How the Individual Alpha Peak Frequency Helps Unravel the Neurophysiologic Underpinnings of Behavioral Functioning in Children With Attention-Deficit/Hyperactivity Disorder.

Attention-deficit/hyperactivity disorder (ADHD) has been associated with an elevated resting-state theta/beta power ratio and elevated theta power. However, the potential confounding effect of a low individual alpha peak frequency (IAPF) on the theta-power estimate has often been disregarded when studying the relationship between ADHD and the theta/beta power ratio or theta power alone. The aim of the present study was to assess whether the theta/beta power ratio and relative theta power are correlated with behavioral functioning in children with ADHD, as expected from previous studies. Subsequently, the influence of IAPF and the amount of supposed overlap between the individually determined alpha-band and the fixed theta-band were studied. For 38 children (aged 8-15 years), electroencephalographic (EEG) and investigator-scored ADHD Rating Scale IV data were available. Additional neurocognitive data were available for 32 children. As expected, the theta/beta power ratio and theta were positively related to the ADHD core symptoms. This relationship strengthened when controlling for IAPF, although correlations did not significantly differ from one another. Eight of 38 children (21%) showed a supposed overlap between their individually determined alpha band and the theta band. Neurocognitive performance did not show any relationship with the theta/beta power ratio or theta. The results of this study confirm that the theta/beta power ratio and theta power are indeed correlated with behavioral symptoms in children with ADHD and underscore the relevance of taking the IAPF into account.