Effect of transcranial direct current stimulation on decision making and cognitive flexibility in gambling disorder

The effect of transcranial alternating current stimulation on cognitive flexibility and attention of children with intellectual disability: a case report

BACKGROUND

Intellectual disability is a neurodevelopmental disorder characterized by significant impairments in intellectual functioning and adaptive behavior. Cognitive flexibility and attention are crucial cognitive domains often affected in children with intellectual disability. This case report explores the novel use of transcranial alternating current stimulation, a noninvasive brain stimulation technique, to enhance these cognitive functions. The study's novelty lies in its focus on alpha-wave frequency transcranial alternating current stimulation targeting specific Brodmann areas and its potential sustained impact on cognitive flexibility and attention in the pediatric population with intellectual disability.

CASE PRESENTATION

The case study involved two elementary school students, both 7 years old with mild intellectual disability, one male and one female, both with Turkic ethnicity, from Shahid Fahmideh School for Exceptional Children in Khosrowshah, Iran. Both participants underwent a 2-week intervention with daily 20-minute sessions of transcranial alternating current stimulation at an alpha-wave frequency (10 Hz), targeting Brodmann areas F3 and P3. Cognitive flexibility and attention were assessed using the Wisconsin Card Sorting Test and the Clock Test, administered at four time points: pre-intervention, week 1, week 2, and 1 month post-intervention. Statistical analysis showed significant improvements in both Wisconsin Card Sorting Test and Clock Test scores for both participants compared with baseline, with sustained enhancement over time.

CONCLUSION

The findings from this case report indicate that transcranial alternating current stimulation may be a promising intervention for improving cognitive flexibility and attention in children with intellectual disability. The significant and sustained improvements observed suggest that transcranial alternating current stimulation could have a meaningful clinical impact on the cognitive development of this population. However, further research is needed to confirm the efficacy of transcranial alternating current stimulation and to explore its broader applicability and long-term effects in larger, more diverse populations.

Comparative efficacy of different interventions on executive function in adolescents with internet use disorder

BACKGROUND

The formation and relapse of Internet use disorder (IUD) are related to the decline in executive function. Previous studies have indicated that exercise intervention and high-definition transcranial direct current stimulation (HD-tDCS) can improve the cognitive abilities of adolescents with IUD. However, the combined intervention's impact on executive function in these adolescents remains unclear. Therefore, this study aims to explore the effects and differences of multimodal exercise, HD-tDCS intervention, and combined intervention on the executive function of adolescents with IUD.

METHODS

Forty-eight adolescents with IUD were randomly assigned to the multimodal exercise group, HD-tDCS intervention group, combined intervention group, and control group. The intervention groups received 4 weeks of moderate-intensity multimodal exercise, HD-tDCS intervention (2 mA, 20min/session, 3 times/week), or combined multimodal exercise with HD-tDCS intervention. The control group received conventional educational learning. Executive function measurements were taken before intervention, after intervention, and 2 weeks post-intervention.

RESULTS

Compared to pre-intervention, different interventions effectively improved the behavioral performance of adolescents with IUD in executive function tasks. In comparison to single interventions, the combined intervention significantly outperformed multimodal exercise and HD-tDCS intervention in influencing the executive function (especially inhibitory control and working memory) in adolescents with IUD.

CONCLUSION

Combined multimodal exercise with HD-tDCS intervention proves to be an effective means of enhancing executive function in adolescents with IUD, particularly contributing to the improvement of explicit behavioral performance related to executive function.

Transcranial direct current stimulation combined with cognitive training improves decision making and executive functions in opioid use disorder: a triple-blind sham-controlled pilot study

Opioid use disorder (OUD) is a chronic disorder with a considerable amount of morbidity and mortality. Despite remarkable improvement achieved by maintenance programs, an array of treatment goals were still unmet. Mounting evidence suggests that transcranial Direct Current Stimulation (tDCS) improves decision making and cognitive functions in addictive disorders. tDCS paired with a decision making task was depicted to diminish impulsivity as well.

The present study aimed to assess the effect of tDCS combined with cognitive training (CT) in OUD for the first time.

In this triple-blind randomized sham-controlled pilot study, 38 individuals with OUD from the Buprenorphine-Naloxone Maintenance Therapy program were administered 20-minutes of 2 mA active/sham tDCS over the dorsolateral prefrontal cortex with concomitant cognitive training. A selected test battery evaluating decision making under risk and ambiguity as well as executive functions, verbal fluency and working memory was utilized before and after the intervention.

Greater improvements were observed in decision making under ambiguity (p = 0.016), set shifting ability and alternating fluency while no improvements were observed in decision making under risk in the active group, compared to sham.

Deficits of decision making and executive functions have a pivotal role in the perpetuation and the relapse of the OUD. Alleviation of these impairments brought tDCS/CT forth as an expedient neuroscientifically-grounded treatment option that merits further exploration in OUD, Trial registration: NCT05568251.

Cluster analysis in gambling disorder based on sociodemographic, neuropsychological, and neuroendocrine features regulating energy homeostasis

BACKGROUND

The heterogeneity of gambling disorder (GD) has led to the identification of different subtypes, mostly including phenotypic features, with distinctive implications on the GD severity and treatment outcome. However, clustering analyses based on potential endophenotypic features, such as neuropsychological and neuroendocrine factors, are scarce so far.

AIMS

This study firstly aimed to identify empirical clusters in individuals with GD based on sociodemographic (i.e., age and sex), neuropsychological (i.e., cognitive flexibility, inhibitory control, decision making, working memory, attention, and set-shifting), and neuroendocrine factors regulating energy homeostasis (i.e., leptin, ghrelin, adiponectin, and liver-expressed antimicrobial peptide 2, LEAP-2). The second objective was to compare the profiles between clusters, considering the variables used for the clustering procedure and other different sociodemographic, clinical, and psychological features.

METHODS

297 seeking-treatment adult outpatients with GD (93.6% males, mean age of 39.58 years old) were evaluated through a semi-structured clinical interview, self-reported psychometric assessments, and a protocolized neuropsychological battery. Plasma concentrations of neuroendocrine factors were assessed in peripheral blood after an overnight fast. Agglomerative hierarchical clustering was applied using sociodemographic, neuropsychological, and neuroendocrine variables as indicators for the grouping procedure. Comparisons between the empirical groups were performed using Chi-square tests (χ2) for categorical variables, and analysis of variance (ANOVA) for quantitative measures.

RESULTS

Three-mutually-exclusive groups were obtained, being neuropsychological features those with the greatest weight in differentiating groups. The largest cluster (Cluster 1, 65.3%) was composed by younger males with strategic and online gambling preferences, scoring higher on self-reported impulsivity traits, but with a lower cognitive impairment. Cluster 2 (18.2%) and 3 (16.5%) were characterized by a significantly higher proportion of females and older patients with non-strategic gambling preferences and a worse neuropsychological performance. Particularly, Cluster 3 had the poorest neuropsychological performance, especially in cognitive flexibility, while Cluster 2 reported the poorest inhibitory control. This latter cluster was also distinguished by a poorer self-reported emotion regulation, the highest prevalence of food addiction, as well as a metabolic profile characterized by the highest mean concentrations of leptin, adiponectin, and LEAP-2.

CONCLUSIONS

To the best of our knowledge, this is the first study to identify well-differentiated GD clusters using neuropsychological and neuroendocrine features. Our findings reinforce the heterogeneous nature of the disorder and emphasize a role of potential endophenotypic features in GD subtyping. This more comprehensive characterization of GD profiles could contribute to optimize therapeutic interventions based on a medicine of precision.

The Effects of Transcranial Direct Current Stimulation (tDCS) on the Cognitive Functions: A Systematic Review and Meta-analysis

Previous studies have investigated the effect of transcranial direct current stimulation (tDCS) on cognitive functions. However, these studies reported inconsistent results due to differences in experiment design, measurements, and stimulation parameters. Nonetheless, there is a lack of meta-analyses and review studies on tDCS and its impact on cognitive functions, including working memory, inhibition, flexibility, and theory of mind. We performed a systematic review and meta-analysis of tDCS studies published from the earliest available data up to October 2021, including studies reporting the effects of tDCS on cognitive functions in human populations. Therefore, these systematic review and meta-analysis aim to comprehensively analyze the effects of anodal and cathodal tDCS on cognitive functions by investigating 69 articles with a total of 5545 participants. Our study reveals significant anodal tDCS effects on various cognitive functions. Specifically, we observed improvements in working memory reaction time (RT), inhibition RT, flexibility RT, theory of mind RT, working memory accuracy, theory of mind accuracy and flexibility accuracy. Furthermore, our findings demonstrate noteworthy cathodal tDCS effects, enhancing working memory accuracy, inhibition accuracy, flexibility RT, flexibility accuracy, theory of mind RT, and theory of mind accuracy. Notably, regarding the influence of stimulation parameters of tDCS on cognitive functions, the results indicated significant differences across various aspects, including the timing of stimulation (online vs. offline studies), population type (clinical vs. healthy studies), stimulation duration (< 15 min vs. > 15 min), electrical current intensities (1-1.5 m.A vs. > 1.5 m.A), stimulation sites (right frontal vs. left frontal studies), age groups (young vs. older studies), and different cognitive tasks in each cognitive functioning aspect. In conclusion, our results demonstrate that tDCS can effectively enhance cognitive task performance, offering valuable insights into the potential benefits of this method for cognitive improvement.

Targeting right orbitofrontal cortex (OFC) with transcranial direct current stimulation (tDCS) can improve cognitive executive function in a major depressive episode, but not depressive mood: A Double-blind Randomized Controlled Pilot Trial

Transcranial direct current stimulation (tDCS) has emerged as a potential treatment for major depressive episodes (MDE). This study aimed to evaluate the efficacy of targeting the right orbitofrontal cortex (rOFC) with tDCS in improving depressed mood and cognitive function in patients with depression. A double-blind, randomized sham-controlled trial was conducted in which 70 patients with depression were randomly assigned to receive rOFC-tDCS (n = 24), left dorsolateral prefrontal cortex (lDLPFC) tDCS (n = 23), or SHAM (n = 23). The treatment course consisted of ten treatments (2 mA, 20 min) delivered over two weeks. Participants were then given once-a-week interventions for the next two weeks. The Hamilton Depression Scale 17 evaluated the severity of depressive symptoms, while the cognitive function was assessed using the Stroop Color-Word Test (SCWT) and the Wisconsin Card Sorting Test (WCST). The primary outcomes were evaluated following ten interventions, with the assessment additionally conducted after maintenance treatment and 4-week follow-up visits. Analyses were performed using linear mixed models. The trial was registered with ChiCTR2000034671. The study did not reveal antidepressant efficacy for rOFC-tDCS or lDLPFC-tDCS over SHAM. Cognitive performance improved for rOFC -tDCS and lDLPFC-tDCS compared to sham for response time on the SWCT and non-perseverative errors in the WCST. However, no statistically significant difference was observed between the two active stimulation groups concerning cognitive performance-enhancing effects. No serious adverse events were noted. In conclusion, while rOFC-tDCS did not present advantages for mood outcomes over lDLPFC-tDCS and SHAM, it may have promising effectiveness in cognitive executive function compared to SHAM.

Exploring the Impact of Smartphone Addiction on Risk Decision-Making Behavior among College Students Based on fNIRS Technology

Smartphone Addiction is a social issue caused by excessive smartphone use, affecting decision-making processes. Current research on the risky decision-making abilities of smartphone addicts is limited. This study used the functional Near-Infrared Spectroscopy (fNIRS) brain imaging technique and a Sequential Risk-Taking Task experimental paradigm to investigate the decision-making behavior and brain activity of smartphone addicts under varying risk levels. Using a mixed experimental design, the research assessed decision-making ability and brain activation levels as dependent variables across two groups (addiction and control), two risk amounts (high and low), and two outcomes (gain and loss). The study included 42 participants, with 25 in the addiction group and 17 in the control group. Results indicated that risk level significantly impacted the decision-making ability of smartphone addicts, with high-risk levels leading to weaker decision-making ability and increased risk-taking. However, at low-risk levels, decision-making abilities between addicts and healthy individuals showed no significant difference. Furthermore, brain imaging results using fNIRS revealed stronger brain activation in the dorsolateral Prefrontal Cortex (dlPFC) region for smartphone addicts under loss outcome conditions, with no significant differences between the two groups in terms of brain activation at varying risk volumes. These findings are critical in promoting healthy smartphone use, guiding clinical treatment, and advancing brain mechanism research.

Transcranial direct current stimulation alters the process of reward processing in children with ADHD: Evidence from cognitive modeling

BACKGROUND

The ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) are the neural underpinnings of reward processing, which is impaired in individuals with attention deficit hyperactivity disorder (ADHD). In the present study, we aimed to explore the impact of the vmPFC and the dlPFC regulation on reward processing.

METHODS

Twenty-six children with ADHD performed the balloon analogue risk-taking task (BART) and chocolate delay discounting task (CDDT) during five different sessions of transcranial direct current stimulation (tDCS), separated by a one-week interval: anodal left dlPFC/cathodal right vmPFC, the reversed electrode positioning, anodal left dlPFC stimulation with extracranial return electrode, anodal right vmPFC stimulation with extracranial return electrodes, and sham stimulation. Four-parameter and constant-sensitivity models were used to model the data.

RESULTS

In the BART, anodal dlPFC/cathodal vmPFC stimulation facilitated conservative decision making, anodal tDCS over dlPFC with extracranial return electrode increased positive beliefs about the explosion of a balloon, and anodal vmPFC/cathodal dlPFC stimulation reduced ongoing learning in the process of decision making. In the CDDT, anodal vmPFC stimulation with extracranial return electrode decreased impatience in the process of the task.

CONCLUSION

These results suggest a role of the left dlPFC and right vmPFC in the outcome of decision making and the process of risky decision making and delay discounting.

Effects of Transcranial Electrical Stimulation on Gambling and Gaming: A Systematic Review of Studies on Healthy Controls, Participants with Gambling/Gaming Disorder, and Substance Use Disorder

Gambling disorder (GD) and internet gaming disorder (IGD) are formally recognized behavioral addictions with a rapidly growing prevalence and limited treatment options. Recently, transcranial electrical stimulation (tES) techniques have emerged as potentially promising interventions for improving treatment outcomes by ameliorating cognitive functions implicated in addictive behaviors. To systematize the current state of evidence and better understand whether and how tES can influence gambling and gaming-related cognitive processes, we conducted a PRISMA-guided systematic review of the literature, focusing on tES effects on gaming and gambling in a diverse range of population samples, including healthy participants, participants with GD and IGD, as well as participants with substance abuse addictions. Following the literature search in three bibliographic databases (PubMed, Web of Science, and Scopus), 40 publications were included in this review, with 26 conducted on healthy participants, 6 focusing on GD and IGD patients, and 8 including participants with other addictions. Most of the studies targeted the dorsolateral prefrontal cortex, using transcranial direct current stimulation (tDCS), and assessed the effects on cognition, using gaming and gambling computerized cognitive tasks measuring risk taking and decision making, e.g., balloon analogue risk task, Iowa gambling task, Cambridge gambling task, etc. The results indicated that tES could change gambling and gaming task performances and positively influence GD and IGD symptoms, with 70% of studies showing neuromodulatory effects. However, the results varied considerably depending on the stimulation parameters, sample characteristics, as well as outcome measures used. We discuss the sources of this variability and provide further directions for the use of tES in the context of GD and IGD treatment.

Anodal Transcranial Direct Current Stimulation over the Right Dorsolateral Prefrontal Cortex Boosts Decision Making and Functional Impulsivity in Female Sports Referees

We investigated the effect of anodal transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (rDLPFC) on the sensitive decision making of female team sports referees. Twenty-four female referees voluntarily participated in this randomized, double-blind, crossover, and sham-controlled study. In three different sessions, participants received either anodal (a-tDCS; anode (+) over F4, cathode (-) over the supraorbital region (SO)), cathodal (c-tDCS; -F4/+SO), or sham tDCS (sh-tDCS) in a randomized and counterbalanced order. a-tDCS and c-tDCS were applied with 2 mA for 20 min. In sh-tDCS, the current was turned off after 30 s. Before and after tDCS, participants performed the computerized Iowa Gambling Task (IGT) and Go/No Go impulsivity (IMP) tests. Only a-tDCS improved IGT and IMP scores from pre to post. The delta (Δ = post-pre) analysis showed a significantly higher ΔIGT in a-tDCS compared to c-tDCS (p = 0.02). The ΔIMP was also significantly higher in a-tDCS compared to sh-tDCS (p = 0.01). Finally, the reaction time decreased significantly more in a-tDCS (p = 0.02) and sh-tDCS (p = 0.03) than in c-tDCS. The results suggest that the a-tDCS improved factors related to sensitive decision making in female team sports referees. a-tDCS might be used as an ergogenic aid to enhance decision performance in female team sports referees.

Betting on Non-Invasive Brain Stimulation to Treat Gambling Disorder: A Systematic Review and Meta-Analysis

Gambling disorder (GD) is a behavioral addiction that severely impacts individuals' functioning, leading to high socioeconomic costs. Non-invasive brain stimulation (NiBS) has received attention for treating psychiatric and neurological conditions in recent decades, but there is no recommendation for its use for GD. Therefore, this study aimed to systematically review and analyze the available literature to determine the effectiveness of NiBS in treating GD. Following the PRISMA guidelines, we screened four electronic databases up to July 2022 and selected relevant English-written original articles. We included ten papers in the systematic review and seven in the meta-analysis. As only two studies employed a sham-controlled design, the pre-post standardized mean change (SMCC) was computed as effect size only for real stimulation. The results showed a significant effect of NiBS in reducing craving scores (SMCC = -0.69; 95% CI = [-1.2, -0.2], p = 0.010). Moreover, considering the GD's frequent comorbidity with mood disorders, we ran an exploratory analysis of the effects of NiBS on depressive symptoms, which showed significant decreases in post-treatment scores (SMCC = -0.71; 95% CI = [-1.1, -0.3], p < 0.001). These results provide initial evidence for developing NiBS as a feasible therapy for GD symptoms but further comprehensive research is needed to validate these findings. The limitations of the available literature are critically discussed.

High-Definition Transcranial Direct Current Stimulation Improves Decision-Making Ability: A Study Based on EEG

High-definition transcranial direct current stimulation (HD-tDCS) has been shown to modulate decision-making; however, the neurophysiological mechanisms underlying this effect remain unclear. To further explore the neurophysiological processes of decision-making modulated by HD-tDCS, health participants underwent ten anodal (n = 16)/sham (n = 17) HD-tDCS sessions targeting the left DLPFC. Iowa gambling task was performed simultaneously with electroencephalography (EEG) before and after HD-tDCS. Iowa gambling task performance, the P300 amplitude, and the power of theta oscillation as an index of decision-making were compared. Behavioral changes were found that showed anodal HD-tDCS could improve the decision-making function, in which participants could make more advantageous choices. The electrophysiological results showed that the P300 amplitude significantly increased in CZ, CPZ electrode placement site and theta oscillation power significantly activated in FCZ, CZ electrode placement site after anodal HD-tDCS. Significant positive correlations were observed between the changes in the percent use of negative feedback and the changes in theta oscillation power before and after anodal HD-tDCS. This study showed that HD-tDCS is a promising technology in improving decision-making and theta oscillation induced by may be a predictor of improved decision-making.

Neural correlates of bribe-taking decision dilemma: An fNIRS study

Bribe-taking decision is a social dilemma for individuals: the pursuit of economic self-interest vs. compliance with social norms. Despite the well-known existence of the conflict in deciding whether to accept bribes, little is known about its neural responses. Using functional near-infrared imaging (fNIRS) technology and the bribe-taking decision game (economic gambling game as a control condition), the current study dissociated the neural correlates of the different motivations in the bribery dilemma, as well as the inhibitory effect of social norms on bribery and its underlying brain mechanisms in supra-cortical regions. Findings revealed that if individuals are more motivated by economic interest, rejecting money (vs. accepting money) accompanies higher activity in the dorsolateral prefrontal cortex (DLPFC) and frontopolar cortex (FPC), which reflects impulse inhibition and decision evaluation; whereas, if individuals are more consider social norms, their DLPFC is more active when they accept bribes (vs. reject bribes), which reflects their fear of punishment. Additionally, the key brain region where social norms inhibit bribery involves the left DLPFC. The current findings contribute to the literature on the neural manifestations of corrupt decisions and provide some insights into the anti-corruption movement.

Effects of transcranial static magnetic field stimulation over the left dorsolateral prefrontal cortex on random number generation

OBJECTIVE

Focal application of transcranial static magnetic field stimulation (tSMS) is a neuromodulation technique, with predominantly inhibitory effects when applied to the motor, somatosensory or visual cortex. Whether this approach can also transiently interact with dorsolateral prefrontal cortex (DLPFC) function remains unclear. The suppression of habitual or competitive responses is one of the core executive functions linked to DLPFC function. This study aimed to assess the impact of tSMS on the prefrontal contributions to inhibitory control and response selection by means of a RNG task.

METHODS

We applied 20 min of tSMS over the left DLPFC of healthy subjects, using a real/sham cross-over design, during performance of a RNG task. We used an index of randomness calculated with the measures of entropy and correlation to assess the impact of stimulation on DLPFC function.

RESULTS

The randomness index of the sequences generated during the tSMS intervention was significantly higher compared to those produced in the sham condition.

CONCLUSIONS

Our results indicate that application of tSMS transiently modulates specific functional brain networks in DLPFC, which indicate a potential use of tSMS for treatment of neuropsychiatric disorders.

SIGNIFICANCE

This study provides evidence for the capacity of tSMS for modulating DLPFC function.

Potential Biological Markers and Treatment Implications for Binge Eating Disorder and Behavioral Addictions

The reward system is highly relevant to behavioral addictions such as gambling disorder (GD), internet gaming disorder (IGD), and food addiction/binge eating disorder (FA/BED). Among other brain regions, the ventral striatum (VS) has been implicated in reward processing. The main objective of the present state-of-the-art review was to explore in depth the specific role of the VS in GD, IGD and FA/BED, understanding it as a possible biomarker of these conditions. Studies analyzing brain changes following interventions for these disorders, and especially those that had explored possible treatment-related changes in VS, are discussed. More evidence is needed on how existing treatments (both pharmacological and psychobehavioral) for behavioral addictions affect the activation of the VS and related circuitry.

Impact of transcranial alternating current stimulation on working memory and selective attention in athletes with attention deficit hyperactivity disorder: randomized controlled trial

OBJECTIVE

The current study aimed to investigate the impact of transcranial alternating current stimulation (tACS) on working memory and selective attention in athletes with attention deficit hyperactivity disorder (ADHD).

METHODS

In total 45 athletes with attention deficit hyperactivity disorder were randomly divided into three equal groups (sham, control and experimental groups). All participants in the sham and experimental groups received stimulations on the F3 and SO with a current of (10 HZ) 1 mA for 15 min over 10 sessions ( P  ≤ 0.05), and after 10 sessions, each group was retested. After 2 weeks, a follow-up test was performed according to the post-test using the Stroop test and N-BACK- (working memory test) to test statistical hypotheses ( P  ≤ 0.05).

RESULTS

The results of repeated measures analysis of variance revealed that applying tACS proved effective in improving the working memory and selective attention of ADHD athletes.

CONCLUSIONS

The study's findings indicated that the protocol of applying tACS 1 MA with 10 HZ improved the working memory and selective attention of ADHD athletes.

Update on Gambling Disorder

Gambling disorder (GD) is estimated to be experienced by about 0.5% of the adult population in the United States. The etiology of GD is complex and includes genetic and environmental factors. Specific populations appear particularly vulnerable to GD. GD often goes unrecognized and untreated. GD often co-occurs with other conditions, particularly psychiatric disorders. Behavioral interventions are supported in the treatment of GD. No medications have a formal indication for the GD, although clinical trials suggest some may be helpful. Noninvasive neuromodulation is being explored as a possible treatment. Improved identification, prevention, and treatment of GD are warranted.

Improvement of Impulsivity and Decision Making by Transcranial Direct Current Stimulation of the Dorsolateral Prefrontal Cortex in a Patient with Gambling Disorder

Gambling disorder (GD) is a form of behavioral addiction. In recent years, it has been suggested that the application of transcranial Direct Current Stimulation (tDCS) to the dorsolateral prefrontal cortex (DLPFC), which plays a key role in top-down inhibitory control and impulsivity, may represent a new therapeutic approach for treating addictions. Here we investigated the effectiveness of a novel low dose tDCS protocol (i.e. six sessions of right anodal/left cathodal tDCS for 20 min, with a current intensity of 1 mA) applied to DLPFC in a patient with GD. To evaluate the effect of the proposed intervention, cognitive, psychological and behavioural evaluations were performed at different time points, pre and post intervention. The results showed improvement of impulsivity, decision making, and cognitive functioning after tDCS intervention. Findings of the present study suggest that low doses of right anodal/left cathodal tDCS to DLPFC may effectively improve gambling behaviour. They also suggest to carefully evaluate the effects of this tDCS polarity on the patient's emotional state. The current protocol warrants further investigation in large groups of patients, as it may provide relevant insights into the design of effective, low dose treatments of gambling disorder.

Concurrent Transcranial Direct Current Stimulation and Resting-State Functional Magnetic Resonance Imaging in Patients with Gambling Disorder

Background/Introduction: Transcranial direct current stimulation (tDCS) delivered over the dorsolateral prefrontal cortex (DLPFC) while patients are at rest can decrease craving in patients with substance-related and addictive disorders. Yet, the effects of tDCS on resting-state brain activity remain unknown in this population. This study examined the effects of tDCS on resting-state functional connectivity (rsFC) with concurrent stimulation and functional magnetic resonance imaging in patients with gambling disorder. Methods: This was a randomized, sham-controlled, double-blind, crossover study. The anodal and cathodal electrodes were applied over the right and left DLPFC, respectively. Patients received 30 min of active and sham stimulation on separate days. rsFC was assessed before and during stimulation with seed-based analyses. Results: There was a significant increase of rsFC between the right DLPFC seed and the right superior parietal lobule during active stimulation as compared to during sham stimulation (p = 0.0059, corrected for multiple comparisons). There was also a positive correlation between rsFC change of this frontoparietal network and brain volume of the right DLPFC (p = 0.0042, corrected for multiple comparisons). Discussion: A single session of tDCS targeting the DLPFC strengthened functional connectivity in a frontoparietal circuit, known to be implicated in cognitive control, especially in patients with a greater volume of the region under the anode electrode. Impact statement Transcranial direct current stimulation increased the functional connectivity of a frontoparietal circuit in patients with gambling disorder. These changes were larger in patients with greater volume of the dorsolateral prefrontal cortex. Transcranial direct current stimulation strengthened the connectivity of a brain network known to be associated with cognitive control.

Is Allodynia a Determinant Factor in the Effectiveness of Transcranial Direct Current Stimulation in the Prophylaxis of Migraine?

OBJECTIVES

Allodynia, the clinical marker of central sensitization, affects even simple daily living activities and increases the tendency for migraine to be more resistant to treatment and have a chronic course. Migraine that impairs quality of life can often be treated with variable pharmaceutical agents, but with various side effects. Transcranial direct current stimulation (tDCS) is a potential alternative treatment for migraine prophylaxis.

MATERIALS AND METHODS

Seventy-seven patients diagnosed with migraine (48 with allodynia and 29 without allodynia) were included in the study. Randomly, 41 of the 77 patients received sham stimulation and 36 patients underwent three sessions of anodal left primary motor cortex stimulation for 2 mA, 20 min. Migraine attack characteristics (frequency, severity, and duration) and analgesic drug use were followed with headache diaries for one month after the stimulation.

RESULTS

After tDCS, migraine attack frequency (p = 0.021), the number of headache days (p = 0.005), duration of attacks (p = 0.008), and symptomatic analgesic drug use (p = 0.007) decreased in patients receiving active tDCS, compared to the sham group. The therapeutic gain of tDCS was calculated as 44% (95% confidence interval [CI]: 22-60%) for headache days and 76% (95% CI: 55-86) for headache duration. Response to tDCS treatment was higher in patients without allodynia (60% vs. 24%; p = 0.028) and allodynia came out as an independent predictor of response to tDCS with logistic regression analysis. Side effects were rare and similar to the sham group.

CONCLUSIONS

tDCS is a safe, efficacious, and fast method for migraine prophylaxis. However, the administration of tDCS before allodynia occurs, that is, before central sensitization develops, will provide increased responsiveness to the treatment.

SIGNIFICANCE

tDCS is more effective before the development of allodynia, but it also improves the quality of life even after the development of allodynia.

Decision-Making in Gambling Disorder, Problematic Pornography Use, and Binge-Eating Disorder: Similarities and Differences

Purpose of Review

The present review attempts to provide a comprehensive and critical overview of the neurocognitive mechanisms of gambling disorder (GD), problematic pornography use (PPU) and binge-eating disorder (BED), focusing specifically on decision-making processes.

Recent findings

GD, PPU and BED have been associated with decision-making impairments both under risk and ambiguity. Features such as intelligence, emotions, social variables, cognitive distortions, comorbidities, or arousal may condition decision-making processes in these individuals.

Summary

Impairments in decision-making seem to be a shared transdiagnostic feature of these disorders We also hypothesized the EG relative to the NEG group would demonstrate weaker relationships between problem-gambling severity and health/functioning measures (e.g., substance use) and gambling behaviors (e.g., more time spent gambling) given that EG would account for some of the variance in the relationships between ARPG and these measures. However, there is varying support for the degree to which different features may affect decision-making. Therefore, the study of decision-making processes can provide crucial evidence for understanding addictions and other disorders with addiction-like symptomatology.

Functional Effects of Bilateral Dorsolateral Prefrontal Cortex Modulation During Sequential Decision-Making: A Functional Near-Infrared Spectroscopy Study With Offline Transcranial Direct Current Stimulation

The ability to learn sequential contingencies of actions for predicting future outcomes is indispensable for flexible behavior in many daily decision-making contexts. It remains open whether such ability may be enhanced by transcranial direct current stimulation (tDCS). The present study combined tDCS with functional near-infrared spectroscopy (fNIRS) to investigate potential tDCS-induced effects on sequential decision-making and the neural mechanisms underlying such modulations. Offline tDCS and sham stimulation were applied over the left and right dorsolateral prefrontal cortex (dlPFC) in young male adults (N = 29, mean age = 23.4 years, SD = 3.2) in a double-blind between-subject design using a three-state Markov decision task. The results showed (i) an enhanced dlPFC hemodynamic response during the acquisition of sequential state transitions that is consistent with the findings from a previous functional magnetic resonance imaging (fMRI) study; (ii) a tDCS-induced increase of the hemodynamic response in the dlPFC, but without accompanying performance-enhancing effects at the behavioral level; and (iii) a greater tDCS-induced upregulation of hemodynamic responses in the delayed reward condition that seems to be associated with faster decision speed. Taken together, these findings provide empirical evidence for fNIRS as a suitable method for investigating hemodynamic correlates of sequential decision-making as well as functional brain correlates underlying tDCS-induced modulation. Future research with larger sample sizes for carrying out subgroup analysis is necessary in order to decipher interindividual differences in tDCS-induced effects on sequential decision-making process at the behavioral and brain levels.

Non-invasive brain stimulation targets and approaches to modulate gambling-related decisions: A systematic review

INTRODUCTION

Despite intense neuroscience research on the neurobiological underpinnings of Gambling Disorder (GD) and gambling-related decision-making, effective treatments targeting these dysfunctions are still lacking. Non Invasive Brain Stimulation (NIBS) techniques, such as transcranial Direct Current Stimulation (tDCS) and Transcranial Magnetic Stimulation (TMS), selectively modulate activity of brain circuits and have the potential to reverse alterations sustaining GD symptoms. Therefore, the aim of this systematic review was to determine the impact of different NIBS interventions on gambling-related decision processes.

METHODS

We conducted a comprehensive and translational search in three online databases (MEDLINE via PubMed, Scopus, Web of Science), in accordance with the PRISMA guidelines. We included studies applying neuromodulation (TMS, tDCS) techniques in GD patients or assessing gambling-related decision-making in healthy subjects. In addition, we explored the potential impact of NIBS in drug-induced GD (e.g., Parkinson's Disease).

RESULTS

Twenty-seven studies have been included. We summarized results to detect the impact of different targets and stimulation/inhibition protocols in terms of gambling-related decision-making. The majority of both tDCS and TMS studies targeted the dorsolateral prefrontal cortex. Although heterogeneous in protocols and parameters, results from tDCS and TMS studies converge in indicating that the stimulation (instead of inhibition) of prefrontal regions could be beneficial to contrast dysfunctional gambling-related decision processes.

CONCLUSION

NIBS interventions show promise to be further tested in controlled clinical settings for the treatment of behavioral addictions. Further studies are also necessary to investigate connectivity changes and laterality issues (unilateral versus bilateral; left versus right) of NIBS application in GD.

Effects of transcranial direct current stimulation on addictive behavior and brain glucose metabolism in problematic online gamers

BACKGROUND AND AIMS

Some online gamers may encounter difficulties in controlling their gaming behavior. Previous studies have demonstrated beneficial effects of transcranial direct current stimulation (tDCS) on various kinds of addiction. This study investigated the effects of tDCS on addictive behavior and regional cerebral metabolic rate of glucose (rCMRglu) in problematic online gamers.

METHODS

Problematic online gamers were randomized and received 12 sessions of either active (n = 13) or sham tDCS (n = 13) to the dorsolateral prefrontal cortex over 4 weeks (anode F3/cathode F4, 2 mA for 30 min, 3 sessions per week). Participants underwent brain 18F-fluoro-2-deoxyglucose positron emission tomography scans and completed questionnaires including the Internet Addiction Test (IAT), Brief Self-Control Scale (BSCS), and Behavioral Inhibition System/Behavioral Activation System scales (BIS/BAS) at the baseline and 4-week follow-up.

RESULTS

Significant decreases in time spent on gaming (P = 0.005), BIS (P = 0.03), BAS-fun seeking (P = 0.04), and BAS-reward responsiveness (P = 0.01), and increases in BSCS (P = 0.03) were found in the active tDCS group, while decreases in IAT were shown in both groups (P < 0.001). Group-by-time interaction effects were not significant for these measures. Increases in BSCS scores were correlated with decreases in IAT scores in the active group (β = -0.85, P < 0.001). rCMRglu in the left putamen, pallidum, and insula was increased in the active group compared to the sham group (P for interaction < 0.001).

DISCUSSION AND CONCLUSIONS

tDCS may be beneficial for problematic online gaming potentially through changes in self-control, motivation, and striatal/insular metabolism. Further larger studies with longer follow-up period are warranted to confirm our findings.

The neural basis of gambling disorder: An activation likelihood estimation meta-analysis

Previous imaging studies suggested that impairments of prefrontal-striatal and limbic circuits are correlated to excessive gambling. However, the neural underpinnings of gambling disorder (GD) continue to be the topic of debate. The present study aimed to identify structural changes in GD and differentiate the specific brain activity patterns associated with decision-making and reward-processing. We performed a systematic review complemented by Activation likelihood estimation (ALE) meta-analyses on morphometric and functional studies on neural correlates of GD. The ALE meta-analysis on structural studies revealed that patients with GD showed significant cortical grey-matter thinning in the right ventrolateral and ventromedial prefrontal cortex compared to healthy subjects. The ALE meta-analyses on functional studies revealed that patients with GD showed a significant hyperactivation in the medial prefrontal cortex and in the right ventral striatum during decision-making and gain processing compared to healthy subjects. These findings suggest that GD is related to an alteration of brain mechanisms underlying top-down control and appraisal of gambling-related stimuli and provided indications to develop new interventions in clinical practice.

The Effects of Non-invasive Brain Stimulation on Impulsivity in People with Mental Disorders: a Systematic Review and Explanatory Meta-Analysis

Impulsivity is a multi-faceted construct that underpins various mental health disorders. Impulsive behavior exacts a substantial health and economic burden, hence the importance of developing specific interventions to target impulsivity. Two forms of non-invasive brain stimulation, namely transcranial direct current stimulation (tDCS) and repetitive transcranial magnetic stimulation (rTMS), have been used to modulate impulsivity. To date, no reviews have systematically examined their effects on modulating impulsivity in people with mental health disorders. We conducted a systematic review and meta-analysis of the literature from AMED, Embase, Medline and PsycINFO databases on the use of rTMS and tDCS to modulate impulsivity in people with mental health disorders. Results from 11 tDCS and 18 rTMS studies indicate that tDCS has a significant, albeit small, effect on modulating impulsivity (g = 0.29; 95% CI, 0.09 to 0.48; p = .004) whereas rTMS has no significant effect on impulsivity (g = -0.08; 95% Cl, -0.35 to 0.19; p = .550). Subgroup analyses identified the key parameters required to enhance the effects of tDCS and rTMS on impulsivity. Gender and stimulation intensity acted as significant moderators for effects of rTMS on impulsivity. There is insufficient evidence to support the use of tDCS or rTMS in clinical practice to reduce impulsivity in people with mental health disorders. The use of standardized non-invasive brain stimulation protocols and outcome measures in patients with the same diagnosis is advised to minimize methodological heterogeneity.

Repeated transcranial direct current stimulation of dorsolateral-prefrontal cortex improves executive functions, cognitive reappraisal emotion regulation, and control over emotional processing in borderline personality disorder: A randomized, sham-controlled, parallel-group study

BACKGROUND

Borderline personality disorder (BPD) is primarily characterized by deficient emotion regulation. Impaired cognitive control over negative emotions is central to emotion dysregulation in BPD. Respective executive dysfunctions are associated with hypoactivation of prefrontal regions, and consecutive alterations of fronto-limbic network functionality. Here, we investigated the effect of increasing activity of the dorsolateral prefrontal cortex (DLPFC) with repeated transcranial direct current stimulation (tDCS) on (1) executive dysfunctions and (2) whether improving cognitive control affects emotion dysregulation and emotional processing in BPD.

METHODS

Thirty-two patients diagnosed with BPD were randomly assigned to active stimulation (N = 16) or sham stimulation (N = 16) group in a randomized, sham-controlled, parallel-group design. They received 10 sessions of active (2 mA, 20 min, anodal left- cathodal right DLPFC) or sham tDCS over 10 days. Major executive functions, emotion regulation strategies, and emotional processing of the patients were assessed before and immediately after the intervention.

RESULTS

The active stimulation group showed a significant improvement in major executive function domains. Importantly, cognitive reappraisal strategy of emotion regulation and several factors of emotional processing involved in the control of emotion significantly improved in the active stimulation group after the intervention. Factors related to emotional expression were, however, not affected.

LIMITATIONS

The single-blind design, absence of follow-up measures, and the intrinsically limited focality of tDCS are limitations of this study.

CONCLUSIONS

Increasing activity of the DLPFC improves executive functioning in BPD and improves ´cognitive control over negative emotions. Cognitive control interventions could be a potential, symptom-driven therapeutic approach in BPD.

Change in core symptoms of borderline personality disorder by tDCS: A pilot study

Borderline personality disorder (BPD) recognizes several psychopathological dimensions related to prefrontal cortex impairments. Transcranial Direct Current Stimulation (tDCS) targeting the right prefrontal dorsolateral cortex (DLPFC) positively influence cognitive functions related to impulsivity in healthy subjects. A randomized double-blind study was designed to investigate whether tDCS could modulate core dimensions (impulsivity, aggression, affective dysregulation) of BPD. Also effects on decision making process and substances craving was assessed. Patients were randomized to receive active-tDCS at 2 mA versus sham-tDCS, once a day for 15 sessions. Anode was placed on the right DLPFC (F4), cathode on the left DLPFC (F3). Impulsivity and aggression measures were significantly reduced only in patients treated with active-tDCS. Decision-making process was marginally influenced by the active current. Craving intensity was reduced only in the active-tDCS sample. Both groups showed improvements in the affective dysregulation dimension and anxious and depressive symptoms. The application of bilateral tDCS targeting right DLPFC with anodal stimulation seems to improve core dimensions of BPD (mainly impulsivity and aggression) probably by restoring prefrontal activity. tDCS might be a potential tool for preventing self-harming behaviors.

Non-invasive Brain Stimulation for Gambling Disorder: A Systematic Review

Background: Gambling disorder (GD) is the most common behavioral addiction and shares pathophysiological and clinical features with substance use disorders (SUDs). Effective therapeutic interventions for GD are lacking. Non-invasive brain stimulation (NIBS) may represent a promising treatment option for GD.

Objective: This systematic review aimed to provide a comprehensive and structured overview of studies applying NIBS techniques to GD and problem gambling.

Methods: A literature search using Pubmed, Web of Science, and Science Direct was conducted from databases inception to December 19, 2019, for studies assessing the effects of repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (t-DCS) on subjects with GD or problem gambling. Studies using NIBS techniques on healthy subjects and those without therapeutic goals but only aiming to assess basic neurophysiology measures were excluded.

Results: A total of 269 articles were title and abstract screened, 13 full texts were assessed, and 11 were included, of which six were controlled and five were uncontrolled. Most studies showed a reduction of gambling behavior, craving for gambling, and gambling-related symptoms. NIBS effects on psychiatric symptoms were less consistent. A decrease of the behavioral activation related to gambling was also reported. Some studies reported modulation of behavioral measures (i.e., impulsivity, cognitive and attentional control, decision making, cognitive flexibility). Studies were not consistent in terms of NIBS protocol, site of stimulation, clinical and surrogate outcome measures, and duration of treatment and follow-up. Sample size was small in most studies.

Conclusions: The clinical and methodological heterogeneity of the included studies prevented us from drawing any firm conclusion on the efficacy of NIBS interventions for GD. Further methodologically sound, robust, and well-powered studies are needed.

Can transcranial direct current stimulation (tDCS) improve impulsivity in healthy and psychiatric adult populations? A systematic review

Impulsivity is a multidimensional phenomenon that remains hard to define. It compounds the core pathological construct of many neuropsychiatric illnesses, and despite its close relation to suicide risk, it currently has no specific treatment. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique whose application results in cognitive function improvement, both in healthy and psychiatric populations. Following PRISMA recommendations, a systematic review of the literature concerning tDCS's effects on impulsive behaviour was performed using the PubMed database. The research was based on the combination of the keyword 'tDCS' with 'impulsivity', 'response inhibition', 'risk-taking', 'planning', 'delay discounting' or 'craving'. The initial search yielded 309 articles, 92 of which were included. Seventy-four papers demonstrated improvement in task performance related to impulsivity in both healthy and clinical adult populations. However, results were often inconsistent. The conditions associated with improvement, such as tDCS parameters and other aspects that may influence tDCS's outcomes, are discussed. The overall effects of tDCS on impulsivity are promising. Yet further research is required to develop a more comprehensive understanding of impulsivity, allowing for a more accurate assessment of its behavioural outcomes as well as a definition of tDCS therapeutic protocols for impulsive disorders.

Effects of Transcranial Direct Current Stimulation Paired With Cognitive Training on Functional Connectivity of the Working Memory Network in Older Adults

Background

Working memory, a fundamental short-term cognitive process, is known to decline with advanced age even in healthy older adults. Normal age-related declines in working memory can cause loss of independence and decreased quality of life. Cognitive training has shown some potential at enhancing certain cognitive processes, although, enhancements are variable. Transcranial direct current stimulation (tDCS), a form of non-invasive brain stimulation, has shown promise at enhancing working memory abilities, and may further the benefits from cognitive training interventions. However, the neural mechanisms underlying tDCS brain-based enhancements remain unknown.

Objective/Hypothesis

Assess the effects of a 2-week intervention of active-tDCS vs. sham paired with cognitive training on functional connectivity of the working memory network during an N-Back working memory task.

Methods

Healthy older adults (N = 28; mean age = 74 ± 7.3) completed 10-sessions of cognitive training paired with active or sham-tDCS. Functional connectivity was evaluated at baseline and post-intervention during an N-Back task (2-Back vs. 0-Back).

Results

Active-tDCS vs. sham demonstrated a significant increase in connectivity between the left dorsolateral prefrontal cortex and right inferior parietal lobule at post-intervention during 2-Back. Target accuracy on 2-Back was significantly improved for active vs. sham at post-intervention.

Conclusion

These results suggest pairing tDCS with cognitive training enhances functional connectivity and working memory performance in older adults, and thus may hold promise as a method for remediating age-related cognitive decline. Future studies evaluating optimal dose and long-term effects of tDCS on brain function will help to maximize potential clinical impacts of tDCS paired with cognitive training in older adults.

Clinical Trial Registration:

www.ClinicalTrials.gov, identifier NCT02137122.

Review: Non-Invasive Brain Stimulation in Behavioral Addictions: Insights from Direct Comparisons With Substance Use Disorders

BACKGROUND AND OBJECTIVES

Treatment models developed for substance use disorders (SUDs) are often applied to behavioral addictions (BAs), even though the correspondence between these forms of addiction is unclear. This is also the case for noninvasive brain stimulation (NIBS) techniques being investigated as potential treatment interventions for SUDs and BAs.

OBJECTIVES

to contribute to the development of more effective NIBS protocols for BAs.

METHODS

Two literature searches using PubMed and Google Scholar were conducted identifying a total of 35 studies. The first search identified 25 studies examining the cognitive and neurophysiological overlap between BAs and SUDs. The second search yielded 10 studies examining the effects of NIBS in BAs.

RESULTS

Impulsivity and cravings show behavioral and neurophysiologic overlaps between BAs and SUDs, however, other outcomes like working-memory abilities or striatal connectivity, differ between BAs and SUDs. The most-employed NIBS target in BAs was dorsolateral prefrontal cortex (DLPFC), which was associated with a decrease in cravings, and less frequently with a reduction of addiction severity.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

Direct comparisons between BAs and SUDs revealed discrepancies between behavioral and neurophysiological outcomes, but overall, common and distinctive characteristics underlying each disorder. The lack of complete overlap between BAs and SUDs suggests that investigating the cognitive and neurophysiological features of BAs to create individual NIBS protocols that target risk-factors associated specifically with BAs, might be more effective than transferring protocols from SUDs to BAs. Individualizing NIBS protocols to target specific risk-factors associated with each BA might help to improve treatment interventions for BAs. (Am J Addict 2019;00:1-23).