Published online by Cambridge University Press: 05 June 2012
INTRODUCTION
Stress and Depression
Depressive disorders are widely regarded as stress-related conditions. Although genetic vulnerability is critical to the development of depression, in the absence of environmental stressors, the incidence of depressive disorders is very low (Kendler et al., 1995), and in approximately 75% of cases of depression there is a precipitating life event (Brown & Harris, 1978; Frank, Anderson, Reynolds, Ritenour, & Kupfer, 1994). Living organisms survive by maintaining a complex dynamic equilibrium or homeostasis that is constantly challenged by intrinsic or extrinsic stressors. These stressors set in motion responses aimed at preserving homeostasis, including activation of a wide variety of neurotransmitters and neuromodulators. The hypothalamic pituitary adrenal (HPA) axis is the body's main stress hormonal system. Corticotropin releasing hormone (CRH) is the principal central effector of the stress response (Chrousos & Gold, 1992). CRH triggers the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary corticotrope, which, in turn, triggers the release of adrenal glucocorticoids. The stress response is terminated by glucocorticoid feedback at brain and pituitary sites.
Depression has been conceptualized as maladaptive, exaggerated responses to stress. Abnormalities of the HPA axis, as manifested by hypercortisolemia and disruption of the circadian rhythm of cortisol secretion, are well established phenomena in depression (Carroll, Curtis, & Mendels, 1976; Sachar et al., 1973).
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.