L2: Health and Ageing: Core Concepts and Transitions

Learning Objectives

• Disability related services at USyd

• Overview of Lecture 1

• Indicators of health

• Changing pattern of health illness and disease

• Theory of demographic transition

• Theory of epidemiological transition

• Theory of gerontological transition

• Determinants of diseases and change in disease and disability patterns

Key Concepts and Definitions

What is International Health?

International health examines health conditions in countries outside national boundaries, focusing on political and economic forces impacting health inequalities and the role of international organizations.

Differences between Public Health, International Health, and Global Health (Adapted from Koplan et al., 2009)

These domains are distinguished by:

1. Geographical Reach: Public Health (national/community), International Health (low/middle-income countries), Global Health (transcends national boundaries).

2. Level of Cooperation: Public Health (national), International Health (bi-lateral), Global Health (multi-lateral).

3. Key Actors: Public Health (government departments), International Health (international aid agencies, government), Global Health (international aid agencies, government, non-state actors).

Key Concepts of Globalisation

1. Globalisation: Free flow of goods, services, capital, technology, and labor among nations, increasing interconnectedness.

2. Liberalisation: Relaxation of government restrictions on economic and social policies (e.g., reducing trade barriers).

3. Privatisation: Involving the private sector in ownership or operation of state-owned/public undertakings.

Indicators of Health

Health is assessed using:

1. Life Expectancy: Average years a newborn expects to live (e.g., Japan, Australia typically high).

2. Infant and Under-Five Mortality Rate: Deaths per $1,000$ live births for under 1 and under 5 years, reflecting health and socio-economic conditions.

3. Mortality (Deaths): Crude, Age-Specific, and Cause-Specific Death Rates per $100,000$.

4. Risk Factors: Attributes increasing disease/injury likelihood (e.g., smoking, unhealthy diet).

5. Morbidity (Disease and Disability): Prevalence and incidence of disease/disability.

6. Health Service Coverage: Proportion of population receiving essential health services.

Theory of Demographic Transition

Explanation

This theory describes the shift in population size and age structure due to changing birth and death rates, focusing on fertility and mortality dynamics.

Four Stages of Demographic Transition

1. Stage 1: High Birth and High Death Rates (pre-industrial).

2. Stage 2: High Birth and Declining Death Rates (population explosion due to public health improvements).

3. Stage 3: Declining Birth and Low Death Rates (industrialization, urbanization, family planning).

4. Stage 4: Low Birth and Low Death Rates (minimal or zero population growth, possible decline).

Australian Context

Australia shows declining fertility since the $1960s$ and consistent mortality decline, leading to slower growth in younger groups and an increase in the older population.

Global Fertility Trends

Global fertility dropped significantly (from $4.9$ to projected $2.0$ children per woman by $2045-2050$), with developed regions below replacement levels and regional differences expected to decrease.

Reasons for Decline in Fertility

Factors include bio-physiological health, socioeconomic changes (children as expensive dependents, women's opportunities), and psychological factors (personal goals over large families).

Mortality Trends

Globally, people live longer, but life expectancy varies greatly. More people survive to older ages, and the female advantage in life expectancy has widened.

Limitations of the Theory of Demographic Transition

It doesn't fully account for policy impacts (e.g., China's one-child policy), cultural contexts, or modern challenges like HIV/AIDS, tending to describe Western patterns primarily.

Theory of Epidemiological Transition

Explanation (Omran, 1971)

This theory describes the shift in dominant causes of death from infectious diseases and famine to non-communicable, degenerative, and man-made diseases as societies develop.

Three Stages of Epidemiological Transition

1. The Age of Pestilence and Famine: High fluctuating mortality, low life expectancy ($20-40$ years), deaths from infectious diseases, malnutrition.

2. The Age of Receding Pandemics: Declining mortality, increasing life expectancy ($30-50$ years), sustained population growth, control over many infectious diseases.

3. The Age of Degenerative and Man-Made Diseases: Mortality approaches stability at low levels, life expectancy exceeds $50$ years, dominance of chronic diseases (e.g., heart disease, cancer) and man-made diseases. Sometimes includes a Delayed Degenerative Diseases and Emerging Infections (Hybristic) stage.

Determinants of the Transition from Infectious to Degenerative Disease

Driven by eco-biologic factors (nutrition, immunity), socioeconomic/political/cultural improvements (living standards, education, healthcare access), and medical/public health advancements (vaccination, sanitation).

Models of Epidemiology Transition (ET)

1. Classical Model (Western): Slow, gradual shift.

2. The Accelerated ET Model: Rapid decline in mortality due to quick development.

3. The Contemporary (Delayed) ET Model: Delayed or incomplete transition, often a 'double burden' in developing countries.

Ecological Change and Emerging Diseases

Ecological changes (dams, air conditioners, reforestation) and globalization (heat waves, air pollution, migration) significantly impact disease probability and spread (e.g., Legionnaire's disease, Lyme disease, pesticide resistance, rapid global spread of infections).

Comparison with Demographic Transition

Demographic Transition (DT) focuses on quantitative population changes (birth/death rates), while Epidemiological Transition (ET) explains qualitative shifts in causes of mortality and morbidity. They are intrinsically linked, with ET driving mortality changes in DT.

Theory of Gerontological Transition

Hypothesis

This theory posits interrelationships between the growth of the aged population, changes in their resources/needs, and their position in society, leading to issues like aged dependency, family support, and ageism.

Stages of Gerontological Transition

• Pre-transition: Young age structure, zero growth/momentum for older population.

• Early Transition: Shifting young age structure, high growth/momentum for older population.

• Late Transition: Mature age structure, low positive growth/momentum for older population.

• Post-transition: Old age structure, zero growth/momentum for older population, stabilized.

Speed of Aging

The older population has more than tripled since $1950$ and is projected to almost triple again by $2050$. It's growing faster than the total population globally, with accelerated aging in less developed regions.

Population Ageing: Impacts and Perspectives

Angola and Australia: Population Structure and Implications

• Angola (2016): Wide base (young population), suggesting Stage 2 DT; health focus on maternal/child health, infectious diseases, basic sanitation.

• Australia (2014): Narrower base, larger older population, suggesting Stage 3 or 4 DT; health focus on chronic/degenerative diseases, aged care, palliative care, healthy aging.

Impacts of an Ageing Population in both Developed and Developing Countries

• Developed Countries: Increased demand on healthcare, strain on social security/pensions, potential labor shortages, emergence of a 'silver economy'.

• Developing Countries: 'Double burden' of disease, limited aged care infrastructure, erosion of traditional support, economic challenges (poverty among elderly).

Theoretical Perspectives on Ageing

1. Disengagement Theory (Cummings and Henry, $1961$): Suggests that withdrawing from society and social relationships is a natural, inevitable, and mutually beneficial part of growing old, preparing for death. People decrease social interaction and society decreases expectations.

2. Activity Theory: Posits that successful aging is associated with maintaining high levels of activity and social engagement. Older adults who remain active and find satisfying substitutes for lost roles tend to experience greater life satisfaction.

Comparison of Activity Theory with Disengagement Theory of Ageing

Disengagement Theory advocates for decreased social bonds as a natural part of aging, while Activity Theory promotes maintained or substituted social bonds for well-being.