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 epinephrine, 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