Learning curves of theta/beta neurofeedback in children with ADHD

Abstract

Neurofeedback is widely applied as non-pharmacological intervention aimed at reducing symptoms of ADHD, even though efficacy has not been unequivocally established. Neuronal changes during the neurofeedback intervention that resemble learning can provide crucial evidence for the feasibility and specificity of this intervention. A total of 38 children (aged between 7 and 13 years) with a DSM-IV-TR diagnosis of ADHD, completed on average 29 sessions of theta (4-8 Hz)/beta (13-20 Hz) neurofeedback training. Dependent variables included training-related measures as well as theta and beta power during baseline and training runs for each session. Learning effects were analyzed both within and between sessions. To further specify findings, individual learning curves were explored and correlated with behavioral changes in ADHD symptoms. Over the course of the training, there was a linear increase in participants' mean training level, highest obtained training level and the number of earned credits (range b = 0.059, -0.750, p < 0.001). Theta remained unchanged over the course of the training, while beta activity increased linearly within training sessions (b = 0.004, 95% CI = [0.0013-0.0067], p = 0.005) and over the course of the intervention (b = 0.0052, 95% CI = [0.0039-0.0065], p < 0.001). In contrast to the group analyses, significant individual learning curves were found for both theta and beta over the course of the intervention in 39 and 53%, respectively. Individual learning curves were not significantly correlated with behavioral changes. This study shows that children with ADHD can gain control over EEG states during neurofeedback, although a lack of behavioral correlates may indicate insufficient transfer to daily functioning, or to confounding reinforcement of electromyographic activity.

Clinical trials registration: This trial is registered at the US National Institutes of Health (ClinicalTrials.gov, ref. no: NCT01363544); https://ichgcp.net/clinical-trials-registry/NCT01363544 .

Keywords: ADHD; EEG; Learning curves; Neurofeedback; Paediatric; Theta/beta-training.

Conflict of interest statement

None of the authors has a conflict of interest in the conduct and reporting of this study.

Figures

Fig. 1

Schematic representation of the neurofeedback intervention. Approximately 3 sessions of neurofeedback were provided in a week, with 30 sessions taking 10 weeks. Each neurofeedback session started with a 1-min theta/beta baseline recording, which was used for the remaining of the session. A session consisted of 10 runs of 2 min each (20 min effective training). Each run comprised 4 trials of 30 s. Children were instructed to decrease theta/beta compared to the baseline recording during each trial. Children were rewarded with credits related to the size of the improvements compared to baseline. The training level increased or decreased based on performance of former runs and ranged between 3 and 52%. Training level increased after two successive runs with three successful trials each or after one run with four successful trials. Training level decreased after two successive runs with only one successful trial or after one run with no successful trials

Fig. 2

EEG learning effects during neurofeedback. These graphs show changes in theta and beta power (μV2) during 1-min baseline EEG recordings preceding each neurofeedback session, across sessions (1–30) and within sessions (runs 1–10). The bold lines are means, and the upper and lower lines are 95% confidence intervals. **p < 0.01, ***p < 0.001