Aging has been defined as the biological process by which the body changes throughout development, particularly as adulthood progresses. Aging is generally linked to a structural degradation which in turn implies capacity losses functional, with particular emphasis on those of adaptation and personal care.
There is currently no consensus in the scientific community around the specific nature and definition of aging. However, we can distinguish three types of aging: primary, secondary and tertiaryO. Each of these types encompasses different changes and is determined by specific causes.
Types of aging
The main types of aging are as follows.
1. Primary aging
When we talk about primary aging we are referring to a number of gradual and inevitable changes that happen in everyone as the years go by. Like other types of aging, it involves a deterioration in general functioning and the ability to adapt to the environment.
All non-pathological processes that occur due to age are classified as primary aging; this is why it is also called “normative aging”. It occurs throughout adulthood, although its effects are much more noticeable in old age, especially in people who are not in good health.
Some of the changes that make up this type of aging include menopause, weakening and graying of hair, decreased speed of cognitive processing, loss of strength, the gradual onset of sensory deficits or an altered sexual response.
The biological processes involved in primary aging alter physical functioning, but are also associated with psychological and social changes. The latter are more influenced by the context, although when we speak of interindividual variability, this type of aging intersects the secondary.
Causes of primary aging
The main theories on primary aging conceptualize it as a genetically preprogrammed process. Factors such as the limited regenerative capacity of cells and the progressive deterioration of the immune system have a key influence on this type of aging.
The theory of genetic programming asserts that with maturity, the genes that trigger aging are activated, and that of the pacemaker proposes that these changes are due to the hormonal imbalance produced by the “disconnection” of the body clock from the body. hypothalamus. According to the immune theory, in old age the immune system attacks the body.
Other perspectives argue that primary aging is a consequence of the build-up of damage in the body, and not of steadfast genetic factors. These assumptions, generally less accepted than genetic assumptions, are known as “non-genetic cell theories” or “random damage theories”.
The free radical theory, the most popular of this group, states that the release of free electrons resulting 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, the inability of the body to protect itself indefinitely from harmful environmental influences, the accumulation of errors in protein synthesis (which would alter genetic transcription) or 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 argued that secondary aging can be avoided, 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 state of health, lifestyle and environmental influences. Thus, suffering from diseases such as cardiovascular disorders, having an unhealthy diet, being sedentary, consuming tobacco, being directly exposed to the sun or breathing polluted air all promote this type of change.
Many physical and psychological deficits typical of old age can be viewed as a consequence of secondary aging, although they tend to be viewed as manifestations of primary; for example, pathological cognitive impairment and cancer become much more common as age progresses, but do not occur in all people.
3. Tertiary aging
The concept of tertiary aging refers to rapid losses that occur shortly before death. Although it affects the body at all levels, this type of aging is particularly noticeable in the cognitive and psychological domain; for example, in the last months or years of life, the personality tends to become destabilized.
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, cognitive abilities and adaptability deteriorate dramatically, leading to increased vulnerability.
Birren and Cunningham Cascade 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 alterations, and these changes are even more marked at the end of life.