Investigational and Therapeutic Applications of Transcranial Magnetic Stimulation in Schizophrenia

The Therapeutic Role of Intermittent Theta Burst Stimulation in Schizophrenia: A Systematic Review and Meta-analysis

ABSTRACT

Schizophrenia affects approximately 1% of the population worldwide. Multifactorial reasons, ranging from drug resistance to adverse effects of medications, have necessitated exploring further therapeutic options. Intermittent theta burst stimulation (iTBS) is a novel high-frequency form of transcranial magnetic stimulation, a safe procedure with minor adverse effects with faster and longer-lasting poststimulation effects with a potential role in treating symptoms; however, the exact target brain regions and symptoms are still controversial. Therefore, we aimed to systematically investigate the current literature regarding the therapeutic utilities of iTBS using Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Twelve studies were included among which 9 found iTBS effective to some degree. These studies targeted the dorsolateral prefrontal cortex and the midline cerebellum. We performed a random-effects meta-analysis on studies that compared the effects of iTBS on schizophrenia symptoms measured by the Positive and Negative Syndrome Scale (PANSS) to sham treatment. Our results showed no significant difference between iTBS and sham in PANSS positive and negative scores, but a trend-level difference in PANSS general scores ( k = 6, P = 0.07), and a significant difference in PANSS total scores ( k = 6, P = 0.03). Analysis of the studies targeting the dorsolateral prefrontal cortex showed improvement in PANSS negative scores ( k = 5, standardized mean difference = -0.83, P = 0.049), but not in PANSS positive scores. Moderators (intensity, pulse, quality, sessions) did not affect the results. However, considering the small number of studies included in this meta-analysis, future works are required to further explore the effects of these factors and also find optimum target regions for positive symptoms.

Instantaneous effects of prefrontal transcranial magnetic stimulation on brain oxygenation: A systematic review

This systematic review investigates how prefrontal transcranial magnetic stimulation (TMS) immediately influences neuronal excitability based on oxygenation changes measured by functional magnetic resonance imaging (fMRI) or functional near-infrared spectroscopy (fNIRS). A thorough understanding of TMS-induced excitability changes may enable clinicians to adjust TMS parameters and optimize treatment plans proactively. Five databases were searched for human studies evaluating brain excitability using concurrent TMS/fMRI or TMS/fNIRS. Thirty-seven studies (13 concurrent TMS/fNIRS studies, 24 concurrent TMS/fMRI studies) were included in a qualitative synthesis. Despite methodological inconsistencies, a distinct pattern of activated nodes in the frontoparietal central executive network, the cingulo-opercular salience network, and the default-mode network emerged. The activated nodes included the prefrontal cortex (particularly dorsolateral prefrontal cortex), insula cortex, striatal regions (especially caudate, putamen), anterior cingulate cortex, and thalamus. High-frequency repetitive TMS most consistently induced expected facilitatory effects in these brain regions. However, varied stimulation parameters (e.g., intensity, coil orientation, target sites) and the inter- and intra-individual variability of brain state contribute to the observed heterogeneity of target excitability and co-activated regions. Given the considerable methodological and individual variability across the limited evidence, conclusions should be drawn with caution.

Prolonged intermittent theta burst stimulation targeting the left prefrontal cortex and cerebellum does not affect executive functions in healthy individuals

Repetitive transcranial magnetic stimulation (rTMS) for alleviating negative symptoms and cognitive dysfunction in schizophrenia commonly targets the left dorsolateral prefrontal cortex (LDLPFC). However, the therapeutic effectiveness of rTMS at this site remains inconclusive and increasingly, studies are focusing on cerebellar rTMS. Recently, prolonged intermittent theta-burst stimulation (iTBS) has emerged as a rapid-acting form of rTMS with promising clinical benefits. This study explored the cognitive and neurophysiological effects of prolonged iTBS administered to the LDLPFC and cerebellum in a healthy cohort. 50 healthy participants took part in a cross-over study and received prolonged (1800 pulses) iTBS targeting the LDLPFC, cerebellar vermis, and sham iTBS. Mixed effects repeated measures models examined cognitive and event-related potentials (ERPs) from 2-back (P300, N200) and Stroop (N200, N450) tasks after stimulation. Exploratory non-parametric cluster-based permutation tests compared ERPs between conditions. There were no significant differences between conditions for behavioural and ERP outcomes on the 2-back and Stroop tasks. Exploratory cluster-based permutation tests of ERPs did not identify any significant differences between conditions. We did not find evidence that a single session of prolonged iTBS administered to either the LDLPFC or cerebellum could cause any cognitive or ERP changes compared to sham in a healthy sample.

Investigational applications of transcranial magnetic stimulation (TMS) in Mood Disorders: Studies from a tertiary care center in India

The investigational potential of TMS in psychiatry is largely underutilized. In the current article, we present the results of five studies with similar TMS protocols that looked at the investigative applications of TMS via measuring cortical reactivity as potential biomarkers in mood disorders. The first two studies, evaluate potential of TMS parameters and Motor neuron system (MNS) as state or trait markers of BD. Third and fourth studies evaluate these as endophenotypic markers of BD. The fifth study which is an RCT evaluating add-on yoga in UD, evaluates if markers of CI can index the therapeutic response of yoga. In study one MT1 was significantly greater in the SM (symptomatic-mania) group compared to HC (healthy-control) (P=0.032). The cortical inhibition measures SICI was reduced in SM(P=0.021) and BD (remitted Bipolar) (P=0.023) groups compared to HC. LICI was increased in the SM(0.021) and BD(P=0.06) groups compared to HC. In study two, a significant group x time interaction effect was observed indicating higher putative MNS-activity mediation in patients compared to HC on SlCl(P=0.024), LlCl(P=0.033). There were no significant group differences noted in the endophenotype studies. The fifth study showed a significant time X group interaction for CSP, favoring improvement in YG (yoga-group) (p<0.01).No significant change was observed for LICI(p=0.2), SICI(p=0.5). Limitations of these studies notwithstanding, we conclude that cortical reactivity measured using TMS is a potential biomarker across the course of mood disorders, starting from state and trait markers to understanding the therapeutic mechanism of a particular treatment modality in these disorders.

Effects of bilateral repetitive transcranial magnetic stimulation on prospective memory in patients with schizophrenia: A double-blind randomized controlled clinical trial

AIMS

To investigate effects of repetitive transcranial magnetic stimulation (rTMS) on the prospective memory (PM) in patients with schizophrenia (SCZ).

METHODS

Fifty of 71 patients completed this double-blind placebo-controlled randomized trial and compared with 18 healthy controls' (HCs) PM outcomes. Bilateral 20 Hz rTMS to the dorsolateral prefrontal cortex at 90% RMT administered 5 weekdays for 4 weeks for a total of 20 treatments. The Positive and Negative Symptom Scale (PANSS), the Scale for the Assessment of Negative Symptoms (SANS), and PM test were assessed before and after treatment.

RESULTS

Both Event-based PM (EBPM) and Time-based PM (TBPM) scores at baseline were significantly lower in patients with SCZ than that in HCs. After rTMS treatments, the scores of EBPM in patients with SCZ was significantly improved and had no differences from that in HCs, while the scores of TBPM did not improved. The negative symptom scores on PANSS and the scores of almost all subscales and total scores of SANS were significantly improved in both groups.

CONCLUSIONS

Our findings indicated that bilateral high-frequency rTMS treatment can alleviate EBPM but not TBPM in patients with SCZ, as well as improve the negative symptoms.

SIGNIFICANCE

Our results provide one therapeutic option for PM in patients with SCZ.

Pre-clinical indications of brain stimulation treatments for non-affective psychiatric disorders, a status update

Over the past two decades noninvasive brain stimulation (NIBS) techniques have emerged as powerful therapeutic options for a range of psychiatric and neurological disorders. NIBS are hypothesized to rebalance pathological brain networks thus reducing symptoms and improving functioning. This development has been fueled by controlled studies with increasing size and rigor aiming to characterize how treatments induce clinically effective change. Clinical trials of NIBS for specific indications have resulted in federal approval for unipolar depression, bipolar depression, smoking cessation, and obsessive-compulsive disorder in the United States, and several other indications worldwide. As a rapidly emerging field, there are numerous pre-clinical indications currently in development using a variety of electrical and magnetic, non-convulsive, and convulsive approaches. This review discusses the state-of-the-science surrounding promising avenues of NIBS currently in pre-approval stages for non-affective psychiatric disorders. We consider emerging therapies for psychosis, anxiety disorders, obsessive-compulsive disorder, and borderline personality disorder, utilizing transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and magnetic seizure therapy (MST), with an additional brief section for early-stage techniques including transcranial focused ultrasound stimulation (tFUS) and transcranial alternating current stimulation (tACS). As revealed in this review, there is considerable promise across all four psychiatric indications with different NIBS approaches. Positive findings are notable for the treatment of psychosis using tDCS, MST, and rTMS. While rTMS is already FDA approved for the treatment of obsessive-compulsive disorder, methodologies such as tDCS also demonstrate potential in this condition. Emerging techniques show promise for treating non-affective disorders likely leading to future regulatory approvals.

Therapeutic effects of repetitive transcranial magnetic stimulation on cognitive impairment in stroke patients: a systematic review and meta-analysis

Background

In recent years, repetitive transcranial magnetic stimulation (rTMS) has emerged as a noninvasive and painless treatment for post-stroke cognitive impairment (PSCI). However, few studies have analyzed the intervention parameters of cognitive function and the effectiveness and safety of rTMS for treating patients with PSCI. Thus, this meta-analysis aimed to analyze the interventional parameters of rTMS and evaluate the safety and effectiveness of rTMS for treating patients with PSCI.

Methods

According to the PRISMA guidelines, we searched the Web of Science, PubMed, EBSCO, Cochrane Library, PEDro, and Embase to retrieve randomized controlled trials (RCTs) of rTMS for the treatment of patients with PSCI. Studies were screened according to the inclusion and exclusion criteria, and two reviewers independently performed literature screening, data extraction, and quality assessment. RevMan 5.40 software was used for data analysis.

Results

12 RCTs involving 497 patients with PSCI met the inclusion criteria. In our analysis, rTMS had a positive therapeutic effect on cognitive rehabilitation in patients with PSCI (P < 0.05). Both high-frequency rTMS and low-frequency rTMS were effective in improving the cognitive function of patients with PSCI by stimulating the dorsolateral prefrontal cortex (DLPFC), but their efficacy was not statistically different (P > 0.05).

Conclusions

rTMS treatment on the DLPFC can improve cognitive function in patients with PSCI. There is no significant difference in the treatment effect of high-frequency rTMS and low-frequency rTMS in patients with PSCI between high-frequency and low-frequency rTMS.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=323720, identifier CRD 42022323720.

Brain Connectivity Signature Extractions from TMS Invoked EEGs

(1) Background: The correlations between brain connectivity abnormality and psychiatric disorders have been continuously investigated and progressively recognized. Brain connectivity signatures are becoming exceedingly useful for identifying patients, monitoring mental health disorders, and treatment. By using electroencephalography (EEG)-based cortical source localization along with energy landscape analysis techniques, we can statistically analyze transcranial magnetic stimulation (TMS)-invoked EEG signals, for obtaining connectivity among different brain regions at a high spatiotemporal resolution. (2) Methods: In this study, we analyze EEG-based source localized alpha wave activity in response to TMS administered to three locations, namely, the left motor cortex (49 subjects), left prefrontal cortex (27 subjects), and the posterior cerebellum, or vermis (27 subjects) by using energy landscape analysis techniques to uncover connectivity signatures. We then perform two sample t-tests and use the (5 × 10^-5) Bonferroni corrected p-valued cases for reporting six reliably stable signatures. (3) Results: Vermis stimulation invoked the highest number of connectivity signatures and the left motor cortex stimulation invoked a sensorimotor network state. In total, six out of 29 reliable, stable connectivity signatures are found and discussed. (4) Conclusions: We extend previous findings to localized cortical connectivity signatures for medical applications that serve as a baseline for future dense electrode studies.

Transdiagnostic investigation into the relationship between mirror neuron system activity, echo-phenomena, and theory of mind in major psychoses

The association between social cognition and putative mirror neuron system (MNS)-activity in major psychoses might be contingent upon frontal dysregulation. We used a transdiagnostic ecological approach to enrich a specific behavioral phenotype (echophenomena or hyper-imitative states) across clinical diagnoses (mania and schizophrenia) to compare behavioral and physiological markers of social cognition and frontal disinhibition. We examined 114 participants with schizophrenia (N = 53) and mania (N = 61) for the presence and severity of echo-phenomena (echopraxia, incidental, and induced echolalia) using an ecological paradigm to simulate real-life social communication. Symptom severity, frontal release reflexes, and theory of mind performance were also assessed. In a proportion of these participants with (N = 20) and without (N = 20) echo-phenomena, we compared motor resonance (motor evoked potential facilitation during action observation compared to static image viewing) and cortical silent period (CSP) as putative markers of MNS-activity and frontal disinhibition, respectively, using Transcranial Magnetic Stimulation. While the prevalence of echo-phenomena was similar between mania and schizophrenia, incidental echolalia was more severe in mania. Participants with echo-phenomena (compared to those without) had significantly greater motor resonance with singlepulse (not with paired-pulse) stimuli, poorer theory of mind scores, higher frontal release reflexes but similar CSP, and greater symptom severity. None of these parameters significantly differed between participants with mania and schizophrenia. We observed relatively better phenotypic and neurophysiological characterization of major psychoses by categorizing participants based on the presence of echophenomena than clinical diagnoses. Higher putative MNS-activity was associated with poorer theory of mind in a hyper-imitative behavioral state.

[Augmentation therapy of resistant schizophrenia with rhythmic transcranial magnetic stimulation]

OBJECTIVE

To identify the clinical efficacy of rhythmic transcranial magnetic stimulation (rTMS) in resistant schizophrenia.

MATERIAL AND METHODS

The study included 44 male patients with resistant schizophrenia, divided into 4 groups: with depressive (group 1; n=11, 25.0%), with hallucinatory (group 2; n=12, 27.3%), with negative (group 3; n=11, 25.0%) and with delusional symptoms (group 4; n=10, 22.7%). Patients received rTMS, the parameters of which were determined depending on the typological variety, for 3 weeks (15 sessions). Psychometric assessment was carried with PANSS, CGI-S, CGI-I, SANS, CDSS, AHRS when included in the study (0 day), after stimulation (21 days) and by the end of the study (42 day) that allowed evaluation of both the severity of the therapeutic effect and its duration.

RESULTS

By the end of the course of stimulation, patients of the first three groups developed a distinct positive effect corresponding to a significant reduction in the total PANSS score: group 1 - 24.4% (p=0.002), group 2 - 8.3% (p=0.02), group 3 - 11.7% (p=0.001), which remained stable by day 42 in patients of the first (p=0.001) and second (p=0.005) groups. In patients with delusional symptoms (group 4), a subpsychotic state developed with a corresponding increase in the total PANSS score by 9.7% (p=0.007) requiring a course of relief therapy, which showed effectiveness by the end of the observation (day 42), indicating that resistance was overcome.

CONCLUSION

The study demonstrated the validity of rTMS as an adjuvant method of treatment in the resistant schizophrenia. To implement the potential of rTMS, it is necessary first of all to take into account the structural features of the condition, as well as to continue improving the stimulation technique itself (increasing the duration of the course, developing supportive courses).

Reconfiguration of Functional Dynamics in Cortico-Thalamo-Cerebellar Circuit in Schizophrenia Following High-Frequency Repeated Transcranial Magnetic Stimulation

Schizophrenia is a serious mental illness characterized by a disconnection between brain regions. Transcranial magnetic stimulation is a non-invasive brain intervention technique that can be used as a new and safe treatment option for patients with schizophrenia with drug-refractory symptoms, such as negative symptoms and cognitive impairment. However, the therapeutic effects of transcranial magnetic stimulation remain unclear and would be investigated using non-invasive tools, such as functional connectivity (FC). A longitudinal design was adopted to investigate the alteration in FC dynamics using a dynamic functional connectivity (dFC) approach in patients with schizophrenia following high-frequency repeated transcranial magnetic stimulation (rTMS) with the target at the left dorsolateral prefrontal cortex (DLPFC). Two groups of schizophrenia inpatients were recruited. One group received a 4-week high-frequency rTMS together with antipsychotic drugs (TSZ, n = 27), while the other group only received antipsychotic drugs (DSZ, n = 26). Resting-state functional magnetic resonance imaging (fMRI) and psychiatric symptoms were obtained from the patients with schizophrenia twice at baseline (t1) and after 4-week treatment (t2). The dynamics was evaluated using voxel- and region-wise FC temporal variability resulting from fMRI data. The pattern classification technique was used to verify the clinical application value of FC temporal variability. For the voxel-wise FC temporary variability, the repeated measures ANCOVA analysis showed significant treatment × time interaction effects on the FC temporary variability between the left DLPFC and several regions, including the thalamus, cerebellum, precuneus, and precentral gyrus, which are mainly located within the cortico-thalamo-cerebellar circuit (CTCC). For the ROI-wise FC temporary variability, our results found a significant interaction effect on the FC among CTCC. rTMS intervention led to a reduced FC temporary variability. In addition, higher alteration in FC temporal variability between left DLPFC and right posterior parietal thalamus predicted a higher remission ratio of negative symptom scores, indicating that the decrease of FC temporal variability between the brain regions was associated with the remission of schizophrenia severity. The support vector regression (SVR) results suggested that the baseline pattern of FC temporary variability between the regions in CTCC could predict the efficacy of high-frequency rTMS intervention on negative symptoms in schizophrenia. These findings confirm the potential relationship between the reduction in whole-brain functional dynamics induced by high-frequency rTMS and the improvement in psychiatric scores, suggesting that high-frequency rTMS affects psychiatric symptoms by coordinating the heterogeneity of activity between the brain regions. Future studies would examine the clinical utility of using functional dynamics patterns between specific brain regions as a biomarker to predict the treatment response of high-frequency rTMS.

Spatial and chronic differences in neural activity in medicated and unmedicated schizophrenia patients

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The medicated schizophrenia group yielded concordant activity among three right lateralized frontal clusters and a left lateralized parietal cluster.

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The unmedicated schizophrenia group yielded concordant activity among right lateralized frontal-parietal regions.

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A neural compensatory mechanism in schizophrenia.

A major caveat with investigations on schizophrenic patients is the difficulty to control for medication usage across samples as disease-related neural differences may be confounded by medication usage. Following a thorough literature search (632 records identified), we included 37 studies with a total of 740 medicated schizophrenia patients and 367 unmedicated schizophrenia patients. Here, we perform several meta-analyses to assess the neurofunctional differences between medicated and unmedicated schizophrenic patients across fMRI studies to determine systematic regions associated with medication usage. Several clusters identified by the meta-analysis on the medicated group include three right lateralized frontal clusters and a left lateralized parietal cluster, whereas the unmedicated group yielded concordant activity among right lateralized frontal-parietal regions. We further explored the prevalence of activity within these regions across illness duration and task type. These findings suggest a neural compensatory mechanism across these regions both spatially and chronically, offering new insight into the spatial and temporal dynamic neural differences among medicated and unmedicated schizophrenia patients.

Potential Locations for Non-Invasive Brain Stimulation in Treating Schizophrenia: A Resting-State Functional Connectivity Analysis

Introduction: Non-invasive brain stimulation (NIBS) techniques have been widely used for the purpose of improving clinical symptoms of schizophrenia. However, the ambiguous stimulation targets may limit the efficacy of NIBS for schizophrenia. Exploring effective stimulation targets may improve the clinical efficacy of NIBS in schizophrenia.

Methods: We first conducted a neurosynth-based meta-analysis of 715 functional magnetic resonance imaging studies to identify schizophrenia-related brain regions as regions of interest. Then, we performed the resting-state functional connectivity analysis in 32 patients with first-episode schizophrenia to find brain surface regions correlated with the regions of interest in three pipelines. Finally, the 10–20 system coordinates corresponding to the brain surface regions were considered as potential targets for NIBS.

Results: We identified several potential targets of NIBS, including the bilateral dorsal lateral prefrontal cortex, supplementary motor area, bilateral inferior parietal lobule, temporal pole, medial prefrontal cortex, precuneus, superior and middle temporal gyrus, and superior and middle occipital gyrus. Notably, the 10-20 system location of the bilateral dorsal lateral prefrontal cortex was posterior to F3 (F4), not F3 (F4).

Conclusion: Conclusively, our findings suggested that the stimulation locations corresponding to these potential targets might help clinicians optimize the application of NIBS therapy in individuals with schizophrenia.

Efficacy and Tolerability of Repetitive Transcranial Magnetic Stimulation on Suicidal Ideation: A Systemic Review and Meta-Analysis

OBJECTIVE

This study aimed to investigate the efficacy of repetitive transcranial magnetic stimulation (rTMS) in treating suicidal ideation in patients with mental illness.

METHOD

We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Major electronic databases were systematically searched from the time of their inception until July 22, 2021. The primary outcome was the mean change in the scores for suicidal ideation. The secondary outcome was the mean change in depression severity.

RESULTS

Ten randomized controlled trials were eligible with 415 participants in the active treatment group (mean age = 53.78 years; mean proportion of women = 54.5%) and 387 participants in the control group (mean age = 55.52 years; mean proportion of women = 51.78%). rTMS significantly reduced suicidal ideation (k = 10, n = 802, Hedges' g = -0.390, 95% confidence interval [CI] = -0.193 to -0.588, p <.001) and severity of depressive symptoms (k = 9, n = 761, Hedges' g = -0.698, 95% CI = -1.023 to -0.372, p < 0.001) in patients with major mental disorders. In the subgroup analysis, rTMS reduced suicidal ideation among patients with non-treatment-resistant depression (non-TRD) (-0.208) but not in those with TRD. rTMS as combination therapy had a larger effect than did monotherapy (-0.500 vs. -0.210). Suicidal ideation significantly reduced in patients receiving more than ten treatment sessions (-0.255). Importantly, the rTMS group showed favorable tolerability without major adverse events.

CONCLUSION

The study showed that rTMS was effective and well-tolerated in reducing suicidal ideation and depression severity in patients with major mental disorders.

Developments in Biological Mechanisms and Treatments for Negative Symptoms and Cognitive Dysfunction of Schizophrenia

The causal mechanisms and treatment for the negative symptoms and cognitive dysfunction in schizophrenia are the main issues attracting the attention of psychiatrists over the last decade. The first part of this review summarizes the pathogenesis of schizophrenia, especially the negative symptoms and cognitive dysfunction from the perspectives of genetics and epigenetics. The second part describes the novel medications and several advanced physical therapies (e.g., transcranial magnetic stimulation and transcranial direct current stimulation) for the negative symptoms and cognitive dysfunction that will optimize the therapeutic strategy for patients with schizophrenia in future.

A transdiagnostic evaluation of cortical inhibition in severe mental disorders using Transcranial Magnetic Stimulation

Multiple lines of investigations suggest the presence of cortical inhibition aberrations as central to the phenotypic manifestations of severe mental disorders. Transcranial Magnetic Stimulation (TMS) combined with electromyography can characterize these inhibitory processes in the motor cortex with satisfactory temporal precision. We examined TMS-evoked short- (SICI) and long-interval intracortical inhibition (LICI) and cortical silent period (CSP) as markers of GABA_A- (SICI) and GABA_B-mediated (LICI and CSP) cortical neurotransmission in symptomatic individuals with mania (n = 40), schizophrenia (n = 76), unipolar depression (n = 86), and OCD (n = 43), and compared them against similar recordings in healthy subjects (n = 125). We hypothesized transdiagnostic GABA_A deficits across all the clinical groups and diagnosis-specific GABA_B alterations in mania (increased) and OCD (decreased). After controlling for potential confounder variables (gender, education, benzodiazepine prescription, and motor threshold) using the ANCOVA, we observed no significant group difference in SICI (F = 1.04, P = 0.38), but a significant group effect in LICI (F = 16.29, P < 0.001) and CSP (F = 3.02, P = 0.018). Post-hoc analyses revealed that LICI was significantly reduced in OCD but increased in mania and schizophrenia with reference to the healthy group. Similarly, CSP was significantly reduced in OCD and depression groups as compared to the reference group. We observed that LICI and CSP, both followed similar descending gradients from mania through schizophrenia and depression to OCD; with significant elevation in mania, and reduction in depression and OCD, as compared to the healthy group. This pattern of GABA_B-mediated cortical inhibition aberrations needs independent validation as potential state-markers of distinct clinical categories.

Clinical Research Center for Neuromodulation in Psychiatry: A Multi-Center Initiative to Advance Interventional Psychiatry in India

This manuscript introduces a unique program titled "Clinical Research Center (CRC) for Neuromodulation in Psychiatry" supported by the prestigious CRC/Public Health Research Center Grant of the DBT Wellcome Trust India Alliance. This multi-institutional research program will be led by NIMHANS (Bengaluru) in collaboration with the Central Institute of Psychiatry (Ranchi), and Kasturba Medical College (Manipal). The goal of this CRC is in alignment with the editorial titled "Need to Develop "Interventional Psychiatry" as a subspecialty in India" published in the January 2020 issue of the Indian Journal of Psychiatry. The translational research studies and the training programs envisaged through this center will facilitate the development of cost-effective, advanced interventional psychiatry tailored to resource-limited Indian clinical settings and similar other countries as well.

Neurotherapeutics for Attention Deficit/Hyperactivity Disorder (ADHD): A Review

This review focuses on the evidence for neurotherapeutics for attention deficit/hyperactivity disorder (ADHD). EEG-neurofeedback has been tested for about 45 years, with the latest meta-analyses of randomised controlled trials (RCT) showing small/medium effects compared to non-active controls only. Three small studies piloted neurofeedback of frontal activations in ADHD using functional magnetic resonance imaging or near-infrared spectroscopy, finding no superior effects over control conditions. Brain stimulation has been applied to ADHD using mostly repetitive transcranial magnetic and direct current stimulation (rTMS/tDCS). rTMS has shown mostly negative findings on improving cognition or symptoms. Meta-analyses of tDCS studies targeting mostly the dorsolateral prefrontal cortex show small effects on cognitive improvements with only two out of three studies showing clinical improvements. Trigeminal nerve stimulation has been shown to improve ADHD symptoms with medium effect in one RCT. Modern neurotherapeutics are attractive due to their relative safety and potential neuroplastic effects. However, they need to be thoroughly tested for clinical and cognitive efficacy across settings and beyond core symptoms and for their potential for individualised treatment.

[Cognitive control in the research domain criteria system: clinical implications for auditory verbal hallucinations]

Cognitive control (CC) represents one of six constructs within the research domain criteria (RDoC) domain of cognitive systems, which can be examined using different units of analyses (from genetic and molecular mechanisms to neural circuits and self-reports). The CC is defined as the ability to execute top-down control over task-specific processes and to coordinate thought and actions to achieve a specific goal. Within the field of cognitive neuroscience, recent studies provided important findings about central neuronal components of the CC network and the interactions with other relevant functional systems. In the development and maintenance of distinct psychiatrically relevant symptoms, such as auditory verbal hallucinations (AVH) or hearing voices, dysfunctional CC is thought to play an essential transdiagnostic role. This selective literature review addresses the specific and clinically relevant question of the extent to which the RDoC construct of CC has been incorporated into studies investigating the neurobiological mechanisms of AVH. In addition, an overview of the extent to which findings exploring the underlying mechanisms have been transferred into daily clinical routine is provided. Furthermore, future research perspectives and therapeutic approaches are discussed. Based on currently preferred neurobiological models of AVH, nonpharmacological strategies, such as brain stimulation techniques and psychotherapy can be derived. Further research perspectives arise in the field of interventional studies oriented towards the RDoC matrix.

A Review of Studies Leveraging Multimodal TMS-fMRI Applications in the Pathophysiology and Treatment of Schizophrenia

The current review provides an overview of the existing literature on multimodal transcranial magnetic stimulation, and functional magnetic resonance imaging (TMS/fMRI) studies in individuals with schizophrenia and discusses potential future avenues related to the same. Multimodal studies investigating pathophysiology have explored the role of abnormal thalamic reactivity and have provided further evidence supporting the hypothesis of schizophrenia as a disorder of aberrant connectivity and cortical plasticity. Among studies examining treatment, low-frequency rTMS for the management of persistent auditory verbal hallucinations (AVH) was the most studied. While multimodal TMS/fMRI studies have provided evidence of involvement of local speech-related and distal networks on stimulation of the left temporoparietal cortex, current evidence does not suggest the superiority of fMRI based neuronavigation over conventional methods or of active rTMS over sham for treatment of AVH. Apart from these, preliminary findings suggest a role of rTMS in treating deficits in neurocognition, social cognition, and self-agency. However, most of these studies have only examined medication-resistant symptoms and have methodological concerns arising from small sample sizes and short treatment protocols. That being said, combining TMS with fMRI appears to be a promising approach toward elucidating the pathophysiology of schizophrenia and could also open up a possibility toward developing personalized treatment for its persistent and debilitating symptoms.

Examining and Modulating Neural Circuits in Psychiatric Disorders With Transcranial Magnetic Stimulation and Electroencephalography: Present Practices and Future Developments

Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation technique uniquely equipped to both examine and modulate neural systems and related cognitive and behavioral functions in humans. As an examination tool, TMS can be used in combination with EEG (TMS-EEG) to elucidate directly, objectively, and noninvasively the intrinsic properties of a specific cortical region, including excitation, inhibition, reactivity, and oscillatory activity, irrespective of the individual's conscious effort. Additionally, when applied in repetitive patterns, TMS has been shown to modulate brain networks in healthy individuals, as well as ameliorate symptoms in individuals with psychiatric disorders. The key role of TMS in assessing and modulating neural dysfunctions and associated clinical and cognitive deficits in psychiatric populations is therefore becoming increasingly evident. In this article, the authors review TMS-EEG studies in schizophrenia and mood disorders, as most TMS-EEG studies to date have focused on individuals with these disorders. The authors present the evidence on the efficacy of repetitive TMS (rTMS) and theta burst stimulation (TBS), when targeting specific cortical areas, in modulating neural circuits and ameliorating symptoms and abnormal behaviors in individuals with psychiatric disorders, especially when informed by resting-state and task-related neuroimaging measures. Examples of how the combination of TMS-EEG assessments and rTMS and TBS paradigms can be utilized to both characterize and modulate neural circuit alterations in individuals with psychiatric disorders are also provided. This approach, along with the evaluation of the behavioral effects of TMS-related neuromodulation, has the potential to lead to the development of more effective and personalized interventions for individuals with psychiatric disorders.

The Role of White Matter Dysfunction and Leukoencephalopathy/Leukodystrophy Genes in the Aetiology of Frontotemporal Dementias: Implications for Novel Approaches to Therapeutics

Frontotemporal dementia (FTD) is a common cause of presenile dementia and is characterized by behavioural and/or language changes and progressive cognitive deficits. Genetics is an important component in the aetiology of FTD, with positive family history of dementia reported for 40% of cases. This review synthesizes current knowledge of the known major FTD genes, including C9orf72 (chromosome 9 open reading frame 72), MAPT (microtubule-associated protein tau) and GRN (granulin), and their impact on neuronal and glial pathology. Further, evidence for white matter dysfunction in the aetiology of FTD and the clinical, neuroimaging and genetic overlap between FTD and leukodystrophy/leukoencephalopathy are discussed. The review highlights the role of common variants and mutations in genes such as CSF1R (colony-stimulating factor 1 receptor), CYP27A1 (cytochrome P450 family 27 subfamily A member 1), TREM2 (triggering receptor expressed on myeloid cells 2) and TMEM106B (transmembrane protein 106B) that play an integral role in microglia and oligodendrocyte function. Finally, pharmacological and non-pharmacological approaches for enhancing remyelination are discussed in terms of future treatments of FTD.

Frontal-striatal connectivity and positive symptoms of schizophrenia: implications for the mechanistic basis of prefrontal rTMS

Repetitive transcranial magnetic stimulation (rTMS), when applied to left dorsolateral prefrontal cortex (LDLPFC), reduces negative symptoms of schizophrenia, but has no effect on positive symptoms. In a small number of cases, it appears to worsen the severity of positive symptoms. It has been hypothesized that high-frequency rTMS of the LDLPFC might increase the dopaminergic neurotransmission by driving the activity of the left striatum in the basal ganglia (LSTR)-increasing striatal dopaminergic activity. This hypothesis relies on the assumption that either the frontal-striatal connection or the intrinsic frontal and/or striatal connections covary with the severity of positive symptoms. The current work aimed to evaluate this assumption by studying the association between positive and negative symptoms severity and the effective connectivity within the frontal and striatal network using dynamic causal modeling of resting state fMRI in a sample of 19 first episode psychosis subjects. We found that the total score of positive symptoms of schizophrenia is strongly associated with the frontostriatal circuitry. Stronger intrinsic inhibitory tone of LDLPFC and LSTR, as well as decreased bidirectional excitatory influence between the LDLPFC and the LSTR is related to the severity of positive symptoms, especially delusions. We interpret that an increase in striatal dopaminergic tone that underlies positive symptoms is likely associated with increased prefrontal inhibitory tone, strengthening the frontostriatal 'brake'. Furthermore, based on our model, we propose that lessening of positive symptoms could be achieved by means of continuous theta-burst or low-frequency (1 Hz) rTMS of the prefrontal area.

Cognitive Enhancing Effect of High-Frequency Neuronavigated rTMS in Chronic Schizophrenia Patients With Predominant Negative Symptoms: A Double-Blind Controlled 32-Week Follow-up Study

Accumulating studies have shown that high-frequency (HF) repetitive transcranial magnetic stimulation (rTMS) may improve cognitive dysfunction of the patients with schizophrenia (SCZ), but with inconsistent results. The present study aims to assess the efficacy of different frequencies of neuronavigated rTMS in ameliorating cognitive impairments and alleviating the psychotic symptoms. A total of 120 patients were randomly assigned to 3 groups: 20 Hz rTMS (n = 40), 10 Hz rTMS (n = 40), or sham stimulation (n = 40) for 8 weeks, and then followed up at week 32. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) was performed to assess the cognitive functions of the patients at baseline, at the end of week 8, and week 32 follow-up. Psychotic symptoms were assessed with the Positive and Negative Syndrome Scale (PANSS) at baseline and at the end of week 2, week 4, week 6, week 8, and week 32 follow-up. Our results demonstrated that 20 Hz rTMS treatment produced an effective therapeutic benefit on immediate memory of patients with chronic SCZ at week 8, but not in the 10 Hz group. Interestingly, both 10 Hz and 20 Hz rTMS treatments produced delayed effects on cognitive functions at the 6-month follow-up. Moreover, in both 10 Hz rTMS and 20 Hz rTMS, the improvements in RBANS total score were positively correlated with the reduction of PANSS positive subscore at the 6-month follow-up. Stepwise regression analysis identified that the visuospatial/constructional index, immediate memory index, and prolactin at baseline were predictors for the improvement of cognitive impairments in the patients. Our results suggest that add-on HF rTMS could be an effective treatment for cognitive impairments in patients with chronic SCZ, with a delayed effect. Trial registration: clinicaltrials.gov identifier-NCT03774927.

Prefrontal cortex alterations in glia gene expression in schizophrenia with and without suicide

BACKGROUND

Patients with schizophrenia (SCZ) run a lifelong risk of suicide. Alterations in glia activities in the prefrontal cortex (PFC) have been reported in relation to suicide in patients with SCZ. While immune processes in the CNS have been related to the susceptibility and course of SCZ, there are hardly any direct comparisons between individuals with SCZ, both those who died of natural causes and those that committed suicide, and healthy controls.

MATERIALS AND METHODS

We compared mRNA expression using real time qPCR of 16 glia-related genes in the dorsal lateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC) between 35 patients with SCZ (7 suicide completers and 28 patients who died of natural causes) and 34 well-matched controls without psychiatric or neurological diseases.

RESULTS

We found an increased expression of the astrocytic gene aldehyde dehydrogenase-1 family member L1 (ALDH1L1) mRNA, a marker involved in dopaminergic activity, in SCZ versus controls. Excluding individuals with SCZ that committed suicide resulted in an elevated expression in the DLPFC of both ALDH1L1 and glutamine synthetase (GS) genes in patients with SCZ, compared to suicide completers and non-psychiatric controls. Regarding microglia genes: in the ACC, homeostatic markers such as chemokine (C-X3-C motif) ligand 1 (CX3CR1) mRNA expression was increased in SCZ without suicide as compared to suicide completers, while no change was found when compared to controls. Another, purinergic receptor 12 (P2RY12) mRNA was exclusively elevated in the ACC of suicide completers, compared to either other group. Triggering receptor expressed on myeloid cells 2 (TREM2) expression, which maintains microglial metabolism, was reduced in non-suicide patients with SCZ, compared to suicide victims and control subjects.

CONCLUSIONS

Differential changes are found in astrocyte and microglia genes in the PFC subregions in relation to SCZ and suicide, indicating possible disturbances of glia homeostasis in these conditions.