Theories & Frameworks

Pathways and Determinants Interactions

2026-02-04

Pathways from Determinants to Health Outcomes

Health outcomes result from causal pathways connecting different levels of influence:

flowchart LR
    A[UPSTREAM<br/>Policy<br/>Structures<br/>Environment] --> B[INTERMEDIATE<br/>Behaviors<br/>Exposures<br/>Stress] --> C[DOWNSTREAM<br/>Disease<br/>Disability<br/>Mortality]
    
    style A fill:#d4edda,stroke:#28a745,stroke-width:3px
    style B fill:#fff3cd,stroke:#ffc107,stroke-width:3px
    style C fill:#f8d7da,stroke:#dc3545,stroke-width:3px

Root causes → Mechanisms → Health outcomes

Example: SES → Cardiovascular Disease

flowchart TD
    U1[Low income] --> I1[Poor diet]
    U2[Limited education] --> I2[Chronic stress]
    U3[Unstable employment] --> I3[Limited healthcare]
    U1 & U2 & U3 --> I4[Smoking]
    
    I1 & I2 & I3 & I4 --> D1[Hypertension]
    D1 --> D2[Heart disease]
    D1 --> D3[Stroke]
    D2 & D3 --> D4[Premature death]
    
    style U1 fill:#d4edda,stroke:#28a745,stroke-width:2px
    style U2 fill:#d4edda,stroke:#28a745,stroke-width:2px
    style U3 fill:#d4edda,stroke:#28a745,stroke-width:2px
    style I1 fill:#fff3cd,stroke:#ffc107,stroke-width:2px
    style I2 fill:#fff3cd,stroke:#ffc107,stroke-width:2px
    style I3 fill:#fff3cd,stroke:#ffc107,stroke-width:2px
    style I4 fill:#fff3cd,stroke:#ffc107,stroke-width:2px
    style D1 fill:#f8d7da,stroke:#dc3545,stroke-width:2px
    style D2 fill:#f8d7da,stroke:#dc3545,stroke-width:2px
    style D3 fill:#f8d7da,stroke:#dc3545,stroke-width:2px
    style D4 fill:#f8d7da,stroke:#dc3545,stroke-width:2px

How Do Determinants Interact?

Understanding health requires examining how factors work together:

1. Mediators: Variables that explain the pathway (the “how”)
2. Moderators: Variables that change the strength of relationships (the “for whom”)
3. Feedback loops: Cyclical processes that amplify or reduce effects
4. Threshold effects: Tipping points where small changes produce large impacts

Mediators: Explaining the Pathway

Definition: A mediator is on the causal pathway between X and Y

flowchart LR
    E[Higher<br/>Education] --> HL[Health<br/>Literacy]
    HL --> H[Better Health<br/>Management]
    E -.-> H
    
    style E fill:#e3f2fd,stroke:#2196f3,stroke-width:3px
    style HL fill:#fff3cd,stroke:#ffc107,stroke-width:4px
    style H fill:#c8e6c9,stroke:#4caf50,stroke-width:3px

Example: Education → Health Literacy → Better Health Outcomes

“Through what mechanism does X affect Y?”

Moderators: Changing the Strength

Definition: A moderator changes the strength of the relationship between X and Y

Low Social Support flowchart TD A[High<br/>Stress] ==> B[Poor<br/>Health] style A fill:#ffcdd2,stroke:#c62828,stroke-width:2px style B fill:#ef5350,stroke:#c62828,stroke-width:3px Strong negative effect

High Social Support flowchart TD A[High<br/>Stress] --> B[Better<br/>Health] style A fill:#ffcdd2,stroke:#c62828,stroke-width:2px style B fill:#81c784,stroke:#2e7d32,stroke-width:3px Weak negative effect

“For whom is this relationship stronger/weaker?”

Feedback Loops in Health

Positive Loop (amplifying) flowchart LR A[Obesity] --> B[Inflammation] B --> C[Insulin<br/>Resistance] C --> A style A fill:#ffccbc,stroke:#d32f2f,stroke-width:2px style B fill:#ffccbc,stroke:#d32f2f,stroke-width:2px style C fill:#ffccbc,stroke:#d32f2f,stroke-width:2px Vicious cycle

Negative Loop (stabilizing) flowchart LR A[Stress] --> B[Seek<br/>Support] B --> C[Reduced<br/>Stress] C -.-> A style A fill:#fff9c4,stroke:#f57c00,stroke-width:2px style B fill:#b2dfdb,stroke:#00897b,stroke-width:2px style C fill:#c8e6c9,stroke:#43a047,stroke-width:2px Resilience

Loops explain persistent inequities (positive) and resilience (negative)

Threshold Effects

Small changes can produce sudden, large shifts in outcomes

flowchart LR
    A[Moderate<br/>Stress] --> B[Adaptive<br/>Responses]
    B -.-> C[THRESHOLD<br/>CROSSED]
    C ==> D[Burnout<br/>Depression<br/>Illness]
    D --> E[Difficult<br/>Recovery]
    
    style A fill:#c8e6c9,stroke:#2e7d32,stroke-width:2px
    style B fill:#c8e6c9,stroke:#2e7d32,stroke-width:2px
    style C fill:#fff176,stroke:#f57c00,stroke-width:4px
    style D fill:#ef9a9a,stroke:#c62828,stroke-width:2px
    style E fill:#ef9a9a,stroke:#c62828,stroke-width:2px

Implication: Early intervention prevents crossing the threshold

Types of Interventions

Effective public health requires multi-level action

flowchart TD
    A["UPSTREAM<br/>Poverty reduction<br/>Housing policy<br/>Education access"] --> B["MIDSTREAM<br/>Smoking bans<br/>Walkable neighborhoods<br/>Nutrition programs"]
    B --> C["DOWNSTREAM<br/>Medications<br/>Surgeries<br/>Rehabilitation"]
    
    style A fill:#d4edda,stroke:#28a745,stroke-width:3px
    style B fill:#fff3cd,stroke:#ffc107,stroke-width:3px
    style C fill:#f8d7da,stroke:#dc3545,stroke-width:3px

Which Level to Intervene?

Upstream interventions: Harder to implement (political will, resources) Greater population impact Prevent problems before they start

Downstream interventions: Easier to implement (medical model) Limited population impact Necessary but insufficient

Best approach: Comprehensive strategies addressing all three levels

Transition to Practice

You’ve learned the concepts:

• Pathways (upstream → intermediate → downstream)
• Mediators and moderators
• Feedback loops and thresholds
• Intervention levels

Now: Apply these frameworks to real health problems

Group Exercise: Complete the Pathway

Task: You’ll receive an incomplete pathway diagram showing an exposure and outcome. Your job:

1. Identify what mediates this relationship (variables ON the pathway)
2. Identify what moderates this relationship (what makes it stronger/weaker for different people)
3. Explain your reasoning

Time: 10 minutes of group work

Group Assignments

Snow Group: Low income → Childhood asthma

Pasteur Group: Rural residence → Type 2 diabetes

Nightingale Group: Academic pressure → Depression

Gupta Group: Discrimination → Cardiovascular disease

Fauci Group: Job loss → Opioid overdose

Instructions

1. Look at your exposure → outcome pathway
2. Brainstorm mediators: What factors are ON the pathway? (How does X lead to Y?)
3. Brainstorm moderators: What factors change the STRENGTH? (For whom is this stronger/weaker?)
4. Choose your top 2-3 for each
5. Be ready to present using the document camera (2-3 minutes)

Presenting Your Work

Each group will share:

• Your exposure → outcome
• Your mediator(s) and why they’re mediators
• Your moderator(s) and why they’re moderators
• Brief discussion of the pathway

Time: 2 minutes per group max

Key Takeaways

• Health pathways are complex and multi-level
• Understanding mediators helps us design interventions
• Identifying moderators helps us target vulnerable populations
• Feedback loops explain persistent inequities
• Effective intervention requires upstream action, not just downstream treatment

Reflection Questions

Consider for yourself:

1. What upstream determinants most strongly shape health in your own community?

2. Can you identify a mediator or moderator in your own health behaviors?

3. Where would you intervene to create the greatest population health impact?