Lecture 9 - Stress

Question 1

Stress in Canada

Answer 1

• 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

Question 2

What is stress?

Answer 2

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.

Question 3

Early Life Stress (ELS)

Answer 3

• Five general patterns observed with regard to ELS and
  mental disorders in the population:
• 1. ELS is common
• 2. ELS increases risk for developing a lifetime mental
     disorder compared to no ELS
• 3. ELS is associated with virtually all commonly
     occurring forms of psychopathology – it appears to
     be non-specific
• 4. ELS is associated with increased vulnerability to
     psychopathology that persists across the life course
• 5. ELS explains a substantial proportion of mental
     disorder onsets in the population (~30%).

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

Question 4

Real-world stressors (ex: the pandemic)

Answer 4

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%

Question 4

Empirically-supported steps to promote well-being

Answer 4

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))

Question 5

Stress and cognitive function

Answer 5

• 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