The Role of Basal Cortisol in Predicting Change in Mental Health Problems Across the Transition to Middle School

PurposeThe period in which the transition to middle school occurs is marked by major changes in social context, social rules, and scholastic responsibilities. Some adolescents thrive during this period whereas others are overwhelmed and fail to cope adequately with their changing environment. We investigated basal cortisol upon waking as a predictor of change in mental health problems across the transition to middle school. By taking into account the transition experience, we extend prior findings that high basal cortisol predicts deteriorated mental health after the transition. In individuals with high awakening cortisol, we expected mental health problems to increase after negative transition experiences and to decrease after positive transition experiences, reflecting differential susceptibility. Evidence for the former but not the latter would suggest diathesis–stress.MethodsData from 1,664 subjects were obtained from two measurement waves (mean ages, 11 and 13.5 years) of the TRacking Adolescents' Individual Lives Survey. Using linear regression, we investigated effects of awakening cortisol level, school transition experience, and their hypothesized interaction on change in mental health problems.ResultsWe found that a negative but not a positive experience was predictive of change in mental health. Importantly, our results showed that a negative experience predicts deteriorated mental health only in adolescents with high awakening cortisol but not in adolescents with low awakening cortisol. This finding was robust across informants. The converse, high awakening cortisol predicting decreasing mental health problems after a positive transition was not found.ConclusionsThese results support the diathesis–stress model but not the differential susceptibility hypothesis.