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EPIDEMIOLOGY OF AGING
• THE STUDY OF THE AGE-RELATED DISTRIBUTION AND CAUSES OF DISEASE, DISABILITY, AND MORTALITY IN HUMAN POPULATIONS.
EPIDEMIOLOGY OF AGING
• WHY IMPORTANT?– AGING OF THE HUMAN POPULATION– HEALTH AND VITALITY OF AN AGING
POPULATION– QUALITY OF LIFE AND COST OF CARE
EPIDEMIOLOGY OF AGING
• CHRONOLOGICAL AGE IS ASSOCIATED WITH INCIDENCE AND PREVALENCE OF MOST HEALTH OUTCOMES.
• DESPITE THIS AGE ASSOCIATION, THERE IS CONSIDERABLE VARIATION IN HEALTH OUTCOMES WITHIN AGE CATEGORIES.
EPIDEMIOLOGY OF AGING
• WHY ARE OLDER PEOPLE AT ELEVATED RISK FOR DISEASE, DISABILITY, AND DEATH?
• ACCUMULATION OF ENVIRONMENTAL/BEHAVIORAL INSULTS.
• REDUCED IMMUNOLOGICAL SURVEILLANCE
EPIDEMIOLOGY OF AGING
• AGING OF THE U.S. POPULATION, PERCENTAGE AGED 65+ YEARS BY YEAR
1900 4.0%1940 8.0%1980 11.5%
2000 12.6% 2030 20.0%
EPIDEMIOLOGY OF AGING
• THERE IS CONSIDERABLE VARIABILITY BY REGION OF THE COUNTRY, 2000
– FLORIDA 18.1%– CALIFORNIA 10.4%– ALASKA 5.8%
EPIDEMIOLOGY OF AGING
• RACE, ETHNICITY, AND AGE, U.S.
2000 2050
NH white 83.5% 64.2%
NH black 8.1 12.2
NH Asian/PI 2.4 6.5
Hispanic 5.6 16.4
EPIDEMIOLOGY OF AGING
• Global Differences in the Aging of the Population– Number of years required to increase the
percentage of people aged 65+ from 7% to 14%.
– France: 115 years (1865-1980)
– Japan: 26 years (1970-1996)
– Chile: 20 years (2000-2020)
– Tunisia 15 years (2020-2035)
Elderly Support Ratio,2000-2030
• Ratio = Number of people aged 65+ per 100 aged 20-64
• USA – 2000 21 per 100– 2030 37 per 100
Elderly Support Ratio2000-2030
2000 2030
• Italy 29 49
• Japan 27 52
• China 12 26
• India 9 15
• Guatemala 8 11
EPIDEMIOLOGY OF AGING
• MAJOR AGE-ASSOCIATED CAUSES OF DEATH
– CARDIOVASCULAR DISEASE
– CANCER
– CHRONIC OBSTRUCTIVE PULMONARY DISEASE
– DIABETES
EPIDEMIOLOGY OF AGING
AGE-SPECIFIC COLORECTAL CANCER INCIDENCE RATES
(Per 100,000 in population)
WM WF BM BF
<65 20.4 14.7 25.3 20.4
65+ 408.0 269.3 385.8 286.1
EPIDEMIOLOGY OF AGING
• COGNITIVE FUNCTION• Moderate/Severe Memory defined as four or fewer
words recalled (out of 20) on combined immediate and delayed recall tests. Source: Health and Retirement Survey.
• Male Female• 65-69 5.3 3.8• 85+ 37.3 35.0
EPIDEMIOLOGY OF AGING
• PERCENT OF MEN AND WOMEN AGED 60+ REPORTING TWO OR MORE HEALTH CONDITIONS
• MEN WOMEN
• 60-69 35 45
• 70-79 47 61
• 80+ 53 70
EPIDEMIOLOGY OF AGING
• FALLS
• 30% OF PEOPLE AGED 65+ FALL EACH YEAR.
• 10-15% OF THOSE FALLS ARE CONSIDERED “SERIOUS/NON-FATAL”
• FALLS REPRESENT THE LEADING CAUSE OF ACCIDENTAL DEATH IN PEOPLE AGED 65 AND OLDER.
• FEAR OF FALLING IS A LEADING REASON FOR NOT ENGAGING IN PHYSICAL ACTIVITY.
EPIDEMIOLOGY OF AGING
• CAUSES OF FALLS IN THE ELDERLY
• - DIZZINESS
• - POOR COGNITIVE FUNCTION
• - VISION PROBLEMS
• - GENERAL FRAILTY
• - ENVIRONMENTAL HAZARDS
EPIDEMIOLOGY OF AGING
• Types of studies– Clinic/Laboratory-Based Studies– Adapted Population Studies– Established Population Studies– Special General Population Studies– Special Chronic Disease Studies
• Types of Research Designs– Case-Control Studies– Longitudinal or Prospective Studies
EPIDEMIOLOGY OF AGING
• STRATEGIES TO ENHANCE HEALTH AND FUNCTIONING THROUGH PHYSICAL ACTIVITY—it seems to be an “elixir”
– RWJ PROGRAM IN “ACTIVE FOR LIFE”– RWJ PROGRAM IN “ACTIVE
ENVIRONMENTS”
Questions
• Why are older people at elevated risk for disease, disability and death?
• In the US, which age/ethnic group will increase the most between 2000 and 2050?
• Who has a higher frequency of 2 or more health conditions, men or women?
• Why is it important to look at the epidemiology of falls, and why are we concerned about this?
TELOMERES
What are they?
Why are they important?
Telomere shortening and the end-replication problem
Telomerase
Telomere hypothesis of aging
Telomeres
Ends of linear chromosomes
Centromere
TelomereTelomere
Repetitive DNA sequence(TTAGGG in vertebrates)
Specialized proteins
Form a 'capped' end structure
TELOMERE STRUCTURE
5’ 3’
5'
3'
Telomerict loop
Telomericproteins:
TRF1TRF2TIN2RAP1
TANKS 1,2POT1
etc
NUCLEARMATRIX
Why are telomeres important?
Telomeres allow cells to distinguish chromosomesends from broken DNA
Stop cell cycle!Repair or die!! Homologous recombination
(error free, but need nearby homologue)
Non-homologous end joining(any time, but error-prone)
Why are telomeres important?Prevent chromosome fusions by NHEJ
NHEJ
Mitosis
FUSIONBRIDGE
BREAKAGE
Fusion-bridge-breakage cycles
Genomic instability
Cell death OR neoplastic transformation
Telomere also provide a means for "counting" cell division
Pro
lifer
ativ
e ca
paci
ty
Number of cell divisions
FiniteReplicativeLife Span"Mortal"
InfiniteReplicativeLife Span"Immortal"
How do cells "know" how many divisions they have completed??
The End Replication Problem:Telomeres shorten with each S phase
OriDNA replication is bidirectional
Polymerases move 5' to 3'
Requires a labile primer
3'5'
3'5'
5'
5' 3'3' 5'
Each round of DNAreplication leaves
50-200 bp DNA unreplicatedat the 3' end
TELOMERASE:Key to replicative immortality
+ TELOMERASE
Overcomes telomere shortening and the end-replication problem
Expressed by germ cells, early embryonic cells
Not expressed by most somatic cells (human)
May be expressed by some stem cells, but highly controlled
Expressed by 80-90% of cancer cells(remaining still need to overcome the end replication problem;
do so by recombinational mechanisms -- ALT (alternative lengthening of telomeres) mechanisms
HOWEVER,
CELLS THAT EXPRESS TELOMERASE
STILL UNDERGO SENESCENCE
(E.G., IN RESPONSE TO DNA DAMAGE, ONCOGENES, ETC.)
Telomerase:Biomedical uses
Expand cells for replacement therapies(burns, joint replacements, etc)
Telomerase inhibitors to selectively kill cancer cells
The telomere hypothesis of aging
Telomeres shorten with each cell division and therefore with age
TRUE
Short telomeres cause cell senescence andsenescent cells may contribute to aging
TRUE
HYPOTHESIS:Telomere shortening causes aging and
telomerase will prevent agingTRUE OR FALSE?
The telomere hypothesis of aging
Telomere length is not related to life span(mice vs human; M musculus vs M spretus)
Telomeres contribute to aging ONLY if senescent cells contribute to aging
Telomerase protects against replicativesenescence but not senescence induce by
other causes
SUMMARY
Telomeres are essential for chromosome stability
Telomere shortening occurs owing to the biochemistry ofDNA replication
Short telomeres cause replicative senescence (other senescence causes are telomere-independent)
Telomerase prevents telomere shortening andreplicative senescence
The telomere hypothesis of aging depends on the cellular senescence hypothesis of aging