Original articleChild’s stress hormone levels correlate with mother’s socioeconomic status and depressive state
Introduction
It is well known that individuals from more advantaged backgrounds enjoy better physical and mental health than do individuals from disadvantaged environments (for a review, see Adler et al 1994). Differential exposure to stress (allostatic load; McEwen 1998) as a function of socioeconomic status (SES) has been invoked as a possible pathway for the relationship between SES and health (Anderson and Armstead 1995). Indeed, individuals with lower SES report greater exposure to stressful life events and greater impact of these events on their lives than do individuals with higher SES, and this relationship between SES and health begins at the earliest stages of life (Dohrenwend 1973).
Physiologic response to environmental stimuli that are perceived as stressful are mediated by catecholamines and by glucocorticoids. Although short-term glucocorticoid responses to stress serves an adaptive function (McEwen 1998), chronic exposure to elevated glucocorticoid concentrations contributes to the onset of physical pathologies and is associated with depressive symptomatology Anderson and Armstead 1995, Lupien et al 1998, Rubin and Mandell 1966, Sachar et al 1973.
To assess whether differences in stress hormone levels attributable to SES exist in children of various ages, we measured basal morning salivary cortisol levels in children with low, medium, and high SES, ranging from 6 to 10 years of age. The second goal of this study was to assess whether scores of children’s mothers on a measure of stress and depression (the Derogatis Stress Profile; DSP; Derogatis and DellaPietra 1994) would differ with regard to SES and whether these scores would be related to their child’s cortisol levels.
Section snippets
Methods and materials
Two hundred seventeen children (random selection of 6-, 8-, and 10-year-olds) with low, medium, and high SES were tested (Table 1). High SES was defined as families with an income higher than $50,000. In Quebec, Canada, the average family income is between $30,000 and $35,000 (Can $). Children from homes with incomes greater than $100,000 were not tested, given that the majority of these children are placed in private schools, which are not part of the school board from which students were
Results
First, confirmation of SES status was obtained in 139 mothers (see distribution across SES and age in Table 2), with significant differences between the three groups of SES for annual family income (p = .0001), education level of both the mother (p = .001) and father (p = .001), and employment type (p = .0001) of both parents. Significant SES group differences were obtained for the children’s cortisol levels at each age (Figure 1). Preliminary analyses were performed to test the existence of
Discussion
In our study, we report for the first time significant differences in stress hormones as a function of SES in children from an urban area, and we show that these differences gradually develop over time, with the largest SES differences appearing around the age of 10. Another study measured salivary cortisol levels in children from different social environments (Flinn and England 1997), and this study was undertaken in a rural Dominican village. Flinn and England (1997) and Flinn (1999) reported
Acknowledgements
This study was supported by a grant from the John D. and Catherine T. MacArthur Foundation. The work of SJL was supported by a Scientist Award from the Fonds de la recherche en santé du Québec and by a Young Investigator Award from the National Alliance for Research on Schizophrenia and Depression.
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