A Critical Review of Cranial Electrotherapy Stimulation for Neuromodulation in Clinical and Non-clinical Samples

Tripod transcranial alternating current stimulation at 5-Hz to alleviate anxiety symptoms: A preliminary report

INTRODUCTION

One of the most common applications of transcranial electrical stimulation (tES) at low current intensity is to induce a relaxed state or reduce anxiety. With technical advancement, different waveforms, montages, and parameters can be incorporated into the treatment regimen. We developed a novel protocol to treat individuals with anxiety disorders by transcranial alternating current stimulation (tACS).

METHODS

A total of 27 individuals with anxiety disorders underwent tACS treatment for 12 sessions, with each session lasting 25 min. tACS at 5 Hz was applied to F4 (1.0 mA), P4 (1.0 mA), and T8 (2.0 mA) EEG lead positions (tripod), with sinewave oscillation between T8 and F4/P4. We evaluated the primary and secondary outcomes using the Beck Anxiety Inventory (BAI) and neuropsychological assessments.

RESULTS

Of the 27 patients, 19 (70.4 %) experienced a reduction in symptom severity >50 %, with an average reduction of BAI 58.5 %. All reported side effects were mild, with itching or tingling being the most common complaint. No significant differences were noted in attention, linguistic working memory, visuospatial working memory, or long-term memory in neuropsychological assessments.

CONCLUSION

The results suggest the potential of this novel tripod tACS design as a rapid anxiety alleviator and the importance of a clinical trial to verify its efficacy.

Evaluating the efficacy of cranial electrotherapy stimulation in mitigating anxiety-induced cognitive deficits

Cranial electrotherapy stimulation (CES) is a form of non-invasive brain stimulation (NIBS) that has demonstrated potential to modulate neural activity in a manner that may be conducive to improved cognitive performance. While other forms of NIBS, such as transcranial direct current stimulation (tDCS), have received attention in the field as potential acute cognitive enhancers, CES remains relatively unexplored. The current study aimed to assess the efficacy of CES in improving acute cognitive performance under normal experimental conditions, as well as during sessions of induced situational anxiety (threat of shock or ToS). To study this question, participants completed a cognitive battery assessing processing speed and distinct aspects of executive functioning (working memory, inhibition, and task switching) in two separate sessions in which they received active and sham CES. Participants were randomly assigned to between subject groups of either situational anxiety (ToS) or control condition (no ToS). We predicted that active CES would improve performance on assessments of executive functioning (working memory, inhibition, and task switching) relative to sham CES under ToS. We did not find any significant effects of ToS, CES, or an interaction between ToS and CES for any measures of executive functioning or processing speed. These findings suggest that a single dose of CES does not enhance executive functioning or processing speed under normal conditions or during ToS.

Effect of cranial electrotherapy stimulation as an add-on therapy on late-life generalized anxiety disorder: An open-label study

INTRODUCTION

Cranial electrotherapy stimulation (CES) is beneficial in reducing anxiety in psychiatric patients. However, no studies have reported on elderly patients with generalized anxiety disorders (GAD). This study aimed to determine the efficacy and safety of a 6-week CES intervention for late-life GAD.

MATERIALS AND METHODS

This single-arm pilot study assessed 6-week CES treatment (Alpha-Stim AID) for late-life GAD and 4-week follow-up post intervention. The Hamilton Rating Scale for Anxiety (HAMA) and Beck Anxiety Inventory (BAI) were used as baseline and outcome measures at weeks 4, 6, and 10, respectively. Treatment response was defined as 50 % or more reduction of the HAMA score and remission was defined as a of score ≤7 on the HAMA. Other measures included depression, sleep quality, and quality of life assessment.

RESULTS

We included participants (n = 27) aged 68.0 ± 5.0 years, 81.5 % of whom were female. Fifteen (55.6 %), 18 (66.7 %), and 15 (55.6 %) patients were concurrently treated with antidepressants, BZDs, and antipsychotics, respectively. Intention-to-treat (ITT) analysis revealed a significant decrease in HAMA scores from baseline (20.96 ± 3.30) to week 6 (12.26 ± 7.09) and one-month (12.85 ± 7.08) follow-up at W10 (all p < 0.001). The response and remission rates were 33.3 %, 40.7 %, and 48.1 % and 25.9 %, 29.6 %, and 25.9 % at W4, W6, and W10, respectively. The CES improved depression and sleep conditions as measured by the Beck Depression Inventory-II and Pittsburgh Sleep Quality Index.

CONCLUSION

CES clinically reduces symptoms of anxiety and depression and may improve sleep quality in late-life GAD. Future randomized controlled study is needed.

Bridging the Gap between Psychophysiological and Audiological Factors in the Assessment of Tinnitus: An EEG Investigation in the Beta Band

BACKGROUND

Despite substantial progress in investigating its psychophysical complexity, tinnitus remains a scientific and clinical enigma. The present study, through an ecological and multidisciplinary approach, aims to identify associations between electroencephalographic (EEG) and psycho-audiological variables.

METHODS

EEG beta activity, often related to stress and anxiety, was acquired from 12 tinnitus patients (TIN group) and 7 controls (CONT group) during an audio cognitive task and at rest. We also investigated psychological (SCL-90-R; STAI-Y; BFI-10) and audiological (THI; TQ12-I; Hyperacusis) variables using non-parametric statistics to assess differences and relationships between and within groups.

RESULTS

In the TIN group, frontal beta activity positively correlated with hyperacusis, parietal activity, and trait anxiety; the latter is also associated with depression in CONT. Significant differences in paranoid ideation and openness were found between groups.

CONCLUSIONS

The connection between anxiety trait, beta activity in the fronto-parietal cortices and hyperacusis provides insights into brain functioning in tinnitus patients, offering quantitative descriptions for clinicians and new multidisciplinary treatment hypotheses.

Psychodynamically Informed Brain Stimulation: Building a Bridge from Brain to Mind

Since its inception, psychiatry has undergone several periods of radical identity transformation. Initially limited to psychotherapy alone, the advent of medications stimulated an era of biological psychiatry. For years, medications served as the mainstay of biological treatments, paralleled by a rise in treatment resistance. Brain stimulation therapies are psychiatry's newest arm of intervention and represent an area ripe for exploration. These techniques offer new hope to treatment-resistant patients, but in a manner often dissociated from psychoanalytic conceptualization and the practice of psychotherapy. There is growing interest in bridging this divide. In this article, we continue the efforts at interweaving what may seem to be disparate approaches through the topic of treatment resistance. This article aims to engage interventional psychiatrists in considering psychosocial dimensions of their treatments and to provide education for psychoanalytic clinicians on the history, mechanism of action, and applications of brain stimulation technologies.

Transcranial alternating current stimulation improves quality of life in Parkinson's disease: study protocol for a randomized, double-blind, controlled trial

BACKGROUND

The neural cells in the brains of patients with Parkinson's disease (PWP) display aberrant synchronized oscillatory activity within the beta frequency range. Additionally, enhanced gamma oscillations may serve as a compensatory mechanism for motor inhibition mediated by beta activity and also reinstate plasticity in the primary motor cortex affected by Parkinson's disease. Transcranial alternating current stimulation (tACS) can synchronize endogenous oscillations with exogenous rhythms, thereby modulating cortical activity. The objective of this study is to investigate whether the addition of tACS to multidisciplinary intensive rehabilitation treatment (MIRT) can improve symptoms of PWP so as to enhance the quality of life in individuals with Parkinson's disease based on the central-peripheral-central theory.

METHODS

The present study was a randomized, double-blind trial that enrolled 60 individuals with Parkinson's disease aged between 45 and 70 years, who had Hoehn-Yahr scale scores ranging from 1 to 3. Participants were randomly assigned in a 1:1 ratio to either the tACS + MIRT group or the sham-tACS + MIRT group. The trial consisted of a two-week double-blind treatment period followed by a 24-week follow-up period, resulting in a total duration of twenty-six weeks. The primary outcome measured the change in PDQ-39 scores from baseline (T0) to 4 weeks (T2), 12 weeks (T3), and 24 weeks (T4) after completion of the intervention. The secondary outcome assessed changes in MDS-UPDRS III scores at T0, the end of intervention (T1), T2, T3, and T4. Additional clinical assessments and mechanistic studies were conducted as tertiary outcomes.

DISCUSSION

The objective of this study is to demonstrate that tACS can enhance overall functionality and improve quality of life in PWP, based on the framework of MIRT. Additionally, it seeks to establish a potential correlation between these therapeutic effects and neuroplasticity alterations in relevant brain regions. The efficacy of tACS will be assessed during the follow-up period in order to optimize neuroplasticity and enhance its potential impact on rehabilitation efficiency for PWP.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2300071969. Registered on 30 May 2023.

Efficacy of cranial electrotherapy stimulation on mood and sense of well-being in people with subclinical insomnia

Cranial electrotherapy stimulation is a non-invasive brain stimulation method characterised by using a microcurrent. The objective of the study was to investigate whether a novel device with a stable supplement of electronic stimulation would improve sleep and the accompanying mood symptoms in people with subclinical insomnia. People who had insomnia symptoms without meeting the criteria for chronic insomnia disorder were recruited and randomly assigned to an active or a sham device group. They were required to use the provided device for 30 min each time, twice a day for 2 weeks. Outcome measures included questionnaires for sleep, depression, anxiety, and quality of life, 4 day actigraphy, and 64-channel electroencephalography. Fifty-nine participants (male 35.6%) with a mean age of 41.1 ± 12.0 years were randomised. Improvement of depression (p = 0.032) and physical well-being (p = 0.041) were significant in the active device group compared with the sham device group. Anxiety was also improved in the active device group, although the improvement was not statistically significant (p = 0.090). Regarding sleep, both groups showed a significant improvement in subjective rating, showing no significant group difference. The change in electroencephalography after the 2 week intervention was significantly different between the two groups, especially for occipital delta (p = 0.008) and beta power (p = 0.012), and temporo-parieto-occipital theta (p = 0.022). In conclusion, cranial electrotherapy stimulation can serve as an adjunctive therapy to ameliorate psychological symptoms and to alter brain activity. The effects of the device in a clinical population and an optimal set of parameters of stimulation should be further investigated.

Evidence of a large current of transcranial alternating current stimulation directly to deep brain regions

Deep brain regions such as hippocampus, insula, and amygdala are involved in neuropsychiatric disorders, including chronic insomnia and depression. Our recent reports showed that transcranial alternating current stimulation (tACS) with a current of 15 mA and a frequency of 77.5 Hz, delivered through a montage of the forehead and both mastoids was safe and effective in intervening chronic insomnia and depression over 8 weeks. However, there is no physical evidence to support whether a large alternating current of 15 mA in tACS can send electrical currents to deep brain tissue in awake humans. Here, we directly recorded local field potentials (LFPs) in the hippocampus, insula and amygdala at different current strengths (1 to 15 mA) in 11 adult patients with drug-resistant epilepsy implanted with stereoelectroencephalography (SEEG) electrodes who received tACS at 77.5 Hz from 1 mA to 15 mA at 77.5 Hz for five minutes at each current for a total of 40 min. For the current of 15 mA at 77.5 Hz, additional 55 min were applied to add up a total of 60 min. Linear regression analysis revealed that the average LFPs for the remaining contacts on both sides of the hippocampus, insula, and amygdala of each patient were statistically associated with the given currents in each patient (p < 0.05-0.01), except for the left insula of one subject (p = 0.053). Alternating currents greater than 7 mA were required to produce significant differences in LFPs in the three brain regions compared to LFPs at 0 mA (p < 0.05). The differences remained significant after adjusting for multiple comparisons (p < 0.05). Our study provides direct evidence that the specific tACS procedures are capable of delivering electrical currents to deep brain tissues, opening a realistic avenue for modulating or treating neuropsychiatric disorders associated with hippocampus, insula, and amygdala.

Noninvasive Brain Stimulation for Cancer Pain Management in Nonbrain Malignancy: A Meta-Analysis

Purpose. Noninvasive brain stimulation (NIBS) has been reported to have analgesic effects on fibromyalgia and chronic neuropathic pain; however, its effects on cancer pain have yet to be determined. The present study aimed to evaluate the effects of NIBS on patients with pain secondary to nonbrain malignancy. Methods. Electronic databases including PubMed, Embase, Cochrane Library, and Web of Science were searched from inception through June 5th, 2022. Parallel, randomized, placebo-controlled studies were included that enrolled adult patients with cancer pain, except for that caused by brain tumors, compared NIBS with placebo stimulation, and reported sufficient data for performing meta-analysis. Results. Four parallel, randomized, sham-controlled studies were included: two of repetitive transcranial magnetic stimulation (rTMS), one of transcranial direct current stimulation (tDCS), and one of cranial electrical stimulation (CES). rTMS significantly improved pain in the subgroup analysis (standardized mean difference (SMD): −1.148, 95% confidence interval (CI): −1.660 to −0.637, ( $p<0.001$ )), while NIBS was not benefited in reducing pain intensity (SMD: −0.632, 95% CI: −1.356 to 0.092, p = 0.087). Also, NIBS significantly improved depressive symptoms (SMD: −0.665, 95% CI: −1.178 to −0.153, p = 0.011), especially in the form of rTMS (SMD: −0.875, 95% CI: −1.356 to −0.395, $p<0.001$ ) and tDCS (SMD: −1.082, 95% CI: −1.746 to −0.418, p = 0.001). Conclusion. rTMS significantly improved pain secondary to nonbrain malignancy apart from other forms of NIBS without major adverse events.

Clinical effectiveness of active Alpha-Stim AID versus sham Alpha-Stim AID in major depression in primary care in England (Alpha-Stim-D): a multicentre, parallel group, double-blind, randomised controlled trial

BACKGROUND

Randomised sham-controlled trials of cranial electrostimulation with the Alpha-Stim Anxiety Insomnia and Depression (AID) device have reported improved anxiety and depression symptoms; however, no adequately powered sham-controlled trials in major depression are available. We investigated whether active Alpha-Stim AID is superior to sham Alpha-Stim AID in terms of clinical effectiveness for depression symptoms in major depression.

METHODS

The Alpha-Stim-D trial was a multicentre, parallel group, double-blind, randomised controlled trial, recruiting participants from 25 primary care centres in two regions in England, UK. Eligible participants were aged 16 years or older with a current diagnosis of primary major depression, a score of 10-19 on the nine-item Patient Health Questionnaire, and had been offered or prescribed and reported taking antidepressant medication for at least 6 weeks in the previous 3 months. Main exclusion criteria were contraindications to Alpha-Stim AID device use, having persistent suicidal ideation or self-harm, neurological conditions, a substance use disorder or dependence, an eating disorder, bipolar disorder, or non-affective psychosis, or receiving psychological treatment in the past 3 months. Eligible participants were randomly assigned (1:1, minimised by region, anxiety disorder, and antidepressant use) to 1 h daily use of active (100 μA) or sham Alpha-Stim AID treatment for 8 weeks. Randomisation was via an independent web-based system, with participants, outcome assessors, and data analyst masked to treatment assignment. The primary outcome was change from baseline in score on the 17-item Hamilton Depression Rating Scale (HDRS-17, GRID version) at 16 weeks after randomisation, with participants analysed by intention to treat (ITT; all randomly assigned participants). Safety was assessed in all randomly assigned participants. The trial is registered with the ISRCTN registry (ISRCTN11853110); status completed.

FINDINGS

Between Sept 8, 2020, and Jan 14, 2022, 236 eligible participants were randomly assigned to active or sham Alpha-Stim AID (n=118 each). 156 (66%) participants were women, 77 (33%) were men, and three (1%) self-reported as other gender; 200 (85%) were White British or Irish; and the mean age was 38·0 years (SD 15·3; range 16-83). 102 (86%) participants in the active Alpha-Stim AID group and 98 (83%) in the sham group were followed up 16 weeks after randomisation. In the ITT population, mean change in GRID-HDRS-17 at 16 weeks was -5·9 (95% CI -7·1 to -4·8) in the active Alpha-Stim AID group and -6·5 (-7·7 to -5·4) in the sham group (mean change difference -0·6 [95% CI -1·0 to 2·2], p=0·46). Among the 236 participants, 17 adverse events were reported in 17 (7%) participants (nine [8%] participants in the active Alpha-Stim AID group; and eight [7%] participants in the sham group). One serious adverse event of suicidal ideation leading to hospitalisation was reported in the sham group, which was judged to be unrelated to the device.

INTERPRETATION

Active Alpha-Stim AID was safe and acceptable, but no more clinically effective than sham Alpha-Stim AID in major depression.

FUNDING

National Institute for Health Research Applied Research Collaboration East Midlands and Electromedical Products International.

Efficacy of electrical cranial stimulation for treatment of psychiatric symptoms in patients with anxiety: A systematic review and meta-analysis

Background

Therapeutic effects of electrical cranial stimulation (CES) in patients suffering from anxiety remained unclear. This meta-analysis aimed at investigating acceptability and therapeutic efficacy of CES against anxiety, depression, and insomnia for patients who experienced symptoms of anxiety.

Methods

Major electronic databases were searched from inception until December 10, 2022 for randomized controlled trials (RCT) focusing on therapeutic effectiveness of CES in patients whose primary complaints included anxiety. Effect sizes (ES) for different treatment outcomes were estimated by using generic inverse variance method.

Results

Eight RCTs were identified including a total of 337 participants. The therapeutic effectiveness of CES was significantly better than that in the control groups for anxiety (ES=-0.96, p <0.00001, eight trials, 337 patients), depression (ES=-0.69, p=0.003, five trials), and insomnia (ES=-1.02, p = 0.0006, three trials) in those who presented with symptoms of anxiety. Subgroup analyses found that CES was equally effective regardless of comorbid presentation of depressive symptoms (ES=-0.94 in patients with anxiety only vs. ES=-1.06 in those with depression and anxiety) and whether CES was used as monotherapy or add-on therapy to medications (ES = -0.88 vs. ES = -1.12, respectively). Moreover, subgroup analysis of RCTs using the same device "Alpha-Stim" for CES was more effective in alleviating anxiety than sham controls (ES = -0.88, p < 0.00001, four trials, 230 patients). Regarding acceptability, the use of CES did not increase the risk of treatment-related dropout compared to the control group (RR = 1.26, p = 0.57, I² = 0%, four trials, 324 patients).

Conclusion

Our study supported the use of CES for symptoms of anxiety, depression, and insomnia in those suffering from anxiety with fair acceptability and demonstrated the efficacy of "Alpha-Stim", the most commonly used device for CES, in this patient population.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022382619.

Clinical Spectrum and Trajectory of Innovative Therapeutic Interventions for Insomnia: A Perspective

Increasing incidences of insomnia in adults, as well as the aging population, have been reported for their negative impact on the quality of life. Insomnia episodes may be associated with neurocognitive, musculoskeletal, cardiovascular, gastrointestinal, renal, hepatic, and metabolic disorders. Epidemiological evidence also revealed the association of insomnia with oncologic and asthmatic complications, which has been indicated as bidirectional. Two therapeutic approaches including cognitive behavioral therapy (CBT) and drugs-based therapies are being practiced for a long time. However, the adverse events associated with drugs limit their wide and long-term application. Further, Traditional Chinese medicine, acupressure, and pulsed magnetic field therapy may also provide therapeutic relief. Notably, the recently introduced cryotherapy has been demonstrated as a potential candidate for insomnia which could reduce pain, by suppressing oxidative stress and inflammation. It seems that the synergistic therapeutic approach of cryotherapy and the above-mentioned approaches might offer promising prospects to further improve efficacy and safety. Considering these facts, this perspective presents a comprehensive summary of recent advances in pathological aetiologies of insomnia including COVID-19, and its therapeutic management with a greater emphasis on cryotherapy.

Lesions causing central sleep apnea localize to one common brain network

Objectives

To characterize the specific brain regions for central sleep apnea (CSA) and identify its functional connectivity network.

Methods

We performed a literature search and identified 27 brain injuries causing CSA. We used a recently validated methodology termed “lesion network mapping” to identify the functional brain network subtending the pathophysiology of CSA. Two separate statistical approaches, the two-sample t-test and the Liebermeister test, were used to evaluate the specificity of this network for CSA through a comparison of our results with those of two other neurological syndromes. An additional independent cohort of six CSA cases was used to assess reproducibility.

Results

Our results showed that, despite lesions causing CSA being heterogeneous for brain localization, they share a common brain network defined by connectivity to the middle cingulate gyrus and bilateral cerebellar posterior lobes. This CSA-associated connectivity pattern was unique when compared with lesions causing the other two neurological syndromes. The CAS-specific regions were replicated by the additional independent cohort of six CSA cases. Finally, we found that all lesions causing CSA aligned well with the network defined by connectivity to the cingulate gyrus and bilateral cerebellar posterior lobes.

Conclusion

Our results suggest that brain injuries responsible for CSA are part of a common brain network defined by connectivity to the middle cingulate gyrus and bilateral cerebellar posterior lobes, lending insight into the neuroanatomical substrate of CSA.

Comparison of the effects of cranial electrotherapy stimulation and midazolam as preoperative treatment in geriatric patients: A CONSORT-compliant randomized controlled trial

BACKGROUND

Although midazolam is widely administered as an anxiolytic premedication, it may cause over-sedation and hypoxia in geriatric patients. Cranial electrotherapy stimulation (CES) is a nonpharmacological device with anxiolytic effect. This study compared the effects of CES and midazolam as a preoperative treatment in geriatric patients.

METHODS

Eighty patients, under the age of 65 to 79 years, undergoing general anesthesia were randomly assigned into midazolam premedication group (M group, n = 40) or CES pretreatment group (CES group, n = 40). The patients in the M group were intramuscularly injected with midazolam (0.07 mg/kg) 30 minutes before receiving general anesthesia. The patients in the CES group received 20 minutes of CES pretreatment on the day before and on the morning of the surgery.

RESULTS

In the preoperative holding area, the anxiety score (P = .02) and the sedation score (P < .001) were significantly lower in the CES group compared with those in the M group. The oxygen saturations at the preoperative holding area and the operating room were significantly higher in the CES group than those in the M group (P < .001).

CONCLUSION

CES pretreatment relieved preoperative anxiety with less risk of over-sedation and respiratory depression than midazolam premedication in geriatric patients.

In vivo Measurements of Electric Fields During Cranial Electrical Stimulation in the Human Brain

Cranial electrical stimulation (CES) has been applied at various current levels in both adults and children with neurological conditions with seemingly promising but somewhat inconsistent results. Stimulation-induced spatial electric fields (EFs) within a specific brain region are likely a significant contributing factor for the biological effects. Although several simulation models have been used to predict EF distributions in the brain, these models actually have not been validated by in vivo CES-induced EF measurements in the live human brain. This study directly measured the CES-induced voltage changes with implanted stereotactic-electroencephalographic (sEEG) electrodes in twenty-one epilepsy participants (16 adults and 5 children) and then compared these measured values with the simulated ones obtained from the personalized models. In addition, we further investigated the influence of stimulation frequency, intensity, electrode montage and age on EFs in parts of participants. We found both measured voltages and EFs obtained in vivo are highly correlated with the predicted ones in our cohort (Voltages: r = 0.93, p &lt; 0.001; EFs: r = 0.73, p &lt; 0.001). In white matter and gray matter, the measured voltages linearly increased when the stimulation intensity increased from 5 to 500 μA but showed no significant changes (averaged coefficient of variation &lt;4.10%) with changing stimulation frequency from 0.5 to 200 Hz. Electrode montage, but not age, significantly affects the distribution of the EFs (n = 5, p &lt; 0.01). Our in vivo measurements demonstrate that the individualized simulation model can reliably predict the CES-induced EFs in both adults and children. It also confirms that the CES-induced EFs highly depend on the electrode montages and individual anatomical features.

Efficacy and Tolerability of Cranial Electrotherapy Stimulation in the Treatment of Anxiety: A Systemic Review and Meta-Analysis

OBJECTIVE

We aimed to investigate the efficacy and tolerability of cranial electrotherapy stimulation (CES) for patients with anxiety symptoms.

METHOD

We searched the Pubmed, Cochrane Central Register of Controlled Trials (CENTRAL), Embase and Medline for randomized control trials (RCTs) from the time of inception until November 15, 2021, following Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. Data were pooled using a random-effects model. The primary outcomes were the mean change scores for anxiety symptoms. The secondary outcomes were the mean change scores for depressive symptoms.

RESULTS

Eleven RCTs were eligible (n = 794, mean age: 41.4, mean population of female: 64.8%). CES significantly reduced the anxiety symptoms compared to the control group [k = 11, n = 692, Hedge's g = -0.625, 95% confidence intervals (CIs) = -0.952 to -0.298, P < 0.001] with moderate effect size. The subgroup analysis showed that CES reduced both primary and secondary anxiety (primary anxiety, k =3, n = 288, Hedges' g = -1.218, 95% CIs = -1.418 to -0.968, P = 0.007; secondary anxiety, k = 8, n = 504, Hedges' g = -0.334, 95% CIs = -0.570 to -0.098, P = 0.006). After performing between group analysis, we found CES has significant better efficacy for patients with primary anxiety than those with secondary anxiety (P < 0.001). For secondary outcome, CES significantly reduced depressive symptoms in patients with anxiety disorders (k = 8, n = 552, Hedges' g = -0.648, 95% CIs = -1.062 to -0.234, P = 0.002). No severe side effects were reported and the most commonly reported adverse events were ear discomfort and ear pain.

CONCLUSION

We found CES is effective in reducing anxiety symptoms with moderate effect size in patients with both primary and secondary anxiety. Furthermore, CES was well-tolerated and acceptable.Systematic Review Registration: PROSPERO, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021267916.

Efficacy of cranial microcurrent stimulation in patients with tension-type headache: A prospective, randomised, double-blinded, sham-controlled clinical trial

OBJECTIVE

To investigate the therapeutic effect of cranial microcurrent stimulation (CMS) in patients with tension-type headaches (TTH).

METHODS

This study was designed as a prospective, randomised, double-blinded and sham-controlled trial. A total of 22 patients with tension-type headache were selected as our study participants and randomly assigned into two groups: CMS group (n = 11) and Sham group (n = 11). To each of the participants, a sham or a true portable CMS stimulation device (CMS; intensity, 25 μA; frequency, 8 Hz) to wear was distributed, and 20-minute daily treatment was provided using the device for 2 weeks. In CMS group, treatment was given by means of electrodes clipped to the ear, whereas, in Sham group, sham treatment was provided by CMS without current. The measurements of Visual Analogue Scale (VAS), Headache Impact Test-6 (HIT6), Patient Health Questionnaire-9 (PHQ9), Generalised Anxiety Disorder 7-item (GAD7) and Hospital Anxiety and Depression Scale (HADS) were performed at pre-treatment (baseline), week 1 and 2 of treatment and two weeks post-treatment.

RESULTS

In CMS group, VAS of maximal headache and VAS of current headache, HIT6, PHQ9 and GAD7 significantly decreased by two weeks post-CMS therapy, but not in Sham group (P < .05). Scores of HADS-A (anxiety), HADS-D (depression) and HADS-T (total) significantly decreased by 2 weeks post-CMS therapy in CMS group, but not in Sham group (P < .05). Changes in scores of PHQ9 and GAD7, HADS-A, HADS-D and HADS-T in CMS group were significantly greater than in Sham group by 2 weeks post-CMS therapy (P < .05).

CONCLUSION

The results indicate that CMS, as an adjunctive treatment for patients with TTH, is safe and analgesic as well as reducing depression or anxiety.