The Physiology of Anxiety and Chronic Stress

In most individuals, stress is a response to an external cause and subsides once the situation has resolved.5,32-34 When an individual is under acute stress, activation of the sympathetic nervous system, the body’s fight-or-flight response, results in release of adrenaline (epinephrine), noradrenaline (norepinephrine), and adrenocorticotropic hormone (ACTH).32 In a short-term situation, a work deadline or on-stage performance, these transmitters allow our bodies to react quickly and perform well under pressure.32 However, when stress is ongoing and results in chronic exposure to these hormones and neurotransmitters, it can have a deleterious effect on well-being.34-36 Elevated cortisol levels lead to increased systemic inflammation and decreased immune function over time. Multiple stress mediators, including monoamines, neuropeptides (neuropeptide Y, calcitonin gene-related peptide, adrenomedullin), and steroid hormones transfer the stress signal to the central nervous system (CNS) through the limbic-hypothalamic-pituitary-adrenal axis.5,34-36 Patients with anxiety disorders have a persistent or disproportional stress reaction to stimuli that is generally not considered threatening.37,38 Anxiety is characterized by a “persistent feeling of apprehension or dread” and severe forms of anxiety disorders include generalized anxiety, panic disorder, phobias, social anxiety, obsessive-compulsive disorder, and post-traumatic stress disorder (PTSD).32,33,37,38 In these cases, individuals experience chronic stress in normal situations and this produces the deleterious effects on their physiology seen in individuals exposed to long-term stressors, such as civilians in a war zone.37,38