Depression: The predisposing influence of stress

Abstract

Aversive experiences have been thought to provoke or exacerbate clinical depression. The present review provides a brief survey of the stress-depression literature and suggests that the effects of stressful experiences on affective state may be related to depletion of several neurotransmitters, including norepinephrine, dopamine, and serotonin. A major element in determining the neurochemical changes is the organism's ability to cope with the aversive stimuli through behavioral means. Aversive experiences give rise to behavioral attempts to cope with the stressor, coupled with increased utilization and synthesis of brain amines to contend with environmental demands. When behavioral coping is possible, neurochemical systems are not overly taxed, and behavioral pathology will not ensue. However, when there can be no behavioral control over the stressful stimuli, or when the aversive experience is perceived as uncontrollable, increased emphasis is placed on coping through endogenous neurochemical mechanisms. Amine utilization increases appreciably and may exceed synthesis, resulting in a net reduction of amine stores, which in turn promotes or exacerbates affective disorder. The processes governing the depletions may be subject to sensitization or conditioning, such that exposure to traumatic experiences may have long-term repercussions when the organism subsequently encounters related stressful stimuli. With continued uncontrollable stimulation, adaptation occurs in the form of increased activity of synthetic enzymes, and levels of amines approach basal values. It is suggested that either the initial amine depletion provoked by aversive experiences or a dysfunction of the adaptive processes, resulting in persistent amine depletion, contributes to behavioral depression. Aside from the contribution of behavioral coping, several organismic, experiential, and environmental variables will influence the effects of aversive experiences on neurochemical activity, and may thus influence vulnerability to depression.

Adult Neurogenesis and Mental Illness

“…Stressful experiences have long been linked as potential contributors to the development of psychiatric disorders (Anisman and Zacharko, 1982;Kessler et al, 1985). Prolonged stress in humans can lead to an overloading of the stress response system, leaving people at risk for the development of illness, both physical and psychiatric (McEwen, 2004).…”

Physiological and behavioral effects of chronic intracerebroventricular infusion of corticotropin-releasing factor in the rat

“…Considering both the crucial role of CRF in the stress response as well as the alterations in central CRF systems in depression, it is important to realize that stressful life events are considered to play an important role in the etiology of human depressive disorders (Anisman and Zacharko, 1982). This causal relationship between stress and depresssion has led to the development of animal models for psychological disorders.…”

Effects of Acute and Chronic Reboxetine Treatment on Stress-induced Monoamine Efflux in the Rat Frontal Cortex

“…This brain region receives a strong modulatory input from monoaminergic neurotransmitters and many affective disorders are thought to reflect disruption of the regulation of these processes (Arnsten 1997;Le Moal and Simon 1991). In addition, interactions between the monoamine systems through heteroreceptors can be influenced by antidepressants as well as stressors.Stress has been shown to activate the monoamine systems and is often associated with the precipitation of depressive symptomatology (Anisman and Zacharko 1982;McEwen 2000). The locus coeruleus (LC) noradrenergic system is a vital component of an individual's response to stressors or challenges and provides the majority of the noradrenergic innervation of the frontal cortex.…”

“…Stress has been shown to activate the monoamine systems and is often associated with the precipitation of depressive symptomatology (Anisman and Zacharko 1982;McEwen 2000). The locus coeruleus (LC) noradrenergic system is a vital component of an individual's response to stressors or challenges and provides the majority of the noradrenergic innervation of the frontal cortex.…”