Role of stress in illness

• immunosuppression (IS)

  • immune system suppressed
  • directly = cortisol produced by the hypothalamic-pituitary-adrenal system (HPA) inhibits production of immune cells
  • indirectly = stress influences lifestyle behaviours (smoking, drinking) that have a negative effect on immune functioning
• chronic stress of exams (IS)

  • Kiecolt-Glaser et al, tested 75 medical students 1 month before exam period (low stress) and on the day of exam (high stress)
  • students also completed questionnaires measuring sources of stress and psychological symptoms
  • the activity of natural killer (NK) and killer T cells decreased between the first and second samples - evidence of an immune response suppressed by a chronic stressor
  • decline was greatest in students who reported feeling lonely and experiencing others sources of stress (eg, life events)
• chronic stress of caring for ill relative (IS)

  • Kiecolt-Glaser et al compared caregivers (looking after a relative with Alzheimer's) with a matched group of non-caregivers
  • over 13 months caregivers had weaker cell-based immune response compared with control participants
  • caregivers also had more infectious illnesses and high levels of depression (32% of caregivers, 6% of control group)
• IS limitation = research shows stress can be protective

  • stress can have immunoenhancing effects (eg, Dharbar exposed rats to mild acute stressors which stimulated a major immune response)
  • immune cells (eg, lymphocytes) flooded into bloodstream and body tissues to protect against acute stress - chronic stress may be more damaging
  • suggest that the relationship between stress, the immune system and illnesses is complex and not yet fully understood
• IS strength = RWA

  • Dharbhar's research could lead to patients getting low doses of stress hormones before surgery to improve recovery
  • students who took a relaxation programme seriously had better immune-functioning during exams
  • these applications benefit real people and confirm the relevance of stress to the immune system
• IS research methods (evaluation)

  • lab experiments measure the effects of acute stressors while controlling confounding variables (can establish causation)
  • BUT lab experiments are unlike real-world stressful situations and also feature demand characteristics
  • => lab experiments are useful for establishing the apparent causes of immunosuppression, but they may not actually be causes in the real world
• cardiovascular disorders (CVDs)

  • CVDs = disorders of heart and blood vessels, including:
  • coronary heart disease (CHD)
  • stroke (blocked blood vessel)
  • acute stress leads to high levels of adrenaline with direct and continuing effects on heart muscles (eg increased heart rate)
• acute stress caused by watching football match (CVDs)

  • Wilbert-Lampen et al
  • looked at incidents of heart attacks during football matches (sudden emotional arousal - an acute stressor) played in Germany during the 1996 World Cup
  • on days Germany played = cardiac emergencies increased by 2.66x compared with a control period
  • acute emotional stress from watching favourite football team more than doubled pps risk of a cardiovascular event
• chronic stressors (CVDs)

  • Yusuf et el
  • his INTERHEART study compared 15000 people (52 countries) who'd had a heart attack (myocardial infarction, MI) with a similar number of people who hadn't
  • several chronic stressors had a strong link to MI, including:
  • stressful life events
  • workplace stress
  • role of stress greater than obesity and 3rd behind smoking and cholesterol
• limitation of CVDs = effects of stress mostly indirect

  • evidence for stress as an indirect factor in CVDs is much stronger than evident that directly causes CVDs
  • Orth-Gomer et al = found that marital stress tripled the risk of heart attack in women who already had CVD (different than causing CVD
  • suggests that stress increases vulnerability to CVDs, mainly through indirect effects (eg lifestyle)
• strength for CVDs = research supporting link between stress and CVDs

  • Song et al = compared people diagnosed with stress-related disorders to their unaffected siblings and members of the general population (controls)
  • people with stress disorders had a 64% risk of a CVD in the first year after diagnosis
  • shows that exposure to chronic psychological stress can significantly increase CVD risk
• CVD extra evaluation = what is the real cause of CVD/stress

  • cause of CVDs could be physiological = stress triggers a physiological response that damages the cardiovascular system (eg the heart muscle)
  • cause could be psychological= eg personality = some people perceive stressors negatively and have a strong physiological reaction
  • => physiology may be the immediate direct cause of CVDs, the underlying cause may be psychological