Relationship of cortisol and alpha amylase to behavioral engagement under three levels of negative evaluative psychosocial stress.

Despite that behavioral engagement is integral to mental health, surprisingly little is known about the relationship of psychosocial stress and behavioral engagement. The current study developed an observer-rated measure of behavioral engagement for lab-based stress inductions, then examined its relationship with stress-responsive biomarkers and affect. Young adults (N = 109, Mage=19.4, SDage=1.59, 57% female) completed one of three Trier Social Stress Test (TSST) conditions-non-stressful Control, Intermediate, or an Explicit Negative Evaluative-and at four timepoints provided self-reports of positive and negative affect and saliva samples for cortisol and salivary alpha-amylase (sAA). Trained study staff (experimenters and TSST judges) completed a programmed questionnaire measure of the novel behavioral engagement measure after the participants completed the TSST. Psychometric review and EFA of the behavioral engagement items resulted in a final 8-item measure with good interrater reliability and well-fitting 2-factor structure, capturing Persistence (4 items; loadings=.41-.89), and Quality of Speech (4 items; loadings=.53-.92). Results indicated that the relationship of positive affect growth and biomarker level to behavioral engagement varied substantially as a function of context: As negative evaluation level strengthened, behavioral engagement became more tightly associated with relative preservation of positive affect. For both cortisol and sAA, the relationship between biomarker levels (but not reactivity) and behavioral engagement varied significantly by condition, such that under milder conditions and elevated levels of biomarkers, engagement was greater, but under Explicit Negative Evaluation, and elevated levels of biomarkers, engagement was less, suggesting behavioral withdrawal. Findings reveal the critical role of context-especially negative evaluation-in the relationship of biomarkers with behavioral engagement.