Sensitivity to the depressogenic effect of stress and HPA-axis reactivity in adolescence: A review of gender differences

Abstract

Adolescence is characterized by major biological, psychological, and social challenges, as well as by an increase in depression rates. This review focuses on the association between stressful experiences and depression in adolescence, and the possible role of the hypothalamus–pituitary–adrenal cortex (HPA-)axis in this link. Adolescent girls have a higher probability to develop depressive symptoms than adolescent boys and preadolescents. Increasing evidence indicates that girls’ higher risk of depression is partly brought about by an increased sensitivity for stressful life events, particularly interpersonal stressors, which are highly prevalent in adolescent girls. Genetic risk factors for depression, as well as those for stress sensitivity, are often expressed differently in girls and boys. Also environmental adversity tends to affect girls’ stress responses more than those of boys. These gender-specific association patterns have been reported for both sensitivity to stressful life events and HPA-axis responses to social stress. Together, the findings suggest that girls are more malleable than boys in response to internal and external influences. This postulated greater malleability may be adaptive in many circumstances, but also brings along risk, such as an increased probability of depression.

Introduction

The period from preadolescence into adulthood is characterized by major biological, psychological, and social challenges and opportunities (e.g., Dahl and Gunnar, 2009, Greenfield et al., 2003, Nelson et al., 2005, Paus et al., 2008). Interactions between the individual and the environment are intense, and developmental pathways are set in motion or become entrenched. Most adolescents handle these challenges and stressors quite well, but some develop mental health problems. Adolescence is characterized by a substantial rise in mental health problems, which are often associated with significant comorbid problems and impairments (Alloy et al., 2003, Bijl and Ravelli, 2000).

Mental health problems are particularly salient in adolescence; not only because they are the number one burden of disease in young people (World Health Organization, 2003), but also because adolescence is the period that lays the foundation for life as an independent human being. Relational and professional trajectories are shaped and if adolescents miss opportunities because they do not feel or behave well, it is often consequential for the rest of their lives (e.g., Kessler and Forthofer, 1999). In fact, a lot of the problems encountered in adult psychiatric patients are rooted in adolescence (e.g., Ferdinand and Verhulst, 1995, Fergusson et al., 2005, Lewinsohn et al., 2003, Rutter et al., 2006).

To understand pathways leading to mental health problems, we need to know how adolescents respond to stress and how this may affect their emotions and behavior. More specifically, we need to understand individual differences in stress-reactivity. This review focuses on the development of depressive symptoms after stressful experiences in adolescence, and physiological stress systems that may be involved in that process, notably the hypothalamus–pituitary–adrenal cortex (HPA) axis, one of the major stress systems of the body. A salient characteristic of depression is that the increase in prevalence in adolescence is predominant in girls. In spite of considerable progress, there are still a number of puzzles to be resolved regarding the mechanisms underlying the gender difference in prevalence. The research findings presented hereafter may provide additional clues about why depression develops during adolescence and why more often in girls than in boys.

As mentioned, the focus of this review is specifically on – gender differences in – the depressogenic effect of stressful experiences and the possible role of the HPA axis therein. While both of these topics have been described in numerous prior articles, the relative scarcity of information regarding the possible link between short-term HPA-axis responses to stress on the one hand, and long-term depressogenic effects of stressful experiences on the other is remarkable. If such a link does exist, the least we would expect is that these two kinds of responses would have overlapping correlates and risk factors.

This paper starts with a brief outline of (gender differences in) adolescent depression and associated risk factors in Section 2 as an introductory framework. A comprehensive review of these topics is beyond the scope of this article, but has been provided elsewhere by several, excellent, other reviews (e.g., Goodman, 2007, Hankin et al., 2007, Hankin et al., 2009, Kuehner, 2003, Rose and Rudolph, 2006). Section 3 provides a review of literature on stressful life events and adolescent depression, while reasons to suspect the HPA axis to play a possible mediating role in this association are given in Section 4. Research concerning HPA-axis responses to stress is discussed in Section 5. Both the effects of stressful life events and HPA-axis responses are considered in the light of the major risk factors of depression: female gender and familial/genetic vulnerability. General conclusions are drawn in Section 6.