Longitudinal age- and sex-related change in background aperiodic activity during early adolescence

Aperiodic activity contains important and meaningful physiological information that has been shown to dynamically change with age. However, no longitudinal studies have examined its development during early-to-mid adolescence. The current study closes this gap by investigating age- and sex-related longitudinal change in aperiodic activity across early-to-mid adolescence (N = 186; 54.3% female). Participants completed a resting state task and a Flanker task while EEG was record at age 13 years and again at age 15 years. Across different tasks and two time points, we observed significant age-related reductions in aperiodic offset and exponent. In addition, we observed significant sex-related differences in the aperiodic offset and exponent over time. We did not find any significant correlation between aperiodic activity and behavioral measures, nor did we find any significant condition-dependent change in aperiodic activity during the Flanker task. However, we did observe significant correlations between aperiodic activity across tasks and over time, suggesting that aperiodic activity may demonstrate stable trait-like characteristics. Collectively, these results may suggest a developmental parallelism between decreases in aperiodic components alongside adolescent brain development during this period; changes to cortical and subcortical brain structure and organization during early adolescence may have been responsible for the observed sex-related effects.