? Depression has consistently been associated with dysregulation of the HPA axis, the major physiological stress response system. The proposed research project will examine the relation between low positive emotionality (PE), a possible temperamental precursor to depression, and HPA functioning in preschoolers after a laboratory stress-inducing task and in their home environment. While several studies have examined the relation between other temperamental factors (e.g., behavioral inhibition) and HPA reactivity, no studies to date have examined the relation between low PE and HPA reactivity. Observations of children's temperament will be conducted in the laboratory, and parental history of psychopathology, parent-child relationship quality, as well as children's depressive symptoms, will be assessed. HPA functioning will be assessed using samples of salivary cortisol, a primary hormonal product of the HPA system. A basal salivary cortisol sample and 3 post-task samples will be collected, in addition to a morning and evening home sample. Mixed effects modeling will be used to predict preschoolers' HPA reactivity from their temperamental style, family history, and parent-child relationship quality. This study will also examine whether parental history of mood disorders and/or parent-child relationship quality moderate the relation between low PE and HPA reactivity. ? ? ?
