EEG spectral analysis of attention in ADHD: implications for neurofeedback training?

Abstract

Objective: In children with attention-deficit/hyperactivity disorder (ADHD), an increased theta/beta ratio in the resting EEG typically serves as a rationale to conduct theta/beta neurofeedback (NF) training. However, this finding is increasingly challenged. As NF may rather target an active than a passive state, we studied the EEG in a condition that requires attention.Methods: In children with ADHD of the DSM-IV combined type (ADHD-C; N = 15) and of the predominantly inattentive type (ADHD-I; N = 9) and in typically developing children (N = 19), EEG spectral analysis was conducted for segments during the attention network test (ANT) without processing of stimuli and overt behavior. Frontal (F3, Fz, F4), central (C3, Cz, C4) and parietal (P3, Pz, P4) electrodes were included in the statistical analysis. To investigate if EEG spectral parameters are related to performance measures, correlation coefficients were calculated.Results: Particularly in the ADHD-C group, higher theta and alpha activity was found with the most prominent effect in the upper-theta/lower-alpha (5.5–10.5 Hz) range. In the ADHD-I group, a significantly higher theta/beta ratio was observed at single electrodes (F3, Fz) and a tendency for a higher theta/beta ratio when considering all electrodes (large effect size). Higher 5.5–10.5 Hz activity was associated with higher reaction time variability with the effect most prominent in the ADHD-C group. A higher theta/beta ratio was associated with higher reaction times, particularly in the ADHD-I group.Conclusions: (1) In an attention demanding period, children with ADHD are characterized by an underactivated state in the EEG with subtype-specific differences. (2) The functional relevance of related EEG parameters is indicated by associations with performance (reaction time) measures. (3) Findings provide a rationale for applying NF protocols targeting theta (and alpha) activity and the theta/beta ratio in subgroups of children with ADHD.

Closed-loop brain training: the science of neurofeedback

“…By contrast, combined EEG-fMRI studies in healthy subjects have found positive correlations between the functional activity of the DMN and the amplitude of EEG theta-alpha rhythms (4-12 Hz) [131][132][133] . Hence, an excess of task-related theta-alpha rhythms 115,134 , which may be reflective of an abnormally upregulated DMN, might be one candidate mechanism responsible for attentional deficits in ADHD. Interestingly, a recent EEG-fMRI study showed that suppressed alpha-rhythm amplitudes after neurofeedback training predicted reduced mind-wandering and were associated with upregulation of task-positive networks and downregulation of the DMN 18 .…”

Alpha modulation during working memory encoding predicts neurocognitive impairment in ADHD

“…This hypothesis is gaining momentum. A recent review (Lenartowicz et al., ) identified 12 published studies since 2009, spanning adult and child samples, to document weakened alpha power modulation during encoding in tasks of cued selective attention (Mazaheri et al., ; Yordanova, Kolev, & Rothenberger, ), visual interference (i.e., flanker)(Hasler et al., ; Heinrich et al., ; Mazaheri et al., ), spatial working memory (Gomarus, Wijers, Minderaa, & Althaus, ; Lenartowicz et al., , ; Missonnier et al., ), as well as spatial visual attention (ter Huurne et al., ; Ter Huurne et al., ; Vollebregt et al., ). Consistent with our results, alpha power deficits have been associated with inattentive symptoms, suggesting that this metric is sensitive to typical behavioral dysfunction in ADHD (Gomarus et al., ; Lenartowicz et al., ; Mazaheri et al., ; Ter Huurne et al., ).…”

“…This hypothesis is gaining momentum. A recent review (Lenartowicz et al, 2018) identified 12 published studies since 2009, spanning adult and child samples, to document weakened alpha power modulation during encoding in tasks of cued selective attention Yordanova, Kolev, & Rothenberger, 2013), visual interference (i.e., flanker) (Hasler et al, 2016;Heinrich et al, 2014; Higher score indicates fewer attention problems, thus greater alpha decrease during encoding, is associated with fewer ADHD symptoms). b Cronbach's alpha for each measure calculated on comparison of odd-numbered trials with even-numbered trials within each participant and is reported for low-load/high-load conditions.…”

Editorial Perspective: How to optimise frequency band neurofeedback for ADHD

“…The aim of the theta/beta training is to decrease the strength of central theta band power and to increase beta oscillations. The rationale for this is that children with ADHD have been observed to have increased theta power accompanied by reduced beta power, which has been interpreted as a sign of cortical hypoarousal (Hammond, ; Heinrich et al., ).…”