A study of cortisol reactivity and recovery among young adolescents: Heterogeneity and longitudinal stability and change.

The dominance of reactivity-based theories of the cortisol response and lack of attention to cortisol recovery makes it difficult to compile an integrated theory of the stress response. This report examined a reactivity and recovery model of the cortisol response using variable-centered and person-centered approaches. Age and sex differences and heterogeneity in the pattern of cortisol response were examined. Participants were 135 healthy young adolescents participating in a three-wave longitudinal study of puberty and psychological development. At each wave, five saliva-cortisol samples were collected prior to and following a modified Trier Social Stressor Test for Children. Linear, quadratic, and piece-wise models of latent growth curve analyses and latent class analyses were conducted. Age differences in cortisol reactivity and recovery were found at wave 1 and sex differences in cortisol reactivity emerged at wave 3. Meaningful heterogeneity in the pattern of cortisol response was found cross-sectionally and longitudinally. The implications of heterogeneity in the cortisol response during early adolescence for developmental science are discussed.