System Theories Ryan Singh, MPH H671

Krieger (1994) Describes the metaphorical “web of causation” and the missing “spider” Epidemiologic approach – bottom up, as opposed to top down No theoretic foundation, thus true cause of disease not recognized Proposes an ecosocial framework involving fractal system Calls for a renewed foundation for epidemiology – social and biologic factors interlinked

Diez Roux (2007) Social and biological factors inextricably linked in systems But how do social factors incorporate into biomedicine? 3 models: 1.Social factors as antecedents 2.Gene-environment interaction 3.Social-biologic systems

Social Factors as Antecedents Social determinants are distal precursors to more proximal biologic causes of illness Social determinants may be related to multiple health outcomes Social Processes Biologic Causes Example: Poor education as an antecedent for multiple outcomes

Social Factors as Antecedents Social determinants are distal precursors to more proximal biologic causes of illness Social determinants may be related to multiple health outcomes Social Processes Biologic Causes Understand biologic pathways and intervene here – Why?

Gene-Environment Interaction Social factors as contexts, which interact with biologic processes leading to health outcomes Particular genotype and environment dictate individual susceptibility to disease Example: HIV transmission

Social-Biologic Systems Social and biologic determinants entwined in complex system Social processes are not only antecedents, or modifiers of biologic processes, but embodied in them Example: Early adversity and toxic stress

Embodiment Krieger (2005) Organisms incorporate material of social world into biology (in utero  death) Humans as social beings and biologic organisms Need for integrative approach at all level of influence to affect behavior change and health outcomes

Social-Biologic Systems Both the antecedent and gene-environment models are part of the holistic system model Key features: Independent units Parts that directly influence one another Emergent properties Properties of the system that arise from the functioning of its interdependent units  Non-linear relationships  Feedback loops  Dynamic instability

Diez Roux (2007)

Glass & McAtee (2006) Inequity persists in health outcomes after accounting for individual-level risk factors Health behaviors are not the result of unconstrained choices Linear, proximal models are limited Social and biologic relationships remain a mystery Adapt the “stream of causation” into a 3D metaphor Interactions of social and biologic determinants over life-course Applicable to individual and population Focus on meta-theoretical level Embodiment as integrating concept of 2 systems Feedback mechanisms and cross-level influence Influence smaller scale theories

Remind you of something?

What is different between the two models?

Disease Causation Debate Attributes (age, race, sex, social class) not causally meaningful, but proxy measures of more complex processes True fundamental causes are biologic and proximal to poor health  Need for a more integrated causative model  Health behaviors shaped by social determinants above the individual in conjunction with biologic influence within the body Powerful levers – regardless of causation, important to identify and target uphill population-level determinants

Risk Regulators Risk regulators – relatively stable feature of a particular patch of the social and built environments, residing at levels of organization above the individual, but below larger-scale macro-social levels Influence multiple pathways to behavior and then health outcomes Remind you of something?

Risk Regulators  Behavior results from interaction between opportunities, constraints, and biologic expression 1.Influence behavior 2.Mediating paths of exposure 3.Symbolic exposure Regulate biological expression

OBESITY

Huang et al. (2009) Implications of obesity epidemic causation: 1.Single cause unlikely 2.Factors that give rise to larger body size probably involved combination of factors at multiple levels of influence 3.Small changes of key factor(s) may be highly impactful in non-linear path 4.Account for both social and biologic causative pathways

Class Discussion Form 2 groups: 1.What is the benefit of including direct streams of influence at the proximal level? 2.Does a broad focus of risk regulators alone outweigh the benefit of a more integrated model? 3.Discuss how Glass and McAtee’s systems model can be applied to a given health problem (cannot choose obesity). Discuss how the TTI can be applied to that same health issue.

24 DECISIONS/INTENTIONS SOCIAL S ITUATION BIOLOGY/ P ERSONALITY THE THEORY OF TRIADIC INFLUENCE ATTITUDES TOWARD THE BEHAVIOR CULTURAL E NVIRONMENT SOCIAL NORMATIVE BELIEFS Trial Behavior EXPERIENCES: Expectancies -- Social Reinforcements -- Psychological/Physiological SELF-EFFICACY BEHAVIORAL CONTROL Nurture/CulturalBiological/Nature Intrapersonal StreamSocial/Normative StreamCultural/Attitudinal Stream Distal Influences Proximal Predictors Levels of Causation Ultimate Causes Social/ Personal Nexus Expectancies & Evaluations Affect and Cognitions Decisions Experiences a b c d e f g h i j k m n o p q r s t u v w x Related Behaviors J K C F I B E H A D G