Effects of Neurofeedback Training on Inhibitory Capacities in ADHD Children: A Single-Blind, Randomized, Placebo-Controlled Study

Resumo

Introduction. Studies performed during the last decades suggest that neurofeedback (NF) training can effectively reduce symptomatology in children with Attention deficit hyperactivity disorder (ADHD). Yet questions remain concerning specific effects of NF training in ADHD children, because these studies did not use a randomized, placebo-controlled approach. To address this issue, such an approach was used in the present study to measure the impact of NF training on inhibitory capacities. Method. Nine ADHD children (with no comorbidity), aged 8 to 13 years, were randomly assigned to either an experimental group (n=5) or a placebo group (n=4). For both groups, training protocols comprised 40 one-hr sessions (20 meetings of 2 sessions each). Sensorimotor rhythm=Theta training was used in the experimental group. Prerecorded sessions of the first author’s EEG activity were used in the placebo group. Pre- and posttraining assessments consisted of the Conner’s Parent Rating Scales (CPRS–R) and neuropsychological tests. A multiple case study strategy was applied for data analysis using a Reliable Change Index when applicable. Results. One experimental participant was a dropout, and one placebo participant had to be discontinued due to adverse effects. The latter participant accepted to undergo posttraining evaluations; hence an Intention-to-Treat analysis was performed on this participant’s data. Remaining participants showed significant improvements on the CPRS–R. Improvements were measured on the Variability measure of the CPT–II consistently across the placebo group and on the Inhibition Condition of the Stroop Task for all but one placebo participant. The same trend was found for the Inhibition=Switching Condition (Stroop Task) across the experimental group (n=4). Conclusion. The small sample size precludes from evaluating specific neurofeedback effects. Still, the presence of placebo responses suggests that other factors, such as motivation or expectations, might contribute to the outcome of NF training in children with ADHD.