (MCAO) reperfusion model of SD rats was made to simulate the occurrence of experimental cerebral infarction by the suture method. After treatment with rTMS, it was studied whether it can regulate the expression of Nrf2 and HO-1, affect the content of MDA and SOD activity, and then activate the Nrf2 pathway to exert its brain protection. The results showed that after MCAO reperfusion, the neurological deficit score of rats increased, and the time to remove the bilateral stickers and the time to cross the balance beam increased, suggesting the successful establishment of the experimental cerebral infarction model. Detecting the brain tissue of experimental cerebral infarction rats found that the expression of Nrf2 and HO-1 decreased, the content of MDA increased, and the activity of SOD decreased. After rTMS treatment, the neuromotor function of experimental cerebral infarction rats improved, the expression of Nrf2 and HO-1 in the brain tissue gradually increased, the content of MDA decreased, and the activity of SOD increased. It indicates that the expression of Nrf2 and HO-1 in experimental cerebral infarction rats is reduced. After treatment with rTMS, it can improve the neuromotor function damage of the rats and reduce the level of oxidative stress. The mechanism may be through promoting the activation of the Nrf2 signaling pathway, acting on the expression of antioxidant proteins, such as HO-1 and SOD1, reducing oxidative stress damage, and playing a protective effect on brain tissue.