L21 - Stress Flashcards
What is stress?
a response to a PERCEIVED averse or threatening situation.
It is associated with feelings of being overloaded, tight, tends and worried.
and be +ve or -ve, exciting motivation // harmful for health and function.
- PERCEIVED LACK OF CONTROL OVER STRESSOR - negative stress
- some control - positive stress - thrill seeking
What are the different types of stress?
- Acute stress - represents a single event that leads to increased flight or fight response, raising levels of arousal.
- Episodic Acute stress - Repeated acute stress often reflects a personality type that either cause their own stress (by living overcomitted chaotic lives) or worry more than they should about normal events - personality traits - how people interact with the world
- Chronic stress - seemingly endless and uncontrollable. eg. dysfunc family, living in a war zone, repeated exposure to trauma, severe financial hardship
What are different situations for stress in mice?
- immobilisation
- restraint
- maternal seperation
- predator odor
- elevated platform
- social defeat
—–> done with both acute and chronic stress
chronic = repeated longer events.
What are the effects of acute stress on the brain?
- interactions b/w brain and body
- optimal performance requires a balance, function is impaired with too little or too much stresss. inverted U shape
- moderate levels of stress = aroused and optimal functioning of the PFC allowing top-down regulation of though, actions and emotions.
- high levels of stress = arousal increases and overwhelms and impairs function of prefrontal cortex, and releasing the influence of emotional responses, habitual action and bodies arousal response, clouding alertness and rationality.
- Hypothalamus is stimulated by the symp NS, triggers emotional responses in the brain > activates pituitary gland > activates adrenal cortex > released cortisol and adrenaline increasing metabolism, blood flow, hear-rate (flight/fight readiness).
this is a perceived, conscious, high level calculation about the potential threat, triggering this response.
What does cortisol do?
It’s a glucocorticoid, increases the glucose metabolism (which is energy that drives the body, thus increasing energy), and can be detected in the blood as a measure of physiological stress.
What are the effects of chronic stress?
- long term changes.
amygdala
- number and strength of neural connections increases - emotion centre becomes more active
hippocampus
- number and strength of neural connections reduces reduces - decreasing memory and storage ability
prefrontal cortex - number and strength of neural connections reduce - executive function lessens, eg. extinguishing fear
What does it mean to say that stress causes primitive brain to become strengthened?
- exposure to stressors causes chemical changes in the brain that impair higher cog funcs while strengthening primitive brain reactions.
- people become more emotionally reactive with impaired rational thinking!
How can stress increase sensitivity to stress?
Impaired emotional and memory function may reduce FLEXIBLE EMOTIONAL PROCESSING and reduce SEPERATION between memories causing OVERGENERALISATION and LESS CAPACITY TO COPE with the real or potential stressful events.
- normal person will interpret ambiguous input as benign, while a stress person may interpret it as aversive due to overgeneralisation
What are the effects of stress on the body?
the release of cortisol / glucocorticoids triggers..
acute effects
- increased energy availability in muscles, breaking down fats and proteins to glucose.
chronic effects
- suppression of immune system
- high blood pressure
- reduced fertility
–> these all perpetuate more stress
Why are we evolved to get stressed?
acute stress - helps animals to respond to threats to their survival - flight/fight. improves survival in immediate danger
chronic - effects of early stress on an individual are negative - leading to increased antisocial behaviour, aggression and/or social isolation - some suggest that this might be beneficial to prepare humans for adversity later in life, through agression, fight readiness and extreme social mistust for eg. if a population lived in a -ve environment
What are genetic and environmental influences of stress?
- both genetics and enviro play a role
- although stress-inducing events are predictable and generalisable in the population, the degree to which people are affected varies with each individual - genetic?
- hot environmental temps linked to higher crime and violence – enviro
- financial crises lead to higher levels of violence against women and children - enviro – absence of resources impacts ability to logically deal with enviro
PTSD?
PTSD
caused by experiencing or witnessing death/serious harm - actual or threatened
associated with recurrent dreams, panic attacks and flash backs, and poor mental and physical health
both enviro and genetic risk factors in PTSD
can impact brain structures - smaller hippocampal volume seen in PTSD .. but can also be found in their non stressed twin. PREDISPOSITION?
There is a relationship of PTSD and number of experiences = enviro influence
THE FEELING OF IMPENDING DOOM WHEN THERE IS NO STIMULI
Stress and psychiatric disorders?
- PTSD
- Depression - similar brain areas implicated in depression and chronic stress , considered a stress-related disorder
- scz and bipolar - stress triggers increased severity of symptoms
alzheimers - women w seriosu stressors in middle age more likely to develop memory impairments
maybe stress leads to less sleep… not healthy
Meditation and stress response?
Mindfulness-based stress - non reactive purposeful monitoring of the moment-to-moment content of experience
moderately improves depression, anxiety, distress, stress and QOL in healthy populations
may reduce stress by increasing cognitive flexibility and tolerance for uncomfortable physical stress/anxiety sensations. could reduce escalation of physical symptoms and hyperarousal and perception of threat
How is stress a brain behaviour cycle?
early life stressors > epigenetic changes resulting in lasting changes > impairs decision making and health > leading to more negative behaviours and life circumstances
