Can poverty get under your skin? Basal cortisol levels and cognitive function in children from low and high socioeconomic status

It is well known that individuals from more advantaged social classes enjoy better mental and physical health than do individuals within lower classes . Various mechanisms have been evoked to explain the association between so cioeconomic status (SES) and health. One mechanism that has received partic ular attention in recent years is stress. It has been shown that individual s lower in SES report greater exposure to stressful life events and a great er impact of these events on their life than individuals higher in SES. In order to measure whether the development of the relationship between SES an d mental health is sustained by exposure to high levels of glucocorticoids, we measured morning salivary cortisol levels as well as cognitive function (memory, attention, and language) in 307 children (from 6 to 16 years of a ge) from low versus high SES in the Montreal area in Canada. The results re vealed that low SES children from 6 to 10 years old present significantly h igher salivary cortisol levels when compared to children from high SES. Thi s difference disappears at the time of school transition, and no SES differ ences are observed in salivary cortisol levels during high school. However, children from low and high SES do not differ with regard to memory or to a ttentional and linguistic functions. Also, mothers of low SES children repo rted higher feelings of depression and more unhealthy behaviors, while moth ers of high SES children reported higher stress related to work or family t ransitions. Altogether, these results show that low SES in young children i s related to increased cortisol secretion. although the impact of SES on co rtisol secretion is absent after transition to high school. These data are interpreted within the context of the equalization process of class pattern ing. Four social explanatory factors are suggested to explain the disappear ance of SES differences in basal cortisol levels after school transition, t aking into account the influence of family environment on the child's secre tion of stress hormones.