Abstract
Prior research has linked either basal cortisol levels or stress-induced cortisol responses to adiposity; however, it remains to be determined whether these distinct cortisol measures exert joint or independent effects. Further, it is unclear how they interact with individual and environmental characteristics to predict adiposity. The present study aims to address whether morning cortisol levels and cortisol responses to a psychosocial stressor independently and/or interactively influence body mass index (BMI) in 218 adolescents (117 female) participating in a longitudinal community study, and whether associations are moderated by sex and exposure to early maternal depression. Reports of maternal depressive symptoms were obtained in infancy and preschool. Salivary cortisol measures included a longitudinal morning cortisol measure comprising sampling points across ages 11, 13, 15, and 18 and measures of stress-induced cortisol responses assessed via the Trier Social Stress Test (TSST) at age 18. Lower morning cortisol and higher TSST cortisol reactivity independently predicted higher age 18 BMI. Morning cortisol also interacted with sex and exposure to early maternal depression to predict BMI. Specifically, girls exposed to lower levels of early maternal depression displayed a strong negative morning cortisol-BMI association, and girls exposed to higher levels of maternal depression demonstrated a weaker negative association. Among boys, those exposed to lower levels of maternal depression displayed no association, while those exposed to higher levels of maternal depression displayed a negative morning cortisol-BMI association. Results point to the independent, additive effects of morning and reactive cortisol in the prediction of BMI and suggest that exposure to early maternal depression may exert sexually dimorphic effects on normative cortisol-BMI associations.