The DemandControl Model Highlights and Future Directions: The StressDisequilibrium Theory

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The Demand-Control Model Highlights and Future
DirectionsThe Stress-Disequilibrium Theory

• Robert Karasek, Ph.D.,
• Work Environment Department, University of
  Massachusetts Lowell, USA
• 2nd Danske Stressforskningskonference,
• Copenhagen, November 2005

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The Demand/Control Model ...
Psychological Demands
Low
High
High
Hypo. 2 Motivation, Active Learning
Active
Lo Strain
Lo Strain Lo Strain
Decision Latitude
Hypo. 1 Illness Risk
Passive
Hi Strain
Low
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FIGURE 2 The Stress Models Demand/Control -
STRAIN
MODERATORS
Job CONTROL
Job Social Support
(--)
NEG. EMOT,
()
STRESSORS
STRAIN
JobDEMANDSS
Personality
Demograph
Job Insccurity
INDIVID.DIFF.
Job Phys. Demand
CHRONIC DISEASE
Family Demands
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FIGURE 3 The Stress Models Full D/C Model
Strain / ACTIVE
ACTIVE BEHAVIOR
MODERATORS
Job CONTROL
ACTIVE
Job Social Support
()
()
(--)
NEG. EMOT,
()
STRAIN
STRESSORS
JobDEMANDSS
INDIVID.DIFF.
Job Insccurity
Personality
Demograph
Job Phys. Demand
CHRONIC DISEASE
Family Demands
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CANONICAL CORRELATION ANALYSIS Swedish Standard
of Living Study 1968Employed Males Age 18 66
(n 1865)
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Epidemiological Evidence for Three Work-Related
Chronic Disease Conditions

• Belkic et al (2004) reviews of 46 CVD Studies
• Scand J Work Environ Health, 30285-128
• In addition to the strong, consistent evidence
  of an association between exposure to job strain
  and CVD, many other elements of causal
  inference, particularily biological plausibility,
  have been shown in this review to support the
  conclusion that job strain is indeed a major CVD
  risk factor(p 117)
• Bongers et al (2002) 28 musculoskeletal
  disorders(MSDs) studies
• Am J Ind Medicine, 41315-342
• It was concluded that monotonous work,
  high-perceived workload, a time pressure are
  related to musculoskeletal symptoms. The data
  also suggest that also low control on the job and
  poor social support may be associated to the
  development of the disease. Almost 10 years later
  and with a more systematic approach to the
  reviewing process, the conclusion are similar
  with the exception that no support was found for
  the role of monotonous workand job demands more
  cautiously interpreted(p 329)
• Van der Doef and Maes (1999) review of 63 mental
  strain studies
• Work Stress, 13287-114
• 28 out of 41 studies on General Psychological
  well-being supported DC model
• 28 out of 42 studies on Job-related well-being
  supported DC model

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D-C Model Boundaries of Theory

• INCONSISTENCIES? - MODEL THE FULL SYSTEM
• 1. Leisure/Political Activity70s Urban,
  employed
• 2. National labor relations assumed 1970s
• - Now global neo-liberal economy
• 3. Disease models CHD, Mental Distress
• a. etiological model slow vs. fast follow-up
• b. MSD limited variance job samples
• 4. Psychosocial explanation of social costs and
  benefits Beyond economic calculus

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Convergence of Job Characteristics in Global
Economy.Evidence from JCQ international
comparative research on scales for job control,
demands, support, and insecurity

• Great similarity of means and standard deviations
  - in full occupation spectrum samples across
  countries
• (not in class subgroups)
• 2. Between-occupation scale variance much greater
  than
• between-country variance
• - (full occupations spectrum samples)
• 3. Great similarity of correlations between JCQ
  scales
• (control, demand, support, etc.) across
  countries
• - except for psychological demands
• 4. Great similarity of Cronback alpha statistics
  across countries
• (full occupational spectrum, not within class
  subgroups)
• 5. Similar JCQ operation in Formal Sector
  Informal Sector
• (in developing countries semi-urban Brazil)

1.
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Between occupational class variations of control
and demands by gender

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A Second Social Class Perspective PSYCHOSOCIAL
JOB CHARACTERISTICS - VS. INCOME
I
II
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Occupational class gradient and Job strain axis
in JACE-JCQ data (Choi and Karasek et al., 2004)
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Stress, Class, Low Control Disease

• Increasingly inverse social class gradient in
  health
• Path I Low status, Absolute Deprivation
• Path II Social inequality, Relative
  Deprivation
• Stress-related morbidity based on sympathetic
  over-arousal from psychosocial demands cannot
  explain it
• Higher work-related psychological demands at
  high status
• Relative Inequality may not explain much of it
• Substantial low control-related
  morbidity-even in relatively income-equalized
  societies
• A STRESS-DISEASE MODEL BASED ON LOW CONTROL
  (Absolute)
• Supplements material deprivation,
  mental-load stress, and status inequality

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Job strain, Cardiovascular Disease and CVD Risk
Factors(Landsbergis, 1/1999)

• ? 72 studies published between 1981 and 1998
• ? 36 studies of CVD (2 of all-cause mortality)
• ? 25 found significant associations with job
  strain
• ? 11 of 19 cohort studies had significant
  associations

• ? Low job decision latitude
• some positive associations in 35 of 46
  studies
• ? High Job demands
• some positive associations in 14 of 40
  studies
• inverse associations in 5 recent studies
• ? Low social support
• positive in 5 of 13 studies

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Definitions of Work and Control-Internal and
External
A. Hypothesis 1
v 
Work External Stressors, Allostatic
Challenge
Work Internal Homeostatic Regulation
Allostatic Regulation


B. Hypothesis 2


?
Control External
Control Internal
External Environment
Internal Environment
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Back to the Reptiles?
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From the 1st Law to the 2nd Law..

• FIRST LAW OF THERMODYNAMICS
• Conservation of Energy
• Count calories-gt Run around track -gtLoose weight
• ? - To Conquer our Exhaustion in the Global
• Economy, could we just Eat More Food - ?
• SECOND LAW OF THERMODYNAMICS
• Limits on Ordering capacity

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ORDERED AND DISORDERED ENERGY - - - -
Definitions

• 1. Work is ordered energy with few degrees of
  freedom. An example is the steam engine's piston
  all energy is channeled to one direction of
  motion which is predictable and usable (another
  example, the speeding bullet).
• 2. Disordered energy - heat - has many random
  degrees-of-freedom It's energy is undirectable,
  and less useful to do work.
• 3. The disorganization component of energy is
  called Entropy. Its opposite, an ordering
  capacity for energy, is sometimes called
  Neg-Entropy (which becomes Work when energy is
  "added" - roughly).
• 4. 2nd Law of Thermodynamics yields Efficiency
  Criteria which limit the amount of Heat Energy
  that can be transferred into Work as useful
  action (typical 25).
• 5. In biology much Work exists in the form of
  Stored Energy of Chemical Bonds.

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The Dual Goal of CNS Regulation External Action
Internal Control
Protecting the Stability of The Internal
Homeostatic Regulatory Environment
CNS
Path II.
Homeostatic Regulation Limits 1. Blood O2
1ltxlt2 2. Body Temp 3. Blood CO2 4. Blood pH
1ltylt2 5.
_at_R. Karasek 10-02, Unpublished
Autonomic NS, and Hormone Regulat.
Environ-mental Demand
Personal Adaptive Action
Allostatic Regulatation 1. Adrenaline 2.
Metabolic 3. Resting 4. Noradrenaline
Path I.
Using Allostatic Resources
I. EXTERNAL ALLOSTATIC CHALLENGES
II. INTERNAL HOMEOSTATIC CHALLENGES
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The Stress Model System, Environment
ControllerAdapting the Standard Thermodynamic
Model

• Figure 1 Entropy Flows - Standard Thermodynamic
  Model

Figure 1b Entropy Flows - Extended Stress Theory
with Controller

• "A Central Controller" is needed to adapt Stress
  Theory to Thermodynamics.
• Complex organisms modify their boundary
  conditions (flows), to maintain equilibria.
• This requires two new flows of Neg-Entropy Flow
  3 and Flow 4

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Ashby's Theory of Requisite Variety Cybernetics,
1956
The goal of Regulation is to block the flow of
variety from the organism's environment which
would disturb its internal variables. "The
perfect thermostat would be the one that, in
spite of disturbance, kept the temperature
constant at the desired level. The Law of
Requisite Variety Only variety in the Regulator
(R) can force down variety in the Environment
(D) Only variety can destroy variety."
Ashby's Proof is a logically general game theory
example R's goal is to insure selection of
a specific desired set of outcomes ( k). D moves
first. Response pairs (R,D) (1,C) (2,A)
(3,B) (9,A) Outcome of game k k
k l Only variety in R's moves can
force down the variety in the outcomes.
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Climbing up - and Moving Down the
Neg-Entropy Hill
Ashby's Regulator "Etch-a-Sketch" CNS "Central
Controller"
Environmental challenges
General Energy
External Work
Light ? Photo- Synthesis ?Glucose, Monomers
Stored Energy Creates 'Constraints
Physiological Sub-systems' Actions Coordinated
Creating Ordering Capacity from Random Energy -
the "Neg-Entropy Pump" - Flow 4
Using Up Ordering Capacity- Facilitating External
Work - Flow 3
Flow 2
Flow 1
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Core of the New HypothesisHigh Level Control
Capacity is created - via Multi-Level
StructureA Negative-Entropy Pump

• a. First, Random Energy at a Low Structural
  Level is transformed into Work in the form of
  Stored Energy. This Structured, Stored Energy is
  used to create "Constraints on Action" - which
  are structures which limits on the
  degrees-of-freedom in the organism at the Next
  Higher Level of Structure. (For example Enzymes,
  promote certain very specific chemical reactions
  at the level at which they are active. Their
  creation occurs at a level below and requires a
  large random energy input at that level to create
  the Stored Energy which they embody).
• b. In the Second Step, the Constraints allow
  the Higher Level to covert large inputs of Random
  Energy into Work large in scale and complex which
  is Constrained to operate within few Degrees-of
  Freedom. Thus organized Work at the Higher Level
  - which is both larger in magnitude and precision
  of effect than achievable in a single level
  transformation - has been created in a two-step
  process, starting with energy input at the Lower
  Level.
• c. This process can "Pump" Neg-Entropy from a
  lower level, to a higher level, at the
  appropriate efficiency costs. In this way one
  might preliminarily speak about Low Level and
  High Level Negative Entropy.
• d. At the Highest Level, a "Controller" can
  control all the resources of the organism at all
  its levels when it undertakes Work, because all
  the Lower Level contributions are the Necessary
  Supports for the higher levels.

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The Biomass Pyramid The Food Chain
Campbell,
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Status of the Evidence 2nd Law Control Capacity
Limit Evidence Through Seven Levels of a Human
Physiological Function
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Campbell and Reece, Biology, 7th edit, 2005, p.
153
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Heart Rate Variability Project

• Overall Goal assess the effect of job stress on
  cardiovascular health via ambulatory ECG
  monitoring
• Robert Karasek, PhD, Department of Work
  Environment, University of Massachusetts Lowell
  initiated the project in 1996
• Kevin Costas, MPH, Doctoral Candidate, Department
  of Work Environment involved since projects
  initiation
• Sean Collins, ScD, Department of Physical
  Therapy, University of Massachusetts Lowell,
  involved since 1997
• HRV Project Collaborations
• Dr. Ira Ockene, University of Massachusetts
  Worcester
• Philip Merriam, University of Massachusetts
  Worcester
• Dr. Robert Mittleman, University of Massachusetts
  Worcester
• Dr. Thomas Bigger Richard Steinman, Columbia
  University
• Dr. Ronald Berger Barry Fetics, Johns Hopkins
  University

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HRV Project Design

• 1. Males, age 40-60
• 2. Normal subject (no CHD, no CHD
  medications)
• 3. Screened with Job Content Questionnaire
• (job strain selection as noted)
• 4. 48 hour monitoring (Friday work
  day/Saturday rest day)
• 5. Diary Four times/day (2 times at 20 min.
  intervals)
• 6. Mental arithmetic (telephone) evening after
  dinner
• (r12 min, 2 min, r12 min)

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High Frequency Power by Job Control
HRV Project Collins, Karasek, and Costas, 2005
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High Frequency Power by Job Strain
HRV Project Collins, Karasek, and Costas, 2005
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Residual Heart Rate by Job Strain
HRV Project Collins, Karasek, and Costas, 2005
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Conclusion

• The effect of low control on internal
  self-regulation could be Both External and
  Internal
• I. Low External control could restrict the
  individual's external action strategies - cutting
  off his/her Ashby response matrix - Due to
  external organizational constraints of modern
  economic and organization
• II. Low External control prevents the development
  of internal Ordering Capacity
• (a) low level inputs are not synthesized,
• (b) homeostatic contexts are not maintained,
• (c) translation of inputs into effective
  higher level action platforms is not
  accomplished.
• - Due to a myriad of social determinants
  dietary emphases, sleep hours, unpredictable
  rest fractured emotional relationships, lack of
  daily equilibrium, etc.

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A High Level Theory of Disease

• A general, "high level theory" functionality or
  control capacity limits - at any level - can be a
  sufficient explanation of disease - without
  contribution of lower level causes.
• Thus, high level failures of control capacity
  could be themselves sufficient to explain
  disease.
• (a) In the LONG TERM, LINKAGE exists between
  levels
• - contributing to high level ordering capacity.
• BUT ..
• (b) In the SHORT TERM, levels can be
  INDEPENDENT
• - implying vulnerability at the higher levels
• Overwhelmed control capacity for the organism
  as a whole could cause failure of high level
  functions first - without low level failure.
• Thus, social organizational changes in control
  structures could have DIRECT health promoting
  effects.

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Effect of Work Organization on Physiological
Regulation
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JCQ 2.0 Macro Decision Latitude.

• ADDITIONAL CONCEPT
• the job" - a long -term platform for life and
  family development. Addresses the EQUILIBRIUM OF
  FLOWS from 2nd-Law and reflects workers
  maintainance of an easy equilibrium.
• THIS BROADER FORM OF "CONTROL" IS
• the freedom to act using your repertoire of
  skills, within the social structures where you
  have made your social investments, and where your
  get your major life-sustaining rewards

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New Directions and Hypotheses

• I. New Directions
• A. Not just molecular biology..
• B. JCQ 2.0 - Global Economy - measure it
• II. Physiological Implications
• A. HRV Methods Workshop
• B. Test physiol. shifts HRV, Glucose, ..
• C. Test short-term, high level depletion risk
• D. Test multi-system equilibrium shifts
• III. Broad Socio-Economic
• A. International forums soft costs of globaliz.
• B. New Political Economy de-emphasizing
• Material production surplus
• Economies of scale.

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JCQ International Project Social cost of poor
work organizationJuly 15, 2004 Robert Karasek
and Bongkyoo Choi
Possibly other JACE sites and other developing
countries will be joined