Neuroimaging Effects of 1 Hz Right Temporoparietal rTMS on Normal Auditory Processing: Implications for Clinical Hallucination Treatment Paradigms

Efficacy and acceptability of brain stimulation for anxiety disorders, OCD, and PTSD: A systematic review and network meta-analysis of randomized controlled trials

BACKGROUND

The present study aimed to conduct a systematic review and network meta-analysis to investigate the efficacy and acceptability of brain stimulation techniques (BSTs) for anxiety disorders, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD).

METHODS

A comprehensive search was performed in Embase, PubMed, Web of Science, PsycINFO, Cochrane, ClinicalTrials.gov and HowNet databases for studies published before September 10, 2023. Randomized clinical trials that involved deep brain stimulation (DBS), electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), sham therapy, or health control were included for analysis. The primary outcome was efficacy, while acceptability was considered as a secondary outcome.

RESULTS

The sample consisted of 1333 patients with various anxiety disorders including social anxiety disorder, general anxiety disorder, panic disorder, social panic, obsessive-compulsive disorder, post-traumatic stress disorder, and agoraphobia, recruited from 41 trials with 86 treatment arms. Network meta-analysis showed that some BSTs had higher efficacy compared to controls, including DBS, ECT, cathodal tDCS, high-frequency rTMS (hf-rTMS), anodal tDCS, and low-frequency rTMS (lf-rTMS). Furthermore, hf-rTMS, lf-rTMS, and ECT had high acceptability in terms of odds ratio (OR).

LIMITATIONS

This study has limitations, including a focus on specific types of brain stimulation for anxiety disorders, OCD and PTSD and not considering factors like stimulation parameters. Future research should explore a broader range of technologies and parameters across various psychiatric and neurological conditions.

CONCLUSION

The study results suggest that BSTs are effective treatments for anxiety disorders, OCD and PTSD; lf-rTMS may be considered as the most promising option.

Impact of low-frequency rTMS on functional connectivity of the dentate nucleus subdomains in schizophrenia patients with auditory verbal hallucination

Despite low-frequency repetitive transcranial magnetic stimulation (rTMS) is effective in treating schizophrenia patients with auditory verbal hallucinations (AVH), the underlying neural mechanisms of the effect still need to be clarified. Using the cerebellar dentate nucleus (DN) subdomain (dorsal and versal DN) as seeds, the present study investigated resting state functional connectivity (FC) alternations of the seeds with the whole brain and their associations with clinical responses in schizophrenia patients with AVH receiving 1 Hz rTMS treatment. The results showed that the rTMS treatment improved the psychiatric symptoms (e.g., AVH and positive symptoms) and certain neurocognitive functions (e.g., visual learning and verbal learning) in the patients. In addition, the patients at baseline showed increased FC between the DN subdomains and temporal lobes (e.g., right superior temporal gyrus and right middle temporal gyrus) and decreased FC between the DN subdomains and the left superior frontal gyrus, right postcentral gyrus, left supramarginal gyrus and regional cerebellum (e.g., lobule 4-5) compared to controls. Furthermore, these abnormal DN subdomain connectivity patterns did not persist and decreased FC of DN subdomains with cerebellum lobule 4-5 were reversed in patients after rTMS treatment. Linear regression analysis showed that the FC difference values of DN subdomains with the temporal lobes, supramarginal gyrus and cerebellum 4-5 between the patients at baseline and posttreatment were associated with clinical improvements (e.g., AVH and verbal learning) after rTMS treatment. The results suggested that rTMS treatment may modulate the neural circuits of the DN subdomains and hint to underlying neural mechanisms for low-frequency rTMS treating schizophrenia with AVH.

Repetitive Transcranial Magnetic Stimulation Modulates Frontal and Temporal Time-Varying EEG Network in Generalized Anxiety Disorder: A Pilot Study

Generalized Anxiety Disorder (GAD) is a highly prevalent yet poorly understood chronic mental disorder. Previous studies have associated GAD with excessive activation of the right dorsolateral prefrontal cortex (DLPFC). This study aimed to investigate the effect of low-frequency repetitive transcranial magnetic stimulation (repetitive TMS, rTMS) targeting the right DLPFC on clinical symptoms and TMS-evoked time-varying brain network connectivity in patients with GAD. Eleven patients with GAD received 1 Hz rTMS treatment targeting the right DLPFC for 10 days. The severity of the clinical symptoms was evaluated using the Hamilton Anxiety Scale (HAMA) and the Hamilton Depression Scale (HAMD) at baseline, right after treatment, and at the one-month follow-up. Co-registration of single-pulse TMS (targeting the right DLPFC) and electroencephalography (TMS-EEG) was performed pre- and post-treatment in these patients and 11 healthy controls. Time-varying brain network connectivity was analyzed using the adaptive directed transfer function. The scores of HAMA and HAMD significantly decreased after low-frequency rTMS treatment, and these improvements in ratings remained at the one-month follow-up. Analyses of the time-varying EEG network in the healthy controls showed a continuous weakened connection information outflow in the left frontal and mid-temporal regions. Compared with the healthy controls, the patients with GAD showed weakened connection information outflow in the left frontal pole and the posterior temporal pole at baseline. After 10-day rTMS treatment, the network patterns showed weakened connection information outflow in the left frontal and temporal regions. The time-varying EEG network changes induced by TMS perturbation targeting right DLPFC in patients with GAD were characterized by insufficient information outflow in the left frontal and temporal regions. Low-frequency rTMS targeting the right DLPFC reversed these abnormalities and improved the clinical symptoms of GAD.

Clinical neuromodulation in psychiatry: the state of the art or an art in a state?

Clinical neuromodulation began in psychiatry with electroconvulsive therapy (ECT), but in recent years several new techniques have been developed: repetitive transcranial magnetic stimulation (rTMS), transcranial direct current stimulation (tDCS), vagal nerve stimulation (VNS), trigeminal nerve stimulation (TNS) and deep brain stimulation (DBS). Each works in a different way, although the principle remains to effect therapeutic change through physically modifying brain activity. Their use in different clinical groups varies between techniques, as does their underlying evidence base. Most support currently exists for rTMS, with a more modest, but growing database for tDCS. Understandably, but problematically, most research in the other techniques has, to date, been in unmasked open trials. This article describes the mechanism of action and current evidence base for each technique, and notes the challenges facing future work in this potentially important field and new clinical avenue.

A systematic review of the effects of low-frequency repetitive transcranial magnetic stimulation on cognition

rTMS is increasingly used for a variety of neuropsychiatric conditions. There are data to support 'fast' rTMS (≥10 Hz) having some positive effects on cognitive functioning, but a dearth of research looking at any such effects of 'slow' rTMS. This question is important as cognitive dysfunction accompanies many neuropsychiatric conditions and neuromodulation that potentially enhances or hinders such functioning has important clinical consequences. To determine cognitive effects of slow (≤1 Hz) rTMS, a systematic review of randomized control trials assayed cognition in neurological, psychiatric, and healthy volunteer ≤1 Hz rTMS paradigms. Both active (fast rTMS) and placebo comparators were included. 497 Records were initially obtained; 20 met inclusion criteria for evaluation. Four major categories emerged: mood disorders; psychotic disorders; cerebrovascular accidents; and 'other' (PTSD, OCD, epilepsy, anxiety, and tinnitus). Cognitive effects were measured across several domains: attention, executive functioning, learning, and psychomotor speed. Variability of study paradigms and reporting precluded meta-analytical analysis. No statistically significant improvement or deterioration was consistently found in any cognitive domain or illness category. These data support the overall safety of rTMS in not adversely affecting cognitive functioning. There are some data indicating that rTMS might have cognitive enhancing potential, but these are too limited at this time to make any firm conclusions, and the literature is marked by considerable heterogeneity in study parameters that hinder interpretation. Greater consensus is required in future studies in cognitive markers, and particularly in reporting of protocols. Future work should evaluate the effects of rTMS on cognitive training.

Brain connectivity and auditory hallucinations: In search of novel noninvasive brain stimulation therapeutic approaches for schizophrenia

Auditory verbal hallucinations (AVH) are among the most characteristic symptoms of schizophrenia and have been linked to likely disturbances of structural and functional connectivity within frontal, temporal, parietal and subcortical networks involved in language and auditory functions. Resting-state functional magnetic resonance imaging (fMRI) has shown that alterations in the functional connectivity activity of the default-mode network (DMN) may also subtend hallucinations. Noninvasive neurostimulation techniques such as repetitive transcranial magnetic stimulation (rTMS) have the ability to modulate activity of targeted cortical sites and their associated networks, showing a high potential for modulating altered connectivity subtending schizophrenia. Notwithstanding, the clinical benefit of these approaches remains weak and variable. Further studies in the field should foster a better understanding concerning the status of networks subtending AVH and the neural impact of rTMS in relation with symptom improvement. Additionally, the identification and characterization of clinical biomarkers able to predict response to treatment would be a critical asset allowing better care for patients with schizophrenia.

Improvements in emotion regulation following repetitive transcranial magnetic stimulation for generalized anxiety disorder

Generalized anxiety disorder (GAD) is characterized by emotion regulation difficulties, which are associated with abnormalities in neural circuits encompassing fronto-limbic regions including the dorsolateral prefrontal cortex (DLPFC). The aim of this study was to determine whether DLPFC neuromodulation improves emotion regulation in patients with GAD. This is a secondary analysis from a randomized-controlled trial comparing 30 sessions of low-frequency right-sided active (n=13) versus sham (n=12, sham coil) repetitive transcranial magnetic stimulation (rTMS) at the right DLPFC in patients with GAD. Results indicated statistically significant improvements in self-reported emotion regulation difficulties at posttreatment and 3-month follow-up in the active group only. Improvements were found primarily in the domains of goal-directed behaviors and impulse control and were significantly associated with a global clinician rating of improvement. These preliminary results support rTMS as a treatment for GAD and suggest improved emotion regulation as a possible mechanism of change.

Repetitive transcranial magnetic stimulation for generalised anxiety disorder: a pilot randomised, double-blind, sham-controlled trial

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) holds promise for treating generalised anxiety disorder (GAD) but has only been studied in uncontrolled research.

AIMS

This is the first randomised controlled trial (clinicaltrials.gov: NCT01659736) to investigate the efficacy and neural correlates of rTMS in GAD.

METHOD

Twenty five participants (active n = 13; sham, n = 12) enrolled. rTMS was targeted at the right dorsolateral prefrontal cortex (DLPFC, 1 Hz, 90% resting motor threshold).

RESULTS

Response and remission rates were higher in the active v. sham groups and there were significant group × time interactions for anxiety, worry and depressive symptoms, favouring active v. sham. In addition, right DLPFC activation during a decision-making gambling task increased at post-treatment for active rTMS only, and changes in neuroactivation correlated significantly with changes in worry symptoms.

CONCLUSIONS

Findings provide preliminary evidence that rTMS may improve GAD symptoms in association with modifying neural activity in the stimulation site.

Self-harm and suicidal acts: a suitable case for treatment of impulsivity-driven behaviour with repetitive transcranial magnetic stimulation (rTMS)

SUMMARY

Suicidal thinking, self-harm and suicidal acts are common, although determining their precise prevalence is complex. Epidemiological work has identified a number of associated demographic and clinical factors, though, with the exception of past acts of self-harm, these are non-specific and weak future predictors. There is a critical need shift focus from managing 'suicidality-by-proxy' through general mental health treatments, to better understand the neuropsychology and neurophysiology of such behaviour to guide targeted interventions. The model of the cognitive control of emotion (MCCE) offers such a paradigm, with an underlying pan-diagnostic pathophysiology of a hypoactive prefrontal cortex failing to suitably inhibit an overactive threat-responding limbic system. The result is a phenotype - from any number of causative gene-environment interactions - primed to impulsively self-harm. We argue that such neural dysconnectivity is open to potential therapeutic modification from repetitive transcranial magnetic stimulation (rTMS). The current evidence base for this is undoubtedly extremely limited, but the societal and clinical burden self-harm and suicide pose warrants such investigation.

DECLARATION OF INTEREST

K.B. is the Editor of BJPsych Open, but had no editorial involvement in the review or decision process regarding this paper.

COPYRIGHT AND USAGE

© The Royal College of Psychiatrists 2015. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence.