ABSTRACT
Depression is a highly prevalent form of mental illness, with a lifetime occurrence of 8-12% in all individuals (Andrade et al. 2003). This condition is often considered a stress-related disorder because some form of stressful life event frequently triggers depressive symptoms. Depression also has a high incidence of comorbidity with anxiety disorders (Lenze et al. 2000, 2001, 2005), which occur in approximately 30% of all adults (Kessler et al. 2005). Both of these conditions place a considerable economic burden on society (Andrade et al. 2003; DuPont et al. 1996). The body’s normal stress response is thought to be essential to survival because it allows for adaptation to environmental demands. Chronic exposure to stress, however, has been hypothesized to lead to long-term alterations of the physiological systems mediating the body’s responses to these demands.
