Doubting the Efficacy/Effectiveness of Electroencephalographic Neurofeedback in Treating Children With Attention-Deficit/Hyperactivity Disorder Is As Yet Unjustified

Abstract

Boomsma et al 1 assessed the efficacy of electroencephalographic (EEG) neurofeedback in children with attention-deficit/hyperactivity disorder by comparing an experimental group (n = 22) receiving EEG neurofeedback to a placebo group (inactive neurofeedback) (n = 19). Results did not show significant differences between the 2 groups. The authors report that, post hoc, the "sample had 80% power to detect a treatment effect of 0.90" and that "it is unlikely that the negative results were due to limited statistical power," 1(p826) concluding that their study sheds serious doubt on the effectiveness of EEG neurofeedback as a way of treating children with attention-deficit/ hyperactivity disorder. First, we want to acknowledge the robust design and methodology of this study. However, we are not sure what the authors meant by stating in their discussion that "the sample had 80% power to detect a treatment effect of 0.90, " and we cannot find an explanation of the rationale behind such a statement. How would statistical power be an issue if the effect size was as high as 0.90 in a sample of 41 participants? We ran a post hoc power analysis, using G*Power Version 3.1.5, 2,3 for a sample size of 41 participants, α of 5% and an effect size of 0.90 resulting from repeated-measures analysis of variance within-group and between-groups interaction tests for 2 groups and 2 measuring times, and found that this sample would have achieved 100% power to detect a treatment effect size of 0.90, not 80% as reported by the authors. Therefore, there is a 100% chance of finding statistically significant differences (P ≤ .05) between the EEG neurofeedback group and the placebo group, 4 although none were found. Impossible, unless the effect size equaled zero. We suspect that the authors made a calculation error. To verify this, we first calculated η 2 effect size for all the comparisons in the group × time effect (interaction) using the

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EEG neurofeedback research: A fertile ground for psychiatry?

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Le neurofeedback dans le trouble déficit de l’attention/hyperactivité de l’enfant est-il efficace ? Depuis les études rigoureuses jusqu’aux bonnes pratiques cliniques

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