With the dramatic rise in psychological disorders diagnosed among children and adolescents, it is critical to study the possible environmental contributors and biological mechanisms that play a role in the development of pervasive disorders like depression and anxiety. Once these factors are better understood, steps can be made to counter their effects and progress will be quantitatively measurable.
One known contributor to adult pathology is chronic stress during adolescence (Romeo and McEwen, 2006). While the effects of chronic stress on behavior are more easily observable, researchers have begun studying the chemical effects stress has on the structures of the brain, particularly the hypothalamic-pituitary-adrenal (HPA) axis.
Romeo and McEwen (2006) describe the effect of chronic stress on the adolescent brain in rodents. Fisher et al. (2006) expand on this by explaining the chemical process many adults have to combat the effects of stress hormones in the brain, which returns them to a state of calm and how this calming effect is altered in foster children exposed to chronic stress at key points in their development. Both studies identify periods of development marked by specific susceptibility to stress, which may have long lasting implications on the individual.
Although development is a continual process, the most dramatic change occurs early-on during childhood and adolescence. Romeo and McEwen (2006) assert that adult animals, when exposed to chronic stress, show a less severe reaction over time as that stressor becomes a part of daily life; but, the effects of chronic stress on the younger populations is very different.
Without the full development of the hormonal mechanisms that mediate stress response; “…prepubertal animals have a much more prolonged ACTH [adrenocorticotropic hormone] and coricosterone stress response compared to adults” (Rome and McEwen, 2006, p. 203). This effect is not universal, however. Prebubertal males experience shorter responses, but with higher peaks (Romeo and McEwen, 2006).
While the effect of stress on the developing adolescent brain is pronounce, its effect on the very young is even greater. According to Fisher et al. (2006), stressors such as “…maternal separation during the first 1 to 2 weeks of life often appears to have the greatest impact on the development of HPA axis.” (p.217). It is this early and profound form of stress, parental separation, which affects the large segment of children in society who populate the foster-care demographic. It is for this reason that Fisher et al. explore the effects of the hormonal mechanisms explained by Romeo and McEwen (2006) on the very young during periods of extreme emotional stress.
According to Fisher et al. (2006), “Numerous studies comparing foster children to nonmaltreated children have found elevated rates of psychopathology, developmental delays, substance abuse, and mortality among individuals placed in foster care.” (p. 216).
Early separation impedes development of the natural hormonal response to stress, which results in stunted modulation later in life. The effect of separation during childhood is explained by the mediating role a caregiver plays between the child and stressors. An effective caregiver supplements a child’s developing stress response, minimizing the stress effect. This mediator is absent in the lives of many children due to maltreatment or the inability of a caregiver to provide adequate service to the child. Many foster children find themselves affected by one or both of these conditions and are therefore easily susceptible to the long-term effects that chronic stress has on their emotional development.
Both Romeo and McEwen and Fisher et al. are interested in identifying what Fisher et al. refers to as stress hyporesponsive periods (p.218). This developmental period is “marked by an absence of HPA axis activation in response to external stress,” which leaves the child vulnerable to stressors. While this period is only the first two weeks of a rodent’s life, it spans the many years that comprise a human’s childhood. If an individual is exposed to chronic stress during this period, particularly that caused by insecure emotional relationships, the effects can be felt by that individual for the rest of their life. It is for this reason that more research must be done to eventually help minimize the effects of these stressors and promote healthy emotional development among young people.
Fisher, P. A., Gunnar, M.R., Dozier, M., Bruce, J., Pears, K.C. (2006) Effect of Therapeutic Interventions for Foster Children on Behavioral Problems, Caregiver Attachment and stress Regulatory Neural Systems. Annals New York Academy of Sciences, 1094, 215-225.
Romeo, R.D., McEwen, B.S., Stress and the Adolescent Brain. Annals New York Academy of Sciences, 1094, 202-214.