Frontal EEG alpha-delta ratio and social anxiety across early adolescence.

Although the mean age of onset of social anxiety disorder (SAD) is during adolescence, we know relatively little about the neurodevelopmental correlates of subsyndromal social anxiety in early adolescence before SAD manifests. Here we examined frontal EEG alpha/delta ratio (a putative proxy of brain maturation) in relation social anxiety symptoms across early adolescence. Resting regional EEG spectral power measures were collected continuously for 4 min (2 min eyes-open, 2 min eyes-closed) in slow (i.e., delta) and fast (i.e., alpha) frequencies at Time 1, and self-reported social anxiety measures were collected concurrently at Time 1 and then prospectively approximately one year later (Time 2) in 103 typically developing 12- to 14-year-olds (46.6% female, Mage = 12.91 years, SDage = 0.81 years). Using a latent class growth curve analysis, stable high and stable low social anxiety classes were derived from the two assessments. Controlling for children's age, sex, and pubertal development, we found that youth in the stable high social anxiety class were more likely to exhibit a relatively lower frontal alpha/delta ratio, reflecting ostensibly less brain maturation relative to youth in the stable low social anxiety class. Results were specific to social anxiety and did not extend to symptoms of generalized anxiety. Findings are discussed in terms of the putative functions of less brain maturation in understanding individual differences in complex human social behavior.