The Demand-Control Model Highlights and Future Directions: The Stress-Disequilibrium Theory

1. The Demand-Control ModelHighlights and Future Directions:The Stress-Disequilibrium Theory Robert Karasek, Ph.D., Work Environment Department, University of Massachusetts Lowell, USA 2nd Danske Stressforskningskonference, Copenhagen, November 2005

2. 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

3. FIGURE 1: The STRESS Model NEG. EMOT, (+) STRESSORS Job DEMANDS Demography Personality Job Insecurity INDIVID.DIFF. Job Phys Dem. CHRONIC DISEASE Family Demands

4. FIGURE 2: The Stress Models: Demand/Control - STRAIN MODERATORS Job CONTROL Job Social Support (--) NEG. EMOT, (+) STRESSORS STRAIN JobDEMANDSS Demograph Personality Job Insccurity INDIVID.DIFF. Job Phys. Demand CHRONIC DISEASE Family Demands

5. 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 Demograph Personality Job Phys. Demand CHRONIC DISEASE Family Demands

6. CANONICAL CORRELATION ANALYSIS Swedish Standard of Living Study 1968Employed Males Age 18 – 66 (n = 1865)

8. Epidemiological Evidence for Three Work-Related Chronic Disease Conditions Belkic et al (2004): reviews of 46 CVD Studies Scand J Work Environ Health, 30;2:85-128 “…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, 41:315-342 “…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 work…and job demands more cautiously interpreted”(p 329) Van der Doef and Maes (1999): review of 63 mental strain studies Work & Stress, 13;2:87-114 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

9. D-C Model: Boundaries of Theory INCONSISTENCIES? - MODEL THE FULL SYSTEM: 1. Leisure/Political Activity’70’s: Urban, employed 2. National labor relations assumed 1970’s - 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

10. Convergence of Job Characteristics in Global Economy:.Evidence from JCQ international comparative research on scales for job control, demands, support, and insecurity: 1. • 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)

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

12. A Second Social Class Perspective: PSYCHOSOCIAL JOB CHARACTERISTICS - VS. INCOME I II

13. Occupational class gradient and Job strain axis in JACE-JCQ data (Choi and Karasek et al., 2004)

14. 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

15. 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

16. Definitions of Work and Control-Internal and External A. Hypothesis #1: √  Work ExternalStressors, Allostatic Challenge Work Internal Homeostatic Regulation Allostatic Regulation B. Hypothesis #2: ? Control External Control Internal External Environment Internal Environment

17. Back to the Reptiles?

19. From the 1st Law to the 2nd Law.. FIRST LAW OF THERMODYNAMICS = Conservation of Energy: Count calories-> Run around track ->Loose weight ? - To Conquer our Exhaustion in the Global Economy, could we just Eat More Food - ? SECOND LAW OF THERMODYNAMICS = Limits on Ordering capacity

20. 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.

21. UNCONTROLLED DEMANDS 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: :1<x<2 2. Body Temp: 3. Blood CO2 4. Blood pH: 1<y<2 5. … @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

22. "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 Flow1 Environment Neg-Entropy Flow1 Environment System Flow2 System Neg-Entropy Flow 4 =? Neg-Entropy Flow3 Neg-Entropy Flow 2 Controller The Stress Model: System, Environment & Controller:Adapting the Standard Thermodynamic Model Figure 1: Entropy Flows - Standard Thermodynamic Model Figure 1b: Entropy Flows - Extended Stress Theory with Controller

23. Table 11/5/1 Ashby, Rmove #A #B #C #1 f f k #2 k e f Dmove #3 m k a #4 b b b #5 c q c #6 h h m 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.

24. 1 A B C 2 3 Action-Possibilities 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

25. Core of the New Hypothesis:High Level Control Capacity is created - via Multi-Level Structure:A “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.

26. The Biomass Pyramid: The Food Chain Campbell,

27. Status of the Evidence: 2nd Law Control Capacity Limit Evidence Through Seven Levels of a Human Physiological Function

28. Campbell and Reece, Biology, 7th edit, 2005, p. 153

29. 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

30. 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 (r=12 min, 2 min, r=12 min)

31. High Frequency Power by Job Control HRV Project: Collins, Karasek, and Costas, 2005

32. High Frequency Power by Job Strain HRV Project: Collins, Karasek, and Costas, 2005

33. Residual Heart Rate by Job Strain HRV Project: Collins, Karasek, and Costas, 2005

34. 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.

35. 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 thehigher 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.

37. 2-h. System Environment Challenge Controller Response Restructuring Of Work Sub-systems Internal Control Capacity vs. External Control Demands Effect of Work Organization on Physiological Regulation

38. 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”

40. 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.

41. 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