Active tDCS Research Articles

Effects of Dual Task Training and Transcranial Direct Current Stimulation in Children with Spastic Cerebral Palsy: A Pilot Randomized Control Trial

ABSTRACT Objective Compare the effectiveness of active and sham transcranial direct current stimulation (tDCS) during the training of a dual task in children with spastic cerebral palsy (CP). Methods Thirty children with CP were submitted to ten sessions of either active (n = 15) or sham (n = 15) tDCS over the motor cortex for 20 minutes during the training of a dual task. Pre-intervention, post-intervention and follow-up evaluations involved measures of functional performance, intellectual performance, functional mobility and cortical excitability. Results The combination of active tDCS and dual task training led to improvements in functional mobility as well as functional and intellectual performances one month after the end of the intervention. Conclusion The combination of active tDCS and dual task training demonstrated promising effects for children with spastic CP.

Frontal tDCS reduces alcohol relapse rates by increasing connections from left dorsolateral prefrontal cortex to addiction networks

BackgroundBrain-based interventions are needed to address persistent relapse in alcohol use disorder (AUD). Neuroimaging evidence suggests higher frontal connectivity as well as higher within-network connectivity of theoretically defined addiction networks are associated with reduced relapse rates and extended abstinence during follow-up periods. Objective/Hypothesis: A longitudinal randomized double-blind sham-controlled clinical trial investigated whether a non-invasive neuromodulation intervention delivered during early abstinence can (i) modulate connectivity of addiction networks supporting abstinence and (ii) improve relapse rates. Hypotheses: Active transcranial direct current stimulation (tDCS) will (i) increase connectivity of addiction networks known to support abstinence and (ii) reduce relapse rates. MethodsShort-term abstinent AUD participants (n = 60) were assigned to 5 days of either active tDCS or sham during cognitive training. Causal discovery analysis (CDA) examined the directional influence from left dorsolateral prefrontal cortex (LDLPFC, stimulation site) to addiction networks that support abstinence. ResultsActive tDCS had an effect on the average strength of CDA-determined connectivity from LDLPFC to the incentive salience and negative emotionality addiction networks - increasing in the active tDCS group only. Active tDCS had an effect on relapse rates following the intervention, with lower probability of relapse in the active tDCS vs. sham. Active tDCS showed an unexpected sex-dependent effect on relapse rates. ConclusionOur results suggest that LDLPFC stimulation delivered during early abstinence has an effect on addiction networks supporting abstinence and on relapse rates. The unexpected sex-dependent neuromodulation effects need to be further examined in larger clinical trials.

Transcranial direct current stimulation to facilitate neurofunctional rehabilitation in children with autism spectrum disorder: a protocol for a randomized, sham-controlled, double-blind clinical trial.

Anodal transcranial direct current stimulation (tDCS) over the primary motor cortex and cerebellum is gaining prominence in the literature due to its potential to favor learning and motor performance. If administered during motor training, tDCS is capable of increasing the effect of training. Considering the motor impairment presented by children with Autism Spectrum Disorders (ASD), atDCS applied during motor training may contribute to the rehabilitation of these children. However, it is necessary to examine and compare the effects of atDCS over the motor cortex and the cerebellum on the motor skills of children with ASD. This information may benefit future clinical indications of tDCS for rehabilitation of children with ASD. The aim of the proposed study is to determine whether anodal tDCS over the primary motor cortex and cerebellum can enhance the effects of gait training and postural control on motor skills, mobility, functional balance, cortical excitability, cognitive aspects and behavioral aspects in children with ASD. Our hypothesis is the active tDCS combined with motor training will enhance the performance of the participants in comparison to sham tDCS. A randomized, sham-controlled, double-blind clinical trial will be conducted involving 30 children with ASD that will be recruited to receive ten sessions of sham or ten sessions of active anodal tDCS (1 mA, 20 min) over the primary motor cortex or cerebellun combined with motor training. The participants will be assessed before as well as one, four and eight weeks after the interventions. The primary outcome will be gross and fine motor skills. The secondary outcomes will be mobility, functional balance, motor cortical excitability, cognitive aspects and behavioral aspects. Although abnormalities in gait and balance are not primary characteristics of ASD, such abnormalities compromise independence and global functioning during the execution of routine activities of childhood. If demonstrated that anodal tDCS administered over areas of the brain involved in motor control, such as the primary motor cortex and cerebellum, can enhance the effects of gait and balance training in only ten sessions in two consecutive weeks, the clinical applicability of this stimulation modality will be expanded as well as more scientifically founded.Clinical trial registration February 16, 2023 (https://ensaiosclinicos.gov.br/rg/RBR-3bskhwf).

Microstructural and functional plasticity following repeated brain stimulation during cognitive training in older adults

The combination of repeated behavioral training with transcranial direct current stimulation (tDCS) holds promise to exert beneficial effects on brain function beyond the trained task. However, little is known about the underlying mechanisms. We performed a monocenter, single-blind randomized, placebo-controlled trial comparing cognitive training to concurrent anodal tDCS (target intervention) with cognitive training to concurrent sham tDCS (control intervention), registered at ClinicalTrial.gov (Identifier NCT03838211). The primary outcome (performance in trained task) and secondary behavioral outcomes (performance on transfer tasks) were reported elsewhere. Here, underlying mechanisms were addressed by pre-specified analyses of multimodal magnetic resonance imaging before and after a three-week executive function training with prefrontal anodal tDCS in 48 older adults. Results demonstrate that training combined with active tDCS modulated prefrontal white matter microstructure which predicted individual transfer task performance gain. Training-plus-tDCS also resulted in microstructural grey matter alterations at the stimulation site, and increased prefrontal functional connectivity. We provide insight into the mechanisms underlying neuromodulatory interventions, suggesting tDCS-induced changes in fiber organization and myelin formation, glia-related and synaptic processes in the target region, and synchronization within targeted functional networks. These findings advance the mechanistic understanding of neural tDCS effects, thereby contributing to more targeted neural network modulation in future experimental and translation tDCS applications.

Multifocal Transcranial Direct Current Stimulation in Primary Progressive Aphasia Does Not Provide a Clinical Benefit Over Speech Therapy.

Primary progressive aphasia (PPA) is a group of neurodegenerative disorders including Alzheimer's disease and frontotemporal dementia characterized by language deterioration. Transcranial direct current stimulation (tDCS) is a non-invasive intervention for brain dysfunction. To evaluate the tolerability and efficacy of tDCS combined with speech therapy in the three variants of PPA. We evaluate changes in fMRI activity in a subset of patients. Double-blinded, randomized, cross-over, and sham-controlled tDCS study. 15 patients with PPA were included. Each patient underwent two interventions: a) speech therapy + active tDCS and b) speech therapy + sham tDCS stimulation. A multifocal strategy with anodes placed in the left frontal and parietal regions was used to stimulate the entire language network. Efficacy was evaluated by comparing the results of two independent sets of neuropsychological assessments administered at baseline, immediately after the intervention, and at 1 month and 3 months after the intervention. In a subsample, fMRI scanning was performed before and after each intervention. The interventions were well tolerated. Participants in both arms showed clinical improvement, but no differences were found between active and sham tDCS interventions in any of the evaluations. There were trends toward better outcomes in the active tDCS group for semantic association and reading skills. fMRI identified an activity increase in the right frontal medial cortex and the bilateral paracingulate gyrus after the active tDCS intervention. We did not find differences between active and sham tDCS stimulation in clinical scores of language function in PPA patients.

Modulating Phonological Working Memory With Anodal High-Definition Transcranial Direct Current Stimulation to the Anterior Portion of the Supplementary Motor Area.

Phonological working memory is key to vocabulary acquisition, spoken word recognition, real-time language processing, and reading. Transcranial direct current stimulation, when coupled with behavioral training, has been shown to facilitate speech motor output processes, a key component of nonword repetition, the primary task used to assess phonological working memory. In this study, we examined the efficacy of combining overt nonword repetition training with anodal high-definition transcranial direct current stimulation (HD tDCS) to the presupplementary motor area (preSMA) to enhance nonword repetition. This study investigated whether 20 min of active or sham anodal HD tDCS targeting preSMA concurrently with a nonword repetition task differentially impacted nonword repetition ability. Twenty-eight neurotypical college-age adults (18-25 years; 19 females, eight males, one nonbinary) completed a 20-min nonword repetition training task where they received either active or sham 1-mA anodal HD tDCS to the preSMA while overtly repeating a list of four-, five-, six-, and seven-syllable English-like nonwords presented in a random order. Whole nonword accuracy and error patterns (phoneme and syllable) were measured prior to and following training. Following training, both groups showed a decrease in nonword repetition accuracy. The drop in performance was significantly greater for the active stimulation group compared to the sham stimulation group at the four-syllable nonword length. The findings suggest that targeting the speech motor component of nonword repetition through overt training and HD tDCS to the preSMA does not enhance phonological working memory ability.

Stratification of responses to tDCS intervention in a healthy pediatric population based on resting-state EEG profiles

Transcranial Direct Current Stimulation (tDCS) is a non-invasive neuromodulation technique with a wide variety of clinical and research applications. As increasingly acknowledged, its effectiveness is subject dependent, which may lead to time consuming and cost ineffective treatment development phases. We propose the combination of electroencephalography (EEG) and unsupervised learning for the stratification and prediction of individual responses to tDCS. A randomized, sham-controlled, double-blind crossover study design was conducted within a clinical trial for the development of pediatric treatments based on tDCS. The tDCS stimulation (sham and active) was applied either in the left dorsolateral prefrontal cortex or in the right inferior frontal gyrus. Following the stimulation session, participants performed 3 cognitive tasks to assess the response to the intervention: the Flanker Task, N-Back Task and Continuous Performance Test (CPT). We used data from 56 healthy children and adolescents to implement an unsupervised clustering approach that stratify participants based on their resting-state EEG spectral features before the tDCS intervention. We then applied a correlational analysis to characterize the clusters of EEG profiles in terms of participant’s difference in the behavioral outcome (accuracy and response time) of the cognitive tasks when performed after a tDCS-sham or a tDCS-active session. Better behavioral performance following the active tDCS session compared to the sham tDCS session is considered a positive intervention response, whilst the reverse is considered a negative one. Optimal results in terms of validity measures was obtained for 4 clusters. These results show that specific EEG-based digital phenotypes can be associated to particular responses. While one cluster presents neurotypical EEG activity, the remaining clusters present non-typical EEG characteristics, which seem to be associated with a positive response. Findings suggest that unsupervised machine learning can be successfully used to stratify and eventually predict responses of individuals to a tDCS treatment.

A Systematic Review of the Effect of Short Term Transcranial Direct Current Stimulation Therapy in Methamphetamine Use Disorder

Background: Methamphetamine use disorder (MUD) has become more and more common. Some studies have shown that Transcranial Direct Current stimulation (tDCS) may reduce craving when stimulating the dorsal lateral prefrontal cortex. Objectives: The aim of this systematic review was to evaluate the effect of transcranial direct current stimulation (tDCS) on MUD. Databases were searched through May 2022. Randomized Controlled Trials (RCT) and pre-post studies investigating the efficacy of tDCS in MUD were included. The Cochrane Manual of Systematic Evaluation 6.3 bias risk assessment tool was used to assess the risk of bias. For each article, where possible, we extracted the population(s), standardized mean differences (SMD), standard deviations, and other study metrics (design, year, randomization, and details) on efficacy and tolerability outcomes. We assessed each article’s quality via the GRADE assessment protocol. Results: Six studies involving 220 patients were included. All six studies included reported continuous data on craving. Results from craving favored active tDCS over sham tDCS at the end of treatment (SMD −0.58, 95% CI −0.85 to −0.30; studies = 6, participants = 220; I2 = 60%). Tolerability data showed that tDCS does not cause more tingling or itching sensation compared to sham tDCS. Conclusions: Further trials with larger sample sizes and longer durations are needed to determine whether tDCS is a valuable tool in treating MUD.

Effects of active and sham tDCS on the soleus H-reflex during standing

Weak transcranial direct current stimulation (tDCS) is known to affect corticospinal excitability and enhance motor skill acquisition, whereas its effects on spinal reflexes in actively contracting muscles are yet to be established. Thus, in this study, we examined the acute effects of Active and Sham tDCS on the soleus H-reflex during standing. In fourteen adults without known neurological conditions, the soleus H-reflex was repeatedly elicited at just above M-wave threshold throughout 30 min of Active (N = 7) or Sham (N = 7) 2-mA tDCS over the primary motor cortex in standing. The maximum H-reflex (Hmax) and M-wave (Mmax) were also measured before and immediately after 30 min of tDCS. The soleus H-reflex amplitudes became significantly larger (by 6%) ≈1 min into Active or Sham tDCS and gradually returned toward the pre-tDCS values, on average, within 15 min. With Active tDCS, the amplitude reduction from the initial increase appeared to occur more swiftly than with Sham tDCS. An acute temporary increase in the soleus H-reflex amplitude within the first minute of Active and Sham tDCS found in this study indicates a previously unreported effect of tDCS on the H-reflex excitability. The present study suggests that neurophysiological characterization of Sham tDCS effects is just as important as investigating Active tDCS effects in understanding and defining acute effects of tDCS on the excitability of spinal reflex pathways.

Primary outcome from the augmenting cognitive training in older adults study (ACT): A tDCS and cognitive training randomized clinical trial

BackgroundThere is a need for effective interventions to stave off cognitive decline in older adults. Cognitive training has variably produced gains in untrained tasks and daily functioning. Combining cognitive training with transcranial direct current stimulation (tDCS) may augment cognitive training effects; however, this approach has yet to be tested on a large-scale. ObjectiveThis paper will present the primary findings of the Augmenting Cognitive Training in Older Adults (ACT) clinical trial. We hypothesize that receiving active stimulation with cognitive training will result in greater improvements on an untrained fluid cognition composite compared to sham following intervention. Methods379 older adults were randomized, and 334 were included in intent-to-treat analyses for a 12-week multidomain cognitive training and tDCS intervention. Active or sham tDCS was administered at F3/F4 during cognitive training daily for two weeks then weekly for 10 weeks. To assess the tDCS effect, we fitted regression models for changes in NIH Toolbox Fluid Cognition Composite scores immediately following intervention and one year from baseline controlling for covariates and baseline scores. ResultsAcross the entire sample, there were improvements in NIH Toolbox Fluid Cognition Composite scores immediately post-intervention and one year following baseline; however, there were no significant tDCS group effects at either timepoint. ConclusionsThe ACT study models rigorous, safe administration of a combined tDCS and cognitive training intervention in a large sample of older adults. Despite potential evidence of near-transfer effects, we failed to demonstrate an additive benefit of active stimulation. Future analyses will continue to assess the intervention's efficacy by examining additional measures of cognition, functioning, mood, and neural markers.

Combining transcranial direct current stimulation with group cognitive behavioral therapy developed to treat rumination: a clinical pilot study.

As part of repetitive negative thinking (RNT), rumination is a maladaptive cognitive response style to stress or negative mood which can increase the risk of depression and may prohibit complete recovery. Cognitive behavioral therapy (CBT) and transcranial direct current stimulation (tDCS) both proved to be effective in decreasing rumination. However, the combined effects of tDCS and CBT interventions on rumination have not yet been explored. The first aim of this pilot study is to investigate whether the combination of tDCS and CBT has an accumulating positive effect on modulating state rumination. The second aim is to assess the feasibility and safety profile of the proposed combined approach. Seventeen adults aged 32-60 years, suffering from RNT, were referred by their primary care professional to participate in an 8-week group intervention for RNT ("Drop It") comprising 8 sessions of CBT. Before each CBT session, patients underwent one double-blinded prefrontal active (2 mA for 20 min) or sham tDCS (anode over F3, cathode over the right supraorbital region) combined with an internal cognitive attention task focused on individual RNT, i.e., online tDCS priming. During each session, the Brief State Rumination Inventory was used to assess state rumination. A mixed effects model analysis revealed no significant differences between the stimulation conditions, weekly sessions, or their interaction in terms of state rumination scores. Overall, the combination of online tDCS priming followed by group CBT was found to be safe and feasible. On the other hand, no significant additional effects of this combined approach on state rumination were established. Although our pilot study may have been too small to find significant clinical effects, future larger RCT studies on combined tDCS-CBT treatment protocols may reevaluate the selection of internal cognitive attention tasks and more objective neurophysiological measurements, consider the optimal timing of the combination (concurrently or sequentially), or may add additional tDCS sessions when following CBT.

Transcranial direct current stimulation impairs updating of avoidance-based associative learning.

Exposure-based psychotherapies for the treatment of anxiety- and fear-based disorders rely on "corrective" associative learning. Namely the repeated confrontation with feared stimuli in the absence of negative outcomes allows the formation of new, corrected associations of safety, indicating that such stimuli no longer need to be avoided. Unfortunately, exposure-facilitated corrective learning tends to be bound by context and often poorly generalizes. One brain structure, the prefrontal cortex, is implicated in context-guided behavior and may be a relevant target for improving generalization of safety learning. Here, we tested whether inhibition of the left prefrontal cortex causally impaired updating of context-bound associations specifically or, alternatively, impaired updating of learned associations irrespective of contextual changes. Additionally, we tested whether prefrontal inhibition during corrective learning influenced subsequent generalization of associations to a novel context. In two separate experiments, participants received either 10 min of 2 mA cathodal transcranial direct current stimulation (tDCS) over EEG coordinate F3 (Experiment 1 n = 9, Experiment 2 n = 22) or sham stimulation (Experiment 1 n = 10, Experiment 2 n = 22) while previously learned associations were reversed in the same or a different context from initial learning. Next, to assess generalization of learning, participants were asked to indicate which of the previously seen images they preferred in a novel, never seen before context. Results indicate that tDCS significantly impaired reversal irrespective of context in Experiment 2 only. When taking learning rate across trials into account, both experiments suggest that participants who received sham had the greatest learning rate when reversal occurred in a different context, as expected, whereas participants who received active tDCS in this condition had the lowest learning rate. However, active tDCS was associated with preferring the originally disadvantageous, but then neural stimulus after stimulus after reversal occurred in a different context in Experiment 1 only. These results support a causal role for the left prefrontal cortex in the updating of avoidance-based associations and encourage further inquiry investigating the use of non-invasive brain stimulation on flexible updating of learned associations.

Short-term ocular dominance plasticity is not modulated by visual cortex tDCS but increases with length of monocular deprivation

Transcranial direct current stimulation (tDCS) of the occipital lobe may modulate visual cortex neuroplasticity. We assessed the acute effect of visual cortex anodal (a-)tDCS on ocular dominance plasticity induced by short-term monocular deprivation (MD), a well-established technique for inducing homeostatic plasticity in the visual system. In Experiment 1, active or sham visual cortex tDCS was applied during the last 20 min of 2-h MD following a within-subjects design (n = 17). Ocular dominance was measured using two computerized tests. The magnitude of ocular dominance plasticity was unaffected by a-tDCS. In Experiment 2 (n = 9), we investigated whether a ceiling effect of MD was masking the effect of active tDCS. We replicated Experiment 1 but used only 30 min of MD. The magnitude of ocular dominance plasticity was decreased with the shorter intervention, but there was still no effect of active a-tDCS. Within the constraints of our experimental design and a-tDCS parameters, visual cortex a-tDCS did not modulate the homeostatic mechanisms that drive ocular dominance plasticity in participants with normal binocular vision.

Effect of tDCS Combined With Physical Training on Physical Performance in a Healthy Population

ABSTRACT Purpose: The effectiveness of transcranial direct current stimulation (tDCS) combined with physical training has shown inconsistent results through research. Hence, a study utilizing a long-term tDCS application over the primary motor cortex and a large sample size is required to determine whether tDCS combined with physical training can increase physical performance (muscular strength, endurance, and explosive strength) in healthy adults. Material and methods: Fifty-six healthy adults were randomly distributed into two groups: active (active tDCS+ physical training) and sham (sham tDCS + physical training) and received the intervention three times per week for six weeks. Muscle strength was assessed using maximal isometric muscle strength (MIMS) by a digital dynamometer. Muscular endurance and lower limb explosive strength were assessed by using muscle fitness testing (MFT), and the Sargent jump test. Results: The active and sham groups exhibited significant improvement in all measured parameters in intragroup analyses. However, intergroup analyses revealed no significant difference between the groups. Conclusion:Our findings suggest that only physical training improved MIMS in the upper and lower extremities, MFT endurance scores, and lower limb explosive power. Thus, tDCS failed to demonstrate its effectiveness in a healthy population according to the protocol used in this study.

Transcranial direct current stimulation and cognitive stimulation therapy in children with autism spectrum disorder: randomized, sham-controlled, double-blind, crossover, clinical trial

BACKGROUND: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulation technic that has been researched as a therapeutic alternative to reduce symptoms and improve cognitive functioning in many disorders, including autism spectrum disorder (ASD), a neurodevelopmental disorder in which functional changes are observed in some brain structures, damaging different areas of the individual’s lives. OBJECTIVE: To compare the effects of active and sham transcranial direct current stimulation during cognitive stimulation tasks training in children with an autism spectrum disorder. METHODS: A randomized, sham-controlled, double-blind, crossover clinical trial was conducted. Twelve children with ASD underwent ten cognitive training sessions combined with active and sham tDCS. Anodal tDCS was administered over the left dorsolateral prefrontal cortex (DLPFC). Executive functions and social cognition were evaluated before, after, and three months after (follow-up) the intervention. RESULTS: No differences were found in the effects between the two interventions. Considering the mean results before and after active tDCS, improvements were seen in the theory of mind function (pre-intervention: 14.58 ± 5.04; post-intervention: 17.08 ± 5.21 [d2 = 0.51)]; follow-up: 16.92 ± 5.52 [d2 = 0.46]) and inhibitory control (pre-intervention: -1.31 ± 1.90; follow-up: 0.25 ± 1.14, d2 = 1.04). CONCLUSION: The administration of active tDCS over the left DLPFC during the training of cognitive stimulation tasks did not result in superior effects compared to sham tDCS combined with training in children with an autism spectrum disorder.

Self-administered transcranial direct current stimulation treatment of knee osteoarthritis alters pain-related fNIRS connectivity networks.

Knee osteoarthritis (OA) is a disease that causes chronic pain in the elderly population. Currently, OA is mainly treated pharmacologically with analgesics, although research has shown that neuromodulation via transcranial direct current stimulation (tDCS) may be beneficial in reducing pain in clinical settings. However, no studies have reported the effects of home-based self-administered tDCS on functional brain networks in older adults with knee OA. We used functional near-infrared spectroscopy (fNIRS) to investigate the functional connectivity effects of tDCS on underlying pain processing mechanisms at the central nervous level in older adults with knee OA. Pain-related brain connectivity networks were extracted using fNIRS at baseline and for three consecutive weeks of treatment from 120 subjects randomly assigned to two groups undergoing active tDCS and sham tDCS. Our results showed that the tDCS intervention significantly modulated pain-related connectivity correlation only in the group receiving active treatment. We also found that only the active treatment group showed a significantly reduced number and strength of functional connections evoked during nociception in the prefrontal cortex, primary motor (M1), and primary somatosensory (S1) cortices. To our knowledge, this is the first study in which the effect of tDCS on pain-related connectivity networks is investigated using fNIRS. fNIRS-based functional connectivity can be effectively used to investigate neural circuits of pain at the cortical level in association with nonpharmacological, self-administered tDCS treatment.

Addition of tDCS and TENS to an education and exercise program in subjects with knee osteoarthritis: A study protocol.

Knee osteoarthritis often leads to chronic pain that frequently becomes disabling.Osteoarthritis has been linked to maladaptive plasticity in the brain, which can contribute to chronic pain. Therapies including neuromodulation and peripheral electrical stimulation are used to counteract the maladaptive plasticity of the brain. To determine the efficacy of the addition of tDCS and TENS to an education and exercise program in reducing pain. Over a 2-week study period, 60 participants will complete an exercise and educational intervention. Eligible participants accepting to participate will be subsequently randomized into one of the three treatment groups: 1) Active Transcranial Direct Current Stimulation (tDCS) and active Transcutaneous Electrical Nerve Stimulation (TENS); 2) Active tDCS and sham TENS; 3) Sham tDCS and sham TENS. The primary outcome will be subjective pain intensity. quality of life, physical function, central sensitization, and pain adjuvants (uncertainty, catastrophizing kinesiophobia, adverse events). This clinical trial will provide data on the effect that the addition of tDCS and/or TENS to an education and exercise program may have to counteract maladaptive plastic changes and improve the benefits of exercises, and whether the combination of both neuromodulator techniques may have a higher magnitude of effect.

Transcranial direct current stimulation to reduce chronic pelvic pain in endometriosis: Phase II Randomized Controlled Clinical Trial.

It is known that various chronic pain conditions lead to maladaptive changes in the central nervous system. Endometriosis is frequently associated with chronic pelvic pain (CPP). Its sufficient treatment remains a clinical challenge. Transcranial direct current stimulation (tDCS) has been shown to be a powerful method to reduce chronic pain. Therefore, this study aimed to investigate pain reduction via anodal tDCS in patients with endometriosis and CPP. This clinical phase-II, placebo-controlled, randomized, parallel designed study included 36 patients with endometriosis and CPP. All patients suffered from CPP defined as ≥ 3/10 on the visual analog scale (VAS) for ≥3 month in the past six months. Anodal or placebo tDCS (18 patients per arm) was applied over the primary motor cortex for 10 days. Primary outcome measure was pressure pain threshold (objective pain measure) as well as secondary outcomes were numerical rating scale (NRS, subjective pain measure), Von-Frey-monofilaments, and disease- and pain-related questionnaires. Data was collected at baseline, after the 10-day stimulation and at a follow-up session, which took place one week after ending tDCS. Statistical analyses were performed using ANOVA and t-tests. Significant decreased pain perception in both pain measurements: i) pressure pain threshold and ii) NRS were found for the active tDCS group compared to the placebo group. This proof-of-concept study shows that tDCS is a helpful/supporting pain therapy for patients with endometriosis and CPP. Moreover, further analyses revealed that one week after finishing the stimulation, pain reduction remained significantly decreased as indexed by pressure pain threshold indicating possible long-term analgesic effects. The present study provides evidence that tDCS is an effective therapy for pain reduction in endometriosis-associated CPP. The results found support the notion that CPP is developed and maintained in the central nervous system making a multimodal pain therapy necessary. NCT05231239.

Prefrontal transcranial direct current stimulation over the right prefrontal cortex reduces proactive and reactive control performance towards emotional material in healthy individuals

The prefrontal cortex plays a crucial role in cognitive processes, both during anticipatory and reactive modes of cognitive control. Transcranial Direct Current Stimulation (tDCS) can modulate these cognitive resources. However, there is a lack of research exploring the impact of tDCS on emotional material processing in the prefrontal cortex, particularly in regard to proactive and reactive modes of cognitive control. In this study, 35 healthy volunteers underwent both real and sham tDCS applied to the right prefrontal cortex in a counterbalanced order, and then completed the Cued Emotion Control Task (CECT). Pupil dilation, a measure of cognitive resource allocation, and behavioral outcomes, such as reaction time and accuracy, were collected. The results indicate that, as compared to sham stimulation, active right-sided tDCS reduced performance and resource allocation in both proactive and reactive modes of cognitive control. These findings highlight the importance of further research on the effects of tDCS applied to the right prefrontal cortex on cognitive engagement, particularly for clinical trials utilizing the present electrode montage in combination with cognitive interventions.

Safety of repeated neuromodulation by transcranial direct current stimulation (tDCS) in dementia: a narrative review

IntroductionTranscranial direct current stimulation (tDCS) is a form of neuromodulation most commonly used in depression. tDCS aims to modulate cortical activity by the application of a weak electrical current to the brain via electrodes placed on the scalp. Several studies have identified the potential of tDCS for managing behavioural and psychological symptoms in a range of dementias, including Alzheimer’s disease, vascular dementia, dementia with Lewy bodies and frontotemporal dementia. Although the preliminary data on efficacy is promising, the safety of repeatedly neuromodulating the brain of a person with dementia, by tDCS, has not been extensively reported.ObjectivesOur aim was to review the current literature on how safe it is to repeatedly neuromodulate a brain with dementia.MethodsAdvanced literature searches of PubMed and the Web of Science Core Collection were conducted to identify relevant publications. The search terms deployed were: “tDCS” or “transcranial direct current stimulation” and “frontotemporal dementia” or “vascular dementia” or “Lewy body” or “Alzheimer’s disease”. The following inclusion criteria were applied to the search: (1) publications which focused on the use of tDCS in patients with either frontotemporal dementia, vascular dementia, dementia with Lewy bodies or Alzheimer’s disease, (2) studies involving human participants and, (3) publications written in, or readily translated to English.Results216 articles were returned in the initial search. Following the removal of 54 duplicate articles, the remaining 162 underwent eligibility screening using the titles and abstracts. 31 articles were then selected for a full text reading and following this, 12 studies were selected to be included in the review. Across all 12 studies, 3590 sessions of active tDCS were performed with no severe adverse effects being reported. The most commonly occurring adverse effect was a tingling/burning sensation underneath the electrodes, followed by headache and skin changes. These reported effects tended to be mild and short lived.ConclusionsOverall, the results of the reviewed papers suggest that repeated neuromodulation by tDCS can be safely performed in dementia patients. More and larger studies should aim to perform a greater number of sessions of tDCS, across a longer time period. Few studies assessed for potential brain damage as a result of tDCS and future studies should consider using MRI or monitoring biomarkers to further investigate this.Disclosure of InterestNone Declared