Disentangling psychobiological mechanisms underlying internalizing and externalizing behaviors in youth: Longitudinal and concurrent associations with cortisol

► Youth with high levels of internalizing behaviors for a short period of time demonstrate elevated levels of morning cortisol. ► Youth with high levels of internalizing behaviors for a long period of time demonstrate blunted levels of morning cortisol. ► Youth with high levels of externalizing behaviors demonstrate a blunted diurnal cortisol slope regardless of amount of time passed. ► Youth with the most extreme levels of internalizing or externalizing behavior had distinct cortisol profiles marked by more dysregulation throughout the day.