Longitudinal trajectories of aperiodic EEG activity in early to middle childhood

Background Emerging evidence suggests that aperiodic EEG activity may follow a nonlinear growth trajectory in childhood. However, existing studies are limited by small assessment windows and cross-sectional samples that are unable to fully capture these patterns. The current study aimed to characterize the developmental trajectories of aperiodic activity longitudinally from infancy to middle childhood. We examined potential trajectory differences by sex and brain region. We further investigated whether aperiodic activity is associated with maternal anxiety symptoms, and whether these associations vary because of differential development trajectories. Methods A community sample of children and their parents ( N =391) enrolled in a longitudinal study of emotion processing were assessed at infancy, and at ages 3 years, 5 years, and 7 years. Analyses included individual growth curve and mixed effect models. Developmental trajectories of the aperiodic slope and offset were investigated across whole brain, frontal, central, temporal, and posterior regions. Associations of whole brain slope and offset with maternal anxiety symptoms were also examined. Results Developmental trajectories for both slope and offset were generally characterized by a relative increase in early childhood and a subsequent decrease or stabilization by age 7, with variation by brain region. Females showed relatively steeper slopes at some ages, and males showed relatively greater offset at certain ages. Maternal anxiety was negatively associated with slope at 3 years and positively associated with slope at 7 years. Conclusions The longitudinal developmental trajectory of aperiodic slope in early childhood is nonlinear and shows variation by sex and brain region. The magnitude and direction of associations with maternal anxiety varied by age, corresponding with changes in trajectories. Developmental stage should be considered when interpreting findings related to aperiodic activity in childhood.