Self- or parent report of (co-occurring) internalizing and externalizing problems, and basal or reactivity measures of HPA-axis functioning: a systematic evaluation of the internalizing-hyperresponsivity versus externalizing-hyporesponsivity HPA-axis hypothesis.

BACKGROUND: Previous research findings on the link between adolescents' psychopathology and hypothalamic-pituitary-adrenal (HPA) axis activity have been heterogeneous.
METHOD: Adolescents (n=211) with a preadolescent DSM-IV diagnosis participated in a lab-based social stress task. Saliva cortisol was assessed at awakening and during social stress. It was investigated if continuous measures of internalizing and externalizing problems and their interaction, using both self- and parent report, were associated with basal or reactivity measures of HPA-axis functioning.
RESULTS: During social stress, an enhanced total release of cortisol was associated with self-reported internalizing problems and a blunted total release of cortisol with self-reported externalizing problems. Post hoc analyses revealed that the association between enhanced cortisol output and internalizing problems held for boys but not for girls. Associations with morning cortisol measures were overall weak.
CONCLUSIONS: Only in the context of stress, and particularly when based on self-report, blunted cortisol output was associated with externalizing and enhanced cortisol output with internalizing problems. Our broad approach demonstrates the importance of who reports on psychopathology, the use of dimensional measures of psychopathology, simultaneous analysis of internalizing and externalizing problems, and the use of awakening and social stress related measures of cortisol.