Associations between EEG trajectories, family income, and cognitive abilities over the first two years of life.

We sought to characterize developmental trajectories of EEG spectral power over the first 2 years after birth and examine whether family income or maternal education alter those trajectories. We analyzed EEGs (n=161 infants, 534 EEGs) collected longitudinally between 2 and 24 months of age, and calculated frontal absolute power across 7 canonical frequency bands. For each frequency band, a piecewise growth curve model was fit, resulting in an estimated intercept and two slope parameters from 2–9 months and 9–24 months of age. Across 6/7 frequency bands, absolute power significantly increased over age, with steeper slopes in the 2–¬9 month period compared to 9–24 months. Increased family income, but not maternal education, was associated with higher intercept (2–3 month power) across delta–gamma bands (p range = 0.002 to 0.04), and reduced change in power between 2–9 months of age in lower frequency bands (delta-alpha, p range = 0.01-0.02). There was no significant effect of income on slope between 9–24 months. EEG intercept and slope measures did not mediate relationships between income and 24-month verbal and nonverbal development. These results add to growing literature concerning the role of socioeconomic factors in shaping brain trajectories.