Frontal brain delta‐beta correlation, salivary cortisol, and social anxiety in children

Background Correlated activity of slow‐wave (e.g. delta) and fast‐wave (e.g. beta) frontal brain oscillations is thought to be an electrophysiological correlate of individual differences in neuroendocrine activity and anxiety in adult samples. We know, however, relatively little about the physiological and functional correlates of delta‐beta coupling in children. Method We examined whether longitudinal patterns of children's basal salivary cortisol and social anxiety across two visits separated by 1 year were associated with frontal brain delta‐beta correlation in children ( M age = 7.59 years, SD = 1.70). At Time 1 (T1), resting baseline electroencephalogram ( EEG ) recordings were collected from the children and delta and beta power was measured, and at both T1 and Time 2 (T2), basal salivary cortisol was measured, and parents reported on children's symptoms of social anxiety. Results Using latent class growth curve analysis, we found that children's salivary cortisol across visits was characterized by a high, stable class (53%), and a low, unstable class (47%), and children's social anxiety was characterized by a high, stable class (50%) and a low, stable class (50%). Using Fisher's r ‐to‐ z transformation, we found that frontal EEG delta‐beta correlation was significantly stronger among children with high, stable salivary cortisol levels (compared to the low, unstable class; z = 2.11, p = .02), and among children with high, stable social anxiety levels (compared to the low, stable class; z = 1.72, p = .04). Conclusions These findings demonstrate that longitudinal patterns of neuroendocrine stress activity and social anxiety may be associated with the correlation of EEG power in slow and fast frontal brain oscillations as early as childhood.