Lecture 9 - Stress Flashcards
Stress in Canada
- According to Statistics Canada (2017), 23% of people between ages 18 and 34 years old
reported that most days are “quite a bit” or “extremely” stressful. - Top Stressors:
1. Work
2. Money
3. Relationships
4. Health
What is stress?
Hippocrates… stress and asthma
Hans Selye… stress from engineering (force on structure that exceeds the structure’sability to respond, cope, adapt). But for people, stress= non-specific response from the body to any external demand on the organism
Stressor vs. stress
*Stressor= external demands that challenges ability to maintain homeostasis (dangers, but also good things like having a baby or new job… but ALSO PERCEIVED stress)
*Stress= the response! How the organism reacts both physically and/or psychologically to a stressor (response varies from person to person)
*Laypeople often use “stress” as to mean both the stressor and the stress response… here we distinguish them
Hypothalamus
*Sympathetic Adrenomedullary System
-Fight/Flight (adrenaline and noradrenaline)
–HR increases, pupils dilate, blood pressure increases, digestion slows, glucose consumption increases
*Hypothalamus-Pituitary-Adrenal Axis
-CRH, ACTH, Cortisol
–Fight/flight! Inhibit immune system
HPA Axis slower than SAM
Allostatic load = how much strain the system is under in order to accomplish these goals (ex: when running away from bear, but also less obvious or immediate stress)
“There is nothing good or bad, but thinking makes it so” -Hamlet …. It’s the appraisal
Cortisol (glucocorticoid)
Not just a stress hormone
Critical for day to day life
Need increase in cortisol to get out of bed in the morning
Normal brain maturation
Inverted U curve
Hippocampus
* Critical to memory, stress regulation
* Shares reciprocal connections with the
hypothalamus
- High concentrations of cortisol receptors
* Acute stress suppresses hippocampal activity
* Chronic stress results in decreased hippocampal
volumes
- Decreased dendritic arborisation
* Altered function
* Can result in cortisol hypersecretion
Prefrontal Cortex
* Important for decision-making, working
memory, self-regulatory behaviors,
mood, impulse control
* Slow to develop
* Repeated stress exposure causes
dendritic shortening
* Chronic stress exposure associated with
decreased volume of prefrontal cortex
“Breaking
down”
Stress
* Increased recognition that certain
properties of stressors may be more closely
linked with disease risk.
* Stressors that are perceived as:
1. Uncontrollable
2. Unpredictable
3. Severe
* These properties of stressors have been
more strongly linked to the development of
some psychiatric disorders – e.g. depression.
* Stressors can also be acute or chronic.
* Type: Some types of stressors are more
strongly associated with some forms of
disease than others (e.g., interpersonal
stress and depression)
* Timing of stress also matters!
o Early versus later life stress exposure.
Early Life Stress (ELS)
- Five general patterns observed with regard to ELS and
mental disorders in the population: - ELS is common
- ELS increases risk for developing a lifetime mental
disorder compared to no ELS
- ELS increases risk for developing a lifetime mental
- ELS is associated with virtually all commonly
occurring forms of psychopathology – it appears to
be non-specific
- ELS is associated with virtually all commonly
- ELS is associated with increased vulnerability to
psychopathology that persists across the life course
- ELS is associated with increased vulnerability to
- ELS explains a substantial proportion of mental
disorder onsets in the population (~30%).
- ELS explains a substantial proportion of mental
Potential mechanisms of risk
* Early life is a critical period of brain development and
stress exposure may disrupt this development.
- E.g., the level of cortisol in moms matters for the
developing brain.
* Exposure to stress in early life may lead to persistent
dysregulation of stress response systems (including
HPA-axis and ANS function).
Fetal exposure to maternal stress
* Growing interest in understanding whether our
first contact with stress may make us more
vulnerable to psychopathology in later life.
o And this begins in utero…
* Maternal stress during pregnancy increases risk for
post-natal complications, as well as emotional and
behavioral problems in infants, children and
adolescents.
* This risk may be passed from mother to child via
fetal programming.
“Fetal
programming
”
* Maternal stress may be transmitted to the fetus
via high levels of glucocorticoids (e.g., cortisol).
* Cortisol may pass through the placenta, and/or
stimulate receptors on the placenta to increase
cortisol production.
* Infants may develop stress response systems that
are hypersensitive to threat.
o Basal cortisol levels and cortisol reactivity are
greater in infants exposed to higher levels of
maternal stress.
- Yong Ping et al. (2015) examined effects of
prenatal maternal stress from a natural
disaster on offspring cortisol reactivity.
o2008 – Iowa Flood (rated as one of the top
disasters in U.S. history) - Recruited pregnant mothers who had
experienced the flood - Rated mothers’ objective exposure to stress and
collected perceived stress - Collected saliva samples from their toddlers
before and after a mother-baby separation
task. - The more severe the mothers’ objective
exposure and subjective stress from a
major flood during pregnancy, the greater
the child’s cortisol reactivity increase in
response to stress. - Maternal subjective stress had no effect on
boys, but in girls greater subjective stress
predicted greater cortisol reactivity
Real-world stressors (ex: the pandemic)
Symptoms of Depression
* Multiple studies from around the world reporting increases in symptoms of
depression across the course of the pandemic (e.g., Stankovaska et al., 2020; Mazza et al.,
2020; C. Wang et al., 2020; Zhang et al., 2020).
* But some evidence increases not evenly distributed across the population
(Fitzpatrick et al., 2020).
* Sample of 10,368 Adults in the US
* Risk for increased depression associated with several variables:
* Social Isolation
* Female gender
* Food insecurity
* Hispanic ethnicity
* Unemployment
COVID Stress and Neural Responses to Rewards
Results: decreased neural response to rewards following the covid stress
Chronic Stress
Pandemic Stress Questionnaire (Kujawa et al., 2020)
* M = 17.26, SD = 7.3, Range = 2 – 27
Top 5 stressors:
1. My work/school has been disrupted due to COVID-19 – 89.7%
2. People around me have been more frightened than usual due to COVID-19 - 89.7%
3. I was unable to be with close family, friends, or partners because of the coronavirus pandemic
– 71.8%
4. I had less contact with good friends because of the coronavirus pandemic – 71.8%
5. People around me have been complaining more than usual due to COVID-19 – 69.2%
Empirically-supported steps to promote well-being
Social Support
* Social support linked to 50%
reduction in mortality risk
* Loneliness associated with higher
blood pressure, increased waking
cortisol levels
* Social Support helps people recover
faster from recent life stress exposure
* Social evaluative stress
*Social support has a buffering effect (especially when partner)… rewatch this part that explains the experiment
-physical contact from partner especially useful for women
- Pet ownership may also buffer
- Pet-owning coronary patients have higher
one-year survival rates - Elderly people with pets make fewer visits to
the physician - People with pets show less HR reactivity
during lab stressors
Exercise
* Physical exercise can protect against hippocampal
degeneration associated with chronic stress
* Regular exercise associated with reduced
physiological reactivity to psychological stressors
* Exercise can improve mood
- Has a stronger effect for people who start out in poorer
physical health
* Some evidence that walking for 2-4 hours a week can
significantly improve mood
* Mood improvements observed after even 10 minutes
of self-selected high intensity exercise
Mindfulness helps (prof skipped over this)
Controlled breathing helps
Sleep
* Sleep deprivation increases allostatic
load
- Increases blood pressure, increases
evening cortisol levels
* Chronic sleep deprivation can affect
hippocampal volumes
* Alters mood, cognitive control
* Associated with increased rates of
illness, accidents, lower life
expectancy
* 7 to 9 hours a night is considered
optimal for 18-64-year-olds
(see sleep hygiene chart (for fun))
Stress and cognitive function
- Acute stress can interfere with goal
pursuit/ learning - Stressed participants tend to fall back
on habitual behavior - Less prone to learn novel
contingencies, learn from
reinforcement - Greater working memory capacity at
baseline can protect against these
effects
Inverted U curve
