Types of aging (primary, secondary and tertiary)

Aging has been defined as the biological process by which the body changes throughout development, especially as adulthood advances. In general, aging is related to a structural degradation which in turn implies losses in capacities 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 tertiaryor. Each of these types includes different changes and is determined by specific causes.

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Types of aging

The main types of aging are as follows.

1. Primary aging

When we speak of 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 in 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 noticeable in 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, decrease in cognitive processing speed, loss of strength, the progressive appearance of sensory deficits or impaired 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 speaking of interindividual variability this type of aging overlaps with the secondary one.

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Causes of primary aging

The main theories about primary aging conceptualize it as a preprogrammed process at the genetic level. Factors such as the limited capacity of cells to regenerate and the progressive deterioration of the immune system play a key role in this type of aging.

The theory of genetic programming states that with maturity genes are activated that trigger aging, and that of the pacemaker proposes that these changes are due to hormonal imbalance produced by the “disconnection” of the biological clock of the hypothalamus. According to the immunological theory, in advanced ages the immune system starts to attack the body.

Other perspectives defend that primary aging is a consequence of the accumulation of damage in the body, and not of unchangeable genetic factors. These hypotheses, which are generally less accepted 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 body causes cumulative damage to cell membranes and chromosomes.

Other close hypotheses attribute the deterioration to the spontaneous construction of harmful molecules, to the inability of the body to protect itself indefinitely from the Harmful environmental influences, the accumulation of errors in protein synthesis (which would alter gene transcription) or the normal effects of metabolism.

2. Secondary aging

This type of aging consists of changes caused by behavioral and environmental factors, oblivious to natural biological processes. It is often stated that secondary aging is one that can be prevented, avoided or reversed, but this is not always the case; the key characteristic is the non-universality of the processes that compose 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, being in direct sunlight, or breathing polluted air enhance this type 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 the primary one; for example, pathological cognitive impairment and cancer become much more common with advancing age, but they do not occur in everyone.

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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 noticeable in the cognitive and psychological field; for example, in the last months or years of life the personality tends to destabilize.

In 1962 Kleemeier proposed the hypothesis of the "terminal drop", which in English is called "terminal drop". This author and some longitudinal research have suggested that, as death approaches, abilities cognitive and adaptive capacity deteriorate very markedly, which causes an increase in the vulnerability.

Birren and Cunningham's Cascading Aging Model proposes that the three types of aging interact with each other, so that their effects are mutually reinforcing. Thus, secondary aging causes an intensification of the effects of natural biological deterioration, and these changes are even more marked at the end of life.