Evaluation of neurofeedback training for improving verbal working memory in typical adults versus adults diagnosed with ADHD (Hebrew)

Verbal working memory is a central component of human cognitive functions. It is a cognitive process in which the brain stores and processes verbal information in the short term, for the purpose of performing tasks such as language comprehension, thinking, problem solving, and learning (Baddeley, 2012; Logie, 2011). This function is supported by complex neural networks, particularly the prefrontal cortex, parietal cortex, and temporal areas involved in language and auditory processing (Eriksson et al., 2015; Schouwenaars et al., 2020). Impairments in verbal working memory can significantly affect daily functioning and may lead to difficulties in communication, learning, and work efficiency. Research indicates that individuals with Attention Deficit Hyperactivity Disorder (ADHD) often exhibit poor performance in this domain, due to impairments in the functioning of those neural networks involved in the verbal working memory process (Ramos et al., 2019; Pawley et al., 2024). Neurofeedback is a technique that provides immediate feedback on brain wave activity given a specific stimulus, with the aim of training the brain for self-control of neural activity. This method allows regulation of brain activity so that it will be optimal for improving cognitive functions through attentional training with the help of focusing on visual stimuli whose manner of appearance is influenced by changes in electrical brain activity. Research shows that neurofeedback is effective in improving attention and working memory functions through real-time brain wave regulation (Xiong et al., 2014; Campos da Paz et al., 2018; Jiang et al., 2022).

The objectives of the study were to examine the effectiveness of a single neurofeedback training session, based on a sensorimotor rhythm (SMR) enhancement protocol, for improving performance on a verbal working memory task among adults with and without ADHD. Additionally, we sought to examine whether the intervention effect varies depending on different cognitive load levels in the task, and to evaluate whether there is a relationship between the severity of Severity of symptoms of hyperactivity and impulsivity and improvement in accuracy in performing the verbal working memory task following intervention. There are many studies that have examined the effects of neurofeedback on attention and memory functions over time. The current study is the first to examine the immediate effect of neurofeedback training in a single session on verbal working memory in a population of adults with ADHD, hence its unique contribution. The study included 37 participants aged 18-50, who were randomly divided into an experimental group (which received neurofeedback training) and a control group (which received sham training), each of which included subjects with ADHD and typical subjects. The main research tool was a verbal N-back task in a 2-back version with four load levels (Meiron & Lavidor, 2013), measuring accuracy and reaction time indices. Additionally, background questionnaires were used to assess baseline variables, a semantic fluency test (Kave, 2005), the ASRS questionnaire for assessing ADHD symptoms (Schweitzer et al., 2001), and the BDI questionnaire for assessing depression (Beck et al., 1988).

We found that a single neurofeedback training session led to a significant improvement in performance accuracy on the working memory task compared to the control group, similar to findings from previous studies (Campos da Paz et al., 2018; Bouny et al., 2022). The improvement was particularly notable among participants with ADHD and at moderate-high load levels, while reaction time was not significantly affected. This finding is consistent with studies that pointed to improvement in accuracy without consistent change in reaction time (Nikolin et al., 2021). Additionally, A positive relationship was found between levels of hyperactivity-impulsivity and improvement in accuracy, a finding that contradicts the study's hypothesis but is consistent with approaches that view symptoms of hyperactivity and impulsivity as a factor that allows "room for improvement" in cognitive functions. (Alderson et al., 2017; Gremillion et al., 2018).

These findings indicate that a single, non-invasive, and accessible neurofeedback training session may serve as an effective tool for improving verbal working memory, particularly among populations with ADHD. These findings strengthen the assumption that neurofeedback may constitute an alternative or addition to existing pharmacological intervention, contribute to improving the quality of learning and functioning in these populations (Arns et al., 2009; Van Doren et al., 2019), and also emphasize the importance of broader research, with a larger sample and over time, that will examine the intervention's effect both in behavioral and neurophysiological measures, with the aim of formulating personalized training protocols adapted to different populations.