Age and sex, but not depression or anxiety, predict P3 amplitude during adolescence

Reduced P3 amplitude during selective attention has been linked to depression in cross-sectional studies primarily with adults. Neurodevelopmental research has yet to examine relations between age-related changes in P3 amplitude, assessed across multiple time points, and the emergence of depressive and anxiety symptoms during adolescence, which may vary by sex. The present study addresses this gap by testing the effects of between- and within-person depressive symptoms, age, and sex on P3 amplitude during the Flanker task, across up to three age time points in a sample of adolescents (N = 190, ages ∼12, 15 and 18) at risk for developing internalizing symptoms. When depression was measured continuously without adjusting for age and sex, higher within-person depressive symptoms emerged as a significant predictor of reduced P3 amplitude. However, when age, sex, and depression (continuous or binary diagnostic status) were modeled together, only age and sex, but not depression, remained significant predictors of P3 amplitude. Specifically, P3 amplitude decreased with age, and males consistently exhibited higher P3 amplitudes than females, with stable age-related decrease across sexes. For anxiety, neither between- nor within-person symptoms were significantly associated with P3 amplitude, with or without age and sex included in the model. Similar to the findings for depression, however, age and sex were significant predictors of P3 amplitude. Thus, previous studies involving a single assessment of P3 amplitude and depression symptoms may be influenced by developmental factors.