Chronic stress is the response to emotional pressure suffered for a prolonged period over which an individual perceives he or she has no control. It involves an endocrine system response in which occurs a release of corticosteroids. While the immediate effects of stress hormones are beneficial in a particular situation, long-term exposure to stress creates a high level of these hormones that remains constant. This may lead to high blood pressure (and subsequently heart disease), damage to muscle tissue, inhibition of growth, suppression of the immune system, and damage to mental health.
Animals exposed to distressing events over which they have no control respond by releasing corticosteroids. The sympathetic branch of the nervous system is activated, also releasing epinephrine and norepinephrine. These, if prolonged, lead to structural changes in the brain. Changes happen to neurons and their synapses in the hippocampus and medial prefrontal cortex. These produce impairments in working memory and spatial memory, as well as increased aggression.
Linked to impairment of the medial prefrontal cortex are deficits in the part of the striatum with which it is linked. This can bias decision-making strategies, as affected individuals shift from flexible behavior to one dominated by habit. Changes also occur to dopaminergic activity in the prefrontal cortex.
Stress has a role in humans as a method of reacting to difficult and possibly dangerous situations. The "fight or flight" response when one perceives a threat helps the body exert energy to fight or run away to live another day. This response is noticeable when the adrenal glands release epinephrine, causing the blood vessels to constrict and heart rate to increase. In addition, cortisol is another hormone that is released under stress and its purpose is to raise the glucose level in the blood. Glucose is the main energy source for human cells and its increase during time of stress is for the purpose of having energy readily available for over active cells.
The release of these hormones is evolved to be temporary. If someone is under stress for long periods of time they may have adverse health effects later on, such as hypertension and increased risk of cardiovascular disease.
Different factors may prolong this "fight or flight" reaction in the body. Chronic stress can be rooted in prolonged psychological stressors. For example, some studies have looked at the health effects of social discrimination in African Americans. This demographic has markedly higher hypertension levels that are attributed to higher levels of perceived social discrimination. This phenomenon has been coined John Henryism by sociologist James Sherman.
In humans, different types of stressors, the timing (duration) of the stressors, and personal characteristics all influence the response of the hypothalamic-pituitary adrenal axis, which is implicated in many theories which related chronic stress with health morbidities. Symptoms of chronic stress can vary from anxiety, depression, social isolation, headache, abdominal pain or lack of sleep to back pain and difficulty concentrating. Other symptoms include:
- upset stomach
- intense mood swings
- hair loss
- loss of concentration / poor concentration
- heightened confusion in mildly stressful situations
- inability to complete tasks
- varicose veins
- suicidal thoughts
- panic attacks or a panic disorder
- cardiovascular diseases
There are a variety of methods to control chronic stress, including exercise, healthy diet, stress management, relaxation techniques, adequate rest, and relaxing hobbies. It has been suggested that magnesium supplements can help.
- Carlson, Neil (2013). Physiology of Behavior. Pearson. pp. 602–606. ISBN 9780205239399.
- Sapolsky RM. (1998). Why Zebras Don't Get Ulcers: An Updated Guide To Stress, Stress Related Diseases, and Coping. 2nd Rev Ed, W. H. Freeman ISBN 978-0-7167-3210-5
- McEwen BS (2007). "Physiology and neurobiology of stress and adaptation: central role of the brain". Physiol Rev 87 (3): 873–904. doi:10.1152/physrev.00041.2006. PMID 17615391.
- Sousa N, Lukoyanov NV, Madeira MD, Almeida OF, Paula-Barbosa MM (2000). "Reorganization of the morphology of hippocampal neurites and synapses after stress-induced damage correlates with behavioral improvement". Neuroscience 97 (2): 253–266. doi:10.1016/S0306-4522(00)00050-6. PMID 0799757.
- Radley JJ, Sisti HM, Hao J, Rocher AB, McCall T, Hof PR, McEwen BS, Morrison JH (2004). "Chronic behavioral stress induces apical dendritic reorganization in pyramidal neurons of the medial prefrontal cortex". Neuroscience 125 (1): 1–6. doi:10.1016/j.neuroscience.2004.01.006. PMID 15051139.
- Mizoguchi K, Yuzurihara M, Ishige A, Sasaki H, Chui DH, Tabira T (2000). "Chronic stress induces impairment of spatial working memory because of prefrontal dopaminergic dysfunction". J Neurosci 20 (4): 1568–74. PMID 10662846.
- Mineur YS, Prasol DJ, Belzung C, Crusio WE (September 2003). "Agonistic behavior and unpredictable chronic mild stress in mice". Behavior Genetics 33 (5): 513–519. doi:10.1023/A:1025770616068. PMID 14574128. Retrieved 2009-08-16.
- Dias-Ferreira E, Sousa JC, Melo I, Morgado P, Mesquita AR, Cerqueira JJ, Costa RM, Sousa N (2009). "Chronic Stress Causes Frontostriatal Reorganization and Affects Decision-Making". Science 325 (5940): 621–625. doi:10.1126/science.1171203. PMID 19644122.
- Tsigos C., Chrousos G.P. (2002). "Hypothalamic-pituitary-adrenal axis, neuroendocrine factors, and stress". Journal of Psychosomatic Research 53: 865–871.
- Blascovich J., Spencer S. J., Quinn D. M., Steele C. M. (2001). "African Americans and high blood pressure: The role of stereotype threat". Psychological Science 13 (3): 225–229.
- James S. A., Hartnett S. A., Kalsbeek W. D (1983). "John Henryism and blood pressure differences among black men". Journal of Behavioral Medicine 6 (3): 259–278.
- Miller, Gregory E.; Chen, Edith; Zhou, Eric S. (January 2007). "If it goes up, must it come down? Chronic stress and the hypothalamic-pituitary-adrenocortical axis in humans". Psychological Bulletin 133 (1): 25–45. doi:10.1037/0033-2909.133.1.25. PMID 17201569.
- Cohen S, Janicki-Deverts D, Miller GE (2007). "Psychological stress and disease". JAMA 298 (14): 1685–1687. doi:10.1001/jama.298.14.1685. PMID 17925521. "Stress Contributes To Range Of Chronic Diseases, Review Shows" ScienceDaily.com (Oct. 10, 2007) 
- Metcalfe, C, Davey Smith G et al. (March 2003). "Self-reported stress and subsequent hospital admissions as a result of hypertension, varicose veins and haemorrhoids". Journal of Public Health Medicine 25 (1): 62–68. doi:10.1093/pubmed/fdg013. PMID 12669921.
- Cernak I, Savic V, Kotur J et al. (March 2000). "Alterations in magnesium and oxidative status during chronic emotional stress". Magnesium research : official organ of the International Society for the Development of Research on Magnesium 13 (1): 29–36. PMID 10761188.