midterm Flashcards
biomedical model
doesn’t include psychological issues
biopsychosocial model
- bidirectional
- whatever sickness you have can be subtle but will effect even your brain
Galen
-realized that certain traits coincided with certain illnesses
Phases of mind-body research
- 1st: case histories
- 2nd: documented assoc b/w stress and illness/death
- 3rd: documented assoc b/w stress and changes in physiology
- 4th: multivariate models linking stress and health, including risk factors; focus on mechanisms relevant for particular diseases
Stress systems
- 2 key stress systems
1. Autonomic nervous system (ANS)
2. Neuroendocrine system (HPA axis)
ANS
- involuntary, innervates internal organs
- regulates things like breathing, digestion, heart rate, temperature, etc.
- two branches: sympathetic (stress) parasympathetic (peace)
Sympathetic nervous system
- fight or flight system
- key hormones: Norepinephrine (NE) and epinephrine (E)
Parasympathetic Nervous System
- rest and digest system
- key hormone: acetylcholine
measures of ANS functioning
- cardiovascular (BP/heart rate)
2. E and NE concentrations in urine/blood
HPA axis
- activated by physical and psychological stress
2. end product: release of glucocorticoids (cortisol in humans) from adrenal glands
what activates physical/psychological stress?
- physical injury
- hunger
- internal bleeding
- uncontrollability
- unpredictability
what does cortisol do?
- helps to mobilize energy
2. modulates aspects of stress response
CRF/CRH
corticotropin releasing factor/hormone
ACTH
adrenocortico-tropic hormone
Regulators of HPA axis
- CRF/CRH
- ACTH
- negative feedback (shuts itself off)
- diurnal rhythm (peaks in morning)
cortisol collection
- blood
- urine
- saliva
what to look at in collecting cortisol
- total output
- diurnal rhythm
core of stress response
- mobilize energy to help muscles work (glucose metabolism)
- transport energy to where it is needed (inc heart rate, BP, breathing to transport glucose)
- turn off long-term projects (no digestion/reproduction)
stress is adaptive if
dealing with short term physical stressors requiring energy mobilization
allostatic load
wear and tear resulting from chronic overactivity or underactivity of stress system
general stress def
environmental demands that tax or exceed the adaptive capacity of an organism
how to conceptualize stress
- something that happens to you
- how you feel about something
- how your body responds to it
((or all three))
event-based
- something that happens to you
- focus on objective, observable events that are normatively assoc with substantial demands
- measured by checklist or interview
life events and difficulties schedule (LEDS)
- 2 hr structured interview asking about stressors in 10 domains of life
- presented to panel of raters who make a contextual rating of the event
pros of event list
- cover major/minor events that might have impact on health
2. interviews can provide detailed information on stressor characteristics (i.e. timing, chronicity and domain)
cons of event lists
- don’t take into account context of event or meaning for individual
- verty time intensive and costly
stress perceptions/ subjective experience
- how you feel about it
- perception that demands exceed one’s ability to cope
- perceived stress scale
pros of stress perceptions
gets closer to person’s individual exp
cons of stress perceptions
colored by mood and personality, which may confound assoc with health
biological stress assessment
- body’s response to an event or experience
- > inc in SNS &/or HPA activity - GOLD STANDARD IN ANIMAL STUDIES
problems with studying stress
- lack of agreement on what is stress and how to measure it causes big problems
- studies typically use diff measure of stress, leading to diff outcomes
- > assoc may depend on type of stressor
experimental study
- ideal
2. manipulate variable of interest, look at effect on outcome
randomly assign lab animal to stress vs no stress condition and look at effects on cancer development and progression
- experimental
- looking at x->z
- to look at x->y look at biological mechanisms with this design
observational studies
- no manipulation of study variables
2. these designs can provide evidence of links b/w stress and disease in humans (x->z pathway)
cross-sectional
- an observational study
- predictor and outcome variables assessed at same time
longitudinal
- an observational study
- predictor variable assessed first, outcome variable assessed at later time
experimental study
- independent variable is manipulated
- can provide evidence that stress causes diseases in animal models (x->z)
- can be used to examine links b/w stress and physiological changes relevant for disease in human studies (x->y)
atherosclerosis
- caused by inflammation of the lining of the blood vessels (endothelium)
- endothelial cells are irritated or damaged by high BP
inflammation
the basic way the body responds to damage, injury or infection
initial stages of atherosclerosis
- inflammatory response in the inner layer of blood vessels
- monocytes recruited to area
- fibrous cap forms on top of area
- tissues are plaques which thicken the arterial wall and can obstruct the flow
acute events
- if plaques rupture this can be bad: heart attack/stroke
heart attack
if plaques block blood flow to heart
stroke
if plaques block blood flow to brain
timing CVD
- starts in childhood and continues throughout adult life
- >fatty steaks and clinically significant lesions inc dramatically during ages 15-34
risk factors for CVD
- high cholesterol
- high BP
- smoking
- diabetes
- high fat diet
- lack of exercise
- stress?
stress and CVD
- conduct large scale study, see whether those who report more stress have more CVD related events
stressors of interest for CVD
- work stress
- bereavement
- social isoltation
- childhood stress
MRFIT study
12,236 men without evidence of CVD but with elevated risk
- assessed 7 types of work related stressors over 6 yr period
- also assessed seperation/divorce
- followed for nine years
MRFIT study results
- men with 3+ work stressors had elevated risk of CVD-related mortality
- men who seperated/divored also had elevated risk of CVD related mortality
vacations and CVD
- vacations reduced it
job strain and cvd
- job strain is the most common type of work-related stress studied
- combination of high demand and low control
combining across studies of job strain and CVD
- many studise examined job strain and CVD
2. meta-analysis yields an ave effect size measure
metaanalysis CVD 1
- effect is 1.2 significant effect of job strain (20% inc risk)
- effect remains sig controlling for health behaviors
updated review of stress and CVD
- hazard ratio of 1.2-1.4 for job strain
2. can compare that to HR of 2+ for other risk factors like high bp, smoking and high BMI
other stressors linked to CVD
- childhood stress
2. social isolation
BP as a Y for CVD
- well BP is a risk factor b/c of its relevance to atherosclerosis
- stress also leads to heightened BP
stress reactivity and CVD evidence
- 756 finnish men
- CV stress response assessed using lab stress tasks
- memory, rxn time, tracing and stroop color-word tasks
- atherosclerosis assessed at 4 yr and 11 yr visits
- results
a. cross sectional: larger BP response, higher carotid IMT -> more artherosclerosis
b. longitudinal: larger BP response -> more rapid inc IMT over time
non invasively measuring atherosclerosis
carotid intima-media thickness (IMT)
pittsburgh healthy heart project
- 340 older adults
- electronic diaries every 45 mins for 3 days
- asked about task demands and decisional control
-also assessed IMT - more demands were assoc with higher bp daily life
- more demands were also assoc with greater IMT
THEREFORE INC BP, INC IMT
does stress trigger heart attacks in ppl with underlying cvd?
- acute stressors are strongly assoc with cardiac events in high risk pops and those with CVD
- may involve diff mechanisms
Control Groups
used to rule out or weaken rival hypotheses or alt explanations
alt explanations
- ruled out by control groups
- history/ maturation: improvement over time
- improvement as a result of completing assessments
- improvement as a result of receiving some kind of treatment, doesn’t depend on actual treatment received