Individual differences in cortisol functioning : longitudinal prediction of the relationship between psychosocial and physiological well being in mothers and children

The purpose of this research was to explore the effects of an adverse psychological environment on physiological well being of mothers and their young children, within an ongoing inter-generational longitudinal project (Concordia Longitudinal Risk Project). The present research examined individual differences in diurnal cortisol functioning as predicted by a variety of historical and current psychosocial variables. Factors related to increased stress (e.g. maternal hostility, smoking, difficult temperament) were expected to predict deviations from the "normal" diurnal cortisol pattern in both mothers and children, whereas variables hypothesized to serve a protective or supportive function were expected to buffer these adverse effects. Salivary cortisol measurements were collected every two hours across one waking day in a sample of 40 mothers and their children, aged 2-6 years. Hierarchical linear modeling (HLM) growth curve analyses were used to estimate the intercept (morning cortisol level), and the slope (steepness of decline in cortisol values) for each mother and child's cortisol pattern across the daytime hours. Findings replicated the well-established diurnal cortisol pattern with high morning cortisol values that decline across the waking day. Consistent with the main hypothesis, a number of stress-related psychosocial factors were predictive of dysregulated cortisol functioning, including hostility, and child extraversion in mothers, and maternal withdrawal and smoking in their children. Other factors such as high SES, maternal stimulation, and high child I.Q. appeared to serve a protective function. This longitudinal study illustrates the potential vulnerability associated with children raised in adverse circumstances and highlights the important relationship between psychosocial variables and physiological well being