Examining the Effect of Transcranial Electrical Stimulation and Cognitive Training on Processing Speed in Pediatric Attention Deficit Hyperactivity Disorder: A Pilot Study

Abstract

ObjectiveProcessing Speed (PS), the ability to perceive and react fast to stimuli in the environment, has been shown to be impaired in children with attention deficit hyperactivity disorder (ADHD). However, it is unclear whether PS can be improved following targeted treatments for ADHD. Here we examined potential changes in PS following application of transcranial electric stimulation (tES) combined with cognitive training (CT) in children with ADHD. Specifically, we examined changes in PS in the presence of different conditions of mental fatigue.MethodsWe used a randomized double-blind active-controlled crossover study of 19 unmedicated children with ADHD. Participants received either anodal transcranial direct current stimulation (tDCS) over the left dorsolateral prefrontal cortex (dlPFC) or transcranial random noise stimulation (tRNS), while completing CT, and the administration order was counterbalanced. PS was assessed before and after treatment using the MOXO-CPT, which measures PS in the presence of various conditions of mental fatigue and cognitive load.ResultstRNS combined with CT yielded larger improvements in PS compared to tDCS combined with CT, mainly under condition of increased mental fatigue. Further improvements in PS were also seen in a 1-week follow up testing.ConclusionThis study provides initial support for the efficacy of tRNS combined with CT in improving PS in the presence of mental fatigue in pediatric ADHD.

Transcranial Random Noise Stimulation combined with Cognitive Training for Treating ADHD: A Randomized, Sham-Controlled Clinical Trial

“…Our ndings further point to a long-lasting effect of treatment, with bene ts lingering for at least 3 weeks following treatment. These results are in accordance with our previous pilot studies showing effects lasting for at least 1 week following 5 treatment sessions [28], [29]. Other studies also reported effects lasting from 8 days to 6 months following 3-5 stimulation sessions in healthy adults [66]- [70].…”

“…Global functioning was measured using the CGI-S (Clinical Global Impression-Severity) scale[48], memory performance was measured using the Digit Span test [49] and PS was measured using the MOXO-CPT task (NeuroTech Solutions Ltd); These measures have been detailed in our previous publications (see [28], [29]). Everyday EFs were assessed using the Behaviour Rating Inventory of Executive Function (BRIEF, [50]), parent and teacher reports.…”

“…tRNS was shown to successfully improve cognitive functions in healthy adults [26] and the outcomes of numerical training in a small sample of children with dyscalculia [27]. We have recently shown that tRNS over the DLPFC and IFC applied concurrently with cognitive training (CT) is favorable to tDCS and CT in improving ADHD symptoms and EFs in a paediatric sample [28] [29], with effects lasting at a 1-week follow-up. However, due to the lack of sham treatment, it was unclear whether the bene cial results for tRNS were due to worsening following the tDCS treatment.…”

Perspectives on heterogeneity-informed cognitive training for attention-deficit/hyperactivity disorder

“…This combination is grounded on the points that neuroplasticity is a prerequisite for CT improvement, and interventions that enhance neuroplasticity can thus improve training effects ( 45 ). Following this perspective, attempts have been made to combine CT with non-invasive brain stimulation; however, the results are inconsistent [see Dakwar-Kawar et al ( 70 ) but also Westwood et al ( 71 )]. The disparity may be due to the different timing and intensity at which brain stimulation was delivered, as the impact of the same brain stimulation on neuroplasticity varies with both time and intensity ( 45 , 72 ).…”

Remote neurocognitive interventions for attention-deficit/hyperactivity disorder – opportunities and challenges

“…One study combining tES with CT found that the effects were a function of stimulation intensity with an inverse-U shape (Ehrhardt et al, 2021). Moreover, although a recent study indeed reported that CT combined with tES elicited larger gains in AD/HD (Dakwar-Kawar et al, 2022), other studies found that the combination may reduce training gains in normal and AD/HD populations (Au et al, 2021;Westwood et al, 2021b). The inconsistent results may be caused by the complex role of neuroplasticity in tES.…”