Stress

Stress

1. Sympatho-adreno-medullary axis = Short term stressors. Lead to arousal of the autonomic nervous system. ANS controls relase of hormones circulate in your blood e.g adrenaline. When the sympathetic branch of the ANS is roused the adrenal medulla releases adrenaline. Causes increased heart rate, sweating, increased breathing rate.

2. Hypothalamic-pituitary-adrenal axis = chronic stressor- the HPA is increasingly activated. Hypothalamus stimulates the pituitary gland which secretes ACTH, which causes the adrenal cortex to swell and release cortisol- helps maintain a steady supply of blood sugar needed for energy to fuel fight or flight response.

   • Parasympathetic reduces arousal.

3. Coronary Heart disease- heart attack - increased blood pressure damaging vessel walls, fatty deposits narrow vessels & strain put on valves & ventricles responsible

4. Hypertension- raised blood pressure due to furring- cortisol facilities fat conversion to energy acids & glucose can clog vessels

5. Atherosclerosis- hardening of blood vessels- Fat converted to energy but not burnt off

6. Wounds take longer to heal- due to HPA immune system suppressed

7. Stroke- fat plaques block tiny blood vessels in brain- fat conversion facilitated by cortisol.

8. Stomach Ulcers- acid attacks lining- digestion inhibited by SAM

9. Frequent colds- cortisol represses immune system

10. Immune System

    • Antigens- any foreign object that enters the body
    • Leucocytes (WBC's) most important. Produced in bone marrow or thymus.
    • T cells- (WBC from thymus) more aggressive for of immunity. Detect cells in body that have been invaded by antigens. They then bump into it & destroy the antigen & the cell its hiding in. (Th1 immunity)
    • B cells (WBC bone marrow) specific- tuned to a specific antigen. When that antigen appears in the body B cell produces millions of immune proteins (antibodies) to illuminate it. (Th2 immunity)
    • Cytokines mediate action of Th1 & Th2 response. When the Th1 response is active (at night) cytokines are produced to inhibit Th2 response. When Th2 response is active (day) cytokines produced to inhibit Th1)
    • Cohen-394 healthy individuals matched for factors e.g. diet, exercise, allergies, smoking (all things that affect immune system). Asked to complete a questionnaire that indicated how stressed they were. Q's to measure perceived levels of stress 'do you feel on top of things'. To measure stress caused by life events 'were you divorced within the last year'. Learn about negative moods 'are you feeling anxious or depressed'. Each ppt given a stress index which determined how stressed they were (3-12). PPts then given 1 of 5 strains of common cold via nasal drops. Kept together for duration of investigation - could go home had to wait to see if cold developed. 1/3 developed cold. Higher stress index- more likely to develop cold (positive correlation). Ppt with stress index score 11-12 over 45% judged to have a cold. Stress reduces efficiency of immune system.
      • + Not stressed by procedure- given via nasal drops. Therefore experiment is scientifically reliable so has high internal validity. Cause can be determined from effect. Data collected was quantitative- can be be accurately measured and interpreted. Other variables can be strictly controlled (experiment). More research is needed as we do not yet know enough about immune system to draw firm conclusions.
    • Kiecolt & Glaser- 75 1st year medical students. Natural experiment (naturally occurring stress- exam). Stress levels assessed using a questionnaire (also looked at psychiatric symptoms, loneliness and life events). Blood test 1 month before exam and during exam. Levels of T cells measured in samples of blood. Significant decrease in the number of T cells during the exam (when they are most stressed). Particularly low for students who felt most lonely and those with anxiety/depression. Number of T cells was reduced because stress was surprising the immune system. The effect was stronger for students who felt lonely or depressed because they lacked social support.
      • + High external validity, low demand characteristics. High ecological validity- can be applied to real life situations. Does not take into account individual differences. Other factors may have affected immune system e.g. recently recovering from illness. Gender, culture, social status and diet could have been confounding variables. Stress-diathesis model states ppts may have have underlying predisposition to have a suppressed immune system that may have only been triggered by stressor. Correlation does not imply causation. Cant thell is stress reduced immune system or reduced immune system made ppts experience stress more. Low population validity (same age). Low control over IV.

11. Personality

    • Friedman & Rosenman- CHD is related to Type A. 3000 men 39-59 living in California examined for signs of CHD (already ill= excluded) & personalities assessed using structured interviews (tried to elicit Type A behaviour by being conductive in provocative manner). Included Q's about how they responded to everyday pressures. After 8.5yrs twice as many type A ppts had died if CV problems. 12.8% type A's had experienced a heart attack compared to 6% of B's. Twice as many Type A's (2.7%) had died of CV problems compared to B's (1.1%). 287 had heart attack, 69% were A's.
      • Support from other studies- Myrtek conducted meta-analysis of 35 studies. Found an association between CHD and one particular Type A behaviours: hostility. Shows like between CHD and personality type. F&R's study has low external validity - used 3000 39-59 californian men which means findings can be generalised to women or people from other countries other than america so the study has low population validity. Could be argued results can even be generalised to other american states. Doesn't take other factors into account.
    • Hardy Personality - see life challenges as problems to overcome, enjoy change as an opportunity for development. Involved in the world around them and have a strong sense of purpose, get stuck in, take n active role. see themselves a s being in control of their lives rather than being controlled by external factors.
      • Kobasa studied 800 american business executives assessed using Holmes & Rahes SRRS. Approx 150 were classified as high stress according to SRRS scores. Of these some had a low illness record, others had high. Suggests something else was modifying the effects of stress because individuals experiencing the same stress levels had different illness records. Kobasa proposed hardy personality encourages resilience. The individuals in the high stress/low illness group scored high on all 3 characteristics of hardy personality, whereas high stress/high illness scored lower on these variables.
      • Maddi studied employees of a US company that was dramatically reducing the size of its workforce over a year. Two thirds suffered stress-realted health problems. Remaining third thrived. Thriving groups showed more evidence of hardiness attributes.
      • Lifton measured hardiness in students at 5 US units to see if hardness is related to the likelihood of their completing their degree. Naturalistic longitudinal. Low scoring students (in hardiness) were disproportionately represented among the drop out students. Students with a high score most likely to compete their degree. Hardy personality type more committed.
      • Most research relied on self-report questionnaires- although Personal Views survey has been developed to reduce long awkwardly worded Q's low internal validity still as ppts may give socially desirable answers. Hardiness characteristics may be explained by concept of negative affectivity (Watson & Clarke) supported by research which found those high in negative affectivity are more likely to report distress & dissatisfaction, dwell on failures and focus on negatives. Hardy people simply low of NA. Hardiness applied to real world- useful in understanding of stress. Navy seals applicants now screened for hardiness and hardiness training becoming more widespread.

12. Life Changes

    • Holmes & Rahe examined 5000 medical records of patients who had recently suffered illness. Then asked patients it they had experienced any life events before the illness. A list of 43 was created. 400 ppts were asked to score the life events in terms of how much readjustment would be required by the average person. Asked to provide a numerical figure for this readjustment taking marriage as an arbitrary baseline of 50. Score totalled & averaged. Correlation of 0.1 between life vents and illness.

13. Workplace Stress

    • Marmot- longitudinal study of 7372 civil servants working in London. PPts answered a questionnaire on workload job control and amount of social support. They were checked for signs of CVD (e.g.chest pains). Researchers obtained and independent assessment of workload and control by checking job specification and role responsibilities with personal management. They were re-assessed 5 years later. No link between high workload & stress related illness- concluded job demand not a significant factor in stress. PPts who had initially reported low levels of job control were more likely to have developed heart disease than those who had reported high levels of job control. Association not linked to employment grade, smoking, physical inactivity, workload or lack of social support. Lack of control creates more workplace stress than high workload.
      • High workload may be seen as stressful by some and challenging by others - particularly those with high hardiness. Workload stressors depend on a persons ability to cope. Schraubeck found some people feel less stressed having no control or responsibilities - better immune responses in such situations. Evolution of work and work stressors- working environment constantly changing due to new technology/practices. Increase in virtual offices and blurring of work/home environment. Current knowledge/understanding of workplace stressors rapidly becomes outdated, Marmots study may not be representative of todays workplaces.
    • Johansson- Two groups of swedish saw mill workers were measured for stress by testing the amount of stress hormones in their urine. High risk group were ten finishes- little control and little social contact. High responsibility- rate at which they worked determined the wages for the whole mill. High degree of isolation due to need to concentrate. Low risk were cleaners who could work at their own pace. Worked in teams = more social contact. Found finishers had higher stress levels than other workers. high blood pressure, higher rate of stomach and intestinal disorders (ulcers) and reported suffering more headaches. Urine samples showed higher levels of adrenaline & noradrenaline. work days had higher levels of hormones than rest days implying they were experiencing long term physiological arousal.
      • Doesn't show cause & effect- study can exclude other variable (receptive jobs usually low paid = poor housing etc). Swedish study= unwise to generalise to other countries. British work longer & harder than other european countries (only 16% take regular lunch break- lasts average of 27 mins). Schaubeck et al found some employees who had control over job responsibilities but didn't have confidence in their ability were more likely to be stressed.