Biology of Aging

Define the key descriptors of human aging such as normal aging, successful aging, life span, life expectancy, average life expectancy.

 * life span
 * The absolute length of time a member of a given species can possibly live. For example, it is consider 122 years, 6 months, based on the person who has lived longer than anyone else.


 * life expectancy
 * The length of time an average member of a particular cohort can expect to live. Refers to age that half of a particular cohort have died. For example, the average life expectancy in the US for women is 79.4 years.


 * age-specific life expectancy
 * Average number of years a specific person or group can expect to live. Example, once women turn 40, their age-specific life expectancy dramatically increases because they didn't die in child birth or childhood.  Ex2: The life expectancy of an 85 year old is 5 years.

Differentiate between aging, disease, and age-associated disease.

 * aging
 * The decline and deterioration of functional properties at the cellular, tissue, and organ level that leads to loss of functional capacity and homeostasis with age. Aging is associated with a decreased ability of the body to adapt to both internal and external stress.


 * disease
 * Tends to be treatable, selective injury to cells or specific tissues, discontinuous process of progression and regressions, can be extrinsic or intrinsic.


 * age-associated disease
 * Age-related changes that tend to be found in older persons such as ischemic heart disease or baldness. They are far from universal and tend to be selective.

Describe the major theories of aging.

 * 1) Evolutionary Theory.
 * 2) * Species survival has to do with propagation, NOT prolongation. Organisms are designed only to reproduce efficiently.  Aging can be maladaptive if Grandma competes with granddaughter for scarce resources.  But it can be adaptive if Grandma helps the child's survival.  Evolution is essentially neutral concerning the post-reproductive phenotype, i.e. once you are no longer fertile it doesn't really matter how messed up you are from an evolutionary viewpoint.
 * 3) * Genes that are beneficial in early life tend to be deleterious in later life (cell senescence prevents a cancer in early life but yields dead cells that contributes to age-related physiology later on; estrogen mediates reproduction (and an excess aids in a "voluptuous phenotype" as we learned from Androgen Insensitivity Syndrome) but the drawback is that it contributes to cancer in middle age.
 * 4) Wear and Tear theory
 * 5) * German biologist introduced the rate-of-living theory of aging, with a strong role for overuse in contributing to damage of systems that have a limited functional use.
 * 6) * Calorie restriction states that a 30-50% reduction in calorie intake will enhance longevity. Proven true in the vast majority of species.  In calorie-restricted animals, there's better glucose control, longer ability to reproduce, better DNA repair and immunity, better cognitive ability, etc.  There are fewer cancers, autoimmune diseases, etc. and less free-radical production.  Diet must be low calorie, high nutrients to prevent malnutrition.  Calorie restriction is highly regulated; sirtuins are a family of proteins that are activated under the stressful conditions produced by calorie restriction (reversatrol, in red wine, is a sirtuin activator, and the one most of us heard about.)  Drosophila data suggests that there is NO age-related "memory" of caloric load, but there is such a memory for temperature.  So, temperature seems to inflict permanent damage but you can "make up for lost time" by starting caloric restriction at a later stage and be no better/worse off.
 * 7) Accumulation of cellular damage
 * 8) * Accumulation of free radicals.
 * 9) * Shortening of telomeres. Cells exhibit replicative senescence.  Telomeres are poly-A caps at the end of chromosomes. that shorten with each successive replication.  Normal cells have a limited number of reproductive cycles.  Telomere length may be associated with the way that people with chhronicaly ill kids experience stress.  Exercising may help maintain longer telomeres.

Describe the demography of aging and its implications for the health care system.
=Links=
 * Between 1990 and 2020, the people 65-74 will grow 74% while people under 65 will only increase 24%. This will create strain on the medical social services that support older, well fed Americans.
 * The demographic transition is related to improved infant mortality rates and decreased mortality rates at all ages. The triangular shaped demographic will become more cylindrical.  Improved mortality is associated with an epidemological shift; in short, when people don't die of infectioous diseases, they get cancer and Alzheimers.  This is not from different exposures, but rather a shift.
 * Portland Calorie Restriction Society: http://wweek.com/editorial/3302/8233/