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Samenvatting Gerontology (PSB3E-CN05)
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Summary GerontologyGerontology = study of social, psychological and biological aspects of aging
NORMAL AGING
Life course trajectories of body functions
A: Normal development and decline
B: Exposure in early life may leave imprints
on structures or function of body systems
C: Exposure acting in mid or in later life
accelerating age-related decline
2014 compared with 1950
- fewer births
- babyboom generation 40-65
Prediction 2060 compared with 2014
- fewer births
- more and more people reach a high age
More developed regions have more > 60 year olds → increasing due to:
- increasing life expectancy at birth (overall)
- number children born per woman is decreasing
Chronological age: measured in units of time (months or years) that have elapsed since birth
Biological age: where people stand relative to the number of years they will live (in terms of body’s
organ system and physical appearance) → speculative
Functional age: person’s competence in carrying out specific tasks → in comparison with
chronological age peers
Psychological age: refers to how well a person adapts to changing conditions
Social age: views held by most members of a society about what individuals in a particular
chronological age group should do and how they should behave
Perspectives on aging process
- normative aging: what is considered as usual, normal, or average outcome
- successful aging: what is considered an ideal rather than average outcome
- positive aging: the ability to find happiness and well-being even in the face of physical and/or
psychological challenges
Theoretical models of aging
1. The Selective Optimization with
Compensation Model of Aging
(Baltes & Baltes, 1990): individuals
engage in adaptation throughout
their lives. They are capable of
learning and changing and calling
upon extra (reserve) capacity that
they might not need to use under
ordinary circumstances
- selection: is a strategy of
concentrating efforts on domains in
,which effective functioning is most likely to remain high
- optimization: is a strategy of focusing on behaviors that maximize not only the quantity but also the
quality of life
- compensation: refers to substituting new strategies when losses occur
2. The Ecological Model of Aging (Lawton
& Nahemow, 1973): the interaction
between a person’s competence and
environment results in some level of
adaptation
- measured in a person’s emotional well-
being
- competence: physical, sensory,
cognitive and social capabilities
- a person with high competence will
adapt positively to a wider range of
environmental press than a person with
low competence
Aging
- biological changes: decremental
physical changes (both structural and functional) that develop with the passage of time and
eventually end with death consequences of ageing rather than the disease
Biology of aging
- gradual and cumulative
- peak in early adulthood
- decline after early adulthood → rate of decline differs strongly between individuals
- not the majority, but even so most older adults are neither helpless nor dependent → ageing is not
by definition a very negative process
Are biological changes a consequence of the aging process rather than the disease?
- aging in the absence of any disease is rare
- the likelihood of many diseases increases with age
Aging affects the consequences of disease when it occurs: aging process and disease process interact
Morbidity: refers to illness and disease
Mortality: refers to death
→ two terms are related:
- illness and disease can result in death
- death is often preceded by illness and disease
- morbidity does not necessarily result in mortality
Life span: the maximum longevity, or extreme upper limit of time, that members of a species can live
(max ≈ 120 years)
- has stayed the same over time
Life expectancy: the average number of years that individuals in a particular birth cohort can be
expected to live
- has increased over time
- affected by factors such as level of nutrition, sanitary conditions, and medical care
- compression of mortality: more and more people will approach the maximum life span (only in the
,last years diseases)
- females have a higher life expectancy than males
Theories of biology of aging
- some theories: biological aging occurs within the organism regardless of outside forces (= primary
aging)
- other theories: biological aging is influenced by our environment and daily habits and the way we
cope with life’s challenges (= secondary aging)
1. Primary aging: unavoidable (inevitable) biological process that affects all members of a species
(universal)
- is set in motion early in life and progress gradually over time
- is intrinsic: is determined by factors within the organism
2. Secondary aging: experienced by most, but not necessarily all members of a species
- neither inevitable or universal
- resulting from hostile environmental influences: disease, disuse (e.g. lack of exercise), abuse (e.g.
smoking)
Time clock theory → finding:
- cells from human infant doubled approximately 50 times, whereas cells from a mouse (maximum
life span 3 years) doubled 10-15 times
- life span is controlled by genetically determined time clock at cellular level
- cells from infants and young children divide more times than cells from older adults
- recent studies: telomeres: protective cap at the end of chromosomes → as cells divide over time,
telomers shorten and eventually cell division stops
Immune theory: (theory:) immune system is programmed to maintain its efficiency for a certain
amount of time, after which it starts to decline
- immune system: defends body against invasion of foreign substances by producing antibodies
- insufficient antibodies
- inferior antibodies: mistakenly attack and destroy normal cells
- linked to cancer
, Evolutionary theory: members of species are genetically programmed to bear and rear their young.
Once they reproduce and raise their offspring to independence, they have fulfilled their service in
perpetuating the species
- depending on levels of energy organism coast along for a period of time
- once excess of energy is used up, susceptibility to disease increases
→ fruit flies forced to delay reproduction lived longer than fruit flies that reproduced early
Stochastic theories of aging: focus on random damage to our vital systems that occurs with the
process of aging
- as damage accumulates, we cease to function efficiently and eventually life becomes impossible to
sustain
- twins: different rates of aging → they rarely live exactly the same amount of time
Error theory
- errors occur at cellular level resulting in the production of faulty molecules:
result from organism’s metabolic processes
exposure to environmental factors (e.g. radiation)
- cells have a repair mechanism, but may not keep up with damage created by faulty molecules
- over time: unrepaired damage builds up resulting into metabolic failure
Wear and tear theory
- we begin life with a fixed amount of physiological energy
- if we expend it quickly, aging begins early and proceeds rapidly
- can we retard aging by conserving energy?
- BUT people who work in physically strenuous jobs do not show signs of aging any earlier than those
who work in less physically demanding jobs (so, not a lot support for this theory)
Stress theory
- two systems that are involved in a stress response:
1. Sympathetic nervous system (inhibits parasympathetic nervous system)
2. Hypothalamic-Pituitary-Adrenal axis (hypothalamus → pituitary gland → ACTH to adrenal
glands → cortisol, epinephrine and norepinephrine)
- stress triggers physiological activation that results in secretion of stress-related hormones
(glucocorticoids)
- young organism: stress system quickly return to normal levels
- older organism: stress system needs more time to return to normal levels → prolonged exposure to
glucocorticoids increases risk of high blood pressure & cardiovascular disease
- stress-related damage to the biological system can accelerate the aging process
Individual differences → nature vs. nurture
1. Nature
- most people who live beyond 70 have at least one parent or grandparent who lived into the 70s
- those who live into their 90s are likely to have at least one very long-lived parent
- identical twins are more similar in longevity than fraternal twins
- nature can not fully account for the rate at which people age and how long they live
2. Nurture: environmental influences: quality of air, diet and exercise habits, educational and work
history, level of stress, health care, marital status, social relationships
- nurture can not fully account for the rate at which people age and how long they live (see non
study)
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