Aging has been defined as the biological process by which the body changes throughout development, especially as adulthood progresses. In general, aging is related to a structural degradation that in turn implies losses in capabilities functional, with special emphasis on adaptation and self-care.
There is currently no consensus in the scientific community regarding the specific nature and definition of aging. However, we can distinguish three types of aging: primary, secondary and tertiary either Each of these types encompasses different changes and is determined by specific causes.
When we talk about primary aging, we are referring to a series of progressive and inevitable changes that occur in all people as the years go by. Like other types of aging, it implies a deterioration in general functioning and the ability to adapt to the environment.
All non-pathological processes that occur as a consequence of age are classified as primary aging; This is why it is also called “normative aging.” It occurs throughout adult life, although its effects are much more notable at advanced ages, especially in people who are not in good health.
Among the changes that make up this type of aging we find menopause, weakening and graying of hair, a decrease in the speed of cognitive processing, loss of strength, the progressive appearance of sensory deficits or impairment of sexual response.
The biological processes involved in primary aging alter physical functioning, but are also associated with psychological and social changes. The latter are influenced to a greater extent by the context, although when talking about interindividual variability this type of aging overlaps with secondary aging.
The main theories on primary aging conceptualize it as a preprogrammed process at the genetic level Factors such as the limited regeneration capacity of cells and the progressive deterioration of the immune system have a key influence on this type of aging.
The genetic programming theory states that with maturity, genes that trigger aging are activated, and the pacemaker theory proposes that these changes are due to the hormonal imbalance produced by the “disconnection” of the biological clock of the hypothalamus. According to the immunological theory, at advanced ages the immune system begins to attack the body.
Other perspectives defend that primary aging is a consequence of the accumulation of damage in the body, and not of unmodifiable genetic factors. These hypotheses, which generally have less acceptance than genetic ones, are known as “non-genetic cell theories” or “random damage theories.”
The free radical theory, the most popular in this group, states that the release of free electrons that results from the normal activity of the organism causes cumulative damage to cell membranes and chromosomes
Other close hypotheses attribute deterioration to the spontaneous construction of harmful molecules, to the body’s inability to protect itself indefinitely from harmful environmental influences, to the accumulation of errors in protein synthesis (which would alter genetic transcription), or to the normal effects of metabolism.
2. Secondary aging
This type of aging consists of changes caused by behavioral and environmental factors, foreign to natural biological processes. It is often stated that secondary aging is that which can be prevented, avoided or reversed, but this is not always the case; The key characteristic is the non-universality of the processes that comprise it.
The main factors that determine the intensity of secondary aging are health status, lifestyle and environmental influences. Thus, suffering from diseases such as cardiovascular disorders, eating an unhealthy diet, being sedentary, consuming tobacco, exposing yourself directly to the sun or breathing polluted air enhance these types of changes.
Many physical and psychological deficits typical of old age can be considered a consequence of secondary aging even though they tend to be seen as manifestations of primary aging; For example, pathological cognitive impairment and cancer become much more common with advancing age, but they do not occur in all people.
3. Tertiary aging
The concept of tertiary aging refers to the rapid losses that occur shortly before death Although it affects the body at all levels, this type of aging is especially notable in the cognitive and psychological sphere; For example, in the last months or years of life the personality tends to destabilize.
In 1962 Kleemeier proposed the “terminal drop” hypothesis, which in English is called “terminal drop”. This author and some longitudinal research have suggested that, as death approaches, cognitive abilities and the ability to adapt deteriorate very markedly, causing an increase in vulnerability.
The Birren and Cunningham cascade model of aging proposes that the three types of aging interact with each other, so that their effects enhance each other. Thus, secondary aging causes an intensification of the effects of natural biological deteriorations, and these changes are even more marked at the end of life.
