The Baltimore Longitudinal
Study of Aging (BLSA) has been investigating human aging since 1858.
Participants range in age from 20 - 90+. BLSA's central question
is "What are the usual or universal aging processes?"
BLSA has come to two conclusions:
- " 'Normal aging'
can be differentiated from disease. As humans age, bodily functions
change and some decline with age, but health problems do not inevitably
- "No single, chronological
timetable of human aging exists. There are more differences among
older people than among younger people. Even within one individual,
organs can age at different rates. This suggests that genetic,
lifestyle, and disease processes all affect the rate of aging..."
Aging theories can be
divided into ones that emphasize "internal biological clocks"
and others that deal with "external or environmental forces
that damage cells and organs until they can no longer function."
The aging theories that
The Biology of Aging investigates are as follows:
- Programmed Scenescence:
- Aging is a result
of switching on and off certain genes. This theory explores
studies in yeast and drosophila that have extended life spans
using genetic manipulations.
- In normal cells,
areas of the chromosome known as telomeres shorten with each
cell division. Specialized reproductive cells and cancer cells
have an enzyme called telomerase that allows the cells to
reproduce indefinitely. Some scientists call this enzyme a
"cellular fountain of youth."
- Hormone Theory:
Some hormones decline with age. Injections of these hormones appear
to reverse some signs of aging.
- Immune System Theory:
T-cells and their products,
interleukins, change with age. Scientists know that our defense
system declines with age and leave us susceptible to bacterial
and viral diseases. Reviving the immune response may hold keys
to limiting the aging process.
- Free Radical Theory:
damage proteins, membranes, and nucleic acids. Anti-oxidants,
such as vitamins C and E and beta carotene, prevent oxidative
damage. Maintaining anti-oxidant defense levels may be critical
- Environmental Links
our bodies respond to sun damage and stress may hold clues to
the aging process. Skin cells and heat shock proteins are areas
of research exploration.
- Caloric Restriction
restricted diets have been shown to extend life spans in animals.
How does this relate to the aging process?
- Behavioral Theory:
Improved diet and exercise may provide elongated life spans.
(1) Research for
a New Age, National Institute on Aging
(2) In Search of
the Secrets of Aging, National Institute on Aging