Distinct trajectories of response to prefrontal tDCS in major depression: results from a 3-arm randomized controlled trial

Effects of transcranial direct current stimulation in children and young people with psychiatric disorders: a systematic review

Transcranial direct current stimulation (tDCS) has demonstrated benefits in adults with various psychiatric disorders, but its clinical utility in children and young people (CYP) remains unclear. This PRISMA systematic review used published and ongoing studies to examine the effects of tDCS on disorder-specific symptoms, mood and neurocognition in CYP with psychiatric disorders. We searched Medline via PubMed, Embase, PsychINFO via OVID, and Clinicaltrials.gov up to December 2022. Eligible studies involved multiple session (i.e., treatment) tDCS in CYP (≤ 25 years old) with psychiatric disorders. Two independent raters assessed the eligibility of studies and extracted data using a custom-built form. Of 33 eligible studies (participant N = 517), the majority (n = 27) reported an improvement in at least one outcome measure of disorder-specific symptoms. Few studies (n = 13) examined tDCS effects on mood and/or neurocognition, but findings were mainly positive. Overall, tDCS was well tolerated with minimal side effects. Of 11 eligible ongoing studies, many are sham-controlled RCTs (n = 9) with better blinding techniques and a larger estimated participant enrolment (M = 79.7; range 15-172) than published studies. Although encouraging, the evidence to date is insufficient to firmly conclude that tDCS can improve clinical symptoms, mood, or cognition in CYP with psychiatric disorders. Ongoing studies appear of improved methodological quality; however, future studies should broaden outcome measures to more comprehensively assess the effects of tDCS and develop dosage guidance (i.e., treatment regimens).

Trajectories of improvement with repetitive transcranial magnetic stimulation for treatment-resistant major depression in the BRIGhTMIND trial

Repetitive transcranial magnetic stimulation (rTMS) is an established non-invasive brain stimulation treatment for major depressive disorder, but there is marked inter-individual variability in response. Using latent class growth analysis with session-by-session patient global impression ratings from the recently completed BRIGhTMIND trial, we identified five distinct classes of improvement trajectory during a 20-session treatment course. This included a substantial class of patients noticing delayed onset of improvement. Contrary to prior expectations, members of a class characterised by early and continued improvement showed greatest inter-session variability in stimulated location. By relating target locations and inter-session variability to a well-studied atlas, we estimated an average of 3.0 brain networks were stimulated across the treatment course in this group, compared to 1.1 in a group that reported symptom worsening (p < 0.001, d = 0.893). If confirmed, this would suggest that deliberate targeting of multiple brain networks could be beneficial to rTMS outcomes.

Application of Transcranial Direct and Alternating Current Stimulation (tDCS and tACS) on Major Depressive Disorder

The exploration of brain stimulation methods offers a promising avenue to overcome the shortcomings of traditional drug therapies and psychological treatments for major depressive disorder (MDD). Over the past years, there has been an increasing focus on transcranial electrical stimulation (tES), notably for its ease of use and potentially fewer side effects. This chapter delves into the use of transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), which are key components of tES, in managing depression. It begins by introducing tDCS and tACS, summarizing their action mechanisms. Following this introduction, the chapter provides an in-depth analysis of existing meta-analyses, systematic reviews, clinical studies, and case reports that have applied tES in MDD treatment. It also considers the role of tES in personalized medicine by looking at specific patient groups and evaluating research on possible biomarkers that could predict how patients with MDD respond to tES therapy.

Early effects predict trajectories of response to esketamine in treatment-resistant depression

BACKGROUND

The efficacy of esketamine in treatment-resistant depression (TRD) has been confirmed. However, its administration is expensive and restrictive, with limited knowledge on how long the treatment should be continued. Predicting the treatment outcome would benefit patients and alleviate the global treatment cost. We aimed to define distinct trajectories of treatment response and assess their predictability.

METHODS

In this longitudinal study, two independent samples of patients with unipolar or bipolar TRD were treated with esketamine in real-world settings. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) before each esketamine administration. Latent class analyses were used to define trajectories of response.

RESULTS

In the original sample (N = 50), we identified two classes whose trajectories depicted response and non-response, respectively. The model was validated in the confirmatory sample (N = 55). Class membership was influenced by a few baseline characteristics such as concomitant benzodiazepine medication, number of depressive episodes or polarity. On the other hand, after only two esketamine administrations, the MADRS score predicted the 90-day trajectory of response with an accuracy of 80 %.

LIMITATIONS

This observational study is not placebo-controlled. Therefore, its results and their generalizability need to be confirmed in experimental settings.

CONCLUSIONS

After the first administrations of esketamine, the MADRS score has a good capacity to predict the most plausible trajectory of response. While thresholds and their predictive values need to be confirmed, this finding suggests that clinicians could base on MADRS scores their decision to discontinue treatment because of poor remaining chances of treatment response.

Mediating Effects of Neural Targets on Depression, Weight, and Anxiety Outcomes of an Integrated Collaborative Care Intervention: The ENGAGE-2 Mechanistic Pilot Randomized Clinical Trial

Background

Integrated treatments for comorbid depression (often with anxiety) and obesity are lacking; mechanisms are poorly investigated.

Methods

In a mechanistic pilot trial, adults with body mass index ≥30 and Patient Health Questionnaire-9 scores ≥10 were randomized to usual care (n = 35) or an integrated behavioral intervention (n = 71). Changes at 6 months in body mass index and Depression Symptom Checklist-20 scores were co-primary outcomes, and Generalized Anxiety Disorder Scale-7 score was a secondary outcome. Changes at 2 months in the activation and functional connectivity of regions of interest in the negative affect circuit were primary neural targets, and secondary targets were in the cognitive control, default mode, and positive affect circuits.

Results

Participants were 47.0 years (SD = 11.9 years), 76% women, 55% Black, and 20% Latino. Depression Symptom Checklist-20 (between-group difference, -0.3 [95% CI: -0.6 to -0.1]) and Generalized Anxiety Disorder Scale-7 (-2.9 [-4.7 to -1.1]) scores, but not body mass index, decreased significantly at 6 months in the intervention versus usual care groups. Only Generalized Anxiety Disorder Scale-7 score changes at 6 months significantly correlated with neural target changes at 2 months in the negative affect (anterior insula, subgenual/pregenual anterior cingulate cortex, amygdala) and cognitive control circuits (dorsal lateral prefrontal cortex, dorsal anterior cingulate cortex). Effects were medium to large (0.41-1.18 SDs). Neural target changes at 2 months in the cognitive control circuit only differed by treatment group. Effects were medium (0.58-0.79 SDs).

Conclusions

Compared with usual care, the study intervention led to significantly improved depression but not weight loss, and the results on neural targets were null for both outcomes. The significant intervention effect on anxiety might be mediated through changes in the cognitive control circuit, but this warrants replication.

Time-course of the tDCS antidepressant effect: An individual participant data meta-analysis

INTRODUCTION

Prefrontal transcranial direct current stimulation (tDCS) shows promise as an effective treatment for depression. However, factors influencing treatment and the time-course of symptom improvements remain to be elucidated.

METHODS

Individual participant data was collected from ten randomised controlled trials of tDCS in depression. Depressive symptom scores were converted to a common scale, and a linear mixed effects individual growth curve model was fit to the data using k-fold cross-validation to prevent overfitting.

RESULTS

Data from 576 participants were analysed (tDCS: n = 311; sham: n = 265), of which 468 were unipolar and 108 had bipolar disorder. tDCS effect sizes reached a peak at approximately 6 weeks, and continued to diverge from sham up to 10 weeks. Significant predictors associated with worse response included higher baseline depression severity, treatment resistance, and those associated with better response included bipolar disorder and anxiety disorder.

CONCLUSIONS

Our findings suggest that longer treatment courses, lasting at least 6 weeks in duration, may be indicated. Further, our results show that tDCS is effective for depressive symptoms in bipolar disorder. Compared to unipolar depression, participants with bipolar disorder may require additional maintenance sessions to prevent rapid relapse.

Association of Changes in Neural Targets and Dietary Outcomes among Patients with Comorbid Obesity and Depression: Post hoc Analysis of ENGAGE-2 Mechanistic Clinical Trial

BACKGROUND

Disruptions in brain circuits that regulate cognition and emotion can hinder dietary change and weight loss among individuals with obesity and depression.

OBJECTIVE

The study aimed to investigate whether changes in brain targets in the cognitive control, negative affect, and positive affect circuits after 2-mo problem-solving therapy (PST) predict changes in dietary outcomes at 2 and 6 mo.

METHODS

Adults with obesity and depression from an academic health system were randomly assigned to receive PST (7-step problem-solving and behavioral activation strategies) over 2 mo or usual care. Seventy participants (mean age = 45.9 ± 11.6 y; 75.7% women, 55.7% Black, 17.1% Hispanic, 20.0% White; mean BMI = 36.5 ± 5.3 kg/m2; mean Patient Health Questionnaire-9 depression score = 12.7 ± 2.8) completed functional MRI and 24-h food recalls. Ordinary least square regression analyses were performed.

RESULTS

Among intervention participants, increased left dorsal lateral prefrontal cortex (dLPFC) activity of the cognitive control circuit at 2 mo was associated with increased diet quality (β: 0.20; 95% CI: -0.02, 0.42) and decreased calories (β: -0.19; 95% CI: -0.33, -0.04), fat levels (β: -0.22; 95% CI: -0.39, -0.06), and high-sugar food intake (β: -0.18; 95% CI: -0.37, 0.01) at 6 mo. For the negative affect circuit, increased right dLPFC-amygdala connectivity at 2 mo was associated with increased diet quality (β: 0.32; 95% CI: -0.93, 1.57) and fruit and vegetable intake (β: 0.38; 95% CI: -0.75, 1.50) and decreased calories (β: -0.37; 95% CI: -1.29, 0.54), fat levels (β: -0.37; 95% CI: -1.50, 0.76), sodium concentrations (β: -0.36; 95% CI: -1.32, 0.60), and alcohol intake (β: -0.71; 95% CI: -2.10, 0.68) at 2 but not at 6 mo. The usual care group showed opposing associations. The 95% CIs of all between-group differences did not overlap the null, suggesting a significant treatment effect.

CONCLUSIONS

Among adults with obesity and depression who underwent PST compared with those under usual care, improved dLPFC-amygdala regulation of negative affective brain states predicted dietary improvements at 2 mo, whereas improvements in dLPFC-based cognitive control predicted dietary improvements at 6 mo. These findings warrant confirmatory studies. This trial was at clinicaltrials.gov as NCT03841682.

Disentangling cognitive inflexibility in major depressive disorder: A transcranial direct current stimulation study

BACKGROUND

Cognitive dysfunction is a persistent residual symptom in major depressive disorders (MDDs) that hinders social and occupational recovery. Cognitive inflexibility is a typical cognitive dysfunction in MDD and refers to difficulty in switching tasks, which requires two subcomponents: forgetting an old task and adapting to a new one. Here, we aimed to disentangle the subcomponents of cognitive inflexibility in MDD and investigate whether they can be improved by transcranial direct current stimulation (tDCS) on the prefrontal cortex.

METHODS

The current study included 20 patients with MDD (seven females) and 22 age-matched healthy controls (HCs) (seven females). The participants received anodal tDCS on either the dorsomedial prefrontal cortex (DMPFC) or dorsolateral prefrontal cortex (DLPFC) in a crossover design. Before and after the application of tDCS, the participants performed a modified Wisconsin Card Sorting Test, in which the task-switching rules were explicitly described and proactive interference from a previous task rule was occasionally released.

RESULTS

We found that the behavioral cost of a task switch was increased in patients with MDD, but that of proactive interference was comparable between patients with MDD and HCs. The response time for anodal DMPFC tDCS was decreased compared with that for anodal tDCS on the DLPFC in MDD.

CONCLUSIONS

These findings suggest that cognitive inflexibility in MDD is primarily explained by the difficulty to adapt to a new task and environment, and that tDCS on the DMPFC improves behavioral performance during cognitively demanding tasks that require conflict resolution.

Integrated Behavioral Interventions for Adults with Comorbid Obesity and Depression: a Systematic Review

PURPOSE OF REVIEW

To synthesize evidence from randomized controlled trials on the effects of integrated behavioral interventions for comorbid obesity and depression in adults.

RECENT FINDINGS

Seven trials (n = 33 to 409) were included. The quality of evidence was mixed. In 2 trials, integrated interventions led to greater improvements in both obesity and depression over 12 months, compared with usual care. Of 4 trials comparing integrated interventions with a standalone obesity intervention, 2 showed incremental effects on depression only, and 2 did not detect a significant effect for either outcome. One 3-arm trial compared an integrated intervention with standalone obesity and depression interventions and only detected incremental effects on obesity when compared with a standalone depression intervention. The effects of integrated interventions for comorbid obesity and depression are varied but promising. Implications for future research to guide intervention optimization and implement integrated interventions in clinical practice are provided.

Transcranial Electrical Stimulation for Psychiatric Disorders in Adults: A Primer

Transcranial electrical stimulation (tES) comprises noninvasive neuromodulation techniques that deliver low-amplitude electrical currents to targeted brain regions with the goal of modifying neural activities. Expanding evidence from the past decade, specifically using transcranial direct current simulation and transcranial alternating current stimulation, presents promising applications of tES as a treatment for psychiatric disorders. In this review, the authors discuss the basic technical aspects and mechanisms of action of tES in the context of clinical research and practice and review available evidence for its clinical use, efficacy, and safety. They also review recent advancements in use of tES for the treatment of depressive disorders, schizophrenia, substance use disorders, and obsessive-compulsive disorder. Findings largely support growing evidence for the safety and efficacy of tES in the treatment of patients with resistance to existing treatment options, particularly demonstrating promising treatment outcomes for depressive disorders. Future directions of tES research for optimal application in clinical settings are discussed, including the growing home-based, patient-friendly methods and the potential pairing with existing pharmacological or psychotherapeutic treatments for enhanced outcomes. Finally, neuroimaging advancements may provide more specific mapping of brain networks, aiming at more precise tES therapeutic targeting in the treatment of psychiatric disorders.

Home-based transcranial direct current stimulation in dual active treatments for symptoms of depression and anxiety: A case series

Transcranial direct current stimulation (tDCS) is a potential treatment strategy across some psychiatric conditions. However, there is high heterogeneity in tDCS efficacy as a stand-alone treatment. To increase its therapeutic potential, researchers have begun to explore the efficacy of combining tDCS with psychological and pharmacological interventions. The current case series details the effect of 6-10 weeks of self-administered tDCS paired with a behavioral therapy smartphone app (Flow™), on depressive and anxiety symptoms, in seven patients (26-51 years old; four female) presenting distinctive psychiatric disorders (major depression, dysthymia, illness anxiety disorder, obsessive-compulsive disorder, and anxiety disorders). tDCS protocol consisted of an acute phase of daily 30 min sessions, across 10 workdays (2 weeks Monday-to-Friday; Protocol 1) or 15 workdays (3 weeks Monday-to-Friday; Protocol 2). A maintenance phase followed, with twice-weekly sessions for 4 or 3 weeks, corresponding to 18 or 21 sessions in total (Protocol 1 or 2, respectively). The Flow tDCS device uses a 2 mA current intensity, targeting the bilateral dorsolateral prefrontal cortex. The Flow app offers virtually guided behavioral therapy courses to be completed during stimulation. We assessed depressive symptoms using MADRS-S and BDI-II, anxious symptoms using STAI-Trait, acceptability using ACCEPT-tDCS, and side effects using the Adverse Effects Questionnaire, at baseline and week 6 of treatment. Six patients underwent simultaneous cognitive-behavioral psychotherapy and two were on antidepressants and benzodiazepines. According to the Reliable Change Index (RCI), for depressive symptoms, we found clinically reliable improvement in five patients using MADRS-S (out of seven; RCI: -1.45, 80% CI; RCI: -2.17 to -4.82, 95% CI; percentage change: 37.9-66.7%) and in four patients using BDI-II (out of five; RCI: -3.61 to -6.70, 95% CI; percentage change: 57.1-100%). For anxiety symptoms, clinically reliable improvement was observed in five patients (out of six; RCI: -1.79, 90% CI; RCI: -2.55 to -8.64, 95% CI; percentage change: 12.3-46.4%). Stimulation was well-tolerated and accepted, with mild tingling sensation and scalp discomfort being the most common side effects. This case series highlights the applicability, acceptability, and promising results when combining home-based tDCS with psychotherapy and pharmacotherapy to manage depression and anxiety symptoms in clinical practice.

Parsing the antidepressant effects of non-invasive brain stimulation and pharmacotherapy: A symptom clustering approach on ELECT-TDCS

BACKGROUND

Transcranial direct current stimulation (tDCS) presents small antidepressant efficacy at group level and considerable inter-individual variability of response. Its heterogeneous effects bring the need to investigate whether specific groups of patients submitted to tDCS could present comparable or larger improvement compared to pharmacotherapy. Aggregate measurements might be insufficient to address its effects.

OBJECTIVE

/Hypothesis: To determine the efficacy of tDCS, compared to pharmacotherapy and placebo, in depressive symptom clusters.

METHODS

Data from ELECT-TDCS (Escitalopram versus Electrical Direct-Current Therapy for Treating Depression Clinical Study, ClinicalTrials.gov, NCT01894815), in which antidepressant-free, depressed patients were randomized to receive 22 bifrontal tDCS (2 mA, 30 min) sessions (n = 94), escitalopram 20 mg/day (n = 91), or placebo (n = 60) over 10 weeks. Agglomerative hierarchical clustering identified "sleep/insomnia", "core depressive", "guilt/anxiety", and "atypical" clusters that were the dependent measure. Trajectories were estimated using linear mixed regression models. Effect sizes are expressed in raw HAM-D units. P-values were adjusted for multiple comparisons.

RESULTS

For core depressive symptoms, escitalopram was superior to tDCS (ES = -0.56; CI_95% = -0.94 to -0.17, p = .009), which was superior to placebo (ES = 0.49; CI_95% = 0.06 to 0.92, p = .042). TDCS but not escitalopram was superior to placebo in sleep/insomnia symptoms (ES = 0.87; CI_95% = 0.22 to 1.52, p = .015). Escitalopram but not tDCS was superior to placebo in guilt/anxiety symptoms (ES = 1.66; CI_95% = 0.58 to 2.75, p = .006). No active intervention was superior to placebo for atypical symptoms.

CONCLUSIONS

Pharmacotherapy and non-invasive brain stimulation produce distinct effects in depressive symptoms. TDCS or escitalopram could be chosen according to specific clusters of symptoms for a bigger response.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01894815.

Distinct trajectories of antidepressant response to intravenous ketamine

BACKGROUND

The N-methyl-D-aspartate receptor antagonist ketamine is potentially effective in treatment resistant depression. However, its antidepressant efficacy is highly variable, and there is little information about predictors of response.

METHODS

We employed growth mixture modeling (GMM) analysis to examine specific response trajectories to intravenous (IV) ketamine (three infusions; mean dose 0.63 mg/kg, SD 0.28, range 0.30 - 2.98 mg/kg over 40 min) in 328 depressed adult outpatients referred to a community clinic. The Quick Inventory of Depressive Symptomatology-Self-Report (QIDS-SR) assessed depression severity at baseline and before each infusion, up to three infusions for four total observations.

RESULTS

GMM revealed three QIDS-SR response trajectories. There were two groups of severely depressed patients, with contrasting responses to ketamine. One group (n=135, baseline QIDS-SR=18.8) had a robust antidepressant response (final QIDS-SR=7.3); the other group (n=97, QIDS-SR=19.8) was less responsive (final QIDS-SR=15.6). A third group (n=96) was less severely depressed at baseline (QIDS-SR=11.7), with intermediate antidepressant response (final QIDS-SR=6.6). Comparisons of demographic and clinical characteristics between groups with severe baseline depression revealed higher childhood physical abuse in the group with robust ketamine response (p=0.01).

LIMITATIONS

This was a retrospective analysis on a naturalistic sample. Patients were unblinded and more heterogenous than those included in most controlled clinical trial samples. Information pertaining to traumatic events occurring after childhood and pre-existing or concurrent medical conditions that may have affected outcomes was not available.

CONCLUSIONS

Overall, ketamine's effect in patients with severe baseline depression and history of childhood maltreatment may be consistent with ketamine-induced blockade of behavioral sensitization.

The intervention, the patient and the illness - Personalizing non-invasive brain stimulation in psychiatry

Current hypotheses on the therapeutic action of non-invasive brain stimulation (NIBS) in psychiatric disorders build on the abundant data from neuroimaging studies. This makes NIBS a very promising tool for developing personalized interventions within a precision medicine framework. NIBS methods fundamentally vary in their neurophysiological properties. They comprise repetitive transcranial magnetic stimulation (rTMS) and its variants (e.g. theta burst stimulation - TBS) as well as different types of transcranial electrical stimulation (tES), with the largest body of evidence for transcranial direct current stimulation (tDCS). In the last two decades, significant conceptual progress has been made in terms of NIBS targets, i.e. from single brain regions to neural circuits and to functional connectivity as well as their states, recently leading to brain state modulating closed-loop approaches. Regarding structural and functional brain anatomy, NIBS meets an individually unique constellation, which varies across normal and pathophysiological states. Thus, individual constitutions and signatures of disorders may be indistinguishable at a given time point, but can theoretically be parsed along course- and treatment-related trajectories. We address precision interventions on three levels: 1) the NIBS intervention, 2) the constitutional factors of a single patient, and 3) the phenotypes and pathophysiology of illness. With examples from research on depressive disorders, we propose solutions and discuss future perspectives, e.g. individual MRI-based electrical field strength as a proxy for NIBS dosage, and also symptoms, their clusters, or biotypes instead of disorder focused NIBS. In conclusion, we propose interleaved research on these three levels along a general track of reverse and forward translation including both clinically directed research in preclinical model systems, and biomarker guided controlled clinical trials. Besides driving the development of safe and efficacious interventions, this framework could also deepen our understanding of psychiatric disorders at their neurophysiological underpinnings.

Neurostimulation Methods in the Treatment of Depression: A Comparison of rTMS, tDCS, and Venlafaxine Using a Pooled Analysis of Two Studies

BACKGROUND

There are no head-to-head studies comparing the antidepressant effect of transcranial direct current stimulation (tDCS) with repetitive transcranial magnetic stimulation (rTMS). This pooled analysis compared indirectly the antidepressant efficacy and acceptability of rTMS, tDCS, and the antidepressant venlafaxine (VNF) extended-release.

METHODS

The analysis (n=117, both patients with treatment-resistant depression (TRD) and non-TRD were included) examined pooled data from two 4-week, single-centered, two-armed, double-blind, randomized studies (EUDRACT n. 2005-000826-22 and EUDRACT n. 2015-001639-19). The antidepressant efficacy of right-sided low-frequency rTMS (n=29) vs VNF (n=31) and left-sided anodal tDCS (n=29) vs VNF (n=28) was evaluated. The primary outcome was a change in the Montgomery-Åsberg Depression Rating Scale (MADRS) score from baseline to the treatment endpoint at week 4. The response was defined as a ≥50% reduction in the MADRS score and remission as the MADRS score ≤10 points, both were calculated for the primary treatment endpoint at week 4.

RESULTS

Mean change in total MADRS scores from baseline to week 4 was 7.0 (95% CI, 4.8-9.1) points in the rTMS group, 7.6 (95% CI, 5.5-9.8) in the tDCS group, and 8.9 (95% CI, 7.4-10.4) among patients in the VNF group, a non-significant difference (F(2111)=0.62, p=0.54). Similarly, neither the response rates nor remission rates for rTMS (response 31%; remission 17%), tDCS (24%, 17%), or VNF (41%; 27%) significantly differed among treatment groups (χ ²=2.59, p=0.28; χ ²=1.66, p=0.44). Twenty patients (17%) dropped out of the studies in a similar proportion across groups (rTMS 3/29, tDCS 6/29, VNF 11/59, χ ²=1.41, p=0.52).

CONCLUSION

Our current analysis found a comparable efficacy and acceptability in all three treatment modalities (rTMS, tDCS, and VNF) and clinical relevance for the acute treatment of major depressive disorder.