Health and Community 16: Aging Demographics and Life Expectancy

Demographics of Aging

  • Overarching Aim: To tackle aspects of health that that affect us at a community level.
  • One of the major aspects is that we all get older, so we're going to examine aging on a community level.
  • Questions to Address:
    • What is our lifespan?
    • What's the effect of natural disasters, wars, economic downturns, diseases, and how does that affect our life expectancy?
    • Later, we're gonna address the biochemistry of aging.
    • Before we do, we're gonna before we're genetics of aging. Why do we age?
    • What genes influence the way we age?
    • Are there any ways we can prolong a healthy, longer life?
    • Does dietary intervention really work, or is that just a myth?

What is Aging?

  • Definition: A set of gradual responses that occur as we mature from an infant to an adult; it's a normal set of physiological changes.
  • Middle Age Onwards:
    • Physiological decline.
    • Loss of physiological integrity.
    • Impaired biological functions.
    • Increased probability of death.
  • Diseases associated with aging are complex, caused by genetic and environmental factors.
  • Key Point: Aging is not just wear and tear; it's programmed into us, with genetic control.

Physical Manifestations of Aging

  • Wrinkles.
  • Declining sight, hearing, taste, and smell.
  • Hair thinning and graying.
  • Weight gain, particularly around the middle.
  • Osteoporosis, especially in females (loss of calcium from bones).
  • Altered gait (the way old people walk).
  • Slower reflexes.
  • Less acute mental agility and declining memory.
  • These are normal physiological aging processes.

Population Demographics and Aging

  • Examining the population pyramid to understand aging trends. Data from the World Factbook (American Central Intelligence Agency).
  • UK Demographics (2023):
    • People above 65 years: 13 million (19% of the population).
    • Social, health, and economic costs of aging, including missed prescriptions.
    • Aging is expensive for a population.
    • Estimated over 20 million people in the UK will be over 65 years by 2040.
    • Small birth rate compared to age peaks at 30 and 55.
  • Aging Population Definition: Japan as an example.
  • Japan:
    • Peak of people around 69-75 years (baby boomers after World War II).
    • Peak following the old peak in the seventies, but terribly declining birth rate.
    • This is very typical of an aging population.

Comparison of Aging Populations

  • UK: 19% of the population is over 65.
  • Japan: 29% are over 65 (significant economic burden).
  • Monaco: More than a third are over 65; small growth rate due to wealthy, old immigrants.
  • Lesotho: High birth rate, increasing death rate from early teens, few people reach 65 (5%).
  • Central African Republic: Only 3.5% reach 65.
  • Chad: Only 2.5% reach 65. Inequalities across the world in life expectancy.

Measuring Life Expectancy

  • Lifespan: Age to which a typical member of any species can expect to survive (not useful).
  • Maximum Lifespan (t max): Not useful because it picks out odd people who survive everything (e.g., Jeanne Calment lived 122 years).
  • Statistical Measure of Life Expectancy: Depends on the country you're born in, the country in which you live.
  • Based on the year of your birth, your current age, your sex, and a measure of the economic success of the country.
  • Measure of overall quality of life of a country.
  • How long you can expect to live, given your date of birth.

Global Life Expectancy Trends

  • Life expectancy globally is increasing.
  • North America: Life expectancy blip in yellow caused by COVID.
  • South America: Took quite a big hit in terms of Covid, but look how quickly life expectancy has recovered.
  • Africa: Still has not recovered from COVID, even though the number of cases were relatively small.
  • Low life expectancy compared to the rest of the world.
  • Inequalities in life expectancy globally.
  • Newborn in African can now expect to live about 63 years old, but a newborn in the same year would be expected to, in The USA, be expected to live seventeen years longer.

Differences in Life Expectancy

  • Monaco: 87 years (highest).
  • Chad: 53 years (lowest).
  • Life expectancy at age 60 in Lesotho and the Central African Republic is approximately 13 years left.

Causes of Reduced Life Expectancy

  • Haiti vs. Dominican Republic:
    • Haiti: Deforested, no natural resources due to corruption.
    • Dominican Republic: Lush, green, verdant, with lots of natural resources.
    • Dominican Republic is the fastest economic growth of any country in Latin America.
  • GDP Comparison:
    • Haiti: 32,000,000,00032,000,000,000
    • Dominican Republic: 900,000,000,000900,000,000,000
  • Inflation:
    • Haiti: 23%
    • Dominican Republic: 7-8%
  • Dominican Republic is wealthy, tourism industry, construction industry, natural goods like coffee.
  • Haiti is still corrupt, hardly any natural resources, and it's poorly educated.

Earthquake Impact Comparison

  • Moment magnitude measures earthquake strength (logarithmic scale).
  • In 02/2003, an earthquake near Puerto Plata in Dominican Republic measured 6.4 on the moment magnitude scale.
  • In 2010, an earthquake near Port Au Prince in Haiti was measured 7 on the moment magnitude scale (eight times larger).
  • Small earthquake in The Dominican Republic actually did affect life expectancy just slightly, all the way across into the poor country.
  • Big earthquake causes severe drop in life expectancy for a year in Haiti, and in The Dominican Republic, which is much wealthier, neither earthquake affected life expectancy.
  • Poor countries suffer from natural disasters, whereas rich countries (wealthy countries) just cope.
  • Aging is expensive for a population, and it's gonna get worse.
  • Poverty reduces life expectancy.
  • Most people of 60 and over seem to get through life without reacting to natural disasters.
  • Cholera in 2010 (introduced by Nepalese peacekeepers) may have killed many older Haitians.

Mortality Shocks and Populations

  • Sudden drop in life expectancy is called a mortality shock.
  • Intuitive view: young people are active, fit, and healthy so will not be affected much by a mortality shock.
  • Older people who are less healthy and active therefore would suffer more from a mortality shock.
  • Hypothesis: is it true that the older people die preferentially?

Examining Mortality Shocks

  • Control group (no mortality shock) is in blue, probability of death on a log scale, exponential curve.
  • Intuitive Model:
    • If older people are more prone to die due to mortality shock, there will be more deaths of older people and fewer deaths of younger people.
    • Expected a steeper log curve.

Australian Prisoner of War Example (WWII)

  • Civilian Australian population in 1941 is in black.
  • Death rate or probability of death on log scale and it's exponential fit as you increase age.
  • Camp death rate similar slope in 1944 and 1945.
  • Older people idea did not die preferentially in prisoner of war camp at the end of World War II.

The Holodomor (1933)

  • Translated from the Ukrainian as hunger plague or hunger death.
  • Data falsification post mortality shock.
  • Death rates increased more for young people than for older people.
  • It looks like the old population could survive starvation better than youngsters.

The Finnish Famine

  • Very high death rates. Mortality shock of the famine really raises death rates more for younger people than for old people.
  • The older you get, the better you get at living.
  • Old people do not respond preferentially to mortality shocks; they are more resilient.

Mortality Shocks

  • Again, we're comparing life expectancy at birth in black with life expectancy at 60.
  • Ebola in Liberia, Sierra Leone, and Guinea (2014-2015 outbreak).
  • Life expectancy at 65 was stable; older people did not succumb as much as young people did to Ebola.
  • Increasing wealth decreases shock and is a great buffer for mortality shock.
  • Older people are more resilient to these events.

Effects of War & Endemic Disease

  • Syrian Civil War started in 2011, immediate mortality shock, entry of ISIS slowed recovery, Russian intervention prolonged recovery.
  • Population pyramids shape shows how well the older population coped.
  • Tsunami in Japan (2011) made no difference overall, their wealth was a great buffer against COVID.
  • Lesotho; the early 2000s, '2 thousand and '4, '2 thousand and '5, a third of the population was HIV positive.
  • Again, look how resilient the older population is. There's also another confounding population about endemic disease.
  • New disease COVID at global level shows that we have still not recovered from Covid.
  • We have inequalities in life expectancy and we have examined the causes of mortality shock, and one of the shocks is that young people are more prone to a mortality shock than older people.

Inequalities in Life Expectancy

  • Life expectancy across the world varies in accordance.
  • Life expectancy is governed by the environment in which you live.
  • Mortality shocks do not preferentially deplete the older population.
  • Mostly, we recover quickly from mortality shock, but prolonged conflicts, prolonged drought, prolonged disease cause long term depression.

Extending Life Expectancy

  • Get yourself born into a Westernized system:
    • Good infrastructure.
    • Good healthcare.
    • Generally high levels of wealth and education.
    • Excellent sanitation.
    • Good care systems.
  • Life expectancy in The US is likely to have reached a peak.

Getting Lucky & Avoiding Health Burdens

  • Avoid wars and natural disasters, avoid as many diseases as you can while still maintaining a healthy immune system.
  • Longer that you live, the more likely you are to succumb to an aging associated disease, and these are results of genetic and environmental interactions.
  • Examples:
    • Atherosclerosis.
    • Cardiovascular Diseases
    • Cancer.
    • Arthritis.
    • Vision problems due to cataracts.
    • Osteoporosis.
    • Type two diabetes.
    • Hypertension.
    • Alzheimer's.
    • Parkinson's.
  • For Long lived societies in general, aging is a health burden which has an economic cost.

Conclusion

  • Address aging in terms of its health aspects to promote a lifelong well-being and reduce economic burden to a population.
  • If some older people have really active phenotypes, does that imply they have a genotype that's characteristic of this?
  • They're aging very well.
  • Are there no mutations that decrease our lifespan?
  • Going to address the genetics of aging on the next lecture.