The Teenage Brain: The Stress Response and the Adolescent Brain

Abstract

Adolescence is a time of many psychosocial and physiological changes. One such change is how an individual responds to stressors. Specifically, adolescence is marked by significant shifts in hypothalamic-pituitary-adrenal (HPA) axis reactivity, resulting in heightened stress-induced hormonal responses. It is presently unclear what mediates these changes in stress reactivity and what impacts they may have on an adolescent individual. However, stress-sensitive limbic and cortical brain areas that continue to mature during adolescence may be particularly vulnerable to these shifts in responsiveness. Consequently, perturbations of the maturing adolescent brain may contribute to the increase in stress-related psychological dysfunctions, such as anxiety, depression, and drug abuse, often observed during this stage of development. The purpose of this review is to describe the changes that occur in HPA function during adolescence, as well as briefly discuss the possible ramifications of these changes on the developing brain and psychological health.

Keywords: Adolescence; Hypothalamic-Pituitary-Adrenal Axis; Puberty; Stress.

Figure 1

A simplified schematic of stress-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis as well as the negative feedback that allows the HPA axis to recover back to baseline following termination of a stressor. Abbreviation: adrenal gland (AD), adrenocorticotropin hormone (ACTH), anterior pituitary (AP), corticosterone (CORT), corticotropin-releasing hormone (CRH), negative feedback (−), positive drive (+).

Figure 2

Mean (± SEM) plasma adrenocorticotropin hormone (ACTH) and corticosterone levels in pre-adolescent (28 days of age) and adult (77days of age) male rats before, during, and after a 30 min session of restraint stress (black bar under x-axis). Asterisks indicate a significant difference between the ages at that time point. Adapted from (Romeo, Lee, Chhua, et al., 2004).

Figure 3

Mean (± SEM) plasma adrenocorticotropin hormone (ACTH) and corticosterone levels throughout pubertal and adolescent development in 30-, 40-, 50-, 60-, and 70-day old male rats before, during, and after a 30 min session of restraint stress (black bar under x-axis). In the upper panel, asterisks indicate significant differences from the 60- and 70-day old rats at that time point. In the lower panel, “#” indicates that 30-day old rats were significantly different from all other ages at that time point. Adapted from (Foilb et al., 2011).

Figure 4

Mean (± SEM) plasma corticosterone levels in pre-adolescent (30 days of age) and adult (77days of age) male rats before, during, and after a 30 min session of restraint stress (black bar under x-axis) following acute, homotypic, or heterotypic stress paradigms. Acute stress consisted of a single 30 min session of restraint stress, homotypic stress a daily 30 min session of restraint stress for 8 consecutive days, and heterotypic stress a daily 30 min session of cold room exposure (at 4°C) for 7 consecutive days followed by 30 min of restraint on the 8^th day. Asterisks indicate a significant difference between the ages at that time point. Adapted from (Lui et al., in press).