Neuro-stimulation Techniques for the Management of Anxiety Disorders: An Update

Non-invasive brain stimulation in the treatment of generalized anxiety disorder: A systematic review and meta-analysis

BACKGROUND

Non-invasive brain stimulation (NIBS), including repetitive transcranial magnetic stimulation (rTMS), continuous theta-burst stimulation (cTBS), and transcranial direct current stimulation (tDCS), is an emerging intervention that has been used to treat various mental illnesses. However, previous studies have not comprehensively compared the efficacies of various NIBS modalities in alleviating anxiety symptoms among patients with generalized anxiety disorder (GAD). Therefore, this study conducted a systematic review and meta-analysis to assess the efficacy of NIBS for patients with GAD.

METHODS

A systematic search of four major bibliographic databases (Embase, PubMed, Web of Science and The Cochrane Library) was conducted from inception dates to November 26, 2023 to identify eligible studies. The data were analyzed using a random-effects model.

RESULTS

Seven randomized controlled trials (RCTs) were included in the meta-analysis. Significant differences were found in changes in Hamilton anxiety rating scale (HARS) scores, study-defined response, and remission between the intervention and control groups. Moreover, the intervention groups experienced a significantly higher frequency of headaches.

CONCLUSION

The results revealed that interventions improved GAD compared to control groups. cTBS and rTMS exhibited better treatment efficacy than tDCS, which did not appear to have a significant therapeutic effect. Longer follow-up periods and larger sample sizes are required in future RCTs.

TRIAL REGISTRATION

This meta-analysis was conducted in accordance with PRISMA guidelines and registered at PROSPERO (https://www.crd.york.ac.uk/PROSPERO/, CRD42023466285).

Pre-clinical indications of brain stimulation treatments for non-affective psychiatric disorders, a status update

Over the past two decades noninvasive brain stimulation (NIBS) techniques have emerged as powerful therapeutic options for a range of psychiatric and neurological disorders. NIBS are hypothesized to rebalance pathological brain networks thus reducing symptoms and improving functioning. This development has been fueled by controlled studies with increasing size and rigor aiming to characterize how treatments induce clinically effective change. Clinical trials of NIBS for specific indications have resulted in federal approval for unipolar depression, bipolar depression, smoking cessation, and obsessive-compulsive disorder in the United States, and several other indications worldwide. As a rapidly emerging field, there are numerous pre-clinical indications currently in development using a variety of electrical and magnetic, non-convulsive, and convulsive approaches. This review discusses the state-of-the-science surrounding promising avenues of NIBS currently in pre-approval stages for non-affective psychiatric disorders. We consider emerging therapies for psychosis, anxiety disorders, obsessive-compulsive disorder, and borderline personality disorder, utilizing transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), and magnetic seizure therapy (MST), with an additional brief section for early-stage techniques including transcranial focused ultrasound stimulation (tFUS) and transcranial alternating current stimulation (tACS). As revealed in this review, there is considerable promise across all four psychiatric indications with different NIBS approaches. Positive findings are notable for the treatment of psychosis using tDCS, MST, and rTMS. While rTMS is already FDA approved for the treatment of obsessive-compulsive disorder, methodologies such as tDCS also demonstrate potential in this condition. Emerging techniques show promise for treating non-affective disorders likely leading to future regulatory approvals.

Aromatherapy for the brain: Lavender's healing effect on epilepsy, depression, anxiety, migraine, and Alzheimer's disease: A review article

Neurological diseases affect the nervous system, including the brain, spinal cord, cranial nerves, nerve roots, autonomic nervous system, neuromuscular junctions, and muscles. Herbal medicine has long been used to cure these diseases. One of these plants is lavender, which is composed of various compounds, including terpenes, such as linalool, limonene, triterpenes, linalyl acetate, alcohols, ketones, polyphenols, coumarins, cineole, and flavonoids. In this review, the literature was searched using scientific search engines and databases (Google Scholar, Science Direct, Scopus, and PubMed) for papers published between 1982 and 2020 via keywords, including review, lavender, and neurological disorders. This plant exerts its healing effect on many diseases, such as anxiety and depression through an inhibitory effect on GABA. The anti-inflammatory effects of this plant have also been documented. It improves depression by regulating glutamate receptors and inhibiting calcium channels and serotonergic factors, such as SERT. Its antiepileptic mechanism is due to an increase in the inhibitory effect of GABA and potassium current and a decrease in sodium current. Therefore, many vegetable oils are also used in herbal medicine. In this review, the healing effect of lavender on several neurological disorders, including epilepsy, depression, anxiety, migraine, and Alzheimer's disease was investigated. All findings strongly support the traditional uses of lavender. More clinical studies are needed to investigate the effect of the plants' pharmacological active constituents on the treatment of life-threatening diseases in humans. The limitations of this study are the low quality and the limited number of clinical studies. Different administration methods of lavender are one of the limitations of this review.

Efficacy and safety of transcutaneous auricular vagus nerve stimulation combined with conventional rehabilitation training in acute stroke patients: a randomized controlled trial conducted for 1 year involving 60 patients

Transcutaneous auricular vagus nerve stimulation (ta-VNS) is a novel noninvasive treat-ment for stroke that directly stimulates the peripheral auricular branch of the vagus nerve. There have been recent reports that ta-VNS combined with conventional rehabilitation training promotes the recovery of neurological function of patients with acute stroke. However, these were small-sample-sized studies on the recovery of neurological function in patients after percutaneous vagus nerve stimulation in the subacute and chronic phases after stroke. This double-blinded randomized controlled trial involved 60 acute ischemic or hemorrhagic stroke patients aged 18-80 years who received treatment in the Second Affiliated Hospital of Chongqing Medical University. The subjects were randomly assigned to receive ta-VNS or sham ta-VNS combined with conventional rehabilitation training. The follow-up results over 1 year revealed that ta-VNS combined with conventional rehabilitation training greatly improved the recovery of motor and sensory functions and emotional responses compared with sham ta-VNS combined with conventional rehabilitation training. There were no obvious side effects. These findings suggest that ta-VNS combined with conventional rehabilitation training for the treatment of acute ischemic or hemorrhagic stroke patients is safe and effective.

An Optimized Miniaturized Ultrasound Transducer for Transcranial Neuromodulation

Transcranial ultrasound stimulation (TUS) is a young neuromodulation technology, which uses ultrasound to achieve non-invasive stimulation or inhibition of deep intracranial brain regions, with the advantages of non-invasive, deep penetration, and high resolution. It is widely considered to be one of the most promising techniques for probing brain function and treating brain diseases. In preclinical studies, developing miniaturized transducers to facilitate neuromodulation in freely moving small animals is critical for understanding the mechanism and exploring potential applications. In this article, a miniaturized transducer with a half-concave structure is proposed. Based on the finite element simulation models established by PZFlex software, several ultrasound transducers with different concave curvatures were designed and analyzed. Based on the simulation results, half-concave focused ultrasonic transducers with curvature radii of 5 mm and 7.5 mm were fabricated. Additionally, the emission acoustic fields of the ultrasonic transducers with different structures were characterized at their thickness resonance frequencies of 1 MHz using a multifunctional ultrasonic test platform built in the laboratory. To verify the practical ability for neuromodulation, different ultrasound transducers were used to induce muscle activity in mice. As a result, the stimulation success rates were (32 ± 10)%, (65 ± 8)%, and (84 ± 7)%, respectively, by using flat, #7, and #5 transducers, which shows the simulation and experimental results have a good agreement and that the miniaturized half-concave transducer could effectively converge the acoustic energy and achieve precise and effective ultrasonic neuromodulation.

Understanding Mental Health Needs and Gathering Feedback on Transcutaneous Auricular Vagus Nerve Stimulation as a Potential PTSD Treatment among 9/11 Responders Living with PTSD Symptoms 20 Years Later: A Qualitative Approach

Posttraumatic stress disorder (PTSD) remains one of the most prevalent diagnoses of World Trade Center (WTC) 9/11 responders. Transcutaneous auricular vagus nerve stimulation (taVNS) is a potential treatment for PTSD, as it can downregulate activity in the brain, which is known to be related to stress responses and hyperarousal. To understand barriers and facilitators to engagement in mental health care and the feasibility and acceptability of using the taVNS device as a treatment for PTSD symptoms, a focus group was conducted among patients from the Queens WTC Health Program who had elevated symptoms of PTSD. The focus group discussion was recorded, transcribed, and analyzed. Three themes and subthemes emerged: (1) the continued prevalence of mental health difficulties and systematic challenges to accessing care; (2) positive reception toward the taVNS device as a potential treatment option, including a discussion of how to increase usability; and (3) feedback on increasing the feasibility and acceptance of the research methodology associated with testing the device in a pilot clinical trial. The findings highlight the need for additional treatment options to reduce PTSD symptoms in this population and provide key formative phase input for the pilot clinical trial of taVNS.

The Slowest Shared Resonance: A Review of Electromagnetic Field Oscillations Between Central and Peripheral Nervous Systems

Electromagnetic field oscillations produced by the brain are increasingly being viewed as causal drivers of consciousness. Recent research has highlighted the importance of the body's various endogenous rhythms in organizing these brain-generated fields through various types of entrainment. We expand this approach by examining evidence of extracerebral shared oscillations between the brain and other parts of the body, in both humans and animals. We then examine the degree to which these data support one of General Resonance Theory's (GRT) principles: the Slowest Shared Resonance (SSR) principle, which states that the combination of micro- to macro-consciousness in coupled field systems is a function of the slowest common denominator frequency or resonance. This principle may be utilized to develop a spatiotemporal hierarchy of brain-body shared resonance systems. It is predicted that a system's SSR decreases with distance between the brain and various resonating structures in the body. The various resonance relationships examined, including between the brain and gastric neurons, brain and sensory organs, and brain and spinal cord, generally match the predicted SSR relationships, empirically supporting this principle of GRT.

Transcranial Electrical Stimulation for Relief of Peripartum Mental Health Disorders in Women Undergoing Cesarean Section With Combined Spinal-Epidural Anesthesia: A Pilot Randomized Clinical Trial

OBJECTIVE

This study aimed to explore transcranial electrical stimulation (tES) to relieve peripartum anxiety and depressive symptoms in women undergoing cesarean section with combined spinal-epidural anesthesia.

METHODS

This double-blind, randomized, sham-controlled trial was conducted in the Affiliated Hospital of Xuzhou Medical University from March 2021 and May 2021. One hundred and forty-eight full-term parturients giving birth by elective cesarean section were selected, and 126 were included in the intent-to-treat analysis. Parturients were provided standardized anesthesia and randomized to the active-tES (a-tES) group and sham-tES group. Parturients and outcome assessors were blinded to treatment allocation. The primary outcome was the changes in peripartum mental health disorders, including anxiety, assessed by the Pregnancy-Related Anxiety Questionnaire-Revised 2 (PRAQ-R2). Secondary outcomes included peripartum depressive symptoms, assessed by the Edinburgh Postnatal Depression Scale (EPDS), maternal satisfaction, fatigue level, sleep quality index, and pain score during and after operation. Data were collected before entering the operating room (T0), between post-anesthesia and pre-surgery (T1), before leaving the operating room (T2), and at 24 h post-surgery (T3).

RESULTS

One hundred and twenty-six eligible parturients were enrolled in the two groups: a-tES group (N = 62) and sham-tES group (N = 64). Treatment with tES resulted in significantly lower scores of anxiety compared with sham-tES (T2: P < 0.001; T3: P = 0.001). Moreover, the a-tES groups showed a significant reduction in depression scores (T2: P = 0.003; T3: P = 0.032).

CONCLUSION

In this randomized pilot study, tES treatment is efficacious in alleviating peripartum anxiety and depressive symptoms in women undergoing cesarean section and has been demonstrated to be a novel strategy for improving peripartum mental health disorders.

CLINICAL TRIAL REGISTRATION

[www.chictr.org.cn], identifier [ChiCTR2000040963].

A Systematic Approach to Neuropsychiatric Intervention: Functional Neuroanatomy Underlying Symptom Domains as Targets for Treatment

An ever-growing population experiences a wide range of psychopathologies, and there is now more than ever a need for clear differential diagnoses between disorders. Furthering this need is the fact that many psychological, psychiatric, and neurological disorders have overlapping features. Functional neuroimaging has been shown to differentiate not only between the function of different brain structures but also between the roles of these structures in functional networks. The aim of this article is to aid in the goal of parsing out disorders on the basis of specific symptom domains by utilizing the most recent literature on functional networks. Current literature on the role of brain networks in relation to different psychopathological symptom domains is examined and corresponding circuit-based therapies that have been or may be used to treat them are discussed. Research on depression, obsession and compulsions, addiction, anxiety, and psychosis is reviewed. An understanding of networks and their specific dysfunctions opens the possibility of a new form of psychopathological treatment.

Effects of cranial electrotherapy stimulation with novel in-ear electrodes on anxiety and resting-state brain activity: A randomized double-blind placebo-controlled trial

BACKGROUND

Cranial Electrotherapy Stimulation (CES) is a promising non-invasive brain stimulation technique with the potential to alleviate anxiety. We examined the effectiveness of home-based CES with novel, headphone-like, in-ear electrodes on anxiety-related symptoms and resting-state brain activity.

METHODS

This study spanned 3-weeks, with randomized, double blind, and active-controlled design. Nonclinical volunteers experiencing daily anxiety were randomly assigned to either the active or the sham groups. CES provides an alternating current (10 Hz frequency, 500 μA intensity), connected to smartphone recording treatment logs. Participants treated themselves with 20 trials of CES at home. We evaluated the effectiveness using State-Trait Anxiety Inventory (STAI), Beck Depression Inventory (BDI), Wisconsin Card Sort Test (WCST), and resting-state electroencephalography (EEG).

RESULTS

The active group showed a significant improvement in state-anxiety compared to sham, while there was a statistical trend in the WCST-Category Completed (p = .061) and no change in depression. In EEG analysis, the active group showed significantly increased relative power for theta in the left frontal region compared with the sham, and this significantly correlated with the changes in state-anxiety. The active group exhibited significantly increased high-beta source activity in cuneus and middle occipital gyrus after intervention compared with the baseline.

LIMITATIONS

This study had a relatively short treatment period and small sample size.

CONCLUSIONS

Our findings provide the first electrophysiological evidence for CES for novel in-ear electrodes to improve anxiety. The modulatory effects of CES on resting-state oscillations of EEG imply that CES could beneficially affect functional brain activity.

Identify potential neuroimaging-based scalp acupuncture and neuromodulation targets for anxiety

Anxiety is a common psychiatric symptom with unsatisfactory treatment. Scalp acupuncture is a new type of acupuncture based on the functions of different brain regions. However, recent brain neuroimaging findings have not been well-integrated into scalp acupuncture practice and research since it was developed. In parallel, recently developed brain stimulation methods have also been applied to treat anxiety. In this study, we integrated meta-analysis (using Neurosynth), resting-state functional connectivity, and diffusion tensor imaging (using the amygdala as the region of interest) to identify potential locations of scalp acupuncture/neuromodulation for anxiety. We found that the superior/middle frontal gyrus, middle/superior temporal gyrus, precentral gyrus, supplementary motor area, supramarginal gyrus, angular gyrus, and superior/inferior occipital gyrus are involved in the pathophysiology of anxiety, and, thus, may be used as the target areas of scalp stimulation for alleviating anxiety. Integrating multidisciplinary brain methods to identify key surface cortical areas associated with a certain disorder may shed light on the development of scalp acupuncture/neuromodulation, particularly in the domain of identifying stimulation locations.

Application of Transcranial Direct Current Stimulation in Psychiatry

Transcranial direct current stimulation (tDCS) is a neuromodulation technique, which noninvasively alters cortical excitability via weak polarizing currents between two electrodes placed on the scalp. Since it is comparably easy to handle, cheap to use and relatively well tolerated, tDCS has gained increasing interest in recent years. Based on well-known behavioral effects, a number of clinical studies have been performed in populations including patients with major depressive disorder followed by schizophrenia and substance use disorders, in sum with heterogeneous results with respect to efficacy. Nevertheless, the potential of tDCS must not be underestimated since it could be further improved by systematically investigating the various stimulation parameters to eventually increase clinical efficacy. The present article briefly explains the underlying physiology of tDCS, summarizes typical stimulation protocols and then reviews clinical efficacy for various psychiatric disorders as well as prevalent adverse effects. Future developments include combined and more complex interactions of tDCS with pharmacological or psychotherapeutic interventions. In particular, using computational models to individualize stimulation protocols, considering state dependency and applying closed-loop technologies will pave the way for tDCS-based personalized interventions as well as the development of home treatment settings promoting the role of tDCS as an effective treatment option for patients with mental health problems.

Potential scalp stimulation targets for mental disorders: evidence from neuroimaging studies

Mental disorders widely contribute to the modern global disease burden, creating a significant need for improvement of treatments. Scalp stimulation methods (such as scalp acupuncture and transcranial electrical stimulation) have shown promising results in relieving psychiatric symptoms. However, neuroimaging findings haven’t been well-integrated into scalp stimulation treatments. Identifying surface brain regions associated with mental disorders would expand target selection and the potential for these interventions as treatments for mental disorders. In this study, we performed large-scale meta-analyses separately on eight common mental disorders: attention deficit hyperactivity disorder, anxiety disorder, autism spectrum disorder, bipolar disorder, compulsive disorder, major depression, post-traumatic stress disorder and schizophrenia; utilizing modern neuroimaging literature to summarize disorder-associated surface brain regions, and proposed neuroimaging-based target protocols. We found that the medial frontal gyrus, the supplementary motor area, and the dorsal lateral prefrontal cortex are commonly involved in the pathophysiology of mental disorders. The target protocols we proposed may provide new brain targets for scalp stimulation in the treatment of mental disorders, and facilitate its clinical application.

Social Anxiety Symptoms and Quality of Life of Secondary School Students of Abha, Saudi Arabia

Interest in social anxiety disorder has grown substantially over the past few decades. Most of the available data from United States and European countries emphasized its high prevalence, comorbidity and morbidity and its association with occupational, educational, social affairs, stress, depression and substance use disorder contributing to poor quality of life. Present study was aimed to assess the social anxiety symptoms and to explore its impact on quality of life of secondary school students. Present study included male (n = 200) and female (n = 200) students enrolled at government secondary schools, Abha, Saudi Arabia. Arabic version of Social Phobia Inventory (SPIN) and World Health Organization Quality of Life Questionnaire (WHOQOL) were implemented to assess the social anxiety symptoms and quality of life of the students. Results revealed that 45% of the students showed social anxiety symptoms. Associated factors were younger age, chronic diseases, parent's status, parent's occupation and income. Quality of life was found significantly lower in students with social anxiety symptoms as compared to the students without symptoms. We suggest that the school health program should include routine screening of students for social anxiety disorder. Students diagnosed with social anxiety symptoms should be promptly managed and their quality of life should be improved.

Effects of transcranial direct current stimulation using miniaturized devices vs sertraline for depression in Korea: A 6 week, multicenter, randomized, double blind, active-controlled study

We compared the efficacy and safety of transcranial direct current stimulation (tDCS) vs. Sertraline in the treatment of Major Depressive Disorder (MDD) in South Korean participants. This was a multi-center, double blind, active controlled study with non-inferiority testing. Patients were randomly assigned to receive tDCS (n = 45) or Sertraline (n = 47). tDCS was administered in 30-min, 2 mA prefrontal stimulation sessions for 10 consecutive weekdays, followed by 2 treatments at 4 and 6 weeks. Sertraline was administered at a dose of 50 mg per day for 6 weeks. The primary outcome measure was a change in the Montgomery-Asberg Depression Rating Scale (MADRS) score at six weeks. Mean MADRS scores decreased by 14.58 ± 8.51 points in the tDCS group and 12.32 ± 8.56 points in the Sertraline group. There was no significant main effect of group (p = 0.5877) or time by group interaction across weeks 0, 3, and 6 (p = 0.1539). Noninferiority of tDCS compared with Sertraline was not demonstrated. The mean difference between the Sertraline and tDCS group was -2.258 (95% confidence interval [CI], -5.795 to 1.27811), and the lower boundary of the CI was lower than the prespecified noninferiority margin of -3.56. There were no significant group differences in the rate of adverse events. In the present study, the noninferiority of tDCS to Sertraline for the treatment of depression was not found in this Korean population.

The Effect of Transcranial Direct Current Stimulation on Relapse, Anxiety, and Depression in Patients With Opioid Dependence Under Methadone Maintenance Treatment: A Pilot Study

Background and Objective

Patients under methadone maintenance therapy (MMT) are susceptible to several complications including mental disturbances and risk of relapse. The present study was designed to evaluate the effects of tDCS on relapse, depression, and anxiety of opioid-dependent patients under methadone maintenance treatment (MMT).

Methods

It was a randomized-clinical trial that conducted among 27 male patients referred to the outpatient addiction clinic of Ibn-e-Sina psychiatric hospital in Mashhad from July 2018 to May 2019. Participants were allocated to two treatment groups including intervention and sham groups. The intervention group received seven sessions of tDCS, in the F3 (cathode) and F4 (anode) areas of the brain, each one lasts 20 min, in two consecutive weeks. Depression, anxiety, and stress scale-21 (DASS-21) were measured before, during, and after the intervention in patients under MMT. Relapse on the morphine, cannabis, and methamphetamine was screened by urine dipstick tests of morphine, cannabis, and methamphetamine.

Results

Depression, anxiety, and stress of participants were significantly reduced in the intervention group compared with the control after the seventh session of tDCS (P < 0.001, P=0.01, and P=0.01, respectively). In addition, the relapse rate showed no significant changes between the two groups (P=0.33).

Conclusion

Overall, our study demonstrated that depression, anxiety, and stress of participants were significantly reduced after the seventh session of tDCS, but did not affect on the relapse rate. Therefore, it can be applied as a safe and effective technique to relieve mental disorder among receiving MMT.

Clinical Trial Registration

http://www.irct.ir, identifier IRCT20180604039979N1.

Transcranial direct current stimulation for the treatment of generalized anxiety disorder: A randomized clinical trial

BACKGROUND

Generalized anxiety disorder (GAD) is a common condition with current treatments being only moderately effective. Non-invasive brain stimulation techniques might provide a novel approach for treating GAD. Transcranial direct current stimulation (tDCS) has shown promising efficacy and tolerability for major depression but has not been investigated for GAD yet. Thus, we investigated the effects of tDCS on patients with GAD.

METHODS

We conducted a pilot, double-blind, randomized, sham-controlled trial on 30 GAD patients. Five sessions of tDCS (2 mA, 20 min, anode over the left dorsolateral prefrontal cortex and cathode over the right supraorbital cortex) were performed. Anxiety was the primary outcome and it was measured by the Hamilton Anxiety Rating Scale and the Beck Anxiety Inventory. Secondary outcomes were accessed by the Lipp Inventory of Stress Symptoms for Adults, Positive and Negative Affect Schedule, and the Beck Depression Inventory (BDI). Data were examined at baseline, after the 5th day of intervention, and at 1-week follow-up.

RESULTS

Thirty patients finished the study. There were no significant improvements in anxiety, mood symptoms of stress, affectivity or depression. Anodal stimulation of the left DLPFC showed significant improvements in physical symptoms of stress in GAD patients.

LIMITATIONS

Additional tDCS sessions could have resulted in larger tDCS effects.

CONCLUSION

Five sessions of anodal tDCS over the DLPFC did not improve the main outcomes for GAD patients, although physical symptoms of stress were improved. The role of tDCS in GAD should be explored in larger patient samples using different parameters.

Novel pharmacological targets in drug development for the treatment of anxiety and anxiety-related disorders

Current medication for anxiety disorders is suboptimal in terms of efficiency and tolerability, highlighting the need for improved drug treatments. In this review an overview of drugs being studied in different phases of clinical trials for their potential in the treatment of fear-, anxiety- and trauma-related disorders is presented. One strategy followed in drug development is refining and improving compounds interacting with existing anxiolytic drug targets, such as serotonergic and prototypical GABAergic benzodiazepines. A more innovative approach involves the search for compounds with novel mechanisms of anxiolytic action using the growing knowledge base concerning the relevant neurocircuitries and neurobiological mechanisms underlying pathological fear and anxiety. The target systems evaluated in clinical trials include glutamate, endocannabinoid and neuropeptide systems, as well as ion channels and targets derived from phytochemicals. Examples of promising novel candidates currently in clinical development for generalised anxiety disorder, social anxiety disorder, panic disorder, obsessive compulsive disorder or post-traumatic stress disorder include ketamine, riluzole, xenon with one common pharmacological action of modulation of glutamatergic neurotransmission, as well as the neurosteroid aloradine. Finally, compounds such as D-cycloserine, MDMA, L-DOPA and cannabinoids have shown efficacy in enhancing fear-extinction learning in humans. They are thus investigated in clinical trials as an augmentative strategy for speeding up and enhancing the long-term effectiveness of exposure-based psychotherapy, which could render chronic anxiolytic drug treatment dispensable for many patients. These efforts are indicative of a rekindled interest and renewed optimism in the anxiety drug discovery field, after decades of relative stagnation.

Non-invasive brain stimulation in generalized anxiety disorder: A systematic review

In the last years, several studies using non-invasive brain stimulation (NIBS) techniques demonstrated that the dorsolateral prefrontal cortex (DLPFC) plays a key role in the neurobiological bases of anxiety disorders. Both transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) applied primarily over the prefrontal cortex have been shown to modulate anxiety symptomatology and attention allocation in the generalized anxiety disorder. A literature search on PubMed and PsycINFO databases following PRISMA guidelines identified 4 TMS studies (one open-label study and three randomized trials with active/sham conditions) and one tDCS case report study that have applied NIBS in patients with GAD. All the studies targeted the DLPFC except one in which the parietal cortex has been stimulated. Overall, the findings would suggest that NIBS could ameliorate anxiety symptoms and that improvements remained stable in the follow-up. Although a limited number of NIBS studies has been conducted on patients with anxiety disorders, these techniques could represent promising tools for the study of neurofunctional basis of anxiety disorders. Further sham-controlled studies are needed to clarify the mechanisms of action of NIBS in order to optimize stimulation protocols and to verify their effectiveness for treating anxiety symptoms.

The Dynamic Duo: Combining noninvasive brain stimulation with cognitive interventions

Pharmacotherapy, psychotherapy, and non-invasive brain stimulation (NIBS)¹ each show efficacy in the treatment of psychiatric disorders; however, more efficacious interventions are needed as reflected by an overall unmet need in mental health care. While each modality has typically been studied and developed as a monotherapy, in practice they are typically used in combination. Research has begun to emerge studying the potential synergistic actions of multi-modal, combination therapies. For example, NIBS combined with rehabilitation strategies have demonstrated some success for speech and motor rehabilitation in stroke patients. In this review we present evidence suggesting that combining NIBS with targeted, cognitive interventions offers a potentially powerful new approach to treating neuropsychiatric disorders. Here we focus on NIBS studies using transcranial direct current stimulation (tDCS)² and transcranial magnetic stimulation (TMS)³ given that these modalities are relatively safe, noninvasive, and can be performed simultaneously with neurocognitive interventions. We review the concept of "state dependent" effects of NIBS and highlight how simultaneous or sequential cognitive interventions could help optimize NIBS therapy by providing further control of ongoing neural activity in targeted neural networks. This review spans a range of neuropsychiatric disorders including major depressive disorder, schizophrenia, generalized anxiety, and autism. For each disorder, we emphasize neuroanatomical circuitry that could be engaged with combination therapy and critically discuss the literature that has begun to emerge. Finally, we present possible underlying mechanisms and propose future research strategies that may further refine the potential of combination therapies.

Predictors of Response to Repetitive Transcranial Magnetic Stimulation in Depression: A Review of Recent Updates

Transcranial magnetic stimulation (TMS) has been increasingly used in the treatment of various neuropsychiatric disorders including depression over the past two decades. The responses to treatment with TMS are variable as found in the recent studies. Evidences suggest that various factors influence the outcome of depression treated with TMS. Understanding the predictors of response to TMS treatment in depression will guide the clinician in appropriate selection of patients for TMS treatment as well as needful modification in the TMS technique and protocol to have a better clinical outcome. This article comprehensively reviews the factors that predict the outcome of TMS treatment in depression.

The effect of bilateral low-frequency rTMS over dorsolateral prefrontal cortex on serum brain-derived neurotropic factor and serotonin in patients with generalized anxiety disorder

To investigate the effect of bilateral low-frequency repetitive transcranial magnetic stimulation (rTMS) over dorsolateral prefrontal cortex on serum brain-derived neurotropic factor (BDNF) and serotonin (5-HT) in patients with generalized anxiety disorders (GAD). As compared with before treatment, the HARS score in patients markedly decreased after treatment, and the levels of serum BDNF and 5-HT were significantly higher. Pearson correlation analysis revealed that the increase in the level of serum 5-HT was positively associated with the increase of the level of serum BDNF, and the change of anxiety score was negatively associated with the change of the level of serum BDNF and 5-HT. The results suggested that alleviation of GAD by bilateral low-frequency rTMS may be involved in the increase of the level of BDNF and the release of 5-HT in the brain.

Clinical predictors of acute response to transcranial direct current stimulation (tDCS) in major depression

BACKGROUND

Transcranial direct current stimulation (tDCS) is a promising neuromodulation intervention for poor-responding or refractory depressed patients. However, little is known about predictors of response to this therapy. The present study aimed to analyze clinical predictors of response to tDCS in depressed patients.

METHODS

Clinical data from 3 independent tDCS trials on 171 depressed patients (including unipolar and bipolar depression), were pooled and analyzed to assess predictors of response. Depression severity and the underlying clinical dimensions were measured using the Hamilton Depression Rating Scale (HDRS) at baseline and after the tDCS treatment. Age, gender and diagnosis (bipolar/unipolar depression) were also investigated as predictors of response. Linear mixed models were fitted in order to ascertain which HDRS factors were associated with response to tDCS.

RESULTS

Age, gender and diagnosis did not show any association with response to treatment. The reduction in HDRS scores after tDCS was strongly associated with the baseline values of "Cognitive Disturbances" and "Retardation" factors, whilst the "Anxiety/Somatization" factor showed a mild association with the response.

LIMITATIONS

Open-label design, the lack of control group, and minor differences in stimulation protocols.

CONCLUSIONS

No differences in response to tDCS were found between unipolar and bipolar patients, suggesting that tDCS is effective for both conditions. "Cognitive disturbance", "Retardation", and "Anxiety/Somatization", were identified as potential clinical predictors of response to tDCS. These findings point to the pre-selection of the potential responders to tDCS, therefore optimizing the clinical use of this technique and the overall cost-effectiveness of the psychiatric intervention for depressed patients.