Repetitive TMS combined with exposure therapy for PTSD: a preliminary study

Intermittent theta burst stimulation of the left dorsolateral prefrontal cortex has no additional effect on the efficacy of virtual reality exposure therapy for acrophobia. A randomized double-blind placebo-controlled study

Anxiety disorders are among the most common mental disorders. Treatment guidelines recommend pharmacotherapy and cognitive behavioral therapy as standard treatment. Although cognitive behavioral therapy is an effective therapeutic approach, not all patients benefit sufficiently from it. In recent years, non-invasive brain stimulation techniques, such as transcranial magnetic stimulation, have been investigated as promising adjuncts in the treatment of affective disorders. The aim of this study is to investigate whether a combination of intermittent theta burst stimulation (iTBS) and virtual reality exposure therapy leads to a significantly greater reduction in acrophobia than virtual reality exposure with sham stimulation. In this randomized double-blind placebo-controlled study, 43 participants with acrophobia received verum or sham iTBS over the left dorsolateral prefrontal cortex prior to two sessions of virtual reality exposure therapy. Stimulation of the left dorsolateral prefrontal cortex with iTBS was motivated by an experimental study showing a positive effect on extinction memory retention. Acrophobic symptoms were assessed using questionnaires and two behavioral approach tasks one week before, after treatment and six months after the second diagnostic session. The results showed that two sessions of virtual reality exposure therapy led to a significant reduction in acrophobic symptoms, with an overall remission rate of 79 %. However, there was no additional effect of iTBS of the left dorsolateral prefrontal cortex on the therapeutic effects. Further research is needed to determine how exactly a combination of transcranial magnetic stimulation and exposure therapy should be designed to enhance efficacy.

Repetitive transcranial magnetic stimulation for post-traumatic stress disorder in adults

BACKGROUND

The estimated lifetime prevalence of post-traumatic stress disorder (PTSD) in adults worldwide has been estimated at 3.9%. PTSD appears to contribute to alterations in neuronal network connectivity patterns. Current pharmacological and psychotherapeutic treatments for PTSD are associated with inadequate symptom improvement and high dropout rates. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive therapy involving induction of electrical currents in cortical brain tissue, may be an important treatment option for PTSD to improve remission rates and for people who cannot tolerate existing treatments.

OBJECTIVES

To assess the effects of repetitive transcranial magnetic stimulation (rTMS) on post-traumatic stress disorder (PTSD) in adults.

SEARCH METHODS

We searched the Cochrane Common Mental Disorders Controlled Trials Register, CENTRAL, MEDLINE, Embase, three other databases, and two clinical trials registers. We checked reference lists of relevant articles. The most recent search was January 2023.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) assessing the efficacy and safety of rTMS versus sham rTMS for PTSD in adults from any treatment setting, including veterans. Eligible trials employed at least five rTMS treatment sessions with both active and sham conditions. We included trials with combination interventions, where a pharmacological agent or psychotherapy was combined with rTMS for both intervention and control groups. We included studies meeting the above criteria regardless of whether they reported any of our outcomes of interest.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed the risk of bias in accordance with Cochrane standards. Primary outcomes were PTSD severity immediately after treatment and serious adverse events during active treatment. Secondary outcomes were PTSD remission, PTSD response, PTSD severity at two follow-up time points after treatment, dropouts, and depression and anxiety severity immediately after treatment.

MAIN RESULTS

We included 13 RCTs in the review (12 published; 1 unpublished dissertation), with 577 participants. Eight studies included stand-alone rTMS treatment, four combined rTMS with an evidence-based psychotherapeutic treatment, and one investigated rTMS as an adjunctive to treatment-as-usual. Five studies were conducted in the USA, and some predominantly included white, male veterans. Active rTMS probably makes little to no difference to PTSD severity immediately following treatment (standardized mean difference (SMD) -0.14, 95% confidence interval (CI) -0.54 to 0.27; 3 studies, 99 participants; moderate-certainty evidence). We downgraded the certainty of evidence by one level for imprecision (sample size insufficient to detect a difference of medium effect size). We deemed one study as having a low risk of bias and the remaining two as having 'some concerns' for risk of bias. A sensitivity analysis of change-from-baseline scores enabled inclusion of a greater number of studies (6 studies, 252 participants). This analysis yielded a similar outcome to our main analysis but also indicated significant heterogeneity in efficacy across studies, including two studies with a high risk of bias. Reported rates of serious adverse events were low, with seven reported (active rTMS: 6; sham rTMS: 1). The evidence is very uncertain about the effect of active rTMS on serious adverse events (odds ratio (OR) 5.26, 95% CI 0.26 to 107.81; 5 studies, 251 participants; very low-certainty evidence [Active rTMS: 23/1000, sham rTMS: 4/1000]). We downgraded the evidence by one level for risk of bias and two levels for imprecision. We rated four of five studies as having a high risk of bias, and the fifth as 'some concerns' for bias. We were unable to assess PTSD remission immediately after treatment as none of the included studies reported this outcome.

AUTHORS' CONCLUSIONS

Based on moderate-certainty evidence, our review suggests that active rTMS probably makes little to no difference to PTSD severity immediately following treatment compared to sham stimulation. However, significant heterogeneity in efficacy was detected when we included a larger number of studies in sensitivity analysis. We observed considerable variety in participant and protocol characteristics across studies included in this review. For example, studies tended to be weighted towards inclusion of either male veterans or female civilians. Studies varied greatly in terms of the proportion of the sample with comorbid depression. Study protocols differed in treatment design and stimulation parameters (e.g. session number/duration, treatment course length, stimulation intensity/frequency, location of stimulation). These differences may affect efficacy, particularly when considering interactions with participant factors. Reported rates of serious adverse events were very low (< 1%) across active and sham conditions. It is uncertain whether rTMS increases the risk of serious adverse event occurrence, as our certainty of evidence was very low. Studies frequently lacked clear definitions for serious adverse events, as well as detail on tracking/assessment of data and information on the safety population. Increased reporting on these elements would likely aid the advancement of both research and clinical recommendations of rTMS for PTSD. Currently, there is insufficient evidence to meta-analyze PTSD remission, PTSD treatment response, and PTSD severity at different periods post-treatment. Further research into these outcomes could inform the clinical use of rTMS. Additionally, the relatively large contribution of data from trials that focused on white male veterans may limit the generalizability of our conclusions. This could be addressed by prioritizing recruitment of more diverse participant samples.

Critically Assessing the Unanswered Questions of How, Where, and When to Induce Plasticity in the Posttraumatic Stress Disorder Network With Transcranial Magnetic Stimulation

Extinction of traumatic memory, a primary treatment approach (termed exposure therapy) in posttraumatic stress disorder (PTSD), occurs through relearning and may be subserved at the molecular level by long-term potentiation of relevant circuits. In parallel, repetitive transcranial magnetic stimulation (TMS) is thought to work through long-term potentiation-like mechanisms and may provide a novel, safe, and effective treatment for PTSD. In a recent failed randomized controlled trial we emphasized the necessity of correctly identifying cortical targets, the directionality of TMS protocols, and the role of memory activation. Here, we provide a systematic review of TMS for PTSD to further identify how, where, and when TMS treatment should be delivered to alleviate PTSD symptoms. We conducted a systematic review of the literature by searching for repetitive TMS clinical trials involving patients with PTSD and outcomes. We searched MEDLINE through October 25, 2023, for "TMS and PTSD" and "transcranial magnetic stimulation and posttraumatic stress disorder." Thirty-one publications met our inclusion criteria (k = 17 randomized controlled trials, k = 14 open label). Randomized controlled trial protocols were varied in terms of TMS protocols, cortical TMS targets, and memory activation protocols. There was no clear superiority of low-frequency (k = 5) versus high-frequency (k = 6) protocols or by stimulation location. Memory provocation or exposure protocols (k = 7) appear to enhance response. Overall, TMS appears to be effective in treating PTSD symptoms across a variety of TMS frequencies, hemispheric target differences, and exposure protocols. Disparate protocols may be conceptually harmonized when viewed as potentiating proposed anxiolytic networks or suppressing anxiogenic networks.

Good moments to stimulate the brain - A randomized controlled double-blinded study on anodal transcranial direct current stimulation of the ventromedial prefrontal cortex on two different time points in a two-day fear conditioning paradigm

It is assumed that extinction learning is a suitable model for understanding the mechanisms underlying exposure therapy. Furthermore, there is evidence that non-invasive brain stimulation (NIBS) can elevate extinction learning by enhancing frontal brain activity and therefore NIBS can augment symptom reduction during exposure therapy in phobias. But, the underlying processes are still not well established. Open questions arise from NIBS time points and electrode placement, among others. Therefore, we investigated in a 2-day fear conditioning experiment, whether anodal transcranial direct current stimulation (tDCS) of the ventromedial prefrontal cortex (vmPFC) modulates either fear memory consolidation or dampened fear reaction during fear extinction. Sixty-six healthy participants were randomly assigned either to a group that received tDCS after fear acquisition (and before fear memory consolidation), to a group that received tDCS directly before fear extinction, or to a control group that never received active stimulation (sham). Differential skin conductance response (SCR) to CS+ vs. CS- was significantly decreased in both tDCS-groups compared to sham group. Our region of interest, the vmPFC, was stimulated best focally with a lateral anode position and a cathode on the contralateral side. But this comes along with a slightly lateral stimulation of vmPFC depending on whether anode is placed left or right. To avoid unintended effects of stimulated sides the two electrode montages (anode left or right) were mirror-inverted which led to differential effects in SCR and electrocortical (mainly late positive potential [LPP]) data in our exploratory analyses. Results indicated that tDCS-timing is relevant for fear reactions via disturbed fear memory consolidation as well as fear expression, and this depends on whether vmPFC is stimulated with either left- or right-sided anode electrode montage. Electrocortical data can shed more light on the underlying neural correlates and exaggerated LPP seems to be associated with disturbed fear memory consolidation and dampened SCR to CS+ vs. CS-, but solely in the right anode electrode montage. Further open questions addressing where and when to stimulate the prefrontal brain in the course of augmenting fear extinction are raised.

Treatment of Posttraumatic Stress Disorder: A State-of-the-art Review

This narrative state-of-the-art review paper describes the progress in the understanding and treatment of Posttraumatic Stress Disorder (PTSD). Over the last four decades, the scientific landscape has matured, with many interdisciplinary contributions to understanding its diagnosis, etiology, and epidemiology. Advances in genetics, neurobiology, stress pathophysiology, and brain imaging have made it apparent that chronic PTSD is a systemic disorder with high allostatic load. The current state of PTSD treatment includes a wide variety of pharmacological and psychotherapeutic approaches, of which many are evidence-based. However, the myriad challenges inherent in the disorder, such as individual and systemic barriers to good treatment outcome, comorbidity, emotional dysregulation, suicidality, dissociation, substance use, and trauma-related guilt and shame, often render treatment response suboptimal. These challenges are discussed as drivers for emerging novel treatment approaches, including early interventions in the Golden Hours, pharmacological and psychotherapeutic interventions, medication augmentation interventions, the use of psychedelics, as well as interventions targeting the brain and nervous system. All of this aims to improve symptom relief and clinical outcomes. Finally, a phase orientation to treatment is recognized as a tool to strategize treatment of the disorder, and position interventions in step with the progression of the pathophysiology. Revisions to guidelines and systems of care will be needed to incorporate innovative treatments as evidence emerges and they become mainstream. This generation is well-positioned to address the devastating and often chronic disabling impact of traumatic stress events through holistic, cutting-edge clinical efforts and interdisciplinary research.

Efficacy of Repetitive Transcranial Magnetic Stimulation (rTMS) Combined with Psychological Interventions: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

(1) Background: Psychological interventions are effective in alleviating neuropsychiatric symptoms, though results can vary between patients. Repetitive transcranial magnetic stimulation (rTMS) has been proven to improve clinical symptoms and cognition. It remains unclear whether rTMS can augment the efficacy of psychological interventions. (2) Methods: We examined the effects of rTMS combined with psychological interventions on clinical, functional, and cognitive outcomes from randomized controlled trials conducted in healthy and clinical populations. We searched PubMed, EMBASE, Cochrane Library, and PsycINFO databases up to April 2023. (3) Results: Twenty-seven studies were ultimately included. Compared to sham rTMS combined with psychological interventions, active rTMS combined with psychological interventions significantly improved overall clinical symptoms (k = 16, SMD  =  0.31, CIs 0.08 to 0.54, p  <  0.01). We found that 10 or more sessions of rTMS combined with cognitive behavioural therapy significantly improved clinical outcomes overall (k = 3, SMD  =  0.21, CIs  0.05 to 0.36, Z = 2.49, p  <  0.01). RTMS combined with cognitive training (CT) significantly improved cognition overall compared to sham rTMS combined with CT (k = 13, SMD  =  0.28, CIs 0.15 to 0.42, p  <  0.01), with a significant effect on global cognition (k = 11, SMD  =  0.45, CIs 0.21 to 0.68, p  < 0.01), but not on the other cognitive domains. (4) Conclusion: The current results provide preliminary support for the augmentation effects of active rTMS on clinical and cognitive outcomes across diverse populations. Future clinical trials are required to confirm these augmentation effects for specific psychological interventions in specific clinical populations.

P3a amplitude to trauma-related stimuli reduced after successful trauma-focused PTSD treatment

An elevated P3a amplitude to trauma-related stimuli is strongly associated with posttraumatic stress disorder (PTSD), yet little is known about whether this response to trauma-related stimuli is affected by treatment that decreases PTSD symptoms. As an analysis of secondary outcome measures from a randomized controlled trial, we investigated the latency and amplitude changes of the P3a in responses in a three-condition oddball visual task that included trauma-related (combat scenes) and trauma-unrelated (threatening animals) distractors. Fifty-five U.S. veterans diagnosed with combat-related PTSD were randomized to receive either active or sham repetitive transcranial magnetic stimulation (rTMS). All received cognitive processing therapy, CPT+A, which requires a written account of the index trauma. They were tested before and 6 months after protocol completion. P3a amplitude and response time decreases were driven largely by the changes in the responses to the trauma-related stimuli, and this decrease correlated to the decrease in PTSD symptoms. The amplitude changes were greater in those who received rTMS + CPT than in those who received sham rTMS + CPT, suggesting that rTMS plays beneficial role in reducing arousal and threat bias, which may allow for more effective engagement in trauma-focused PTSD treatment.

Neuromodulatory effects and reproducibility of the most widely used repetitive transcranial magnetic stimulation protocols

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is widely used in both research and clinical settings to modulate human brain function and behavior through the engagement of the mechanisms of plasticity. Based upon experiments using single-pulse TMS as a probe, the physiologic mechanism of these effects is often assumed to be via changes in cortical excitability, with 10 Hz rTMS increasing and 1 Hz rTMS decreasing the excitability of the stimulated region. However, the reliability and reproducibility of these rTMS protocols on cortical excitability across and within individual subjects, particularly in comparison to robust sham stimulation, have not been systematically examined.

OBJECTIVES

In a cohort of 28 subjects (39 ± 16 years), we report the first comprehensive study to (1) assess the neuromodulatory effects of traditional 1 Hz and 10 Hz rTMS on corticospinal excitability against both a robust sham control, and two other widely used patterned rTMS protocols (intermittent theta burst stimulation, iTBS; and continuous theta burst stimulation, cTBS), and (2) determine the reproducibility of all rTMS protocols across identical repeat sessions.

RESULTS

At the group level, neither 1 Hz nor 10 Hz rTMS significantly modulated corticospinal excitability. 1 Hz and 10 Hz rTMS were also not significantly different from sham and both TBS protocols. Reproducibility was poor for all rTMS protocols except for sham. Importantly, none of the real rTMS and TBS protocols demonstrated greater neuromodulatory effects or reproducibility after controlling for potential experimental factors including baseline corticospinal excitability, TMS coil deviation and the number of individual MEP trials.

CONCLUSIONS

These results call into question the effectiveness and reproducibility of widely used rTMS techniques for modulating corticospinal excitability, and suggest the need for a fundamental rethinking regarding the potential mechanisms by which rTMS affects brain function and behavior in humans.

The Role of Psychotherapy in the Management of Treatment-Resistant Depression

This article reviews the role of psychotherapy in management of treatment-resistant depression (TRD). Meta-analyses of randomized trials show that psychotherapy has a positive therapeutic benefit in TRD. There is less evidence that one type of psychotherapy approach is superior to another. However, more trials have examined cognitive-based therapies than other forms of psychotherapy. Also reviewed is the potential combination of psychotherapy modalities and medication/somatic therapies as an approach to TRD. There is significant interest in ways that psychotherapy modalities could be combined with medication/somatic therapies to harness a state of enhanced neural plasticity and improve longer-term outcomes in mood disorders.

Effectiveness of repetitive transcranial magnetic stimulation combined with a brief exposure procedure for post-stroke posttraumatic stress disorder

The incidence of posttraumatic stress disorder (PTSD) following stroke ranges from 6.5 % to 25 %. Presently few studies have focused on its treatment. Repetitive transcranial magnetic stimulation (rTMS) is often applied as a rehabilitation method after stroke, and it also represents a novel approach to PTSD. The aim of this study was to explore the effect of rTMS (or combined with a brief stroke re-exposure) on treating post-stroke PTSD. Sixty participants with post-stroke PTSD were randomly assigned into three groups (rTMS + brief exposure group, TMS + BE; rTMS alone group, TMS; sham treatment group, ST) and received 10 sessions of treatment accordingly over two weeks. Changes in PTSD symptoms (Impact of Event Scale-Revised, IES-R) were evaluated at pre-treatment (T1), the end of the first (T2), and the end of the second treatment week (T3). At the three-month follow-up (T4), a PTSD interview and IES-R assessment were given. Results showed that from T1 to T3, IES-R (and its intrusion subscale) scores of TMS + BE group and TMS group were significantly lower than the ST group, and the effect remained at three-month follow-up. The treatment effect was comparable between TMS + BE group and TMS group at T3, however, it was better for TMS + BE group than TMS group at T2, indicating a brief exposure promotes the effect of rTMS. At follow-up, the rates of PTSD were lower in TMS + BE group and TMS group than ST group. In conclusion, rTMS can effectively treat post-stroke PTSD and the effects may be accelerated by combining a brief exposure procedure. TRIAL REGISTRATION: Chinese Clinical Trial Registry, identifier: ChiCTR2100043444.

Effects of transcranial direct current stimulation (tDCS) in "Kiss nightclub fire" patients with post-traumatic stress disorder (PTSD): A phase II clinical trial

Objective

Considered the second biggest tragedy with fatal victims caused by fire, the Kiss nightclub fire tragedy that occurred in the interior of southern Brazil brought several problems to survivors. It is reported that 30-40% of victims of disasters can develop post-traumatic stress disorder. Application of repetitive transcranial magnetic stimulation has shown promising results in the treatment of post-traumatic stress disorder. Transcranial direct current stimulation similar to repetitive transcranial magnetic stimulation, a neuromodulation technique, has shown promise in treatment of neuropsychiatric disorders.

Method

A clinical trial was conducted from March 2015 to July 2016 in "KISS nightclub fire" disaster patients diagnosed with post-traumatic stress disorder without complete remission of symptoms, over 18 years, and who maintained pharmacological treatment. Treatment was given using electrodes as cathode (right dorsolateral prefrontal cortex) and anode (contralateral deltoid muscle); a current of 2 mA was used for 25 cm² area (0.08 mA/cm² current density); 30 min once a day for 10 days continuously. Patients assessed pre- and post-intervention, 30 days' and 90 days' post-intervention. Post-Traumatic Stress Disorder Checklist, Civilian version, Montreal Cognitive Assessment, and Hamilton Depression and Anxiety Rating Scale were used.

Results

One hundred forty-five subjects were screened and eight analyzed; 87.5% were female; 30.88 ± 7.74 years were of mean age. Post-intervention results: no cognitive impairment (Montreal Cognitive Assessment), 60% reduction in Hamilton Depression Rating Scale (moderate depression turns normal) (p < 0.001), 54.39% Hamilton Anxiety Rating Scale reduction (moderate-to-severe symptoms turn into mild symptoms) (p < 0.001), and 20% Post-Traumatic Stress Disorder Checklist, Civilian version scale decrease (high severity post-traumatic stress disorder symptoms turn moderate to moderately high severity) (p < 0.001). Post-traumatic stress disorder symptoms improvement was maintained 30-days post-intervention (Post-Traumatic Stress Disorder Checklist, Civilian version, p = 0.025) and improvement in symptoms of depression (Hamilton Depression Rating Scale, p = 0.006) and anxiety (Hamilton Anxiety Rating Scale, p = 0.028) in 90 days post-intervention.

Conclusion

Despite decrease over time, improvement in post-traumatic stress disorder, depression and anxiety symptoms was maintained throughout the first month after treatment. Transcranial direct current stimulation adjuvant can be an alternative treatment to refractory post-traumatic stress disorder, either as monotherapy or as treatment enhancement strategy. They can also be an option for patients who do not want or do not tolerate pharmacological management.

Resting-state connectivity subtype of comorbid PTSD and alcohol use disorder moderates improvement from integrated prolonged exposure therapy in Veterans

BACKGROUND

Posttraumatic stress disorder (PTSD) and alcohol use disorder (AUD) are highly comorbid and are associated with significant functional impairment and inconsistent treatment outcomes. Data-driven subtyping of this clinically heterogeneous patient population and the associated underlying neural mechanisms are highly needed to identify who will benefit from psychotherapy.

METHODS

In 53 comorbid PTSD/AUD patients, resting-state functional magnetic resonance imaging was collected prior to undergoing individual psychotherapy. We used a data-driven approach to subgroup patients based on directed connectivity profiles. Connectivity subgroups were compared on clinical measures of PTSD severity and heavy alcohol use collected at pre- and post-treatment.

RESULTS

We identified a subgroup of patients associated with improvement in PTSD symptoms from integrated-prolonged exposure therapy. This subgroup was characterized by lower insula to inferior parietal cortex (IPC) connectivity, higher pregenual anterior cingulate cortex (pgACC) to posterior midcingulate cortex connectivity and a unique pgACC to IPC path. We did not observe any connectivity subgroup that uniquely benefited from integrated-coping skills or subgroups associated with change in alcohol consumption.

CONCLUSIONS

Data-driven approaches to characterize PTSD/AUD subtypes have the potential to identify brain network profiles that are implicated in the benefit from psychological interventions - setting the stage for future research that targets these brain circuit communication patterns to boost treatment efficacy.

Contemporary Approaches Toward Neuromodulation of Fear Extinction and Its Underlying Neural Circuits

Neuroscience and neuroimaging research have now identified brain nodes that are involved in the acquisition, storage, and expression of conditioned fear and its extinction. These brain regions include the ventromedial prefrontal cortex (vmPFC), dorsal anterior cingulate cortex (dACC), amygdala, insular cortex, and hippocampus. Psychiatric neuroimaging research shows that functional dysregulation of these brain regions might contribute to the etiology and symptomatology of various psychopathologies, including anxiety disorders and post traumatic stress disorder (PTSD) (Barad et al. Biol Psychiatry 60:322-328, 2006; Greco and Liberzon Neuropsychopharmacology 41:320-334, 2015; Milad et al. Biol Psychiatry 62:1191-1194, 2007a, Biol Psychiatry 62:446-454, b; Maren and Quirk Nat Rev Neurosci 5:844-852, 2004; Milad and Quirk Annu Rev Psychol 63:129, 2012; Phelps et al. Neuron 43:897-905, 2004; Shin and Liberzon Neuropsychopharmacology 35:169-191, 2009). Combined, these findings indicate that targeting the activation of these nodes and modulating their functional interactions might offer an opportunity to further our understanding of how fear and threat responses are formed and regulated in the human brain, which could lead to enhancing the efficacy of current treatments or creating novel treatments for PTSD and other psychiatric disorders (Marin et al. Depress Anxiety 31:269-278, 2014; Milad et al. Behav Res Ther 62:17-23, 2014). Device-based neuromodulation techniques provide a promising means for directly changing or regulating activity in the fear extinction network by targeting functionally connected brain regions via stimulation patterns (Raij et al. Biol Psychiatry 84:129-137, 2018; Marković et al. Front Hum Neurosci 15:138, 2021). In the past ten years, notable advancements in the precision, safety, comfort, accessibility, and control of administration have been made to the established device-based neuromodulation techniques to improve their efficacy. In this chapter we discuss ten years of progress surrounding device-based neuromodulation techniques-Electroconvulsive Therapy (ECT), Transcranial Magnetic Stimulation (TMS), Magnetic Seizure Therapy (MST), Transcranial Focused Ultrasound (TUS), Deep Brain Stimulation (DBS), Vagus Nerve Stimulation (VNS), and Transcranial Electrical Stimulation (tES)-as research and clinical tools for enhancing fear extinction and treating PTSD symptoms. Additionally, we consider the emerging research, current limitations, and possible future directions for these techniques.

Boosting psychological change: Combining non-invasive brain stimulation with psychotherapy

Mental health disorders and substance use disorders are a leading cause of morbidity and mortality worldwide, and one of the most important challenges for public health systems. While evidence-based psychotherapy is generally pursued to address mental health challenges, psychological change is often hampered by non-adherence to treatments, relapses, and practical barriers (e.g., time, cost). In recent decades, Non-invasive brain stimulation (NIBS) techniques have emerged as promising tools to directly target dysfunctional neural circuitry and promote long-lasting plastic changes. While the therapeutic efficacy of NIBS protocols for mental illnesses has been established, neuromodulatory interventions might also be employed to support the processes activated by psychotherapy. Indeed, combining psychotherapy with NIBS might help tailor the treatment to the patient's unique characteristics and therapeutic goal, and would allow more direct control of the neuronal changes induced by therapy. Herein, we overview emerging evidence on the use of NIBS to enhance the psychotherapeutic effect, while highlighting the next steps in advancing clinical and research methods toward personalized intervention approaches.

Combining Trauma Script Exposure With rTMS to Reduce Symptoms of Post-Traumatic Stress Disorder: Randomized Controlled Trial

BACKGROUND

Innovative therapeutic interventions for post-traumatic stress disorder (PTSD) are required. We opted to facilitate fear extinction by combining trauma script exposure with repetitive transcranial magnetic stimulation (rTMS) to reduce symptoms of PTSD.

OBJECTIVE

The efficacy and safety of 10 Hz rTMS of the right dorsolateral prefrontal cortex simultaneously with exposure to personal traumatic narrative were studied in patients with PTSD.

MATERIALS AND METHODS

This trial was a single-center randomized controlled trial (NCT02584894). Patients were randomly assigned 1:1 to receive eight daily sessions of 110% of motor threshold high frequency (HF) 10 Hz rTMS (110% HF rTMS) or 70% low frequency (LF) 1 Hz rTMS (70% LF rTMS) with trauma script exposure in both groups. Severity of PTSD, depression, and anxiety were assessed before and after study treatment (one month, three months) by an assessor masked to the trial group assignment. The primary outcome was the severity of PTSD assessed by the Clinician Administered PTSD Scale (CAPS). We used mixed linear regression models for statistical comparisons.

RESULTS

Thirty-eight patients (65.8% females) were randomly assigned to 110% HF rTMS (n = 18, 31.3 ± 10.0 years, 13 females) or 70% LF rTMS (n = 20, 33.5 ± 11.1 years, 12 females). From baseline to three months, mean CAPS scores decreased by 51% in the 110% HF rTMS group (from 83.7 ± 14.4 to 41.8 ± 31.9) and by 36.9% in the 70% LF rTMS group (from 81.8 ± 15.6 to 51.6 ± 23.7), but with no significant difference in improvement (time by treatment interaction -3.61 [95% confidence interval (CI), -9.70 to 2.47]; p = 0.24; effect size 0.53). One serious adverse event occurred during the study (psychogenic nonepileptic seizure).

CONCLUSION

We found no evidence of difference in clinical improvement or remission rates between the 110% HF and 70% LF stimulation. These findings may reflect the importance of exposure procedure and that larger number of participants is needed.

The Use of Repetitive Transcranial Magnetic Stimulations for the Treatment of Post-Traumatic Stress Disorder: A Scoping Review

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive procedure in which brain neural activity is stimulated by the direct application of a magnetic field to the scalp. Despite its wide and continuous usage for the management of psychiatric disorders, the use of rTMS for post-traumatic stress disorder (PTSD) is not well established and evaluated by researchers. This scoping review seeks to explore the relevant literature available regarding the use of rTMS as a mode of treatment for PTSD, to map evidence in support of the use of rTMS for PTSD, and recommendations on future clinical and research work. Five databases were searched (MEDLINE, CINAHL, Psych INFO, SCOPUS, and EMBASE) to identify empirical studies and randomized controlled trials aimed at the treatment of PTSD with rTMS. A total of 10 studies were eligible for this review. The search results are up to date as of the date of the electronic data search of 20 December 2020. The frequencies applied in the studies ranged from low (1 Hz) to high (10 Hz) at different thresholds. Nine reported significant positive outcomes and PTSD symptoms improvement. rTMS was reported as well tolerated with no significant side effects. The application of rTMS for PTSD looks promising despite the diversity in terms of its outcomes and its clinical significance. Studies with well-defined stimulation parameters need to be conducted in the future.

Auditory N2 Correlates of Treatment Response in Posttraumatic Stress Disorder

Emotional processing and cognitive control are implicated as being dysfunctional in posttraumatic stress disorder (PTSD) and targeted in cognitive processing therapy (CPT), a trauma-focused treatment for PTSD. The N2 event-related potential has been interpreted in the context of emotional processing and cognitive control. In this analysis of secondary outcome measures from a randomized controlled trial, we investigated the latency and amplitude changes of the N2 in responses to task-relevant target tones and task-irrelevant distractor sounds (e.g., a trauma-related gunshot and a trauma-unrelated lion's roar) and the associations between these responses and PTSD symptom changes. United States military veterans (N = 60) diagnosed with combat-related PTSD were randomized to either active or sham repetitive transcranial magnetic stimulation (rTMS) and received a CPT intervention that included a written trauma account element (CPT+A). Participants were tested before and 6 months after protocol completion. Reduction in N2 amplitude to the gunshot stimulus was correlated with reductions in reexperiencing, |r| = .445, and hyperarousal measures, |r| = .364. In addition, in both groups, the latency of the N2 event-related potential to the distractors became longer with treatment and the N2 latency to the task-relevant stimulus became shorter, η_p ²  = .064, both of which are consistent with improved cognitive control. There were no between-group differences in N2 amplitude and latency. Normalized N2 latencies, reduced N2 amplitude to threatening distractors, and the correlation between N2 amplitude reduction and PTSD symptom reduction reflect improved cognitive control, consistent with the CPT+A objective of addressing patients' abilities to respond more appropriately to trauma triggers.

Neuromodulation Treatments of Pathological Anxiety in Anxiety Disorders, Stressor-Related Disorders, and Major Depressive Disorder: A Dimensional Systematic Review and Meta-Analysis

BACKGROUND

Pathological anxiety is responsible for major functional impairments and resistance to conventional treatments in anxiety disorders (ADs), posttraumatic stress disorder (PTSD) and major depressive disorder (MDD). Focal neuromodulation therapies such as transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS) and deep brain stimulation (DBS) are being developed to treat those disorders.

METHODS

We performed a dimensional systematic review and meta-analysis to assess the evidence of the efficacy of TMS, tDCS and DBS in reducing anxiety symptoms across ADs, PTSD and MDD. Reports were identified through systematic searches in PubMed/Medline, Scopus and Cochrane library (inception to November 2020), followed by review according to the PRISMA guidelines. Controlled clinical trials examining the effectiveness of brain stimulation techniques on generic anxiety symptoms in patients with ADs, PTSD or MDD were selected.

RESULTS

Nineteen studies (RCTs) met inclusion criteria, which included 589 participants. Overall, focal brain activity modulation interventions were associated with greater reduction of anxiety levels than controls [SMD: -0.56 (95% CI, -0.93 to-0.20, I ² = 77%]. Subgroup analyses revealed positive effects for TMS across disorders, and of focal neuromodulation in generalized anxiety disorder and PTSD. Rates of clinical responses and remission were higher in the active conditions. However, the risk of bias was high in most studies.

CONCLUSIONS

There is moderate quality evidence for the efficacy of neuromodulation in treating pathological anxiety.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=233084, identifier: PROSPERO CRD42021233084. It was submitted on January 29th, 2021, and registered on March 1st, 2021. No amendment was made to the recorded protocol. A change was applied for the subgroup analyses based on target brain regions, we added the putative nature (excitatory/inhibitory) of brain activity modulation.

A Multivoxel Pattern Analysis of Anhedonia During Fear Extinction: Implications for Safety Learning

BACKGROUND

Pavlovian learning processes are central to the etiology and treatment of anxiety disorders. Anhedonia and related perturbations in reward processes have been implicated in Pavlovian learning. Associations between anhedonia symptoms and neural indices of Pavlovian learning can inform transdiagnostic associations among depressive and anxiety disorders.

METHODS

Participants ages 18 to 19 years (67% female) completed a fear extinction (n = 254) and recall (n = 249) paradigm during functional magnetic resonance imaging. Symptom dimensions of general distress (common to anxiety and depression), fears (more specific to anxiety), and anhedonia-apprehension (more specific to depression) were evaluated. We trained whole-brain multivoxel pattern decoders for anhedonia-apprehension during extinction and extinction recall and tested the decoders' ability to predict anhedonia-apprehension in an external validation sample. Specificity analyses examined effects covarying for general distress and fears. Decoding was repeated within canonical brain networks to highlight candidate neurocircuitry underlying whole-brain effects.

RESULTS

Whole-brain decoder training succeeded during both tasks. Prediction of anhedonia-apprehension in the external validation sample was successful for extinction (R² = 0.047; r = 0.276, p = .002) but not extinction recall (R² < 0.001, r = -0.063, p = .492). The extinction decoder remained significantly associated with anhedonia-apprehension covarying for fears and general distress (t₁₂₁ = 3.209, p = .002). Exploratory results highlighted activity in the cognitive control, default mode, limbic, salience, and visual networks related to these effects.

CONCLUSIONS

Results suggest that patterns of brain activity during extinction, particularly in the cognitive control, default mode, limbic, salience, and visual networks, can be predictive of anhedonia symptoms. Future research should examine associations between anhedonia and extinction, including studies of exposure therapy or positive affect treatments among anhedonic individuals.

Transcranial magnetic stimulation for post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a debilitating psychiatric disorder. While current treatment options are effective for some, many individuals fail to respond to first-line psychotherapies and pharmacotherapy. Transcranial magnetic stimulation (TMS) has emerged over the past several decades as a noninvasive neuromodulatory intervention for psychiatric disorders including depression, with mounting evidence for its safety, tolerability, and efficacy in treating PTSD. While several meta-analyses of TMS for PTSD have been published to date showing large effect sizes on PTSD overall, there is marked variability between studies, making it difficult to draw simple conclusions about how best to treat patients. The following review summarizes over 20 years of the existing literature on TMS as a PTSD treatment, and includes nine randomized controlled trials and many other prospective studies of TMS monotherapy, as well as five randomized controlled trials investigating TMS combined with psychotherapy. While the majority of studies utilize repetitive TMS targeted to the right dorsolateral prefrontal cortex (DLPFC) at low frequency (1 Hz) or high frequency (10 or 20 Hz), others have used alternative frequencies, targeted other regions (most commonly the left DLPFC), or trialed different stimulation protocols utilizing newer TMS modalities such as synchronized TMS and theta-burst TMS (TBS). Although it is encouraging that positive outcomes have been shown, there is a paucity of studies directly comparing available approaches. Biomarkers, such as functional imaging and electroencephalography, were seldomly incorporated yet remain crucial for advancing our knowledge of how to predict and monitor treatment response and for understanding mechanism of action of TMS in this population. Effects on PTSD are often sustained for up to 2-3 months, but more long-term studies are needed in order to understand and predict duration of response. In short, while TMS appears safe and effective for PTSD, important steps are needed to operationalize optimal approaches for patients suffering from this disorder.

Repetitive Transcranial Magnetic Stimulation for the Treatment of Post-traumatic Stress Disorder: A Systematic Review and Network Meta-analysis: La Stimulation Magnétique Transcrânienne Répétitive Pour le Traitement du Trouble de Stress Post-Traumatique : Une Revue Systématique et une Méta-Analyse en Réseau

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) is a promising treatment modality for Post-traumatic stress disorder (PTSD). Several targets and stimulation parameters have been investigated, and while previous meta-analyses have suggested that rTMS is efficacious, these have pooled different stimulation parameters and targets, and the relative efficacy of each is unknown.

METHODS

We therefore performed a systematic review and network meta-analysis of randomized controlled trials (RCTs) by searching MEDLINE, EMBASE, CENTRAL, and PsycINFO and retaining RCTs with at least 5 individuals per arm and clinician-rated PTSD symptoms (PROSPERO CRD42019134984). We adhered to PRISMA guidelines, and 2 independent reviewers screened studies for eligibility and extracted the primary outcome of clinician-rated PTSD symptoms. Dropouts were extracted as a proxy for acceptability. Random effects pairwise meta-analyses and a network meta-analysis were performed.

RESULTS

We synthesize data from 10 RCTs with a total of 421 participants. Two rTMS interventions targeting the right dorsolateral prefrontal cortex (DLPFC) improved PTSD symptoms relative to sham: low-frequency stimulation (SMD = 0.70; 95% CI, 0.22 to 1.18) and high-frequency stimulation (SMD = 0.71; 95% CI, 0.11 to 1.31). Medial PFC dTMS, right DLPFC intermittent theta-burst stimulation, and left DLPFC high-frequency stimulation did not separate from sham. Dropouts as a proxy for acceptability revealed no differences between any of the active conditions or sham nor did any of the active conditions differ from each other.

CONCLUSION

The current literature does not support efficacy differences between interventions; however, protocols stimulating the right DLPFC appear superior to sham. It is unclear whether this reflects heterogeneity in pathology requiring a personalized medicine approach or nonspecific mechanisms of rTMS.

Distinct projections from the infralimbic cortex exert opposing effects in modulating anxiety and fear

Anxiety-related disorders can be treated by cognitive therapies and transcranial magnetic stimulation, which involve the medial prefrontal cortex (mPFC). Subregions of the mPFC have been implicated in mediating different and even opposite roles in anxiety-related behaviors. However, precise causal targets of these top-down connections among diverse possibilities have not been established. Here, we show that the lateral septum (LS) and the central nucleus of the amygdala (CeA) represent 2 direct targets of the infralimbic cortex (IL), a subregion of the mPFC that modulates anxiety and fear. Two projections were unexpectedly found to exert opposite effects on the anxious state and learned freezing: the IL-LS projection promoted anxiety-related behaviors and fear-related freezing, whereas the IL-CeA projection exerted anxiolytic and fear-releasing effects for the same features. Furthermore, selective inhibition of corresponding circuit elements showed opposing behavioral effects compared with excitation. Notably, the IL-CeA projection implemented top-down control of the stress-induced high-anxiety state. These results suggest that distinct IL outputs exert opposite effects in modulating anxiety and fear and that modulating the excitability of these projections with distinct strategies may be beneficial for the treatment of anxiety disorders.

Safety learning during development: Implications for development of psychopathology

Fear and safety learning are necessary adaptive behaviors that develop over the course of maturation. While there is a large body of literature regarding the neurobiology of fear and safety learning in adults, less is known regarding safety learning during development. Given developmental changes in the brain, there are corresponding changes in safety learning that are quantifiable; these may serve to predict risk and point to treatment targets for fear and anxiety-related disorders in children and adolescents. For healthy, typically developing youth, the main developmental variation observed is reduced discrimination between threat and safety cues in children compared to adolescents and adults, while lower expression of extinction learning is exhibited in adolescents compared to adults. Such distinctions may be related to faster maturation of the amygdala relative to the prefrontal cortex, as well as incompletely developed functional circuits between the two. Fear and anxiety-related disorders, childhood maltreatment, and behavioral problems are all associated with alterations in safety learning for youth, and this dysfunction may proceed into adulthood with corresponding abnormalities in brain structure and function-including amygdala hypertrophy and hyperreactivity. As impaired inhibition of fear to safety may reflect abnormalities in the developing brain and subsequent psychopathology, impaired safety learning may be considered as both a predictor of risk and a treatment target. Longitudinal neuroimaging studies over the course of development, and studies that query change with interventions are needed in order to improve outcomes for individuals and reduce long-term impact of developmental psychopathology.

Transcranial magnetic stimulation as a treatment for posttraumatic stress disorder: A meta-analysis

BACKGROUND

Posttraumatic stress disorder (PTSD) is a pervasive mental health condition with limited treatment success. Transcranial magnetic stimulation (TMS) has shown positive outcomes for people with PTSD, using different treatment protocols. This meta-analysis sought to examine which variables in TMS treatment are associated with treatment benefits.

METHODS

A literature search of major online research databases from inception to September 15, 2020 was conducted to identify primary research studies using TMS to treat PTSD. Treatment effect data and TMS treatment variables were coded and analysed using a random effects model. Meta-regression and analyses of moderating variables were conducted to ascertain which variables were associated with significant treatment effects.

RESULTS

An overall effect size of d = 1.17, 95% CI [0.89 - 1.45] for TMS as a treatment for PTSD was found. Analysis of moderators showed that there was a significantly larger treatment effect for high frequency TMS (d = 1.44) compared with low frequency (d = 0.72), p = .006; there was no significant difference between TMS targeting the left dorsolateral prefrontal cortex (DLPFC) and the right DLPFC; and larger treatment doses were not associated with stronger treatment effects.

LIMITATIONS

Not all published studies were available in English or reported the necessary data to be included in this meta-analysis.

CONCLUSIONS

TMS shows potential as a treatment for PTSD, although further research is required to understand the neurological mechanisms of TMS on specific PTSD symptoms so that more effective treatment can be designed for individuals.

Does non-invasive brain stimulation modulate emotional stress reactivity?

Excessive emotional responses to stressful events can detrimentally affect psychological functioning and mental health. Recent studies have provided evidence that non-invasive brain stimulation (NBS) targeting the prefrontal cortex (PFC) can affect the regulation of stress-related emotional responses. However, the reliability and effect sizes have not been systematically analyzed. In the present study, we reviewed and meta-analyzed the effects of repetitive transcranial magnetic (rTMS) and transcranial direct current stimulation (tDCS) over the PFC on acute emotional stress reactivity in healthy individuals. Forty sham-controlled single-session rTMS and tDCS studies were included. Separate random effects models were performed to estimate the mean effect sizes of emotional reactivity. Twelve rTMS studies together showed no evidence that rTMS over the PFC influenced emotional reactivity. Twenty-six anodal tDCS studies yielded a weak beneficial effect on stress-related emotional reactivity (Hedges’ g = −0.16, CI_95% = [−0.33, 0.00]). These findings suggest that a single session of NBS is insufficient to induce reliable, clinically significant effects but also provide preliminary evidence that specific NBS methods can affect emotional reactivity. This may motivate further research into augmenting the efficacy of NBS protocols on stress-related processes.

Advances in repetitive transcranial magnetic stimulation for posttraumatic stress disorder: A systematic review

Repetitive transcranial magnetic stimulation (rTMS) as a treatment for posttraumatic stress disorder (PTSD) has gained interest over the past two decades. However, it has yet to be recommended in major treatment guidelines. We conducted a systematic review of randomized controlled trials to examine the efficacy of rTMS for PTSD. Thirteen studies with 549 participants were included in this review. We compared the effects of (1) rTMS versus sham, and (2) high-frequency (HF) versus low-frequency (LF) rTMS, on posttreatment PTSD scores and other secondary outcomes. We calculated the standardized mean differences (SMD) to determine the direction of effects, and unstandardized mean differences to estimate the magnitude of efficacy. At post-treatment, rTMS was superior to sham comparison in reducing PTSD (SMD = -1.13, 95% CI: -2.10 to -0.15) and depression severity (SMD = -0.83, 95% CI: -1.30 to -0.36). The quality of evidence, however, was rated very low due to small samples sizes, treatment heterogeneity, inconsistent results, and an imprecise pooled effect. HF rTMS was associated with slightly improved, albeit imprecise, outcomes compared to LF rTMS on PTSD (SMD = -0.19, 95% CI: -1.39 to 1.00) and depression (SMD = -1.09, 95% CI: -1.65 to -0.52) severity. Further research is required to advance the evidence on this treatment.

Neurostimulation for treatment-resistant posttraumatic stress disorder: an update on neurocircuitry and therapeutic targets

Posttraumatic stress disorder (PTSD) is a widespread and often devastating psychiatric condition. Core symptoms include intrusive and distressing thoughts, heightened reactivity, mood changes, cognitive impairments, and consequent avoidance of trauma-related stimuli. Symptoms of PTSD are often refractory to standard treatments, and neuromodulatory techniques have therefore drawn significant interest among the most treatment-resistant patients. Transcranial magnetic stimulation has demonstrated minimal efficacy, and deep brain stimulation trials are currently ongoing. PTSD is a disorder of neural circuitry; the current understanding includes involvement of the amygdala (basolateral and central nuclei), the prefrontal cortex (ventral medial and dorsolateral regions), and the hippocampus. Neuroimaging and optogenetic studies have improved the understanding of large-scale neural networks and the effects of microcircuitry manipulation, respectively. This review discusses the current PTSD literature and ongoing neurostimulation trials, and it highlights the current understanding of neuronal circuit dysfunction in PTSD. The authors emphasize the anatomical correlations of PTSD's hallmark symptoms, offer another potential deep brain stimulation target for PTSD, and note the need for continued research to identify useful biomarkers for the development of closed-loop therapies. Although there is hope that neuromodulation will become a viable treatment modality for PTSD, this concept remains theoretical, and further research should involve institutional review board-approved controlled prospective clinical studies.

Personalization of Repetitive Transcranial Magnetic Stimulation for the Treatment of Major Depressive Disorder According to the Existing Psychiatric Comorbidity

Repetitive transcranial magnetic stimulation (rTMS) and intermittent theta-burst stimulation (iTBS) are evidenced-based treatments for patients with major depressive disorder (MDD) who fail to respond to standard first-line therapies. However, although various TMS protocols have been proven to be clinically effective, the response rate varies across clinical applications due to the heterogeneity of real-world psychiatric comorbidities, such as generalized anxiety disorder, posttraumatic stress disorder, panic disorder, or substance use disorder, which are often observed in patients with MDD. Therefore, individualized treatment approaches are important to increase treatment response by assigning a given patient to the most optimal TMS treatment protocol based on his or her individual profile. This literature review summarizes different rTMS or TBS protocols that have been applied in researches investigating MDD patients with certain psychiatric comorbidities and discusses biomarkers that may be used to predict rTMS treatment response. Furthermore, we highlight the need for the validation of neuroimaging and electrophysiological biomarkers associated with rTMS treatment responses. Finally, we discuss on which directions future efforts should focus for developing the personalization of the treatment of depression with rTMS or iTBS.

The Effects of Functionally Guided, Connectivity-Based rTMS on Amygdala Activation

While repetitive transcranial magnetic stimulation (rTMS) is widely used to treat psychiatric disorders, innovations are needed to improve its efficacy. An important limitation is that while psychiatric disorders are associated with fronto-limbic dysregulation, rTMS does not have sufficient depth penetration to modulate affected subcortical structures. Recent advances in task-related functional connectivity provide a means to better link superficial and deeper cortical sources with the possibility of increasing fronto-limbic modulation to induce stronger therapeutic effects. The objective of this pilot study was to test whether task-related, connectivity-based rTMS could modulate amygdala activation through its connectivity with the medial prefrontal cortex (mPFC). fMRI was collected to identify a node in the mPFC showing the strongest connectivity with the amygdala, as defined by psychophysiological interaction analysis. To promote Hebbian-like plasticity, and potentially stronger modulation, 5 Hz rTMS was applied while participants viewed frightening video-clips that engaged the fronto-limbic network. Significant increases in both the mPFC and amygdala were found for active rTMS compared to sham, offering promising preliminary evidence that functional connectivity-based targeting may provide a useful approach to treat network dysregulation. Further research is needed to better understand connectivity influences on rTMS effects to leverage this information to improve therapeutic applications.

A Systematic Review on the Effect of Transcranial Direct Current and Magnetic Stimulation on Fear Memory and Extinction

Anxiety disorders are among the most prevalent mental disorders. Present treatments such as cognitive behavior therapy and pharmacological treatments show only moderate success, which emphasizes the importance for the development of new treatment protocols. Non-invasive brain stimulation methods such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) have been probed as therapeutic option for anxiety disorders in recent years. Mechanistic information about their mode of action, and most efficient protocols is however limited. Here the fear extinction model can serve as a model of exposure therapies for studying therapeutic mechanisms, and development of appropriate intervention protocols. We systematically reviewed 30 research articles that investigated the impact of rTMS and tDCS on fear memory and extinction in animal models and humans, in clinical and healthy populations. The results of these studies suggest that tDCS and rTMS can be efficient methods to modulate fear memory and extinction. Furthermore, excitability-enhancing stimulation applied over the vmPFC showed the strongest potential to enhance fear extinction. We further discuss factors that determine the efficacy of rTMS and tDCS in the context of the fear extinction model and provide future directions to optimize parameters and protocols of stimulation for research and treatment.

Augmentation of fear extinction by theta-burst transcranial magnetic stimulation of the prefrontal cortex in humans

BACKGROUND

Fear extinction alone does not erase the original fear memory. Interventions that enhance extinction can be beneficial for the treatment of fear-related disorders. Repetitive transcranial magnetic stimulation has been shown to improve memory performance. The present study examined the effects of intermittent theta-burst stimulation (iTBS) on fear extinction and the return of fear memory in humans.

METHODS

Ninety-one young healthy volunteers underwent 3 experiments using a randomized controlled experimental design. Participants first acquired fear conditioning, after which they received 30 Hz iTBS before and after extinction training. The iTBS was applied to 1 of 2 targets: the left dorsolateral prefrontal cortex (dlPFC) and the vertex (control). Fear responses were measured 24 hours later and 1 month later.

RESULTS

During the spontaneous recovery and reinstatement tests, iTBS of the left dlPFC before and after extinction significantly reduced fear response, whereas iTBS of the vertex had no effect on fear memory performance. This combined approach had a relatively long-lasting effect (i.e., at least 1 month).

LIMITATIONS

We did not explore the effect of iTBS of the dlPFC on the expression of fear without extinction training. The neural mechanisms of iTBS with fear extinction to inhibit the fear response are unclear. Our results are preliminary and should be interpreted with caution.

CONCLUSION

`The present results showed that 30 Hz iTBS of the left dlPFC enhanced retention of fear extinction. Our study introduces a new intervention for fear memory and suggests that the left dlPFC may be a treatment target for fear-related disorders.

tDCS-Augmented in vivo exposure therapy for specific fears: A randomized clinical trial

Exposure therapy is highly effective for anxiety-related disorders, but there is a need for enhancement. Recent trials of adjunctive neuromodulation have shown promise, warranting evaluation of transcranial direct current stimulation (tDCS) as an augmentation. In a double-blind, placebo-controlled trial, contamination- and animal-phobic participants (N = 49) were randomized to active tDCS (1.7 mA, 20 min; n = 27), or sham tDCS (1.7 mA, 30 s; n = 22), followed by 30 min of in-vivo exposure. Active tDCS targeted excitation of the left mPFC and inhibition of the right dlPFC; polarity was counterbalanced for controls. We predicted tDCS would result in accelerated and better maintained gains, contingent on the subsequent in-session response, and baseline negative prognostic indicators. Consistent with predictions, tDCS promoted engagement and reductions in threat appraisals during exposure, and greater reductions in distress and threat appraisals through 1-month, although effects did not uniformly generalize. tDCS was most beneficial given high phobic severity, anxiety sensitivity, and a suboptimal early response. tDCS may promote engagement and response among individuals who are resistant or refractory to standard treatment. tDCS should be applied to more severe anxiety-related disorders, with parameters yoked to individual differences to improve outcomes in exposure-based interventions.

Characterization of Comorbid Posttraumatic Stress Disorder and Major Depressive Disorder Using Ketamine as an Experimental Medicine Probe

Comorbid posttraumatic stress disorder and major depressive disorder (PTSD + MDD) is the most common pathological response to trauma, yet despite their synergistic detriment to health, knowledge regarding the neurobiological mechanism underlying PTSD + MDD is extremely limited. This study proposes a novel model of PTSD + MDD that is built on biological systems shown to underlay PTSD + MDD and takes advantage of ketamine’s unique suitability to probe PTSD + MDD due to its rescue of stress-related neuroplasticity deficits. The central hypothesis is that changes in PTSD + MDD clinical symptoms are associated with functional connectivity changes and cognitive dysfunction and that ketamine infusions improve clinical symptoms by correction of functional connectivity changes and improvement in cognition. Participants with PTSD + MDD (n = 42) will be randomized to receive a series of six ketamine infusions or saline-placebo over three weeks. Pre/post-measures will include: (1) neuroimaging; (2) cognitive functioning task performance; and (3) PTSD, MDD, and rumination self-report measures. These measures will also be collected once in a trauma-exposed group including PTSD-only (n = 10), trauma-exposed-MDD (TE-MDD; n = 10), and healthy controls (HC, n = 21). Successful completion of the study will strongly support the concept of a biologically-based model of PTSD + MDD. The results will (1) identify functional imaging signatures of the mechanisms underpinning pathological responses to trauma, (2) shift focus from mono-diagnostic silos to unified biological and behavioral disease processes and, thus, (3) inform interventions to correct dysregulation of PTSD + MDD symptom clusters thereby supporting more precise treatments and better outcomes.

Considerations for Pairing Cognitive Behavioral Therapies and Non-invasive Brain Stimulation: Ignore at Your Own Risk

Multimodal approaches combining cognitive behavioral therapies (CBT) with non-invasive brain stimulation (NIBS) hold promise for improving the treatment of neuropsychiatric disorders. As this is a relatively new approach, it is a critical time to identify guiding principles and methodological considerations to enhance research rigor. In the current paper, we argue for a principled approach to CBT and NIBS pairings based on synergistic activation of neural circuits and identify key considerations about CBT that may influence pairing with NIBS. Careful consideration of brain-state interactions and CBT-related nuances will increase the potential for these combinations to be positively synergistic.

A Review of PTSD Augmentation Strategies for Older Adults and Case of rTMS-Augmented Prolonged Exposure

Evidence-based psychotherapies such as prolonged exposure therapy (PE) are recommended by clinical practice guidelines as first-line treatments for post-traumatic stress disorder (PTSD) and are safe and acceptable for use with older adults. One third to one half of all patients do not achieve a clinically meaningful response to standard outpatient PE and recent research suggests that older adults in particular may experience barriers to full engagement and response. Standard treatment may be challenging in older adults due to cognitive, medical, and psychosocial barriers. This article reviews the current state of the evidence on adjunctive and second-tier interventions that show promise for increasing response and/or engagement in evidence-based psychotherapy for PTSD, including medications such as d-cycloserine and 3,4-methylenedioxy-methamphetamine, neuromodulation techniques such as repetitive transcranial magnetic stimulation, and augmentations to the structure and content of psychotherapy, such as intensive outpatient formats. A case illustration of successful application of multiple augmentations to PE with an initially nonresponsive older adult patient is presented. A creative interdisciplinary approach based in available research may be beneficial for older adults who do not respond to first-line treatments.

A Randomized Sham-controlled Trial of 1-Hz and 10-Hz Repetitive Transcranial Magnetic Stimulation (rTMS) of the Right Dorsolateral Prefrontal Cortex in Civilian Post-traumatic Stress Disorder: Un essai randomisé contrôlé simulé de stimulation magnétique transcrânienne repetitive (SMTr) de 1 Hz et 10 Hz du cortex préfrontal dorsolatéral droit dans le trouble de stress post-traumatique chez des civils

OBJECTIVE

Despite effective psychological and pharmacological treatments, there is a large unmet burden of illness in post-traumatic stress disorder (PTSD). Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive intervention and a putative treatment strategy for PTSD. The evidence base to date suggests that rTMS targeting the dorsolateral prefrontal cortex (DLPFC), in particular the right DLPFC, leads to improvements in PTSD symptoms. However, optimal stimulation parameters have yet to be determined. In this study, we examine the efficacy of high- and low-frequency rTMS of the right DLPFC using a randomized, double-blind, sham-controlled design in civilian PTSD.

METHODS

We conducted a 2-week single-site randomized sham-controlled trial of rTMS targeting the right DLPFC. We recruited civilians aged 19 to 70 with PTSD and randomized subjects with allocation concealment to daily 1-Hz rTMS, 10-Hz rTMS, or sham rTMS. The primary outcome was improvement in Clinician Administered PTSD Scale-IV (CAPS-IV). Secondary outcomes included change in depressive and anxiety symptoms.

RESULTS

We recruited 31 civilians with PTSD. One 1-Hz-treated patient developed transient suicidal ideation. Analyses revealed significant improvement in CAPS-IV symptoms in the 1-Hz group relative to sham (Hedges' g = -1.07) but not in the 10-Hz group. This was not attributable to changes in anxious or depressive symptomatology. Ten-Hz stimulation appeared to improve depressive symptoms compared to sham.

CONCLUSION

Low-frequency rTMS is efficacious in the treatment of civilian PTSD. Our data suggest that high-frequency rTMS of the right DLPFC is worthy of additional investigation for the treatment of depressive symptoms comorbid with PTSD.

Treating Post-traumatic Stress Disorder with Neuromodulation Therapies: Transcranial Magnetic Stimulation, Transcranial Direct Current Stimulation, and Deep Brain Stimulation

Post-traumatic stress disorder (PTSD) is a prevalent and debilitating illness. While standard treatment with pharmacotherapy and psychotherapy may be effective, approximately 20 to 30% of patients remain symptomatic. These individuals experience depression, anxiety, and elevated rates of suicide. For treatment-resistant patients, there is a growing interest in the use of neuromodulation therapies, including transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and deep brain stimulation (DBS). We conducted a systematic review on the use of neuromodulation strategies for PTSD and pooled 13 randomized clinical trials (RCTs), 11 case series, and 6 case reports for analysis. Overall, most studies reported favorable outcomes in alleviating both PTSD and depressive symptoms. Although several RCTs described significant differences when active and sham stimulations were compared, others found marginal or nonsignificant differences between groups. Also positive were studies comparing PTSD symptoms before and after treatment. The side effect profile with all 3 modalities was found to be low, with mostly mild adverse events being reported. Despite these encouraging data, several aspects remain unknown. Given that PTSD is a highly heterogeneous condition that can be accompanied by distinct psychiatric diagnoses, defining a unique treatment for this patient population can be quite challenging. There has also been considerable variation across trials regarding stimulation parameters, symptomatic response, and the role of adjunctive psychotherapy. Future studies are needed to address these issues.

Non-invasive brain stimulation for posttraumatic stress disorder: a systematic review and meta-analysis

Approximately 7-9% of people develop posttraumatic stress disorder in their lifetime, but standard pharmacological treatment or psychotherapy shows a considerable individual variation in their effectiveness. Repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) hold promise for the treatment of posttraumatic stress disorder. The objective of this meta-analysis was to summarize the existing evidence on the therapeutic effects of these brain stimulation treatments on posttraumatic core symptoms. We systematically retrieved articles published between 1st January 2000 and 1st January 2020 comparing the effects of active with sham stimulation or no intervention in posttraumatic patients from eight databases. Random-effects model was used for meta-analysis. Meta-regression and subgroup meta-analysis was performed to investigate the influence of stimulation dose and different stimulation protocols, respectively. 20 studies were included in this review, where of 11 randomized controlled trials were subjected to quantitative analysis. Active stimulation demonstrated significant reductions of core posttraumatic symptoms with a large effect size (Hedge's g = -0.975). Subgroup analysis showed that both excitatory and inhibitory rTMS of the right dorsolateral prefrontal cortex led to symptom reductions with a large (Hedges' g = -1.161, 95% CI, -1.823 to -0.499; p = 0.015) and medium effect size (Hedges' g = -0.680, 95% CI: -0.139 to -0.322; p ≤ 0.001) respectively. Results further indicated significant durability of symptom-reducing effects of treatments during a two to four weeks period post stimulation (Hedges' g = -0.909, 95% CI: -1.611 to -0.207; p = 0.011). rTMS of the right dorsolateral prefrontal cortex appears to have a positive effect in reducing core symptoms in patients with posttraumatic stress disorder.

Dosing parameters for the effects of high-frequency transcranial magnetic stimulation on smoking cessation: study protocol for a randomized factorial sham-controlled clinical trial

BACKGROUND

Despite the considerable success of comprehensive tobacco control efforts, tobacco use remains one of the greatest preventable causes of death and disease today. Over half of all smokers in the US make quit attempts every year, but over 90% relapse within 12 months, choosing the immediate reinforcement of smoking over the long-term benefits of quitting. Conceptual and empirical evidence supports continued investigation of high frequency repetitive transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex in reducing relapse and decreasing cigarette consumption. While this evidence is compelling, an optimal dosing strategy must be determined before a long-term efficacy trial can be conducted. The goal of this study is to determine a dosing strategy for 20 Hz rTMS that will produce the best long-term abstinence outcomes with the fewest undesirable effects.

METHODS

This is a fully crossed, double-blinded, sham-controlled, 3x2x2 randomized factorial study. The three factors are duration (stimulation days: 8, 12, and 16); intensity (900 or 1800 pulses per day); and sham control. Participants (n = 258) will consist of adults (18-65) who are motivated to quit smoking cigarettes and who will be followed for 6 months post-quit. Outcomes include latency to relapse, point prevalence abstinence rates, delay discounting rates, cognitive-behavioral skills acquisition, and multiple measures of potential undesirable effects that impact participant compliance.

DISCUSSION

This study integrates existing theoretical concepts and methodologies from neuropsychology, behavioral economics, brain stimulation, clinical psychology, and the evidence-based treatment of tobacco dependence in the development of a promising and innovative approach to treat tobacco dependence. This study will establish an optimal dosing regimen for efficacy testing. Findings are expected to have a significant influence on advancing this approach as well as informing future research on clinical approaches that combine rTMS with other evidence-based treatments for tobacco dependence and perhaps other addictions.

TRIAL REGISTRATION

Clinical Trials NCT03865472 (retrospectively registered). The first participant was fully enrolled on November 26, 2018. Registration was posted on March 7, 2019.

Neurostimulation in Anxiety Disorders, Post-traumatic Stress Disorder, and Obsessive-Compulsive Disorder

Many pharmacological treatments were proved effective in the treatment of panic disorder (PD), generalized anxiety disorder (GAD), social anxiety disorder (SAD), post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD); still many patients do not achieve remission with these treatments. Neurostimulation techniques have been studied as promising alternatives or augmentation treatments to pharmacological and psychological therapies. The most studied neurostimulation method for anxiety disorders, PTSD, and OCD was repetitive transcranial magnetic stimulation (rTMS). This neurostimulation technique had the highest level of evidence for GAD. There were also randomized sham-controlled trials indicating that rTMS may be effective in the treatment of PTSD and OCD, but there were conflicting findings regarding these two disorders. There is indication that rTMS may be effective in the treatment of panic disorder, but the level of evidence is low. Deep brain stimulation (DBS) was most studied for treatment of OCD, but the randomized sham-controlled trials had mixed findings. Preliminary findings indicate that DBS could be affective for PTSD. There is weak evidence indicating that electroconvulsive therapy, transcranial direct current stimulation, vagus nerve stimulation, and trigeminal nerve stimulation could be effective in the treatment of anxiety disorders, PTSD, and OCD. Regarding these disorders, there is no support in the current literature for the use of neurostimulation in clinical practice. Large high-quality studies are warranted.

Evidence-based guidelines on the therapeutic use of repetitive transcranial magnetic stimulation (rTMS): An update (2014-2018)

A group of European experts reappraised the guidelines on the therapeutic efficacy of repetitive transcranial magnetic stimulation (rTMS) previously published in 2014 [Lefaucheur et al., Clin Neurophysiol 2014;125:2150-206]. These updated recommendations take into account all rTMS publications, including data prior to 2014, as well as currently reviewed literature until the end of 2018. Level A evidence (definite efficacy) was reached for: high-frequency (HF) rTMS of the primary motor cortex (M1) contralateral to the painful side for neuropathic pain; HF-rTMS of the left dorsolateral prefrontal cortex (DLPFC) using a figure-of-8 or a H1-coil for depression; low-frequency (LF) rTMS of contralesional M1 for hand motor recovery in the post-acute stage of stroke. Level B evidence (probable efficacy) was reached for: HF-rTMS of the left M1 or DLPFC for improving quality of life or pain, respectively, in fibromyalgia; HF-rTMS of bilateral M1 regions or the left DLPFC for improving motor impairment or depression, respectively, in Parkinson's disease; HF-rTMS of ipsilesional M1 for promoting motor recovery at the post-acute stage of stroke; intermittent theta burst stimulation targeted to the leg motor cortex for lower limb spasticity in multiple sclerosis; HF-rTMS of the right DLPFC in posttraumatic stress disorder; LF-rTMS of the right inferior frontal gyrus in chronic post-stroke non-fluent aphasia; LF-rTMS of the right DLPFC in depression; and bihemispheric stimulation of the DLPFC combining right-sided LF-rTMS (or continuous theta burst stimulation) and left-sided HF-rTMS (or intermittent theta burst stimulation) in depression. Level A/B evidence is not reached concerning efficacy of rTMS in any other condition. The current recommendations are based on the differences reached in therapeutic efficacy of real vs. sham rTMS protocols, replicated in a sufficient number of independent studies. This does not mean that the benefit produced by rTMS inevitably reaches a level of clinical relevance.

Neuromodulatory treatments for post-traumatic stress disorder (PTSD)

Electroconvulsive therapy has been used successfully in some individuals with posttraumatic stress disorder (PTSD) whose symptoms have not improved with other treatments. But there are only a few reports. Meanwhile, an array of new neuromodulation strategies, including repetitive transcranial magnetic stimulation, transcranial direct current stimulation, vagus nerve stimulation, trigeminal nerve stimulation, and deep brain stimulation have been developed and applied experimentally in the treatment of other psychiatric disorders. This article will review the clinical evidence and mechanistic basis for their use in PTSD.

Transcranial magnetic stimulation in anxiety and trauma-related disorders: A systematic review and meta-analysis

BACKGROUND

Transcranial magnetic stimulation (TMS) has been evaluated as an effective treatment option for patients with major depressive disorder. However, there are limited studies that have evaluated the efficacy of TMS for other neuropsychiatric disorders such as anxiety and trauma-related disorders. We reviewed the literature that has evaluated TMS as a treatment for anxiety and trauma-related disorders.

METHODS

We searched for articles published up to December 2017 in Embase, Medline, and ISI Web of Science databases, following the Preferred Items for Reporting of Systematic Reviews and Meta-Analyses (PRISMA) statement. Articles (n = 520) evaluating TMS in anxiety and trauma-related disorders were screened and a small subset of these that met the eligibility criteria (n = 17) were included in the systematic review, of which nine evaluated TMS in posttraumatic stress disorder (PTSD), four in generalized anxiety disorder (GAD), two in specific phobia (SP), and two in panic disorder (PD). The meta-analysis was performed with PTSD and GAD since PD and SP had an insufficient number of studies and sample sizes.

RESULTS

Among anxiety and trauma-related disorders, TMS has been most widely studied as a treatment for PTSD. TMS demonstrated large overall treatment effect for both PTSD (ES = -0.88, 95% CI: -1.42, -0.34) and GAD (ES = -2.06, 95% CI: -2.64, -1.48), including applying high frequency over the right dorsolateral prefrontal cortex. Since few studies have evaluated TMS for SP and PD, few conclusions can be drawn.

CONCLUSIONS

Our meta-analysis suggests that TMS may be an effective treatment for GAD and PTSD.

Noninvasive Brain Stimulation and Psychotherapy in Anxiety and Depressive Disorders: A Viewpoint

Among the most prevalent psychiatric conditions stand anxiety and depression. Psychotherapy and medications are considered effective treatments in these clinical settings. However, pharmacotherapy and psychotherapy (i.e., cognitive behavioral therapy (CBT)) administered in monotherapy or in a combined regimen do not result in satisfactory outcomes in all patients. Therefore, finding new treatments would be of great help. In the last three decades, noninvasive brain stimulation (NIBS) has emerged as a safe tool to improve several neuropsychiatric symptoms. The following work revisits the available reports that assessed the add-on value of NIBS techniques when combined to psychotherapy (CBT or related interventions) in mood and anxiety disorders. The available protocols targeted the prefrontal cortex, a region that was previously found to have an enhanced activity or functional connectivity after psychotherapeutic interventions. Promising yet scarce evidence exists on this matter. A discrepancy exists among the available reports regarding the type and duration of interventions, the patients’ clinical profiles, and the presence of a sham intervention. NIBS may have acted by enhancing psychotherapy effects on the top-down cognitive control of emotions. Combining both therapies may result in promising effects, but future large-scale trials are needed to judge the utility of this combination in psychiatric populations.

Efficacy and mechanisms of non-invasive brain stimulation to enhance exposure therapy: A review

Though cognitive behavioral techniques are generally effective in the treatment of anxiety disorders, some people fail to benefit from exposure therapy or experience a return of fear after terminating exposure therapy. The burgeoning field of non-invasive brain stimulation provides a potential method of augmenting exposure therapy so that it is more effective. Successful exposure therapy is hypothesized to occur due to inhibition, and research suggests that brain stimulation can alter inhibitory learning and related processes. As such, one can reasonably posit that brain stimulation could be used to test the inhibitory learning theory of exposure therapy and to increase the efficacy of exposure therapy by inducing stronger inhibitory learning during exposures. Four known studies that pair brain stimulation with exposure therapy have yielded promising preliminary evidence in support of the therapeutic use of brain stimulation. In this review we describe research illustrating the mechanisms and efficacy of non-invasive brain stimulation to enhance the understanding of and outcomes produced by exposure therapy.