Stress reactivity moderates the association between early experiences of unpredictability and emotional problems in adolescents.

Researchers have documented that exposure to different kinds of psychosocial stressors can lead to emotional difficulties and, further, that heightened reactivity to stress can moderate these associations. Recently, investigators have distinguished among threat, deprivation, and unpredictability as different dimensions of early life stress (ELS). It is not clear, however, whether reactivity in specific stress response systems functions as a diathesis to lead to emotional difficulties following exposure to these dimensions of ELS. In this study (N = 154) we examined whether stress reactivity, assessed across different psychobiological systems during the Trier Social Stress Test, is a unitary or multidimensional construct, and if reactivity differentially moderates the associations between ELS dimensions and adolescents' susceptibility to emotional and behavioral problems two years later. A factor analysis conducted on stress reactivity measures yielded two factors: one composed of reactivity in heart rate, heart rate variability, and cortisol, and one composed of reactivity in skin conductance and self-reported mood. These two factors independently moderated the associations between early unpredictability and subsequent emotional problems. For each factor, the combination of higher unpredictability and higher stress reactivity predicted higher emotional problems; stress reactivity factors were not significant moderators of the effects of threat and deprivation. Our findings suggest that increased stress reactivity, assessed across several domains of functioning, functions as a diathesis that interacts with ELS characterized by unpredictability to predict subsequent mental health difficulties in adolescents and, further, that low stress reactivity buffers against mental health difficulties in adolescents who have experienced unpredictability early in life.