Transcranial direct current brain stimulation decreases impulsivity in ADHD

Allenby, Cheyenne; Falcone, Mary; Bernardo, Leah; Wileyto, E. Paul; Rostain, Anthony L.; Ramsay, J. Russell; Lerman, Caryn; Loughead, James

doi:10.1016/j.brs.2018.04.016

Cited by 92 publications

(97 citation statements)

References 95 publications

(131 reference statements)

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“…In total, 11 separate experiments from 10 studies published from 2014—April 2018 were included in this meta-analysis. In 8 of 10 studies (or 9 of 11 experiments), effects of tDCS on inhibitory control was investigated [6, 68–74] and in 5 of 10 studies (or 6 of 11 experiments), tDCS effects on WM were explored [6, 69, 74–76]. In what follows, we describe the effect size obtained from studies to examine the efficacy of tDCS in ADHD major neuropsychological symptoms (Please see Fig 2).…”

Section: Resultsmentioning

confidence: 99%

“…This was supported by the findings from two studies conducted on adult ADHD. The study with 2 mA intensity reported significant improvement in inhibitory control performance [68] while the study with 1 mA intensity reported no significant effects on Go/No-Go task performance [71] despite the fact both studies targeted left dlPFC with anodal tDCS. Stimulation intensity has, therefore, an impact on the effectiveness of tDCS, which is not necessarily linear [99] and should be considered in clinical applications.…”

Section: Discussionmentioning

confidence: 99%

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Transcranial direct current stimulation in attention-deficit hyperactivity disorder: A meta-analysis of neuropsychological deficits

et al. 2019

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Transcranial direct current stimulation (tDCS) is a promising method for altering cortical excitability with clinical implications in neuropsychiatric diseases. Its application in neurodevelopmental disorders especially attention-deficit hyperactivity disorder (ADHD), is in early stage and promising but its effectiveness has not been systematically examined yet. We conducted a meta-analysis on the effectiveness of tDCS on the most studied neuropsychological symptoms of ADHD, which is the first reported meta-analysis of tDCS studies on ADHD. Data from 10 randomized controlled studies (including 11 separate experiments) targeting inhibitory control, and/or working memory (WM) in ADHD were included. Results show that overall tDCS significantly improved inhibitory control. Sub-analyses further show that dorsolateral prefrontal cortex (dlPFC) (but not right inferior frontal gyrus) tDCS and anodal (but not cathodal) tDCS significantly improved inhibitory control with a small effect size. Anodal dlPFC-tDCS had the largest significant effect on inhibitory control with a small-to-medium effect size. Additionally, a significant improving effect of tDCS on inhibitory control accuracy (but not response time) and WM speed (but not accuracy) were found. Overall, this meta-analysis supports a beneficial effect of tDCS on inhibitory control and WM in ADHD with a small-to-medium effect size. TDCS seems to be a promising method for improving neuropsychological and cognitive deficits in ADHD. However, there might be a dissociation between neuropsychological deficits and clinical symptoms of ADHD and therefore, the significance of this meta-analysis for clinical purposes is limited. Future studies should systematically evaluate the role of inter-individual factors (i.e., ADHD subtype, types of the deficit) and stimulation parameters (i.e., site, polarity, intensity, duration, repetition rate) on tDCS efficacy in ADHD population and examine whether benefits are long-term.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Transcranial direct current stimulation in attention-deficit hyperactivity disorder: A meta-analysis of neuropsychological deficits

et al. 2019

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“…Alpha oscillations following stimulus onset have been increased after multichannel stimulation depending on initially baseline performance. Stimulation-induced changes of alpha oscillations during this nontarget task suggests a transfer effect of the stimulation to functions that have not been entrained during stimulation (Allenby et al, 2018 ). The increase in alpha following stimulus onset could reflect increased response inhibition through the inhibition of related cortical areas (Klimesch, 1996 ; Schmiedt-Fehr et al, 2009 ).…”

Section: Discussionmentioning

confidence: 99%

Individual Baseline Performance and Electrode Montage Impact on the Effects of Anodal tDCS Over the Left Dorsolateral Prefrontal Cortex

Splittgerber

Salvador²,

Brauer

et al. 2020

Front. Hum. Neurosci.

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Anodal transcranial direct current stimulation (tDCS), applied over the left dorsolateral prefrontal cortex (lDLPFC), can produce significant effects on working memory (WM) performance and associated neurophysiological activity. However, results from previous studies are inconsistent and occasionally contradictory. This inconsistency may be attributed to methodological and individual differences during experiments. This study therefore investigated two hypotheses: (1) A multichannel-optimized montage was expected to be more effective than a classical bipolar montage, because of increased focality. (2) The subjects were expected to benefit differently from the stimulation depending on their initial task performance. In a sham-controlled crossover study, 24 healthy participants received bipolar, multichannel, and sham stimulation for 20 min in randomized order, targeting the lDLPFC while performing a 2-back WM task. After stimulation, electroencephalography (EEG) was recorded at rest and during 2-back and nontarget continuous performance task (CPT) performance. Bipolar and multichannel stimulations were both well tolerated and effectively blinded. We found no effect of stimulation on behavioral performance or neuronal oscillations comparing the classical bipolar or multichannel montage with sham stimulation. We did, however, find an interaction between stimulation and initial task performance. For multichannel stimulation, initially low-performing participants tended to improve their WM performance while initially high-performing participants tended to worsen their performance compared to sham stimulation. Both tDCS montages induced changes in neural oscillatory power, which correlated with baseline performance. The worse the participants’ initial WM performance was, the more task-related theta power was induced by multichannel and bipolar stimulation. The same effect was observed for alpha power in the nontarget task following multichannel stimulation. Notably, we were not able to show a superiority of multichannel stimulation compared to bipolar stimulation. Still, comparing both montages with sham stimulation, multichannel stimulation led to stronger effects than bipolar stimulation. The current study highlights the importance of investigating different parameters with potential influence on tDCS effects in combination. Our results demonstrate how individual differences in cognitive performance and electrode montages influence effects of tDCS on neuropsychological performance. These findings support the idea of an individualized and optimized stimulation setting, potentially leading to increased tDCS effects.

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“…However, the lack of significant changes in the SSRT suggests no effects on reactive inhibition. Although there have been positive results in tDCS studies using the SST in a healthy population targeting other areas like the right inferior frontal gyrus [37][38][39][40][41][42] , previous tDCS studies with ADHD patients using the SST and targeting the DLPFC have also found a lack of significant effects on the SSRT and accuracy 28,43 . These results support the formulation of inhibitory control and impulsivity as complex multimodal processes with subdomain specificity (e.g.…”

Section: Flanker Taskmentioning

confidence: 99%

tDCS to the left DLPFC improves cognitive control but not action cancellation in patients with ADHD: a behavioral and electrophysiological study

Dubreuil-Vall

Gomez-Bernal

Villegas

et al. 2020

Preprint

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ADHD is a neurodevelopmental disorder associated with significant morbidity and mortality that affects 5% of children, adolescents and adults worldwide. Pharmacological and behavioral therapies exist, but critical symptoms such as dysexecutive deficits remain unaffected. In this randomized, placebo-controlled, double-blind, cross-over study we assess the cognitive and physiological effects of tDCS in adult ADHD patients in order to understand (1) the role of DLPFC laterality in ADHD dysexecutive deficits, (2) the physiological dynamics sustaining the modulation of executive function by tDCS, and (3) the impact of state-dependent dynamics of tDCS effect. The participants consisted of a random sample of 40 adult patients with a primary diagnosis of ADHD. Each patient performed three experimental sessions in which they received 30 minutes of 2mA tDCS stimulation targeting the left DLPFC (anodal F3, cathodal Fp2), the right DLPFC (anodal F4, cathodal Fp1) and Sham. Before and after each session, half of the patients completed the Flanker task (EFT) and the other half performed the Stop Signal Task (SST), while we assessed cognitive (reaction time, accuracy) and neurophysiological measures (EEG Event-Related-Potentials). Results show that anodal tDCS to the left DLPFC modulated cognitive (reaction time) and physiological measures (P300 amplitude) in the Flanker task in a state-dependent manner, but there were no significant effects in the Stop Signal Reaction Time of the SST. We interpret these results as an improvement in interference cognitive control (captured by the EFT) but not in action cancellation (assessed by the SST), supporting the hypothesis of the existence of different impulsivity constructs with overlapping but distinct anatomical substrates and therapeutic strategies. We conclude that anodal tDCS over the left DLPFC using a simple bipolar montage has pro-cognitive effects in dysexecutive patients with ADHD associated with the modulation of physiological signatures of cognitive control (i.e. treatment target), supporting specific hypotheses and strategies for neuromodulation treatment development under an experimental therapeutics framework aiming to link target engagement (cognitive and physiological) with clinical benefit. In addition, we also provide empirical evidence supporting the value of the P200, N200 and P300 as cross-sectional biomarkers of cognitive performance across tasks. Last, we provide mechanistic support for the state-dependent nature of the effects of tDCS, highlighting the importance of controlling the neural states before and during stimulation as a relevant therapeutic strategy.

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Transcranial direct current brain stimulation decreases impulsivity in ADHD

Cited by 92 publications

References 95 publications

Transcranial direct current stimulation in attention-deficit hyperactivity disorder: A meta-analysis of neuropsychological deficits

Transcranial direct current stimulation in attention-deficit hyperactivity disorder: A meta-analysis of neuropsychological deficits

Individual Baseline Performance and Electrode Montage Impact on the Effects of Anodal tDCS Over the Left Dorsolateral Prefrontal Cortex

tDCS to the left DLPFC improves cognitive control but not action cancellation in patients with ADHD: a behavioral and electrophysiological study

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