STRESS AND PATHOGENESIS OF MAJOR DEPRESSIVE DISORDER. A NARRATIVE REVIEW

Three main conclusions are drawn, namely: 1. the possibility that, under the current diagnostic criteria of MDD, several diseases with different physiopathological but common clinical presentation are hidden; 2. the importance of early detection and prevention of disorder - in the light of data that supports the degenerative and progressive nature of major depression; 3. study of the role of stress in the pathogenesis of depression raises new possibilities in terms of psychosocial interventions, as well as the delimitation of the vulnerable populations to major depressive disorder. Keywords: stress, oxidative stress, major depressive disorder, corticotropin releasing hormone, amygdala, hypotalamo-hypophyseal-adrenal axis, brain-derived neurotrophic factor, glutamate. 1.INTRODUCTION The term "stress" has been used for a long time to define several components of the stress pathway: the stressor (or stimulus), processing systems - including both psychological and physiological manifestations, as well as the final result - the stress response (e.g., increased blood pressure) [1]. In the late 1960s and 1970s, Lazarus and his colleagues developed a theory that emphasizes the importance of individual's evaluation of the stressful events and personal coping mechanisms, a theory that contradicts the one previously suggested by Selye (which emphasized the nonspecific nature of the stress response). [...]an individual in contact with a certain stressor makes a cognitive assessment of the situation, in order to determine if there is a threat and if he/ she has the resources or abilities to meet the requirements of that context. The stress response Stress responses can be (but are not limited to): (a) behavioral responses - which can be beneficial (for example, exercise) or detrimental (smoking, alcohol consumption) for an individual; (b) affective responses - the degree of emotional distress that a person experiments when confronting a stressor; (c) physiological responses - the hypothalamic-pituitary (HPA) and sympatho-adrenal medullary systems are activated in response to stress [7].