Physiological effects of stress - Adrenaline and Cortisol

Depression, Heart, General, Mental Health | May 17, 2016 | Author: The Super Pharmacist

mental health, depression

Physiological effects of stress - Adrenaline and Cortisol

What are the physical changes that occur from a pathophysiogical perspective that occur as a result of chronic stressful situations? What are the differences between acute stress and chronic stress on the sympathetic nervous system? What are the physical consequences of elevated cortisol levels for prolonged periods on the body?                                                                                                                                                                                         Stress is defined as a state of mental or emotional strain or tension resulting from adverse or demanding circumstances. There are three different types of stress;

Acute stress is the most common type and comes from the demands and pressures of both the recent past and the anticipated future. Acute stress can be experienced in everyday life – rushing to meet deadlines, a close call in peak hour traffic, children experiencing difficulties at school, and attending a job interview are all practical examples of acute stress. It is highly treatable and manageable, although acute stress can often result in a number of symptoms including emotional distress (such as anger, irritability and depression), muscular problems such as tension headaches and back pain, and periods of over-arousal that can result in elevated blood pressure, migraine headaches, and sweaty palms.
Episodic acute stress affects individuals who suffer acute stress frequently. It typically manifests in individuals who worry constantly, or who regularly take on too many responsibilities without understanding the impact it has on their wellbeing. Individuals who have episodic acute stress regularly present as being short-tempered, tense, irritable and anxious.
Chronic stress is, as the name suggests, a condition that affects people on a constant basis. It is often present for many years and can be exacerbated by factors such as being trapped in a cycle of poverty, living in a dysfunctional or chaotic setting, or being stuck in an unrewarding job or career. Chronic stress can significantly increase the likelihood of stroke, heart attack, suicide and violence (1).shutterstock_316922972

What impact does stress have on the body from a pathophysiological perspective?

In its acute form, stress can be a necessary adaptive mechanism for survival. In this sense, it is only associated with slightly transient changes within the brain. More negatively, episodes of severe and/or prolonged stress can cause significant overactivation and dysregulation of the hypothalamic pituitary adrenal (HPA) axis, resulting in detrimental changes to the brain structure and function (2). Chronic stress is widely considered, and evidenced, to be a negative modulator of the cognitive functions (the learning and memory processes). It disrupts normal brain structure and function, impairing memory by elevating excitatory amino acid and glucocorticoid levels (3). As well as diminishing health, exposure to long-lasting stress can also increase vulnerability to mental disorders, with stress exacerbating functional changes associated with various brain disorders including Alzheimer’s disease and Parkinson’s disease(4).

What effects does acute and chronic stress have on the sympathetic nervous system?Using antidepressants in teenagers: Discussions of suicide risk

Individuals who are exposed to distressing events beyond their control respond physiologically by releasing corticosteroids. Stress activates the sympathetic branch of the nervous system, triggering the release of adrenaline and noradrenaline(5). In periods of acute stress, levels of chemicals released during the body’s response will return to normal once the stressor(s) cease. However, if the stressors continue to be present, and experience of stress is chronic, this leads to structural changes in the brain - physiological changes to neurons and their synapses in the hippocampus, as well as the medial prefrontal cortex, results in impairments in working and spatial memory (6). In some individuals, the presence of chronic stress can also significantly increase the risk of perpetrating aggression (7). The impairment of the medial prefrontal cortex can lead to changes in individual decision-making strategies, with individuals shifting from patterns of flexible behaviour to patterns of behaviour that more habitual and regimented (8).

What physical effects do prolonged elevated cortisol levels have on the body?

shutterstock_310753160The ‘fight or flight’ response to stress results in the adrenal glands releasing adrenaline, causing the blood vessels to constrict and heart rate to increase. Cortisol is also released under stressful conditions and its purpose is to raise the glucose level in the blood: as the main source of energy for human cells it is released in order to provide readily available energy for over active cells to allow the fight or flight response to take place. Cortisol also works to curb functions that are not essential and would hamper an individual in a stressful situation – it suppresses the digestive and reproductive systems, and also alters immune system responses. Problems with elevated levels of cortisol begin to develop when the stress-response system of the body ceases to be self-limiting. Once threats have passed, hormone levels should return to normal – cortisol and adrenaline levels drop, heart rate and blood pressure returns to baseline levels, and the body resumes its regular activity. If cortisol is released regularly due to chronic stress, or significant stressors being present for a lengthy amount of time, it can result in significant health effects and risks including hypertension and a greatly increased risk of cardiovascular disease (9). It can also result in a number of other conditions including anxiety, depression, heart disease, sleep problems, weight gain and problems affecting memory and concentration (10). The problems that can develop as a result of ongoing exposure to cortisol highlight the importance of individuals learning effective stress management techniques in order to safeguard their health and live a longer, healthier life.

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REFERENCES:

  1. Waltes R, Chiocchetti AG, Freitag CM (2015) The neurobiological basis of human aggression: A review on genetic and epigenetic mechanisms Am J Med Neuro Gen doi: 10.1002/ajmg.b.32388
  2. Stephens MA, Mahon PB, McCaul ME, Wand GS (2015) Hypothalamic-pituitary-adrenal axis response to acute psychosocial stress: Effects of biological sex and circulating sex hormones J Psychneur 24;66:47-55
  3. Ismaili N, Garabedian MJ: (2004) Modulation of glucocorticoid receptor function via phosphorylation Ann N Y Acad Sci 1024:86-101
  4. Abuirmeileh A, Harkavyi A, Lever R, Biggs CS, Whitton PS (2007) Urocortin, a CRF-like peptide, restores key indicators of damage in the substantia nigra in a neuroinflammatory model of Parkinson's disease J Neuroinflammation 4:19
  5. Kohm AP, Sanders VM (2000) Norepinephrine: a messenger from the brain to the immune system Immunol Today 21:539-542
  6. White BD, Dean RG, Edwards GL, Martin RJ (1994)Type II corticosteroid receptor stimulation increases NPY gene expression in basomedial hypothalamus of rats Am J Physiol 266:R1523-R1529
  7. Mineur YS, Prasol DJ, Belzung C, Crusio WE (2003) Agonistic behaviour and unpredictable chronic mild stress in mice J Behavior Genetics 33(5): 513–519
  8. 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 J Science 325(5940):621–625
  9. Blascovich J, Spencer SJ, Quinn DM, Steele CM (2001) African Americans and high blood pressure: The role of stereotype threat Psychological Science 12(3):225–229
  10. Miyake S, Yoshikawa G, Yamada K, Sasaguri KI, Yamamoto T, Onozuka M, Sato S (2012) Chewing ameliorates stress-induced suppression of spatial memory by increasing glucocorticoid receptor expression in the hippocampus J Brain Res 1446:34-9
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