Stress (biology)


Stress (biology)

Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance. It refers to the consequence of the failure of an organism — human or other animal — to respond adequately to mental, emotional, or physical demands, whether actual or imagined.[1] When the person perceives a threat, their nervous system responds by releasing a flood of stress hormones, including adrenaline and cortisol. These hormones rouse the body for emergency action. The stress response is the body’s way of protecting the person. When working properly, it helps in staying focused, energetic, and alert.

Contents

Origin and terminology

The term stress was first employed in a biological context by the endocrinologist Hans Selye in the 1930s.[2] He later[when?] broadened and popularized the concept to include inadequate physiological response to any demand. In his usage stress refers to a condition and stressor to the stimulus causing it. It covers a wide range of phenomena, from mild irritation to drastic dysfunction that may cause severe health breakdown.

Symptoms

Signs of stress may be cognitive, emotional, physical, or behavioral.

Cognitive symptoms

  • Memory problems
  • Inability to concentrate
  • Poor judgment
  • Seeing only the negative
  • Anxious or racing thoughts
  • Constant worrying

Emotional symptoms

  • Moodiness
  • Irritability or short temper
  • Agitation, inability to relax
  • Feeling overwhelmed
  • Sense of loneliness and isolation
  • Depression or general unhappiness

Physical symptoms

  • Aches and pains
  • Diarrhea or constipation
  • Nausea, dizziness
  • Chest pain, rapid heartbeat
  • Loss of sex drive
  • Frequent colds

Behavioral symptoms

  • Eating more or less
  • Sleeping too much or too little
  • Isolating yourself from others
  • Procrastinating or neglecting responsibilities
  • Using alcohol, cigarettes, or drugs to relax
  • Nervous habits (e.g. nail biting, pacing)

Models

General adaptation syndrome

A diagram of the General Adaptation Syndrome model.

Physiologists define stress as how the body reacts to a stressor, real or imagined, a stimulus that causes stress. Acute stressors affect an organism in the short term; chronic stressors over the longer term.

Selye researched the effects of stress.

Alarm is the first stage. When the threat or stressor is identified or realized, the body's stress response is a state of alarm. During this stage, adrenaline will be produced in order to bring about the fight-or-flight response. There is also some activation of the HPA axis, producing cortisol.

Resistance is the second stage. If the stressor persists, it becomes necessary to attempt some means of coping with the stress. Although the body begins to try to adapt to the strains or demands of the environment, the body cannot keep this up indefinitely, so its resources are gradually depleted.

Exhaustion is the third and final stage in the GAS model. At this point, all of the body's resources are eventually depleted and the body is unable to maintain normal function. The initial autonomic nervous system symptoms may reappear (sweating, raised heart rate, etc.). If stage three is extended, long-term damage may result, as the body's immune system becomes exhausted, and bodily functions become impaired, resulting in decompensation.

The result can manifest itself in obvious illnesses such as ulcers, depression, diabetes, trouble with the digestive system, or even cardiovascular problems, along with other mental illnesses.

Selye: eustress and distress

Selye published in 1975 a model dividing stress into eustress and distress.[3] Where stress enhances function (physical or mental, such as through strength training or challenging work), it may be considered eustress. Persistent stress that is not resolved through coping or adaptation, deemed distress, may lead to anxiety or withdrawal (depression) behavior.

The difference between experiences that result in eustress and those that result in distress is determined by the disparity between an experience (real or imagined) and personal expectations, and resources to cope with the stress. Alarming experiences, either real or imagined, can trigger a stress response.[4]

Lazarus: cognitive appraisal model

Lazarus[5] argued that, in order for a psychosocial situation to be stressful, it must be appraised as such. He argued that cognitive processes of appraisal are central in determining whether a situation is potentially threatening, constitutes a harm/loss or a challenge, or is benign.

Both personal and environmental factors influence this primary appraisal, which then triggers the selection of coping processes. Problem-focused coping is directed at managing the problem, whereas emotion-focused coping processes are directed at managing the negative emotions. Secondary appraisal refers to the evaluation of the resources available to cope with the problem, and may alter the primary appraisal.

In other words, primary appraisal includes the perception of how stressful the problem is and the seconday appraisal of estimating whether one has more than or less than adequate resources to deal with the problem that affects the overall appraisal of stressfulness. Further, coping is flexible in that, in general, the individual examines the effectiveness of the coping on the situation; if it is not having the desired effect, s/he will, in general, try different strategies.[6]

Neurochemistry and physiology

Although the basic neurochemistry of the stress response is now well understood, much remains to be discovered about how the components of this system interact with one another, in the brain, and throughout the body. In response to a stressor, neurons with cell bodies in the paraventricular nuclei (PVN) of the hypothalamus secrete corticotropin-releasing hormone (CRH) and arginine-vasopressin (AVP) into the hypophyseal portal system.

The locus ceruleus and other noradrenergic cell groups of the adrenal medulla and pons, collectively known as the LC/NE system, also become active and use brain epinephrine to execute autonomic and neuroendocrine responses, serving as a global alarm system.[7]

The autonomic nervous system provides the rapid response to stress commonly known as the fight-or-flight response, engaging the sympathetic nervous system and withdrawing the parasympathetic nervous system, thereby enacting cardiovascular, respiratory, gastrointestinal, renal, and endocrine changes.[7] The HPA axis, a major part of the neuroendocrine system involving the interactions of the hypothalamus, the pituitary gland, and the adrenal glands, is also activated by release of CRH and AVP.

This results in release of adrenocorticotropic hormone (ACTH) from the pituitary into the general bloodstream, which results in secretion of cortisol and other glucocorticoids from the adrenal cortex. The related compound cortisone is frequently used as a key anti-inflammatory component in drugs that treat skin rashes and in nasal sprays that treat asthma and sinusitis. Recently, scientists realized the brain also uses cortisol to suppress the immune system and reduce inflammation within the body.[8] These corticoids involve the whole body in the organism's response to stress and ultimately contribute to the termination of the response via inhibitory feedback.[7]

Impact on disease

Chronic stress can significantly affect many of the body's immune systems, as can an individual's perceptions of, and reactions to, stress. The term psychoneuroimmunology is used to describe the interactions between the mental state, nervous and immune systems, and research on the interconnections of these systems. Immune system changes can create more vulnerability to infection, and have been observed to increase the potential for an outbreak of psoriasis for people with that skin disorder.[9]

Chronic stress has also been shown to impair developmental growth in children by lowering the pituitary gland's production of growth hormone, as in children associated with a home environment involving serious marital discord, alcoholism, or child abuse.[10]

Chronic stress is seen to affect parts of the brain where memories are processed through and stored. When people feel stressed, stress hormones get over-secreted, which affects the brain. This secretion is made up of glucocorticoids, including cortisol, which are steroid hormones that the adrenal gland releases.[11]

Studies of female monkeys at Wake Forest University (2009) discovered that individuals suffering from higher stress have higher levels of visceral fat in their bodies. This suggests a possible cause-and-effect link between the two, wherein stress promotes the accumulation of visceral fat, which in turn causes hormonal and metabolic changes that contribute to heart disease and other health problems.[12]

Post traumatic stress disorder

Post traumatic stress disorder (PTSD) is a severe anxiety disorder that can develop after exposure to any event that results in psychological trauma. This event may involve the threat of death to oneself or to someone else, or to one's own or someone else's physical, sexual, or psychological integrity, overwhelming the individual's ability to cope. As an effect of psychological trauma, PTSD is less frequent and more enduring than the more commonly seen acute stress response. Diagnostic symptoms for PTSD include re-experiencing the original trauma(s) through flashbacks or nightmares, avoidance of stimuli associated with the trauma, and increased arousal – such as difficulty falling or staying asleep, anger, and hypervigilance. Formal diagnostic criteria (both DSM-IV-TR and ICD-10) require that the symptoms last more than one month and cause significant impairment in social, occupational, or other important areas of functioning.

Common sources

Both negative and positive stressors can lead to stress. The intensity and duration of stress changes depending on the circumstances and emotional condition of the person suffering from it (Arnold. E and Boggs. K. 2007). Some common categories and examples of stressors include:

Stress tests

Measuring stress level independent of differences in people's personalities has been inherently difficult: Some people are able to process many stressors simultaneously, while others can barely address a few. Such tests as the Trier Social Stress Test attempted to isolate the effects of personalities on ability to handle stress in a laboratory environment. Other psychologists, however, proposed measuring stress indirectly, through self-tests.

Because the amount of stressors in a person's life often (although not always) correlates with the amount of stress that person experiences, researchers combine the results of stress and burnout self-tests. Stress tests help determine the number of stressors in a person's life, while burnout tests determine the degree to which the person is close to the state of burnout. Combining both helps researchers gauge how likely additional stressors will make him or her experience mental exhaustion.[18]

Adaptation

Responses to stress include adaptation, psychological coping such as stress management, anxiety, and depression. Over the long term, distress can lead to diminished health and/or increased propensity to illness; to avoid this, stress must be managed.

Stress management encompasses techniques intended to equip a person with effective coping mechanisms for dealing with psychological stress, with stress defined as a person's physiological response to an internal or external stimulus that triggers the fight-or-flight response. Stress management is effective when a person uses strategies to cope with or alter stressful situations.

There are several ways of coping with stress,[citation needed] such as controlling the source of stress or learning to set limits and to say "No" to some demands that bosses or family members may make.

A person's capacity to tolerate the source of stress may be increased by thinking about another topic such as a hobby, listening to music, or spending time in a wilderness.

History and usage

The term stress had none of its contemporary connotations before the 1950s. It is a form of the Middle English destresse, derived via Old French from the Latin stringere, "to draw tight."[19]

It had long been in use in physics to refer to the internal distribution of a force exerted on a material body, resulting in strain. In the 1920s and 1930s, the term was occasionally being used in psychological circles to refer to a mental strain or unwelcome happening, and by advocates of holistic medicine to refer to a harmful environmental agent that could cause illness. Walter Cannon used it in 1934 to refer to external factors that disrupted what he called homeostasis.

The novel usage arose out of Selye's 1930s experiments. He started to use the term to refer not just to the agent but to the state of the organism as it responded and adapted to the environment. His theories of a universal non-specific stress response attracted great interest and contention in academic physiology and he undertook extensive research programs and publication efforts.[20]

However, while the work attracted continued support from advocates of psychosomatic medicine, many in experimental physiology concluded that his concepts were too vague and unmeasurable. During the 1950s, Selye turned away from the laboratory to promote his concept through popular books and lecture tours. He wrote for both non-academic physicians and, in an international bestseller entitled Stress of Life, for the general public.

A broad biopsychosocial concept of stress and adaptation offered the promise of helping everyone achieve health and happiness by successfully responding to changing global challenges and the problems of modern civilization. He coined the term "eustress" for positive stress, by contrast to distress.

He argued that all people have a natural urge and need to work for their own benefit, a message that found favor with industrialists and governments.[20] He also coined the term stressor to refer to the causative event or stimulus, as opposed to the resulting state of stress.

From the late 1960s, academic psychologists started to adopt Selye's concept; they sought to quantify "life stress" by scoring "significant life events," and a large amount of research was undertaken to examine links between stress and disease of all kinds. By the late 1970s, stress had become the medical area of greatest concern to the general population, and more basic research was called for to better address the issue.

There was renewed laboratory research into the neuroendocrine, molecular, and immunological bases of stress, conceived as a useful heuristic not necessarily tied to Selye's original hypotheses. By the 1990s, "stress" had become an integral part of modern scientific understanding in all areas of physiology and human functioning, and one of the great metaphors of Western life.[20] Focus grew on stress in certain settings, such as workplace stress. Stress management techniques were developed.

Its psychological uses are frequently metaphorical rather than literal, used as a catch-all for perceived difficulties in life. It also became a euphemism, a way of referring to problems and eliciting sympathy without being explicitly confessional, just "stressed out."

It covers a huge range of phenomena from mild irritation to the kind of severe problems that might result in a real breakdown of health. In popular usage, almost any event or situation between these extremes could be described as stressful.[19]

The most extreme events and reactions may elicit the diagnosis of posttraumatic stress disorder (PTSD), an anxiety disorder that can develop after exposure to one or more terrifying events that threatened or caused grave physical harm. PTSD is a severe and ongoing emotional reaction to an extreme psychological trauma; as such, it is often associated with soldiers, police officers, and other emergency personnel.

This stressor may involve viewing someone's actual death, a threat to the patient's or someone else's life, serious physical injury, or threat to physical or psychological integrity, overwhelming usual psychological defenses coping. In some cases, it can also be from profound psychological and emotional trauma, apart from any actual physical harm. Often, however, the two are combined.

The US military became a key center of stress research,[citation needed] attempting to understand and reduce combat neurosis and psychiatric casualties.

Diagnosis

A renewed interest in salivary alpha amylase as a marker for stress has surfaced. Yamaguchi M, Yoshida H (2005) have analyzed a newly introduced hand-held device called the Cocorometer developed by Nipro Corp., Japan. They state that this can be reliably used to analyze the amylase levels and is definitely a cheaper alternative as compared to the more expensive ELISA kits. The working consists of a meter and a saliva collecting chip, which can be inserted into the meter to give the readings. The levels of amylase obtained have been calibrated according to standard population, and can be categorized into four levels of severity.[21]

See also

References

Notes

  1. ^ The Stress of Life, Hans Selye, New York: McGraw-Hill, 1956.
  2. ^ Hans Selye, History of the Stress Concept. Ch. 2 in Leo Goldberger and Shlomo Breznitz Handbook of Stress: Theoretical and Clinical Aspects. Free Press, 1982
  3. ^ Selye (1975). "Confusion and controversy in the stress field". Journal of Human Stress 1: 37–44. 
  4. ^ Ron de Kloet, E; Joels, M. & Holsboer, F. (2005). "Stress and the brain: from adaptation to disease". Nature Reviews Neuroscience 6 (6): 463–475. doi:10.1038/nrn1683. PMID 15891777. 
  5. ^ Lazarus, R.S. (1966). Psychological Stress and the Coping Process. New York: McGraw-Hill. 
  6. ^ Aldwin, Carolyn (2007). Stress, Coping, and Development, Second Edition. New York: The Guilford Press. ISBN 1572308400. 
  7. ^ a b c Tsigos, C. & Chrousos, G.P. (2002). Hypothalamic-pituitary-adrenal axis, neuroendocrine factors, and stress. Journal of Psychosomatic Research, 53, 865–871.
  8. ^ National Institute of Health, Harrison Wein, PhD, "Stress and Disease: New Perspectives"
  9. ^ Treating Stress And Skin Disease In Tandem by Allison Aubrey. Morning Edition, National Public Radio. 14 September 2009.
  10. ^ Powell, Brasel, & Blizzard, 1967.
  11. ^ "Renew-Stress on the Brain". The Franklin Institute. http://www.fi.edu/learn/brain/stress.html. 
  12. ^ Alice Park (2009-08-08). "Fat-Bellied Monkeys Suggest Why Stress Sucks". Time. http://www.time.com/time/health/article/0,8599,1915237,00.html. Retrieved 2009-08-08. 
  13. ^ Glavas, M.M.; Weinberg, J. (2006). "Stress, Alcohol Consumption, and the Hypothalamic-Pituitary-Adrenal Axis". In Yehuda, S.; Mostofsky, D.I.. Nutrients, Stress, and Medical Disorders. Totowa, NJ: Humana Press. pp. 165–183. ISBN 978-1-58829-432-6. 
  14. ^ Davis et al. (June 2007). Prenatal Exposure to Maternal Depression and Cortisol Influences Infant Temperament. Journal of the American Academy of Child & Adolescent Psychiatry, v46 n6 p737.
  15. ^ O'Connor, Heron, Golding, Beveridge & Glover. (June 2002). Maternal antenatal anxiety and children's behavioural/emotional problems at 4 years. Br J Psychiatry. 180:478–9.
  16. ^ Schore, Allan (2003). Affect Regulation & the Repair of the Self. New York: W.W. Norton. ISBN 0393704076. 
  17. ^ Michael D. DeBellis, George P. Chrousos, Lorah D. Dorn, Lillian Burke, Karin Helmers, Mitchel A. Kling, Penelope K. Trickett, and Frank W. Putnam. Hypothalamic—Pituitary—Adrenal Axis Dysregulation in Sexually Abused Girls
  18. ^ Truby, William. "Stress Test", Stress Test – self assessment, December, 2009.
  19. ^ a b Keil, R.M.K. (2004) Coping and stress: a conceptual analysis Journal of Advanced Nursing, 45(6), 659–665
  20. ^ a b c Viner, R. (1999) Putting Stress in Life: Hans Selye and the Making of Stress Theory. Social Studies of Science, Vol. 29, No. 3 (June 1999), pp. 391–410
  21. ^ Shankar, A.A.; Dandekar, R.C. "Assessment of stress in patients with Recurrent Aphthous Stomatitis, by salivary alpha amylase using a Cocorometer" dissertation submitted for Oral Pathology to Maharashtra University of Health Sciences, Nashik in December 2009.

Bibliography

  • Petersen, C.; Maier, S.F.; Seligman, M.E.P. (1995). Learned Helplessness: A Theory for the Age of Personal Control. New York: Oxford University Press. ISBN 0-19-504467-3
  • Seligman, M.E.P. (1975). Helplessness: On Depression, Development, and Death. San Francisco: W.H. Freeman. ISBN 0-7167-2328-X
  • Seligman, M.E.P. (1990). Learned Optimism. New York: Knopf. (Reissue edition, 1998, Free Press, ISBN 0-671-01911-2).
  • Holmes, T.H. and Rahe, R.H. (1967). The social readjustments rating scales. Journal of Psychosomatic Research 11:213–218.

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