Stress & illness: Mini presentations: Group 1: The immune system & stress related illness (slides 1-5) (Nikki & Micah) Group 2: Direct mechanical effects & energy mobilization (slides 6/7) (Christina) Group 3: How the immune system works(slide 7/8) (Audrey) Group 4: stress response & suppression of immune system (slides 9- 11) (Alessandra & Krystal) Group 5: Kiecolt-Glaser et al. (1984) study (slide 12) (Louis & Klaire) Group 6: Cohen et al's (1993) Study (slide 13) (Zach & Dillon) Group 7: Evaluation & conclusion(14-16) (Hyn Kyu & Katalyna) **Make sure you prepare 5 questions to check understanding also**

Psychological Stress and Physical Illness

In the distant past we used to encounter many physical stressors, nowadays, stressors are mainly psychological – and stress can have a negative effect on the body and cause illness.

Stress and physical illness The immune system is a very complex system of cells and chemicals which protect the body from infection by viruses and bacteria. But during stress all resources are geared to escape, so protection and tissue repair can wait till later Its an excellent survival mechanism – but long term activation can lead to the shutting down of other systems which are also important (IE immune system)

Stress related illness The following cardiovascular disorders are related to stress Hypertension – ‘furring up’ of the cardiovascular system (fatty deposits building up) Atherosclerosis – raised blood pressure wearing away the blood vessel lining, scarring blood vessels, which then leads to the clogging of the blood vessels Stroke - caused by plaques blocking tiny blood vessels in the brain Raised blood pressure – can cause haemorrhage (breaking of the tiny blood vessels in the brain) Coronary heart disease (CHD)– (heart attack) – caused by damage to the functioning of the heart (responsible for pumping blood around the body – due to the build-up of fatty deposits in the arteries Is stress the only cause of these?

However, these can also have other causes E.g. heart disease can have a genetic component & diet also important Stress can interact with other factors to make things worse Chronic stress can damage the body, making illness more likely to occur. Four categories of the effect of stress on the body Direct mechanical Effects Energy mobilisation Suppression of immune system Other effects

Direct mechanical effects of the stress response on the body Stress response increases heart rate Blood is pumped around the body at a higher pressure Increased mechanical pressure on the cardiovascular system which can lead to the wearing away of the lining where blood vessels branch Like any hydraulic system – higher pressure leads to increased damage

The negative effects of Energy mobilisation Nowdays stress comes from psychological sources such as the workplace/ relationships Physical activity rare in the response to stress – but GAS response preparing us for fight or flight Glucose and fatty acids produced to prepare for fight or flight cant all be re-absorbed into the body if stress is chronic, and the ‘furring up’ of the cardiovascular system (hypertension & atherosclerosis)

How does the Immune System work? Structures and mechanisms that allow the body to resist and fight off infection by: – Bacteria – Viruses (aka antigens) White blood cells provide mechanisms of immunity (white blood cell) T-LymphocytePhagocyte

Non specific immunity – These cells surround and ingest foreign particles whenever they find them (white blood cell) Phagocyte (white blood cell) T-Lymphocyte Cell-based immunity –produced in the thymus gland they search & destroy foreign cells and cells infected with antigens such as bacteria

The stress response and suppression of the immune system Immune system very complex & stress- response can affect it directly E.g. high levels of corticosteroids (CORTISOL) can shrink the thymus gland – preventing the development of T- Lymphocyte cells Long term stress causes long term reductions in immune function (Willis et al. 1987) It is important to note that diet, exercise, and social support can improve immune function and it will recover if the stressful situation is resolved (Sapolsky, 1994)

Stress & Immune Function OnsetModerately prolongedChronic Duration of Stressor Immune Functioning 100% Merson (2001) This graph shows that only chronic (those that go on for a long time) stressors impair immune functioning,but acute (shorter stressors actually increase immune functioning).

Negative effects of Stress on Immune Function Research support: Cohen & Herbert (1996) – Stress associated with increased susceptibility to cold, flu, herpes virus, chickenpox Bartrop et al (1977) – Immune suppression followed loss of intimate relationship through death or divorce Levy et al (1989) – PPs who scored high on a scale of daily hassles had lower natural killer (immune) cell activity

Kiecolt-Glaser et al. (1984) study of the functioning of the immune system Aim: To investigate whether stress of important examinations has an effect on the functioning of the immune system. Procedures: Natural experiment with 75 medical students, Blood samples taken 1 month before finals (lower stress), and during exams (high stress) & questionnaires about loneliness and life events Findings: NK (natural killer) Cells significantly less active in during examination sample, NK Cell activity lowest in PPs which reported loneliness and high levels of life events. Conclusions: Exam stress reduces immune system functioning – leaving people vulnerable to illness and infections Immune function is also affected by psychological variables such as life events and feelings of loneliness. These long term stressors make individuals more vulnerable to the added effect of short term stressors. Evaluation: Correlational study-cause and effect? High ecological validity? Student population? However, further studies also showed a link between low immune function in Alzheimer's carers, those going through divorce proceedings, and short term marital conflict. It is important to note that this is not a direct study of physical illness – but immune function Stress and the immune system

Cohen et al's (1993) Study of stress and the common cold Aims: To investigate the link between stress and the immune system. Procedures: The participants were 394 healthy individuals. The were asked to complete a questionnaire that indicated how stressed they were. Each participant was given a stress index questionnaire to complete (1 = little stress etc.). The participants were then subjected to one of five strains of the common cold via nasal drops. Cohen then waited to see how many of the participants actually developed a cold. Findings: 1/3 of the participants came down with a cold. It was found that the higher the stress index was, the more likely they were to develop a cold Conclusion: There is a direct link between stress and the immune system. It appears that stress reduces the efficiency of it. Evaluation: The fact that the cold virus was administered via nasal drops, excludes the factor that the participants were stressed by the procedure. For example, administering them by injection may have produced more stress and interfered with the results. This was an experiment, therefore it is scientifically reliable and it means that CAUSE CAN BE DETERMINED FROM EFFECT. The data collected was QUANTITIVE, meaning it could be accurately measured and interpreted. Because it was an experiment, OTHER VARIABLES can be strictly controlled. The immune system is VERY COMPLEX and we do not yet know enough about it to draw firm conclusions from these results. So more research is needed. Other Points: This study can be used as an alternative to the Kiecolt-Glaser study which is also about stress and the immune system. Stress and the immune system

Other effects of stress on the body Stress hormones such as corticosteroids(CORTISOL) may influence the pituitary gland ‘the master gland’ (which controls many bodily functions) The pituitary gland controls sexual and reproductive functions – In males, testosterone in males declines in the stress response. In females, the menstrual cycles can be disrupted Growth hormones are also controlled by the pituitary gland – some children suffer from ‘stress dwarfism’

An evaluation of the relationship between Stress & Immune Function Evidence supports a weak link (Correlation) between chronic stress and reduced immune functioning. The research shows correlations that are often small but significant These are also important factors – Personality & coping style – Social support – Lifestyle Suppression of immune functioning need not lead to illness and disease, you still need to be exposed to an infectious agent for illness to develop

Conclusion: There is a relationship between psychological stress and physical illness, and this may be due to suppression of the immune system, and can also be explained by Selye’s (1956) GAS. However, compared to impact of e.g. age, genes, nutrition stress is relatively unimportant An evaluation of the relationship between Stress & Immune Function

Quick quiz: stress and physical illness 1.What does the immune system do and how does it work? 2.Name three stress related illnesses 3.What type of stressors are most common in our modern world? 4.What effect on physical health does increased heart rate and blood pressure have? 5.In order for the immune system to impaired, the stress needs to be ……..………. 6.What can be done to improve immune function? 7.Why does suppression of the immune system not always lead to illness and disease? 8.What are the Aims, procedures and findings of Keicolt Glazer (1984) study? 9.Make an evaluative point about Keicolt Glazers (1984) study 10.What are the aims, procedures and findings of Cohen’s (1993) study? 11.Make an evaluative point about Cohen’s (1993) study