A new study published in Neuroendocrinology revealed a possible relationship between socioeconomic status in childhood and cortisol levels in adolescence. The research team attempted to uncover the relationship between genetics and the environment, as both affect cortisol levels.
Their research revealed that cortisol levels, as measured in hair samples of 19-year-olds, were only 39% genetic. The remaining 61% was due to environmental factors. The term “heritability” refers to the degree to which differences between groups of people can be attributed to genetic factors. These findings suggest that socioeconomic status has long-term consequences on the functioning of the stress response system and its release of cortisol.
Previous research has found that children who live in or near poverty have more health problems and experience more stress in the long term. There is evidence that these two factors are linked. The hypothalamic-pituitary-adrenal (HPA) axis is the system that releases cortisol when stressful or dangerous situations occur.
Christian Kantave and colleagues state that “children from low socioeconomic (SES) backgrounds are disproportionately exposed to chronic stressors in their daily lives, which may erode physiological stress systems and increase subsequent risks for psychiatric illness.” Previous research has not been able to quantify how much cortisol activity is genetic and how much it is the result of environmental stimuli; For Kantav and his colleagues, this has become the focus of their study.
The participants were 442 pairs of twins who were part of the Quebec Neonatal Study. The twins joined the group in the late 1990s, and included 121 monozygotic (identical) and 261 dizygotic (fraternal) twins. Thirty percent of these twins have families that make less than C$30,000 a year.
For example, in the year 2000, a family of four with an income of less than C$35,000 was considered to be in poverty. Socioeconomic data were collected at different times from these families over a period of 19 years. When the twins were 19 years old, hair samples were collected and analyzed for cortisol levels.
Statistical analysis of differences in cortisol levels in monozygotic and monozygotic twin groups showed that cortisol levels in late adolescence reflect environmental rather than genetic factors. In this case, 61% of the variance in cortisol levels was due to individual negative experiences.
The research found evidence of childhood socioeconomic status in cortisol levels at 19, leaving the research team to conclude, “The fact that early childhood is still associated with elevated cortisol after 14 years, even if indirectly, underscores the importance of implementing psychosocial interventions aimed at resetting Titration of HPA axis activity to youth after early adversity or to prevent the effects of later adversity on cortisol elevation”.
Some of the recognized limitations include the lack of sex-specific data, and that potential differences may be relevant to therapeutic interventions. Nor were they able to draw any conclusions about the evolutionary timing of adverse environmental influences and the consequences on the HPA axis and cortisol levels. This information will be useful for determining what types of interventions will be beneficial at which stage of development.
the study, “Relationship between the timing of family socioeconomic deprivation and adolescent hair cortisol among adolescent twins: a study of the genetic and environmental processes involved.Written by Christina Cantave, Mara Brindgen, Sonia Lupien, Jeannette Dionne, Franck Vitaro, Michel Boivin, and Isabelle Olé Morin.