Researchers examined the determinants of hair cortisol concentration, a biomarker for chronic stress, in 11-year-old children using Structural Equation Modeling.
Data from 346 participants in the INMA-Gipuzkoa cohort were analyzed to assess how environmental, social, and individual factors contribute to cortisol levels. The average HCC was 11.13 pg/mg with a standard deviation [SD] of 13.11. In girls, the mean hair cortisol concentration (HCC) was 11.52 pg/mg (SD = 15.33), while in boys, it was 10.64 pg/mg (SD = 9.52).
The study, published in Hormones and Behavior, found that higher levels of behavioral problems were associated with increased HCC, particularly in boys. Environmental noise showed an inverse relationship with cortisol concentrations. Specifically, higher levels of day-evening-night environmental noise (Lden) were linked to lower HCC (b = -0.15; p = 0.007), with a similar effect observed for nighttime noise (Lnight) (b = -0.12; p = 0.038). These associations were significant only in boys, with no observed effects in girls.
The analysis also investigated how maternal stress, neighborhood greenness, and traffic-related air pollution influenced HCC. Maternal stress was positively associated with children's behavioral issues (b = 0.20, p < 0.001), which in turn were linked to elevated HCC in boys. Greater exposure to traffic-related air pollution and reduced access to green spaces were related to elevated environmental noise levels, which influenced cortisol concentrations.
Increased neighborhood greenery was associated with reduced noise levels (b = -0.27, p < 0.001) and decreased traffic-related air pollution (b = -0.55, p < 0.001). The study also found that higher deprivation index (lower neighborhood socioeconomic status) was related to higher neighborhood greenness and higher traffic-related air pollution.
The model explained 5% of the variance in HCC overall and 16% in boys when stratified by sex. The researchers highlight the importance of considering the simultaneous exposure to different environmental, social, and individual factors when studying HCC determinants in children. They declared no competing financial interests related to this study.