The Link Between Stress and Depression

Both stress and depression have been associated with decreased function of the limbic system and prefrontal cortex as well as systemic vascular inflammation and elevated serum cytokine levels.^5,22,43 Emotional disorders, including depression/depressive state and anxiety/anxiety state, are the most frequently observed symptoms resulting from psychological stress.^25,26 In fact, 50-60% of depressed patients also meet the lifetime criteria for an anxiety disorder and anxiety disorders have been implicated in the underlying etiology of depression in many cases.^44-46 Current hypotheses regarding the interaction of stress and anxiety suggest that the relationship is bidirectional—psychological stress can lead to depression in susceptible individuals and depression may exacerbate anxiety disorders and stress. It has also been suggested that the elevated pro-inflammatory cytokines associated with psychological stress and poor coping mechanisms may worsen or contribute to depressive symptoms in some patients.^47,48 Nonpharmacological interventions, including cognitive behavioral therapy (CBT) and acceptance and commitment therapy (ACT) focus on altering coping mechanisms and mindset to improve depression perception and symptoms in susceptible individuals. Antidepressant medications also have the potential to reduce the effects of these proinflammatory cytokines on the brain and, thus, result in symptom amelioration.⁴⁹ It has also been suggested that additional deleterious habits, such as smoking and alcohol consumption, may be associated with both conditions leading to a worsening of symptoms overall.⁵⁰