Discovering the individual brain: brain stimulation in psychiatry : Editorial I to the supplement from the 2nd European conference on brain stimulation in psychiatry

Incisionless MR-guided focused ultrasound: technical considerations and current therapeutic approaches in psychiatric disorders

INTRODUCTION

MR-guided focused ultrasound operating at higher intensities have been reported to effectively and precisely ablate deeper brain structures like the basal ganglia or the thalamic nuclei for the treatment of refractory movement disorders, neuropathic pain and most recently neuropsychiatric disorders, while low-intensity focused ultrasound represents an approach promoting mechanical blood-brain-barrier opening and neuromodulation. This narrative review summarizes the technical development and the therapeutic potential of incisionless MRgFUS in order to treat neuropsychiatric disorders.

AREAS COVERED

A narrative review of clinical trials assessing the safety and efficacy of MRgFUS. A literature review was performed using the following search terms: MR-guided focused ultrasound, psychiatric disorders, noninvasive and invasive brain modulation/stimulation techniques.

EXPERT OPINION

MRgFUS ablation is under clinical investigation (unblinded study design) for obsessive-compulsive disorders (OCDs) [capsulotomy; ALIC] and depression/anxiety disorders [capsulotomy] and has demonstrated an improvement in OCD and depression, although of preliminary character. Low-intensity ultrasound applications have been explored in Alzheimer´s disease (phase 1 study) and healthy subjects. Currently, limited evidence hinders comparison and selection between MRgFUS and noninvasive/invasive brain modulation therapies. However, comparative, sham-controlled trials are needed to reexamine the preliminary findings for the treatment of psychiatric disorders.

The influence of personality on the effect of iTBS after being stressed on cortisol secretion

Over the last years, individualization of repetitive Transcranial Magnetic Stimulation (rTMS) parameters has been a focus of attention in the field of non-invasive stimulation. It has been proposed that in stress-related disorders personality characteristics may influence the clinical outcome of rTMS. However, the underlying physiological mechanisms as to how personality may affect the rTMS response to stress remains to be clarified. In this sham-controlled crossover study, after being stressed by the Trier Social Stress Test, 38 healthy females received two sessions of intermittent theta burst stimulation (iTBS) applied to the left dorsolateral prefrontal cortex. To take possible personality influences into account, they also completed the Temperament and Character Inventory. Mood and salivary cortisol were assessed throughout the experimental protocol. Overall, two iTBS sessions did not significantly alter mood or influenced cortisol secretion. When taking into account personality features, higher scores on the character dimension Cooperativeness was related to decreased cortisol output, only when active iTBS was administered after the social stressor. In line with other studies, personality features such as the character dimension Cooperativeness may be of particular interest to explain individual neurobiological responses to neurostimulation.

Repetitive transcranial magnetic stimulation treatment for depressive disorders: current knowledge and future directions

PURPOSE OF REVIEW

After three decades of clinical research on repetitive transcranial magnetic stimulation (rTMS), major depressive disorder (MDD) has proven to be the primary field of application. MDD poses a major challenge for health systems worldwide, emphasizing the need for improving clinical efficacy of existing rTMS applications and promoting the development of novel evidence-based rTMS treatment approaches.

RECENT FINDINGS

Several promising new avenues have been proposed: novel stimulation patterns, targets, and coils; combinatory treatments and maintenance; and personalization and stratification of rTMS parameters, and treatment of subpopulations.

SUMMARY

This opinion review summarizes current knowledge in the field and addresses the future direction of rTMS treatment in MDD, facilitating the establishment of this clinical intervention method as a standard treatment option and continuing to improve response and remission rates, and take the necessary steps to personalize rTMS-based treatment approaches.

[Brain stimulation for the selective treatment of schizophrenia symptom domains : Non-invasive and invasive concepts]

Given that one third of patients with schizophrenia (SZ) only show limited response to established treatments, alternative therapeutic strategies such as non-invasive/invasive brain stimulation approaches have emerged as an adjunctive treatment option for distinct SZ symptom domains (e.g. acoustic hallucinations, negative/positive symptoms and cognitive impairment). Taking comparative interventional studies and standardized technical parameters into consideration, current meta-analyses indicate that adjunctive electroconvulsive therapy, repetitive transcranial magnetic stimulation and transcranial direct current stimulation have a positive effect. Invasive deep brain stimulation and MR-guided ultrasound brain ablation procedures represent treatment modalities that are currently being clinically tested. Complementary pre-interventional screening approaches (e.g. electrophysiology, neuroimaging and molecular inflammatory profiling) have been recommended in order to identify symptom-tailored predictive measures for diagnosis and treatment.

Antidepressant outcomes of high-frequency repetitive transcranial magnetic stimulation (rTMS) with F8-coil and deep transcranial magnetic stimulation (DTMS) with H1-coil in major depression: a systematic review and meta-analysis

BACKGROUND

The current study aims to systematically assess and compare the antidepressant outcomes of repetitive transcranial magnetic stimulation (rTMS) with the figure-of-eight (F8)-coil and deep transcranial magnetic stimulation (DTMS) with the H1-coil in studies matched on stimulation frequency in unipolar major depressive disorder (MDD).

METHODS

Electronic search of Medline and PsycInfo identified 19 studies with stimulation frequency of 18-20 Hz using F8-coil (k = 8 randomised sham-controlled trials, RCTs, k = 3 open-label; n = 168 patients) or H1-coil (k = 1 RCT, k = 7 open-label; n = 200). Depression severity (the primary outcome) and response/remission rates (the secondary outcomes) were assessed at session 10.

RESULTS

Effects pooled with random-effects meta-analysis showed a large reduction in depression severity, 29% response, and 15% remission rates after 10 sessions of active stimulation with either coil relative to baseline. Reduction in depression severity was greater in studies with younger patients using either coil. The comparison between coils showed a larger reduction in depression severity in H1-coil vs. F8-coil studies (independent of the study design or the concurrent pharmacotherapy) and a trend towards higher remission rates in F8-coil vs. H1-coils studies. These effects are based on a low volume of studies, are not controlled for placebo, and may not be clinically-relevant. The stimulation protocols differed systematically because stimulation was more focal but less intense (80-110% of the resting motor threshold, MT) in the F8-coil studies and less focal but more intense (120% MT) in the H1-coil studies. Two seizures occurred in the H1-coil studies relative to none in the F8-coil studies.

CONCLUSION

When matched on frequency, the higher-intensity and less focal stimulation with the H1-coil reduces depression more than the lower-intensity and more focal stimulation with the F8-coil. Head-to-head trials should compare the antidepressant outcomes of F8-coil and H1-coil to identify the most optimal stimulation protocols for acute and longer-lasting efficacy.

Accelerated rTMS: A Potential Treatment to Alleviate Refractory Depression

Three decades of clinical research on repetitive transcranial magnetic stimulation (rTMS) has yielded one clear treatment indication in psychiatry for major depression disorder (MDD). Although the clinical response equals the standard treatment algorithms, the effect sizes on the beneficial outcome remain rather modest. Over the last couple of years, to improve the efficacy in resistant depression, two new avenues have been developed: personalization and intensifying rTMS treatment. For the latter, we retrospectively compared accelerated high-frequency rTMS (arTMS) with accelerated intermittent theta burst stimulation (aiTBS) in the refractory depressed state. Although the clinical efficacy was not significantly different between both protocols, our observations substantiate the potential of the accelerated stimulation to shorten the treatment duration from the depressed state to the response state. Any time gain from the depressed state to the recovered state is in the patients’ interest.