Transcript Psychological Stress and Physical Illness

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
Suppression of immune system
Direct mechanical
Effects
Other effects
Energy mobilisation
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)
Phagocyte
White blood cells provide
mechanisms of
immunity
T-Lymphocyte
– Bacteria
– Viruses (aka antigens)
(white blood cell)
• Structures and
mechanisms that allow
the body to resist and
fight off infection by:
(white blood cell)
How does the Immune System
work?
• Non specific immunity –
These cells surround
and ingest foreign
particles whenever they
find them
(white blood cell) Phagocyte
• Cell-based immunity
–produced in the
thymus gland they
search & destroy
foreign cells and cells
infected with antigens
(white blood cell) T-Lymphocyte 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 TLymphocyte 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
Immune Functioning
100%
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).
Onset
Merson (2001)
Moderately prolonged
Duration of Stressor
Chronic
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
Stress and the immune system
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
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.
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
An evaluation of the relationship between
Stress & Immune Function
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
Quick quiz: stress and physical illness
1.
2.
3.
4.
What does the immune system do and how does it work?
Name three stress related illnesses
What type of stressors are most common in our modern world?
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