Effects Of Transcranial Direct Current Stimulation Research Articles

Effects of TDCS combined with Mat exercises on balance in patients with stroke

Abstract The purpose of the present study was to evaluate the effect of transcranial direct current stimulation (TDCS) along with Mat exercises in stroke. A single blinded RCT with ‘intention to treat’ analysis was conducted according to the ‘Consolidated standards of reporting trial (CONSORT)’ 2010 guidelines. Patients suffering from haemorrhagic/ischemic stroke with unilateral hemiplegia having balance problems and age group above the 40 years were included in this study. A total of 32 participants were randomly allocated into two groups: Group A (n = 16) and Group B (n = 16). The patients in Group A were treated with TDCS and Mat exercises whereas participants of Group B were given sham TDCS for 15 min and conventional balance training. The treatment was given alternatively, thrice a week, for 2 weeks. Entire procedure was completed within 45-60 min. Two outcome measures were used to assess the balance, i.e. functional reach test (FRT) and time up & go test (TUG). There were more males than females in both experimental groups. Results of baseline comparison reported that there was a statistically non-significant difference in the variables and the data were normally distributed. Results of the within group analysis found that there was statistically significant improvement in pre- and post-intervention scores of both groups. Results of between group analysis showed that there was a statistically significant improvement in the variables of Group A compared to Group B. This study concludes that the combined use of TDCS along with Mat exercises can improve the balance as compared to Sham TDCS along with conventional balance training.

Transcranial Direct-Current Stimulation Over the Primary Motor Cortex and Cerebellum Improves Balance and Shooting Accuracy in Elite Ice Hockey Players.

To investigate the effects of transcranial direct-current stimulation (tDCS) applied over the primary motor cortex (M1) and cerebellum on balance control and shooting accuracy in elite ice hockey players. Twenty-one elite ice hockey players underwent anodal tDCS over theM1 (a-tDCSM1), anodal tDCS over the cerebellum (a-tDCSCB), concurrent dual-site anodal tDCS over the M1 and the cerebellum (a-tDCSM1+CB), and sham stimulation (tDCSSHAM). Before and after receiving tDCS (2mA for 15min), participants completed an ice hockey shooting-accuracy test, Pro-Kin balance test (includes stance test and proprioceptive assessment), and Y-balance test in randomized order. For static balance performance, the ellipse area in the 2-legged stance with eyes open and the 1-legged stance with the dominant leg significantly improved following a-tDCSM1, a-tDCSCB, and concurrent dual-site a-tDCSM1+CB, compared with tDCSSHAM (all P < .05, Cohen d = 0.64-1.06). In dynamic balance performance, the average trace error of the proprioceptive assessment and the composite score of the Y-balance test with the dominant leg significantly improved following a-tDCSM1 and concurrent dual-site a-tDCSM1+CB (all P < .05, Cohen d = 0.77-1.00). For the ice hockey shooting-accuracy test, shooting-accuracy while standing on the unstable platform significantly increased following a-tDCSM1 (P = .010, Cohen d = 0.81) and a-tDCSCB (P = .010, Cohen d = 0.92) compared with tDCSSHAM. tDCS could potentially be a valuable tool in enhancing static and dynamic balance and shooting accuracy on unstable platforms in elite ice hockey players.

Effectiveness of Transcranial-Direct Current Stimulation in Individuals with Methamphetamine Use Disorder: A Systematic Review and Meta-Analysis

Context: Non-alcoholic substance abuse is a major public health concern worldwide, with methamphetamine being the second most widely used non-alcoholic substance globally, and Iran ranks fifth in methamphetamine addiction. To date, no approved pharmacological or non-pharmacological treatment by the Food and Drug Administration has been introduced for methamphetamine use disorder (MUD). Therefore, various treatment methods are currently utilized. One non-pharmacological approach that has gained attention is transcranial-direct current stimulation (tDCS), with various clinical evaluations focused on it. Objectives: The aim of this review is to assess the effectiveness of this method in improving symptoms in individuals with MUD. Methods: Databases were reviewed up to October 10, 2023, in both Persian and English languages, using PubMed, Scopus, Web of Science, Google Scholar, Science Direct, Scientific Information Database (SID), and Noormags. Keywords were MUD, tDCS, Addiction, Craving, and Cognitive Function. Studies were included based on Population, Intervention, Comparison (sham or active control), Outcomes (craving or cognition), and Study Design (randomized controlled trial). Studies were excluded if they involved brain mapping or neuroimaging. Meta-analysis was conducted based on Standardized Mean Difference (SMD) to compare tDCS to sham intervention (P ≤ 0.05, two-tailed). Random effects models were used for individual MUD data from studies that reported end-of-treatment craving data. The risk of bias was calculated using the Cochrane Risk-of-Bias Tool (RoB-2), and meta-analysis was conducted using Comprehensive Meta-Analysis Software. Results: A total of 870 studies were initially identified; twenty-three studies (mean age 30.13 ± 6.67) were identified that examined the effects of tDCS on MUD outcomes (e.g., craving, cognition). After removing heterogeneous studies, meta-analyses were performed for tDCS vs. sham control studies in the craving domain. We found that tDCS reduced craving, indicated by medium to large effect sizes (Hedges' g: -0.64; SMD -0.58, 95% CI -0.85 to -0.30; I² = 10.71%, Q value: 8.96). Results showed that complementary treatment with tDCS can be useful. The DLPFC (F3, F4) was the most commonly targeted brain region for stimulation or inhibition. However, the number of sessions and their duration varied significantly across studies. Conclusions: This systematic review and meta-analysis found that tDCS can reduce momentary and cue-induced cravings. However, the studies varied in quality and sample size and used different scales for assessing cravings and cognitive functions, leading to inconsistencies. The review highlighted the importance of targeting the DLPFC due to its role in executive functions and self-control, with right-sided stimulation showing greater effectiveness. Emotional dysregulation in MUD, such as anxiety and depression, was also noted, with tDCS showing limited support for emotion regulation. The review identified the need for larger RCTs, standardized measurement tools, and detailed participant information to improve the understanding and effectiveness of tDCS in treating MUD.

Effects of Transcranial Direct-Current Stimulation on Rumination and Self-inhibition in Patients with Panic Disorder

Background: Panic disorder causes patients to cease their daily activities and avoid social interactions. Appropriate treatment helps these patients manage their worries, rumination, and self-inhibition, allowing them to return to normalcy. Objectives: This research aims to investigate the effectiveness of transcranial direct-current stimulation (tDCS) on rumination and self-inhibition in patients with panic disorder. Methods: This quasi-experimental research used a pretest-posttest control group design. The statistical population comprised patients with panic disorder aged 18 - 45 years who visited psychotherapy centers in Ahvaz, Iran, in 2023. Convenience sampling was employed to select 40 eligible participants, who were then randomly assigned to an experimental group (n = 20) and a control group (n = 20). Participants completed rumination and self-inhibition questionnaires at the pretest and posttest stages. The experimental group received ten 20-minute sessions of tDCS. Data were collected using the Ruminative Response Scale (RRS) and Self-Restraint Scale (SRS). Analysis of covariance (ANCOVA) was used for data analysis. Results: The results indicated that tDCS improved rumination and self-inhibition in the posttest stage, demonstrating the treatment's effectiveness (P &lt; 0.001). Conclusions: Transcranial direct-current stimulation can alleviate rumination and improve self-inhibition in patients with panic disorder. It is recommended that tDCS be used as a complementary treatment for these patients.

Baseline brain volume predicts home-based transcranial direct current stimulation effects on inattention in adults with attention-deficit/hyperactivity disorder

BackgroundHome-based transcranial direct current stimulation (Hb-tDCS) is a non-invasive brain stimulation technique that utilizes low-intensity electric currents delivered via scalp electrodes to modulate brain activity. It holds significant promise for addressing inattention in adults with attention-deficit/hyperactivity disorder (ADHD). However, its effectiveness varies among individuals, and predicting outcomes remains uncertain, partially due to the influence of individual differences in ADHD-related brain anatomy. MethodsWe analyzed data from a subsample, composed by twenty-nine adult patients with ADHD, of the Treatment of Inattention Symptoms in Adult Patients with ADHD (TUNED) trial. Fourteen patients underwent active anodal right cathodal left dorsolateral prefrontal cortex (DLPFC) Hb-tDCS for 4 weeks and fifteen received sham-related tDCS intervention. Inattention outcome was evaluated at both baseline and endpoint (4th week). Baseline structural measures of the DLPFC, anterior cingulate cortex (ACC) and subcortical structures, previously associated with ADHD, were quantified. Several linear mixed models, with a three-way interaction between the fixed predictors brain volume or thickness, time, and treatment were calculated. Multiple comparison corrections were applied using the Benjamini-Hochberg method. ResultsBaseline volume of the left DLPFC regions middle frontal gyrus (t (25) = 3.33, p-adjusted = 0.045, Cohen's d = 1.33, 95% CI = [0.45, 2.19]), inferior frontal gyrus (orbital part) (t (25) = 3.10, p-adjusted = 0.045, Cohen's d = 1.24, 95% CI = [0.37, 2.08]), and of the left ACC supragenual (t (25) = 3.15, p-adjusted = 0.045, Cohen's d = 1.26, 95% CI = [0.39, 2.11]) presented significant association with the inattentive score improvement only in the active tDCS group. More specifically, the smaller these regions were, the more the symptoms improved following anodal right cathodal left DLPFC Hb-tDCS. ConclusionHb-tDCS was associated with greater improvement in brain areas related to attention regulation. Brain MRI can be potentially used to predict clinical response to tDCS in ADHD adults.

Investigating the neural mechanisms of transcranial direct current stimulation effects on human cognition: current issues and potential solutions.

Transcranial direct current stimulation (tDCS) has been studied extensively for its potential to enhance human cognitive functions in healthy individuals and to treat cognitive impairment in various clinical populations. However, little is known about how tDCS modulates the neural networks supporting cognition and the complex interplay with mediating factors that may explain the frequently observed variability of stimulation effects within and between studies. Moreover, research in this field has been characterized by substantial methodological variability, frequent lack of rigorous experimental control and small sample sizes, thereby limiting the generalizability of findings and translational potential of tDCS. The present manuscript aims to delineate how these important issues can be addressed within a neuroimaging context, to reveal the neural underpinnings, predictors and mediators of tDCS-induced behavioral modulation. We will focus on functional magnetic resonance imaging (fMRI), because it allows the investigation of tDCS effects with excellent spatial precision and sufficient temporal resolution across the entire brain. Moreover, high resolution structural imaging data can be acquired for precise localization of stimulation effects, verification of electrode positions on the scalp and realistic current modeling based on individual head and brain anatomy. However, the general principles outlined in this review will also be applicable to other imaging modalities. Following an introduction to the overall state-of-the-art in this field, we will discuss in more detail the underlying causes of variability in previous tDCS studies. Moreover, we will elaborate on design considerations for tDCS-fMRI studies, optimization of tDCS and imaging protocols and how to assure high-level experimental control. Two additional sections address the pressing need for more systematic investigation of tDCS effects across the healthy human lifespan and implications for tDCS studies in age-associated disease, and potential benefits of establishing large-scale, multidisciplinary consortia for more coordinated tDCS research in the future. We hope that this review will contribute to more coordinated, methodologically sound, transparent and reproducible research in this field. Ultimately, our aim is to facilitate a better understanding of the underlying mechanisms by which tDCS modulates human cognitive functions and more effective and individually tailored translational and clinical applications of this technique in the future.

Effects of transcranial direct current stimulation and sensorimotor training in anterior cruciate ligament patients: a sham-controlled pilot study.

Studies showed changes in the central nervous system in patients who sustained an anterior cruciate ligament tear. There is a lack of evidence regarding the effectiveness of transcranial direct-current stimulation in such patients. A sham-controlled randomised study. One group of patients (n = 6) underwent 6 weeks of sensorimotor training after an anterior cruciate ligament tear during transcranial direct-current stimulation. The stimulation consisted of 20 minutes (3 sessions/week; 2 weeks) of 2 mA anodal transcranial direct-current stimulation over the primary motor and premotor cortex. The second group (n = 6) received sham stimulation with 6 weeks of sensorimotor training. Centre of pressure deviations in the medio-lateral and anterior-posterior direction and centre of pressure velocity were measured. The results demonstrated a significant effect of sensorimotor training on the centre of pressure in medio-lateral and anterior-posterior direction (p=0.025) (p=0.03) in the leg in which an anterior cruciate ligament tear occurred. The type of training did not affect the results. Post-hoc tests showed no significant effect of training in the subgroups (p≥0.115). Sensorimotor training led to a decrease in sway of the centre of pressure in patients who sustained an anterior cruciate ligament tear, but the addition of anodal transcranial direct-current stimulation placed over the primary motor cortex did not potentiate the adaptive responses of the sensorimotor training.

Effectiveness of Transcranial Direct-Current Stimulation on Impulsivity and Anxiety in Patients with Paranoid Personality Disorder

Background: Individuals with paranoid personality disorder (PPD) usually suffer from impulsive behavior and anxiety and constantly imagine others trying to humiliate, harm, or threaten them. This disorder causes mistrust towards others and may interfere with a person's ability to form close relationships. Objectives: The present study aimed to investigate the effects of transcranial direct-current stimulation (tDCS) on impulsivity and anxiety in patients with PPD. Methods: This quasi-experimental research adopted a pretest-posttest control group design. The statistical population included all patients aged 30 – 50 years with PPD referred to psychological and psychiatric clinics and hospitals in Yazd, (Iran), in 2022. Convenience sampling was employed to select 30 individuals with PPD. The participants were randomly assigned to an experimental group (n = 15) and a control (n = 15) group using a table of random numbers. The participants completed impulsivity and anxiety questionnaires during the pretest and posttest stages. The experimental group received ten 20-minute sessions of tDCS. The collected data were analyzed using SPSS v25.0. Results: The participants included 30 men and women with PPD with an average age of 41.23 ± 8.40 years. In the posttest, the mean ± SD of impulsivity for tDCS and control groups were 54.67 ± 4.03 and 93.93 ± 3.67, respectively. Moreover, the mean ± SD of anxiety in tDCS and control groups in the posttest were 16.40 ± 2.79 and 42.39 ± 2.99, respectively. The results indicated that tDCS significantly improved impulsivity and reduced anxiety at the posttest stage (P &lt; 0.001). Conclusions: Transcranial direct-current stimulation can alleviate impulsivity and anxiety in patients with PPD. Therefore, therapists can implement the tDCS method as a complementary therapy to improve impulsivity and anxiety in patients with PPD.

Electrode positioning errors reduce current dose for focal tDCS set-ups: Evidence from individualized electric field mapping

ObjectiveElectrode positioning errors contribute to variability of transcranial direct current stimulation (tDCS) effects. We investigated the impact of electrode positioning errors on current flow for tDCS set-ups with different focality. MethodsDeviations from planned electrode positions were determined using data acquired in an experimental study (N = 240 datasets) that administered conventional and focal tDCS during magnetic resonance imaging (MRI). Comparison of individualized electric field modeling for planned and empirically derived “actual” electrode positions was conducted to quantify the impact of positioning errors on the electric field dose in target regions for tDCS. ResultsPlanned electrode positions resulted in higher current dose in the target regions for focal compared to conventional montages (7–12%). Deviations from planned positions significantly reduced current flow in the target regions, selectively for focal set-ups (26–30%). Dose reductions were significantly larger for focal compared to conventional set-ups (29–43%). ConclusionsPrecise positioning is crucial when using focal tDCS set-ups to avoid significant reductions of current dose in the intended target regions. SignificanceOur results highlight the urgent need to routinely implement methods for improving electrode positioning, minimization of electrode drift, verification of electrode positions before and/or after tDCS and also to consider positioning errors when investigating dose–response relationships, especially for focal set-ups.

Brain-behavior analysis of transcranial direct current stimulation effects on a complex surgical motor task.

Transcranial Direct Current Stimulation (tDCS) has demonstrated its potential in enhancing surgical training and performance compared to sham tDCS. However, optimizing its efficacy requires the selection of appropriate brain targets informed by neuroimaging and mechanistic understanding. Previous studies have established the feasibility of using portable brain imaging, combining functional near-infrared spectroscopy (fNIRS) with tDCS during Fundamentals of Laparoscopic Surgery (FLS) tasks. This allows concurrent monitoring of cortical activations. Building on these foundations, our study aimed to explore the multi-modal imaging of the brain response using fNIRS and electroencephalogram (EEG) to tDCS targeting the right cerebellar (CER) and left ventrolateral prefrontal cortex (PFC) during a challenging FLS suturing with intracorporeal knot tying task. Involving twelve novices with a medical/premedical background (age: 22-28 years, two males, 10 females with one female with left-hand dominance), our investigation sought mechanistic insights into tDCS effects on brain areas related to error-based learning, a fundamental skill acquisition mechanism. The results revealed that right CER tDCS applied to the posterior lobe elicited a statistically significant (q < 0.05) brain response in bilateral prefrontal areas at the onset of the FLS task, surpassing the response seen with sham tDCS. Additionally, right CER tDCS led to a significant (p < 0.05) improvement in FLS scores compared to sham tDCS. Conversely, the left PFC tDCS did not yield a statistically significant brain response or improvement in FLS performance. In conclusion, right CER tDCS demonstrated the activation of bilateral prefrontal brain areas, providing valuable mechanistic insights into the effects of CER tDCS on FLS peformance. These insights motivate future investigations into the effects of CER tDCS on error-related perception-action coupling through directed functional connectivity studies.

Transcranial Direct Current Stimulation (tDCS) Effects on Quantitative Sensory Testing (QST) and Nociceptive Processing in Healthy Subjects: A Systematic Review and Meta-Analysis.

The aim of this study is to determine the effect that different tDCS protocols have on pain processing in healthy people, assessed using quantitative sensory tests (QST) and evoked pain intensity. We systematically searched in EMBASE, CINAHL, PubMed, PEDro, PsycInfo, and Web of Science. Articles on tDCS on a healthy population and regarding QST, such as pressure pain thresholds (PPT), heat pain thresholds (HPT), cold pain threshold (CPT), or evoked pain intensity were selected. Quality was analyzed using the Cochrane Risk of Bias Tool and PEDro scale. Twenty-six RCTs were included in the qualitative analysis and sixteen in the meta-analysis. There were no significant differences in PPTs between tDCS and sham, but differences were observed when applying tDCS over S1 in PPTs compared to sham. Significant differences in CPTs were observed between tDCS and sham over DLPFC and differences in pain intensity were observed between tDCS and sham over M1. Non-significant effects were found for the effects of tDCS on HPTs. tDCS anodic over S1 stimulation increases PPTs, while a-tDCS over DLPFC affects CPTs. The HPTs with tDCS are worse. Finally, M1 a-tDCS seems to reduce evoked pain intensity in healthy subjects.

Effects of Transcranial Direct Current Stimulation and Behavior Therapy Using the Start-Stop Method on the Treatment of Men with Sexual Disorder Premature Ejaculation

Background: Men suffering from premature ejaculation often report emotional and relational problems, and some of them do not pursue sex due to embarrassment. This condition leads to mental disorders, e.g., anxiety and depression, and the couple's relationship may suffer. Objectives: The present study aimed to investigate the effectiveness of transcranial direct-current stimulation (tDCS) and behavior therapy using the start-stop method in improving premature ejaculation. Methods: This was a quasi-experimental study with two experimental groups and a control group. The statistical population comprised all men with premature ejaculation residing in Tehran (2021) who visited sexual health centers in this city. A sample of 45 men aged 25-65 was selected using convenience sampling and divided into three groups of 15. The research instrument included the International Index of Erectile Function (IIEF). The data were analyzed in SPSS-23 using the analysis of covariance. Results: The mean ± SD of the pretest of premature ejaculation in the tDCS, start-stop method, and control groups was 13.60 ± 5.45, 12.86 ± 3.24, and 15.68 ± 4.87, respectively; while in the posttest was 23.53 ± 9.65, 18.66 ± 5.25 and 17.53 ± 4.83, respectively. Based on the results, tDCS alleviated premature ejaculation (P &lt; 0.001). The start-stop method also decreased the symptoms of premature ejaculation, but this reduction was not significant. There was a significant difference between the two treatment methods, and tDCS proved more effective. Conclusions: tDCS demonstrated acceptable effectiveness in the treatment of premature ejaculation. Given its effectiveness in increasing marital satisfaction, it should be considered in the treatment of premature ejaculation.

The effects of transcranial direct-current stimulation (tDCS) on pain intensity of patients with fibromyalgia: a systematic review and meta-analysis

IntroductionFibromyalgia (FM) is a chronic pain condition that affects millions of people worldwide. Transcranial Direct Current Stimulation (tDCS) is a non-invasive brain stimulation technique that has shown promise as a potential treatment for FM by modulating pain perception and reducing symptoms, such as fatigue and depression. We aimed to systematically review studies that assess the effect of tDCS on pain reduction in FM patients.MethodsSeven electronic databases (PubMed, Scopus, Embase, PsycINFO, Web of Science, Cochrane, and CINAHL Complete) were searched for records in English. Studies that measured the effect of tDCS on pain intensity in FM patients were included. The Cochrane Collaboration’s tool was used to assess the quality of the included studies. A random-effect model was preferred, and statistical analysis was performed by Stata software version 17.ResultsTwenty studies were included for qualitative, and eleven for quantitative analysis. Out of 664 patients included in the study, 443 were in the stimulation group. The left M1 area was the most common stimulation target (n = 12), and 2 mA was the most common stimulation amplitude (n = 19). The analysis showed that active tDCS significantly reduced pain intensity in FM patients in comparison to the sham group (SMD= -1.55; 95% CI -2.10, -0.99); also, no publication bias was noted.ConclusionOur systematic review highlights the potential effect of tDCS on the reduction of pain intensity in FM patients. Additionally, this current evidence could suggest that tDCS applied at an intensity of 2mA to the left M1 is the most effective strategy.

Effects of Transcranial Direct-Current Stimulation (tDCS) Treatment Sessions on Neuropsychological ‎Functioning Among Detoxified Inpatients with Alcohol Dependence: A Randomized Sham-Controlled Clinical Trial

ABSTRACT Individuals with alcohol dependence often experience cognitive dysfunction after detoxification, which can persist even after sustained abstinence. Transcranial direct current stimulation (tDCS) has shown promise in improving cognitive functioning in these patients. The main objective of this research was to assess the impact of ten sessions of transcranial direct-current stimulation (tDCS) targeting the dorsolateral prefrontal cortex (DLPFC) on the neuropsychological functioning of hospitalized individuals with alcohol dependence who have undergone detoxification. This single-center, parallel, and single-blind randomized controlled trial assessed the effects of ten sessions of add-on tDCS treatment on neuropsychological functions. 44 recently detoxified alcohol-dependent inpatients were randomly assigned to either treatment as usual (TAU) plus ten sessions of active tDCS over left DLPFC, or TAU plus ten sessions of sham tDCS and assessed the effect of tDCS sessions and time on neuropsychological functions. Neuropsychological functions were evaluated in inpatients undergoing treatment for alcohol dependence at T1 (9.95 + 2.42 days abstinence) and T2 (19 ± 1.48 days abstinence), and while time had a significant impact on mean scores of various neuropsychological tests, neither active tDCS treatment nor its interaction with time displayed a significant effect on neuropsychological functioning, as revealed by two-way ANOVAs with repeated measurements. In detoxified inpatients with alcohol dependence, tDCS treatment was not found to have a significant impact on neuropsychological functioning when compared to sham treatment, whereas abstinence from alcohol for approximately three weeks resulted in significant improvements in various cognitive domains including mental speed, verbal learning & memory, visual memory, verbal fluency, and response inhibition.

Transcranial Direct Current Stimulation Effects on the Neural Substrate of Conceptual Representations.

The aim of this study was to shed light on the neural substrate of conceptual representations starting from the construct of higher-order convergence zones and trying to evaluate the unitary or non-unitary nature of this construct. We used the 'Thematic and Taxonomic Semantic (TTS) task' to investigate (a) the neural substrate of stimuli belonging to biological and artifact categories, (b) the format of stimuli presentation, i.e., verbal or pictorial, and (c) the relation between stimuli, i.e., categorial or contextual. We administered anodal transcranial direct current stimulation (tDCS) to different brain structures during the execution of the TTS task. Twenty healthy participants were enrolled and divided into two groups, one investigating the role of the anterior temporal lobes (ATL) and the other the temporo-parietal junctions (TPJ). Each participant underwent three sessions of stimulation to facilitate a control condition and to investigate the role of both hemispheres. Results showed that ATL stimulation influenced all conceptual representations in relation to the format of presentation (i.e., left-verbal and right-pictorial). Moreover, ATL stimulation modulated living categories and taxonomic relations specifically, whereas TPJ stimulation did not influence semantic task performances.

Use of the P300 event-related potential component to index transcranial direct current stimulation effects in drug users

Drug use causes significant social and financial problems and these are exacerbated by difficulties in stopping use and subsequent maintenance of abstinence. There is also difficulty in identifying the beneficial treatment for an individual, made more problematic given the high drop-out rates in treatment programs. Here, the effects of transcranial direct current stimulation (tDCS) on the amplitude of the P300 event-related potential component, previously suggested to be indicative of successful remission, was measured in recently abstinent amphetamine users. This component was collected during a Posner cuing task which was presented to this group and to control (non-user) participants, using task cues of neutral and drug-related images. The abstinent drug users were divided into two groups, one of which received tDCS daily for five days, with the cathode over the left dorsolateral prefrontal cortex (DLPFC) and the anode over the right DLPFC, and one receiving sham stimulation over the same time period. Behavioral performance and P300 amplitudes were measured before and after the period of tDCS delivery. Control participants were tested with the same time-schedule of task presentation but without administration of tDCS. Drug users initially showed a larger cost of invalid cues on task performance compared to control (non-drug user) participants and this was reduced following delivery of tDCS. Additionally, tDCS resulted in increased amplitude of the P300 component, significantly so for neutral cues, with the resulting pattern being more similar to that of the non-users. This provides a good basis for further investigation of both the utility of tDCS in modulation of cognition in addict groups, and to investigate the effects of modulating the P300 component on remission rates, a relationship that seems to be the case for this measure without use of tDCS modulation. Importantly, this study also provides a further addiction group showing P300 amplitude modulation as a result of tDCS administration.

Patient-tailored transcranial direct current stimulation to improve stroke rehabilitation: study protocol of a randomized sham-controlled trial

BackgroundMany patients do not fully regain motor function after ischemic stroke. Transcranial direct current stimulation (TDCS) targeting the motor cortex may improve motor outcome as an add-on intervention to physical rehabilitation. However, beneficial effects on motor function vary largely among patients within and across TDCS trials. In addition to a large heterogeneity of study designs, this variability may be caused by the fact that TDCS was given as a one-size-fits-all protocol without accounting for anatomical differences between subjects. The efficacy and consistency of TDCS might be improved by a patient-tailored design that ensures precise targeting of a physiologically relevant area with an appropriate current strength.MethodsIn a randomized, double-blinded, sham-controlled trial, patients with subacute ischemic stroke and residual upper-extremity paresis will receive two times 20 min of focal TDCS of ipsilesional primary motor hand area (M1-HAND) during supervised rehabilitation training three times weekly for 4 weeks. Anticipated 60 patients will be randomly assigned to active or sham TDCS of ipsilesional M1-HAND, using a central anode and four equidistant cathodes. The placement of the electrode grid on the scalp and current strength at each cathode will be personalized based on individual electrical field models to induce an electrical current of 0.2 V/m in the cortical target region resulting in current strengths between 1 and 4 mA. Primary endpoint will be the difference in change of Fugl-Meyer Assessment of Upper Extremity (FMA-UE) score between active TDCS and sham at the end of the intervention. Exploratory endpoints will include UE-FMA at 12 weeks. Effects of TDCS on motor network connectivity and interhemispheric inhibition will be assessed with functional MRI and transcranial magnetic stimulation.DiscussionThe study will show the feasibility and test the efficacy of personalized, multi-electrode anodal TDCS of M1-HAND in patients with subacute stroke patients with upper-extremity paresis. Concurrent multimodal brain mapping will shed light into the mechanisms of action of therapeutic personalized TDCS of M1-HAND. Together, the results from this trial may inform future personalized TDCS studies in patients with focal neurological deficits after stroke.

Transcranial direct current stimulation effects in the pain threshold and in oxidative stress parameters of neuropathic pain rats

Transcranial direct current stimulation (tDCS) can modulate cortical excitability and relieve neuropathic pain (NP), but the role of several biomarkers in this process is not well understood. This study aimed to analyze the effects of tDCS on biochemical parameters in rats with neuropathic pain (NP) induced by chronic constriction injury (CCI) of the right sciatic nerve. Eighty-eight male 60-day-old Wistar rats were divided into nine groups: control (C), control-electrode off (CEoff), control-tDCS (C-tDCS), sham-lesion (SL), sham-lesion electrode off (SLEoff), sham-lesion (SL-tDCS), lesion (L), lesion electrode off (LEoff), and lesion-tDCS (L-tDCS). After NP establishment, 20-minute bimodal tDCS for 8 consecutive days was applied to the rats. Fourteen days after the induction of NP, rats developed mechanical hyperalgesia with a decreased threshold, and at the end of treatment, an increase in the pain threshold was observed in NP rats. In addition, NP rats had increased levels of reactive species (RS) in the prefrontal cortex, while superoxide dismutase (SOD) activity was decreased in NP rats. In the spinal cord, nitrite levels and glutathione-S-transferase (GST) activity decreased in the L-tDCS group, and it was observed that increased levels in total sulfhydryl content for neuropathic pain rats were reversed by tDCS. In serum analyses, the neuropathic pain model increased the levels of RS and thiobarbituric acid-reactive substances (TBARS) and decreased the activity of butyrylcholinesterase (BuChE). In conclusion, bimodal tDCS increased total sulfhydryl content in the spinal cord of rats with neuropathic pain, positively modulating this parameter.

Opposite pattern of transcranial direct current stimulation effects in middle-aged and older adults: Behavioral and neurophysiological evidence.

Episodic memory (EM) exhibits an age-related decline, with overall increased impairment after the age of 65. The application of transcranial direct current stimulation (tDCS) to ameliorate cognitive decline in ageing has been extensively investigated, but its efficacy has been reported with mixed results. In this study, we aimed to assess whether age contributes to interindividual variability in tDCS efficacy. Thirty-eight healthy adults between 50 and 81 years old received anodal tDCS over the left prefrontal cortex during images encoding and then performed an EM recognition task while event-related potentials (ERPs) were recorded. Our results showed an opposite pattern of effect between middle-aged (50-64 years) and older (65-81 years) adults. Specifically, performance in the recognition task after tDCS was enhanced in older adults and was worsened in middle-aged adults. Moreover, ERPs acquired during the recognition task showed that two EM components related to familiarity and post-retrieval monitoring, i.e., Early Frontal and Late Frontal Old-New effects, respectively, were significantly reduced in middle-aged adults after anodal tDCS. These results support an age-dependent effect of prefrontal tDCS on EM processes and its underlying electrophysiological substrate, with opposing modulatory trajectories along the aging lifespan.

Ambiguous tDCS: variability of the transcranial direct current stimulation effects in a reinforcement learning task

Ambiguous tDCS: variability of the transcranial direct current stimulation effects in a reinforcement learning task