Pediatric Neuromodulation Comes of Age

Sequential bilateral accelerated theta burst stimulation in adolescents with suicidal ideation associated with major depressive disorder: Protocol for a randomized controlled trial

BACKGROUND

Suicide is a leading cause of death in adolescents worldwide. Previous research findings suggest that suicidal adolescents with depression have pathophysiological dorsolateral prefrontal cortex (DLPFC) deficits in γ-aminobutyric acid neurotransmission. Interventions with transcranial magnetic stimulation (TMS) directly address these underlying pathophysiological deficits in the prefrontal cortex. Theta burst stimulation (TBS) is newer dosing approach for TMS. Accelerated TBS (aTBS) involves administering multiple sessions of TMS daily as this dosing may be more efficient, tolerable, and rapid acting than standard TMS.

MATERIALS AND METHODS

This is a randomized, double-blind, sham-controlled trial of sequential bilateral aTBS in adolescents with major depressive disorder (MDD) and suicidal ideation. Three sessions are administered daily for 10 days. During each session, continuous TBS is administered first to the right DPFC, in which 1,800 pulses are delivered continuously over 120 seconds. Then intermittent TBS is applied to the left DPFC, in which 1,800 pulses are delivered in 2-second bursts and repeated every 10 seconds for 570 seconds. The TBS parameters were adopted from prior research, with 3-pulse, 50-Hz bursts given every 200 ms (at 5 Hz) with an intensity of 80% active motor threshold. The comparison group will receive 3 daily sessions of bilateral sham TBS treatment for 10 days. All participants will receive the standard of care for patients with depression and suicidal ideation including daily psychotherapeutic skill sessions. Long-interval intracortical inhibition (LICI) biomarkers will be measured before and after treatment. Exploratory measures will be collected with TMS and electroencephalography for biomarker development.

DISCUSSION

This is the first known randomized controlled trial to examine the efficacy of sequential bilateral aTBS for treating suicidal ideation in adolescents with MDD. Results from this study will also provide opportunities to further understand the neurophysiological and molecular mechanisms of suicidal ideation in adolescents.

TRIAL REGISTRATION

Investigational device exemption (IDE) Number: G200220, ClinicalTrials.gov (ID: NCT04701840). Registered August 6, 2020. https://clinicaltrials.gov/ct2/show/NCT04502758?term=NCT04701840&draw=2&rank=1.

Neurostructural Differences in Adolescents With Treatment-Resistant Depression and Treatment Effects of Transcranial Magnetic Stimulation

BACKGROUND

Despite its morbidity and mortality, the neurobiology of treatment-resistant depression (TRD) in adolescents and the impact of treatment on this neurobiology is poorly understood.

METHODS

Using automatic segmentation in FreeSurfer, we examined brain magnetic resonance imaging baseline volumetric differences among healthy adolescents (n = 30), adolescents with major depressive disorder (MDD) (n = 19), and adolescents with TRD (n = 34) based on objective antidepressant treatment rating criteria. A pooled subsample of adolescents with TRD were treated with 6 weeks of active (n = 18) or sham (n = 7) 10-Hz transcranial magnetic stimulation (TMS) applied to the left dorsolateral prefrontal cortex. Ten of the adolescents treated with active TMS were part of an open-label trial. The other adolescents treated with active (n = 8) or sham (n = 7) were participants from a randomized controlled trial.

RESULTS

Adolescents with TRD and adolescents with MDD had decreased total amygdala (TRD and MDD: -5%, P = .032) and caudal anterior cingulate cortex volumes (TRD: -3%, P = .030; MDD: -.03%, P = .041) compared with healthy adolescents. Six weeks of active TMS increased total amygdala volumes (+4%, P < .001) and the volume of the stimulated left dorsolateral prefrontal cortex (+.4%, P = .026) in adolescents with TRD.

CONCLUSIONS

Amygdala volumes were reduced in this sample of adolescents with MDD and TRD. TMS may normalize this volumetric finding, raising the possibility that TMS has neurostructural frontolimbic effects in adolescents with TRD. TMS also appears to have positive effects proximal to the site of stimulation.

A Systematic Review of the Safety and Tolerability of Theta Burst Stimulation in Children and Adolescents

OBJECTIVES

Theta burst stimulation (TBS) is often used in clinical practice and research protocols for adults with neuropsychiatric disorders. There are substantial knowledge gaps related to the application of TBS in children and adolescents. This systematic review examined the safety and tolerability of TBS in children and adolescents.

MATERIALS AND METHODS

A systematic review of human TBS studies in children and adolescents was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The following inclusion criteria were applied: 1) articles in English language only; 2) studies that included child and adolescent participants (up to 21 years of age); 3) studies that administered intermittent TBS or continuous TBS or both to participants; 4) studies that had an outcome measure; and 5) availability of full text material. The primary outcome measures were tolerability and safety. When feasible, the clinical effects were reviewed.

RESULTS

Twenty relevant articles met the criteria for inclusion. The reported adverse events were mild and similar to what is noted in adult studies. The most common symptom was headache. One case report described a seizure induced by TBS. Collectively, the studies were heterogeneous but the methodologic quality of randomized trials was high.

CONCLUSIONS

TBS interventions in children may have similar safety, tolerability, and feasibility as compared to adults. However, long-term, follow-up studies of TBS are lacking. Future dose-ranging studies with systematic assessment of adverse events will be important in the translation of findings with TBS from adults to youth.

A Preclinical Study of Standard Versus Accelerated Transcranial Magnetic Stimulation for Depression in Adolescents

Objective: Ongoing studies are focused on adapting transcranial magnetic stimulation (TMS) for the treatment of major depressive disorder in adolescent humans. Most protocols in adolescent humans to date have delivered daily 10 Hz prefrontal stimulation with mixed results. Novel TMS dosing strategies such as accelerated TMS have recently been considered. There are knowledge gaps related to the potential clinical and pragmatic advantages of accelerated TMS. This pilot study compared the behavioral effects of a standard daily and accelerated low-intensity TMS (LI-TMS) protocol in an adolescent murine model of depression. Methods: Male adolescent Sprague Dawley rats were placed in transparent plexiglass tubes for 2.5 hours daily for 13 days as part of a study to validate the chronic restraint stress (CRS) protocol. Rats subsequently received 10 minutes of active or sham 10 Hz LI-TMS daily for 2 weeks (standard) or three times daily for 1 week (accelerated). Behavior was assessed using the elevated plus maze and forced swim test (FST). Hippocampal neurogenesis was assessed by injection of the thymidine analogue 5-ethynyl-2'-deoxyuridine at the end of LI-TMS treatment (2 weeks standard, 1 week accelerated), followed by postmortem histological analysis. Results: There were no significant differences in behavioral outcomes among animals receiving once-daily sham or active LI-TMS treatment. However, animals treated with accelerated LI-TMS demonstrated significant improvements in behavioral outcomes compared with sham treatment. Specifically, animals receiving active accelerated treatment showed greater latency to the first immobility behavior (p < 0.05; active: 130 ± 46 seconds; sham: 54 ± 39 seconds) and increased climbing behaviors (p < 0.05; active: 16 ± 5; sham: 9 ± 5) during FST. There were no changes in hippocampal neurogenesis nor any evidence of cell death in histological sections. Conclusions: An accelerated LI-TMS protocol outperformed the standard (once-daily) protocol in adolescent male animals with depression-like behaviors induced by CRS and was not accompanied by any toxicity or tolerability concerns. These preliminary findings support the speculation that novel TMS dosing strategies should be studied in adolescent humans and will inform future clinical protocols.

Left prefrontal transcranial magnetic stimulation for treatment-resistant depression in adolescents: a double-blind, randomized, sham-controlled trial

Treatment-resistant depression (TRD) is prevalent and associated with a substantial psychosocial burden and mortality. There are few prior studies of interventions for TRD in adolescents. This was the largest study to date examining the feasibility, safety, and efficacy of 10-Hz transcranial magnetic stimulation (TMS) for adolescents with TRD. Adolescents with TRD (aged 12-21 years) were enrolled in a randomized, sham-controlled trial of TMS across 13 sites. Treatment resistance was defined as an antidepressant treatment record level of 1 to 4 in a current episode of depression. Intention-to-treat patients (n = 103) included those randomly assigned to active NeuroStar TMS monotherapy (n = 48) or sham TMS (n = 55) for 30 daily treatments over 6 weeks. The primary outcome measure was change in the Hamilton Depression Rating Scale (HAM-D-24) score. After 6 weeks of blinded treatment, improvement in the least-squares mean (SE) HAM-D-24 scores were similar between the active (-11.1 [2.03]) and sham groups (-10.6 [2.00]; P = 0.8; difference [95% CI], - 0.5 [-4.2 to 3.3]). Response rates were 41.7% in the active group and 36.4% in the sham group (P = 0.6). Remission rates were 29.2% in the active group and 29.0% in the sham group (P = 0.95). There were no new tolerability or safety signals in adolescents. Although TMS treatment produced a clinically meaningful change in depressive symptom severity, this did not differ from sham treatment. Future studies should focus on strategies to reduce the placebo response and examine the optimal dosing of TMS for adolescents with TRD.

Deep transcranial magnetic stimulation for obsessive compulsive disorder

INTRODUCTION

Obsessive-compulsive disorder (OCD) is a common psychiatric disorder that can be chronic and debilitating if not properly treated. Current first-line treatments for OCD include cognitive-behavioral therapy with exposure and response prevention and serotonin uptake inhibitor medications; however, these therapies are not effective for all individuals.

AREAS COVERED

Deep transcranial magnetic stimulation (dTMS) has been hypothesized to be an effective alternative for individuals with treatment-resistant OCD. dTMS has thought to be favorable due to its low side effect profile and its minimally invasive nature.

EXPERT OPINION

This review evaluates the current research on effectiveness of dTMS therapy for individuals with treatment-resistant OCD. This review also investigates shortcomings in current dTMS research and the hypothesized future of dTMS therapy.

Depression in Medically Ill Children and Adolescents

Depression risk is 2 to 3 times higher in medically ill youth compared with the general pediatric population. The relationship between medical illness and depression is bidirectional with significant contributions from psychological, developmental, illness-related, familial, and treatment factors. This article discusses the presentation, early identification, evaluation, and management of depression in medically ill youth and identifies specific risk factors and reviewing selected medical illness-specific considerations.

Eternal sunshine of the neuromodulated mind: Altering fear memories through neuromodulation

Anxiety disorders pose one of the greatest threats to mental health. Modern treatment methods exist but are hindered by relapse, toxicity, and low efficacy. The use of neuromodulation to treat anxiety disorders has shown promising results, yet its underpinning mechanisms remain poorly understood. In this review, we make the case for further development of neuromodulation techniques to alter fear memories, with particular regard to future clinical applications in treating anxiety disorders. We start by briefly summarizing the neural circuitry of fear while identifying the pros and cons of possible neuromodulation targets. We then highlight recent advances in neuromodulation techniques that have been used to alter fear memories. Next, we apply a novel network-based approach to elucidate possible mechanisms of neuromodulation which may disrupt the consolidation of fear memory. Finally, we emphasize the need for more systematic neuromodulation studies on animal models and the developing brain. Overall, we aim to provide an integrated framework for future action, identifying key research priorities that must be addressed before effective neuromodulation-based treatments can be developed for practical use.

Transcranial Magnetic Stimulation for Adolescent Depression

Adolescent depression is a substantial global public health problem that contributes to academic failure, occupational impairment, deficits in social functioning, substance use disorders, teen pregnancy, and completed suicide. Existing treatment options often have suboptimal results and uncertain safety profiles. Transcranial magnetic stimulation may be a promising, brain-based intervention for adolescents with depression. Existing work has methodological weaknesses, and larger, neurodevelopmentally informed studies are urgently needed. Treatment with transcranial magnetic stimulation may modulate cortical GABAergic and glutamatergic imbalances. Future study will inform dosing approaches for TMS based on GABAergic and glutamatergic biomarkers.

Neuroethics of Neuromodulation: An Update

This article reviews neuroethics issues that arise with the development, translation, and use of technologies for neuromodulation. Three electronic databases (PubMed, Embase, and PhilPapers) were searched for relevant articles published between 1/1/16 - 6/26/18. We focus on pressing ethical issues related to the use of deep brain stimulation (DBS), adaptive DBS (aDBS), transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and associated technologies. The neuroethics issues we address include privacy, continued access to devices, device removal, do-it-yourself neurostimulation, neuroenhancement, media coverage, changes in personal identity and agency, informed consent, and neuromodulation in minors. This review should be of assistance to a variety of stakeholders, including neurotechnology developers, as they make important decisions that will drive these neurotechnologies.