Sometimes it is hard to define aging because it comprises such a broad spectrum of changes.

1. DEFINITION OF
AGING
FARHAD ZARGARI, MD, PHD

2. DEFINITION OF AGEING

3. DEFINITION
 Entropy always wins. Each multicellular organism, using
energy from the sun, is able to develop and maintain its
identity for only so long. Then deterioration prevails over
synthesis, and the organism ages. Aging can be defined
as the time-related deterioration of the physiological
functions necessary for survival and fertility. The
characteristics of aging—as distinguished from diseases
of aging (such as cancer and heart disease)—affect all
the individuals of a species

4. DEFINITION

5. DEFINITION
 Aging is the process of becoming older. It represents the
accumulation of changes in a person over time. Ageing
in humans refers to a multidimensional process of
physical, psychological, and social change. Most
developed world countries have accepted the
chronological age of 65 years as a definition of 'elderly'
or older person.

6. DEFINITION
 1. The process of growing old, especially by failure of
replacement of cells in sufficient number to maintain full
functional capacity; particularly affects cells (neurons)
incapable of mitotic division.
 2. The gradual deterioration of a mature organism
resulting from time-dependent, irreversible changes in
structure that are intrinsic to the particular species, and
eventually lead to decreased ability to cope with the
stresses of the environment, thereby increasing the
probability of death.
 3. In the cardiovascular system, the progressive
replacement of functional cell types by fibrous
connective tissue.
 4. A demographic term, meaning an increase over time

7. DEFINITION
 Aging has been defined as the collection of changes
that render human beings progressively more likely to die
(Medawar, 1952). Indeed, one hallmark of aging in
humans and in many other species is an age-related
increase in mortality rates shortly after maturity.
Mortality rates, expressed in deaths per 100,000 people, as a function of age for the 2010

8. DEFINITION
 Aging can also be defined as a progressive functional
decline, or a gradual deterioration of physiological
functions with age, including a decrease in fecundity
(Partridge and Mangel, 1999; Lopez-Otin et al., 2013), or
the intrinsic, inevitable, and irreversible age-related
process of loss of viability and increase in vulnerability
(Comfort, 1964). Clearly, human aging is associated with
a wide range of physiological changes that not only
make us more susceptible to death but limit our normal
functions and render us more susceptible to a number of
diseases.

9. DEFINITION
 The cells of the elderly (regardless of when they last
underwent mitosis) look the same as young cells.
However, old cells do not withstand a variety of
challenges quite so well as younger cells.
 Various theories of aging attempt to explain the process -
bottom line, there is disruption of homeostasis.

10. DEFINITION

11. STAGES OF LIFE
 Chronologic
al age
typically used
to note life’s
transitions:

12. DEFINITION
Chronological Age
Biological Age
Psychological Age
Functional Age
Population Age
Age

13. CHRONOLOGICAL AGE
 Chronological age is defined as the number of years a
person has lived. Years, of course, being Earth revolutions
around the sun. This is the one we're all very familiar with.
When looking at chronological age, is 45 different than
20? Yes, but that number on its own fails to inform us of
anything else. All it says is that they were born 25 years, or
Earth-Sun revolutions, apart. In other words “Chronologic
age is not an accurate predictor of physical condition or
behavior”.

14. BIOLOGICAL AGE
 Biological age (an organism's physical state as it ages) is
defined as a description of an individual's development
based on biomarkers. A biomarker is a recordable
molecular or cellular event. Here we're looking at the
individuals as they are, not necessarily when they were
born. Humans, in most cases, follow the same biological
path. For example, the easiest one that comes to mind is
the beginning of puberty and the increase of sex
hormones. More complicated ones exist, such as
increases and decreases in human growth hormone,
myelination events in the brain, and the degradation of
certain tissues as one gets older. So, it's like a continuum.
What if we aren't interested in the body?

15. PSYCHOLOGICAL AGE
 Psychological age is defined as a subjective description
of one's experience using non-physical features. Now
we're trying to say how old a person is without markers.
We used the Earth's revolutions and biomarkers before,
now we have to rely on something that's a little more
ephemeral: experience, logic, and emotions.
Psychological age has been attempted by many
psychologists in the form of stage theories, which are
developmental steps that every person goes through.
Some of the more famous one's include Freud, Erikson,
and Piaget. What they attempt to do is define a person
by how they think, act, and reason without worrying as
much about your chronological age.

16. FUNCTIONAL AGE
 Functional age is defined as a combination of
chronological, biological, and psychological ages. What
is happening is instead of focusing on one aspect at a
time, we are summarizing them to create a more holistic
picture of a person. Functional age would give you the
clearest understanding of a person. It is their listed age,
how far along their body systems have developed, and
a glimpse of their emotional and logical maturity.
However, if you haven't guessed it, this type of age is not
often used. The requirements to describe someone this
thoroughly means that you will need a lot of expert input
- test after test after test to give you the clearest
understanding of how old the person is.

17. POPULATION AGE
 Population ageing is the increase in the number and
proportion of older people in society. Population ageing
has three possible causes: migration, longer life
expectancy (decreased death rate) and decreased
birth rate.

18. OLD AGE STAGES
 Young-Old - (ages 65 - 74)
 Middle-Old - (ages 75 - 84)
 Old-Old - (age 85 and older)

19. IMPORTANT REMARKS
 Adulthood is attainment of physiologically optimal
integrated function.
 Function in adulthood is the standard measure.
 Unsound and incorrect to state that changes with aging
are necessarily “abnormal”.
 Three observations of the elderly:
 Greater heterogeneity in responses
 Changes in function do not occur simultaneously
 Changes in function do not occur to the same degree
 Old age should not be viewed as a “disease” nor should
a time clock be put on aging.

20. IMPORTANT REMARKS
 Significant increase in longevity over past decades.
 Due to decline in deaths resulting from infectious disease
along with improved public health.
 Heart disease, cancer and stroke now most common
cause of death in the old age.
 Death rates have actually declined in the elderly.
 Is there a limit to human life span and should we prolong
life at the expense of overall health?
 We should be talking in the context of “health span” not
life span.

21. SUCCESSFUL AGING
homeostasis less efficient, but still present
Homeostasis Less Efficient, but Still Present