General mechanisms of aging, causes of aging. Human aging is a biological process inherent in nature itself. Study of human aging

Human aging

Human aging- like aging of other organisms, this is a biological process of gradual degradation of parts and systems of the human body and the consequences of this process. While the physiology of the aging process is similar to that of other mammals, some aspects of the process, such as the loss of mental abilities, are of greater importance to humans. In addition, psychological, social and economic effects are of great importance.

Aging has always had a special meaning for humans. For centuries, philosophers have discussed the causes of aging, alchemists have searched for the elixir of youth, and many religions have attached sacred meaning to aging. The results of experiments to increase the average and maximum life expectancy of model animals (mice - increase in life by 2.5 times) and organisms (yeast - increase in life by 15 times, nematodes - increase in life by 10 times) in recent years, as well as the discovery of a negligible phenomenon aging in many animals (including people at the “survival” stage) and organisms allows us to hope that advances in science will soon make it possible to slow down or reverse aging (to achieve the effect of negligible aging for younger people). However, despite the mentioned successes, the existing fundamental possibility of at least seriously slowing down aging, as well as the fact that aging is recognized as the main cause of mortality in developed countries, and human life is proclaimed as a fundamental value in many countries, societies and states have not yet realized The need to focus on anti-aging, research in this area is not sufficiently funded. .

From a philosophical point of view, the aging process is caused by the natural degeneration of a colony of body cells under the influence of environmental factors. In humans and animals, during reproduction, lost or damaged genetic information is replenished due to the effect of superimposing the properties of two individuals of the opposite sex at the gene level. That is, the principle of probabilistic compensation works. That is why it is possible for species to resist harmful environmental influences. In general, any multicellular organism on Earth can be considered as a complexly organized colony of unicellular organisms that are capable of three stages of their evolution (which ones?). The aging process is caused only by the influence of external factors (relict radiation, negative environmental factors, etc.) that destroy the genetic structures of the colony and contribute to their degeneration, since the organism can be considered as a separate system, incapable of reproduction and exchange of its body in terms of replenishment lost information at the third stage of development. There are theories, confirmed by scientific results, that the introduction of viruses and other carriers from outside helps to replenish the damaged structure of genes and thereby delays the process of degeneration of the body’s cells, that is, the aging process. Despite this, today the aging of the body is not only inevitable, but also necessary process for every creature on Earth. There are philosophical and religious movements that include the intellect as a human property, which is capable of controlling the aging process as a carrier and exchanger of damaged genetic information. One can only hope that this is the first step towards the birth of super beings who never age.

Theories of aging

All theories of aging can be divided into two large groups: evolutionary theories and theories based on random cell damage.

The first believe that aging is not a necessary property of living organisms, but a programmed process. According to them, aging developed as a result of evolution due to some advantages it provides to an entire population.

In contrast, damage theories suggest that aging is the result of a natural process of accumulation of damage that the body tries to fight, and differences in aging different organisms are the result of the different effectiveness of this struggle.

The latter approach is now considered established in the biology of aging. However, some researchers still defend the evolutionary approach, and some others completely ignore the division between evolutionary and damage theories. The latter statement is partly the result of a change in terminology: in some recent work, the term "evolutionary theories" refers not to theories of "programmed aging", which propose the evolutionary emergence of aging as a beneficial phenomenon, but to an approach that describes why organisms should age, as opposed to the question of the biochemical and physiological basis of aging.

The hormonal-genetic approach is that during a person’s life, starting from birth, there is an increase in the sensitivity threshold of the hypothalamus, which ultimately, after 40 years, leads to hormonal imbalance and progressive disruption of all types of metabolism, including hypercholesterolemia. Therefore, treatment of diseases of old age must begin with improving the sensitivity of the hypothalamus.

• Epigenetic theory of aging
• Mitochondrial theory
• Somatic mutation theory
• Free radical theory
• Evolutionary genetic approach
• hormonal-genetic approach-

Causes of aging

History of the study

The first attempts to scientifically explain aging began at the end of the 19th century. In one of the first works, Weisman proposed a theory of the origin of aging as a property that arose as a result of evolution. According to Weisman, “organisms that do not age are not only not useful, they are harmful because they take the place of the young,” which, according to Weisman, should have led evolution to the emergence of aging.

An important step in the study of aging was Professor Peter Medawar's report to the Royal Society of London in 1951, entitled "An Unsolved Problem in Biology". In this lecture, he emphasized that animals in nature rarely live to an age when aging becomes noticeable, so evolution could not influence the development of aging. This work marked the beginning of a whole series of new studies.

Over the next 25 years, research was predominantly descriptive. However, since the end of the 1990s, a large number of theories have arisen that have tried to explain aging. For example, a famous review of the literature on the subject, published by Caleb Finch in 1990, had about 4 thousand references. Only at the end of the 2000s the situation began to become clearer, and most authors began to come to general conclusions.

All theories of aging can be divided into two large groups: evolutionary theories and theories based on random cell damage. The first believe that aging is not a necessary property of living organisms, but a programmed process. According to them, aging developed as a result of evolution due to some advantages it provides to an entire population. In contrast, damage theories suggest that aging is the result of a natural process of damage accumulated over time that the body tries to combat, and that differences in aging between organisms result from differences in the effectiveness of this fight. The latter approach is now considered established in the biology of aging. However, some researchers still defend the evolutionary approach, and some others completely ignore the division between evolutionary and damage theories. The latter statement is partly the result of a change in terminology: in some recent work, the term "evolutionary theories" refers not to theories of "programmed aging", which propose the evolutionary emergence of aging as a beneficial phenomenon, but to an approach that describes why organisms should age, as opposed to the question of biochemical and physiological basis of aging.

Why does aging occur?

Evolutionary genetic approach

The hypothesis that formed the basis of the genetic approach was proposed by Peter Medawar in 1952 and is now known as the “mutation accumulation theory” (eng. Mutation accumulation theory). Medawar noted that animals in nature very rarely live to an age when aging becomes noticeable. According to his idea, alleles that appear throughout later periods life and which arise as a result of mutations of germ cells are subject to fairly weak evolutionary pressure, even if such properties as survival and reproduction suffer as a result of their action. Thus, these mutations can accumulate in the genome over many generations. However, any individual that has managed to avoid death for a long time experiences their effects, which manifests itself as aging. The same is true for animals in protected environments.

Evolutionary-physiological approach

The theory of antagonistic pleiotropy predicts that there should be genes with a pleiotropic effect, the natural selection of which leads to the occurrence of aging. Several genes with a pleiotropic effect at different stages of life have actually been found - sigma-70 in E. coli, telomerase in eukaryotes, but a direct connection with aging has not been shown, much less it has not been shown that this is a typical phenomenon for all organisms and responsible for all the effects of aging. That is, these genes can only be considered as candidates for the role of genes predicted by theory. On the other hand, a number of physiological effects are shown without identifying the genes responsible for them. We can often talk about trade-offs similar to those predicted by antagonistic pleiotropy theory without clearly identifying the genes on which they depend. The physiological basis for such trade-offs lies in the so-called “disposable soma theory” (eng. Disposable soma theory) . This theory asks how the body should allocate its resources (in the first version of the theory it was only about energy) between the support and repair of the soma and other functions necessary for survival. The need for compromise arises from limited resources or the need to choose the best way to use them.

Maintenance of the body should be carried out only as far as is necessary during the normal period of survival in nature. For example, since 90% of wild mice die within the first year of life, mostly from exposure, the investment of resources to survive over the long term will concern only 10% of the population. Thus, the three-year lifespan of mice is completely sufficient for all the needs of nature, and from an evolutionary point of view, resources should be spent, for example, on improving heat conservation or reproduction, instead of fighting old age. Thus, the lifespan of a mouse best corresponds to the environmental conditions of its life.

The “disposable body” theory makes several assumptions that relate to the physiology of the aging process. According to this theory, aging results from nonideal repair and maintenance functions of somatic cells that are adapted to meet environmental demands. Damage, in turn, is the result of stochastic processes associated with the life of cells. Longevity is controlled through the control of genes that are responsible for these functions, and the immortality of generative cells, unlike somatic cells, is the result of large expenditures of resources and, possibly, the absence of some sources of damage.

How does aging occur?

Molecular mechanisms

There is evidence of several the most important mechanisms damage to macromolecules that usually act parallel to one another or depend on one another. It is likely that any of these mechanisms may play a dominant role under certain circumstances.

In many of these processes, reactive oxygen species (in particular free radicals) play an important role; a set of evidence about their influence was obtained quite a long time ago and is now known as the “free radical theory of aging.” Today, however, the mechanisms of aging are much more detailed.

Somatic mutation theory

Many studies have shown an increase in somatic mutations and other forms of DNA damage with age, suggesting DNA repair as an important factor in supporting cell longevity. DNA damage is typical for cells, and is caused by factors such as hard radiation and reactive oxygen species, and therefore DNA integrity can only be maintained through repair mechanisms. Indeed, there is a relationship between longevity and DNA repair, as has been demonstrated by the enzyme poly-ADP-ribose polymerase-1 (PARP-1), an important player in the cellular response to stress-induced DNA damage. Higher levels of PARP-1 are associated with longer lifespan.

Accumulation of altered proteins

Protein turnover is also important for cell survival, for which the appearance of damaged and excess proteins is critical. Oxidized proteins are a typical result of the influence active forms oxygen, which are formed as a result of many metabolic processes of the cell and often interfere with the correct functioning of the protein. However, repair mechanisms cannot always recognize damaged proteins and become less effective with age due to a decrease in proteasome activity. In some cases, proteins are part of static structures, such as a cell wall, that cannot be easily destroyed. Protein turnover also depends on chaperone proteins, which help proteins obtain the required conformation. With age, there is a decrease in repair activity, although this decrease may be the result of chaperones (and protoasomes) being overloaded with damaged proteins.

There is evidence that the accumulation of damaged proteins does occur with age and may be responsible for age-associated diseases such as Alzheimer's disease, Parkinson's disease and cataracts.

Mitochondrial theory

The importance of the link between molecular stress and aging has been suggested based on observations of the effect of accumulation of mutations in mitochondrial DNA (mtDNA). These data were reinforced by the observation that the number of cells lacking cytochrome c oxidase (COX) increases with age, which is associated with mtDNA mutations. Such cells often have disturbances in ATP production and cellular energy balance.

The mitochondrial theory of aging was first proposed in 1978 (mitochondrial theory of development, aging and malignant growth). Its essence lies in the fact that the slowdown in the proliferation of mitochondria in highly differentiated cells due to a deficiency of mitochondrial proteins encoded in the nucleus creates conditions for the emergence and selective selection of defective deletion mtDNA, an increase in the proportion of which gradually reduces the energy supply of cells.

Telomere loss

In many human cells, the loss of the ability of cells to divide is associated with the loss of telomeres at the ends of chromosomes, which are lost after a certain number of divisions. This occurs due to the absence of the enzyme telomerase, which is usually expressed only in germ cells and stem cells. It has recently been discovered that oxidative stress (excessive production of reactive oxygen species) may also have an effect on telomere loss, significantly accelerating the process in certain tissues.

Epigenetic theory of aging

Cells slowly lose markers of repressed chromatin over time, which may be associated with cell differentiation in the body. The loss of repression markers should sooner or later lead to derepression of dormant transposons and, accordingly, to an increase in the amount of DNA damage they cause with subsequent activation of the cellular DNA repair system. The latter, in addition to participating in DNA repair, also cause unauthorized recombinations in telomeres. It is also possible that transposon recombinases can directly initiate such recombinations. As a result, extended sections of telomeric DNA are converted into rings and lost, and telomeres are shortened by the length of the lost circular DNA. This process accelerates the loss of telomeric DNA tens of times, and the subsequent apoptosis of most cells determines aging as a biological phenomenon. The proposed theory is an alternative to the hypothesis of genetically programmed aging and the hypothesis of aging as a consequence of the accumulation of errors and damage, explains the mechanism of accelerated telomere loss in the case of oxidative stress and DNA damage, as well as the relationship between aging and the occurrence of tumors.

System and network mechanisms

In the early stages of aging research, numerous theories were seen as competing theories to explain the effects of aging. However, it is now believed that many cell injury mechanisms operate in parallel, and cells must also expend resources to combat multiple mechanisms. To investigate the interactions between all damage control mechanisms, a systems approach to aging has been proposed that attempts to simultaneously take into account a large number of such mechanisms. Moreover, this approach can clearly separate the mechanisms that operate at different stages of an organism's life. For example, the gradual accumulation of mutations in mitochondrial DNA often leads to the accumulation of reactive oxygen species and decreased energy production, which in turn leads to an increased rate of damage to DNA and cell proteins.

Another aspect that makes the systems approach attractive is understanding the differences between different types of cells and tissues in the body. For example, cells that are actively dividing with more likely suffer from the accumulation of mutations and telomere loss than differentiated cells. At the same time, it is necessary to clarify that this thesis does not apply to rapidly and repeatedly dividing transformed and tumor cells that do not lose telomeres and do not accumulate mutations. Differentiated cells are more likely to suffer from protein damage than cells that divide rapidly and “dilute” damaged proteins with newly synthesized ones. Even if a cell loses its ability to proliferate due to aging processes, the balance of damage mechanisms in it shifts.

Population approach

Another approach to studying aging is studies of population dynamics of aging. All mathematical models of aging can be roughly divided into two main types: data models and system models. Data models are models that do not use or attempt to explain any hypotheses about the physical processes in the systems for which the data are obtained. Data models include, in particular, all models mathematical statistics. In contrast, system models are built primarily on the basis of physical laws and hypotheses about the structure of the system; the main thing in them is to test the proposed mechanism.

The first law of aging is Gompertz's law, which provides a simple quantitative model of aging. This law makes it possible to separate two types of parameters of the aging process. Studies of the deviation of the law of aging from the Gompertz curve can provide additional information regarding specific mechanisms of aging of a given organism. The most famous effect of such a deviation is that mortality reaches a plateau at late age instead of the exponential growth observed in many organisms. Several models have been proposed to explain this effect, including variations of the Strehler-Mildwan model and reliability theory.

System models consider many individual factors, events and phenomena that directly influence the survival of organisms and the birth of offspring. These models view aging as a balance and redistribution of resources in both physiological (during the life of one organism) and evolutionary aspects. As a rule, especially in the latter case, we are talking about the distribution of resources between the direct costs of the birth of offspring and the costs of survival of the parents.

Cellular response to aging

An important issue in aging at the cellular and tissue level is the cellular response to damage. Due to the stochastic nature of damage, individual cells age, for example due to reaching the Hayflick limit, faster than other cells. Such cells can potentially threaten the health of the entire tissue. This threat is most pronounced among stem cells in which fast division, such as bone marrow or intestinal epithelial cells, due to the great potential of such tissues to create mutant, possibly cancerous, cells. It is known that it is the cells of these tissues that quickly respond to damage by initiating the apoptosis program. For example, even low doses of radiation (0.1 μm) cause apoptosis in intestinal epithelial cells, and even mild chemical stress causes apoptosis in stem cells of old mice.

Typically, in such tissues, massive apoptosis is a sign of increasing cell damage. On the other hand, in other tissues the response to an increase in the level of damage may be the arrest of cells at a certain stage cell cycle to stop division. The balance between apoptosis and the arrest of damaged cells is most important as a trade-off between aging and cancer. That is, either the body must kill the damaged cells, or allow them to exist, increasing the risk of cancer. Thus, p53 and telomere shortening, important factors in inducing cell apoptosis, can be considered an example of antigonistic pleiotropy, as stated above.

To summarize, by modern ideas, the cell ages as a result of the accumulation of damage. The rate of this accumulation is determined, first of all, by the genetically determined costs of repairing and maintaining cellular structures, which in turn are determined by the body to satisfy its environmental needs. Long-lived organisms have higher costs (sometimes longer metabolism), resulting in slower accumulation of damage. To combat the risk posed by damaged cells, the body has developed a system of coping mechanisms that often involve a second set of trade-offs.

Sociology and economics of aging

Social aspects

The social status of each age group and its influence in society are closely related to the economic productivity of that group. In agrarian societies, older people have high status and are the object of attention. Their life experiences and knowledge are highly valued, especially in preliterate societies where knowledge was passed down orally. The need for their knowledge allows older people to continue to be productive members of society.

In societies with high level With industrialization and urbanization, the status of older people has changed markedly, reducing the importance of older people, and in some cases even reaching negative attitudes towards old people - ageism. It turns out that the physical inability of older people to work plays a relatively small role, and several other factors are responsible for the loss of value. Among them, the greatest role is played by the constant introduction of new technologies, which require continuous education and training, which are less accessible to older people. A smaller role is played by the large number of still quite strong old workers, which limit the employment opportunities for the new generation and the reduction in the number of people who work for themselves, which could give the old people the opportunity to gradually reduce the amount of work. Due to the general increase in the level of education, the experience of old people, on the contrary, plays a less and less role.

Although in some areas old people are still highly active, for example in politics, in general case Increasingly, older people retire at the end of the most productive period of life, which leads to problems of psychological adaptation to new conditions. First of all, problems arise due to the decrease in the influence of old people, the feeling of not being in demand and the presence of a significant amount of free time. In addition, for large quantity As people age, financial problems become more acute, although in many cases these problems fall on society.

Due to the availability of free time, family relationships increasingly tend to be the center of attention of older people. However, due to changes in family structure in developed countries, large families have become divided and older people are increasingly not living close to their children and other relatives. This poses a challenge for societies to make older people more adaptable to independent living.

An important factor in the sociology of aging is sexual and reproductive activity. In developed countries, men continue to become fathers even at the age of 65 and older.

Elderly people are characterized by resistance to change, although to a greater extent this is explained not by an inability to adapt, but by an increase in tolerance. To help older people adapt to new conditions, special learning programs designed for this category of people.

Economic aspects

Due to the declining ability to perform most types of work in industrial and post-industrial societies, older people are gradually losing sources of income. Thus, they must rely on their own savings, the help of children and society. Due to less confidence in the future, older people tend to save and invest instead of spending on consumer goods. At the state level, the older population is dropping out of the workforce, increasing the burden on active workers and opening the way to industrial automation.

Government social programs that help older people exist in society have existed at some level since the times of the Roman Empire. In medieval Europe, the first law on state responsibility towards older people was passed in England in 1601. Pensions proper were first introduced in 1880 by Otto von Bismarck in Germany. Today, most states have some form of social security programs for older citizens. Although these government programs and ease the burden of old age, they do not bring older people to the level of income characteristic of young people.

Health protection

Although the physiological effects of aging differ among individuals, the body as a whole becomes vulnerable to numerous diseases with the onset of old age, especially chronic ones, requiring more time and money to treat. Since the Middle Ages and Antiquity, the average life expectancy in Europe has been estimated between 20 and 30 years. Today, life expectancy has increased significantly, resulting in an increasing percentage of older people. Therefore, cancer and heart disease typical of old age have become much more common.

The increasing cost of medical care causes certain problems both among older people themselves and for societies that create special institutions and targeted programs aimed at helping older people. Many developed countries expect a significant aging population in the near future, and therefore worry about increasing costs to maintain the quality of health care at an appropriate level. Areas of action to overcome this problem include improving health system performance, more targeted care delivery, supporting alternative health care providers, and influencing demographics.

Cultural variations

There is much variation between countries in both the definition of and attitudes towards aging. For example, retirement age varies between countries, ranging from 55 to 70 years. This difference is primarily explained by differences in the average life expectancy and working ability of older people. In addition, as noted above, there are significant differences between industrial and traditional agrarian societies. While in the former the importance of old people is negligible, in the latter old age is a sign of wisdom and old people have a great influence on society.

Legal aspects

Although in most states some rights and responsibilities are granted to a person starting from a certain age (the right to vote, the right to buy alcohol, criminal liability etc.), often older people are deprived of some rights. Typical examples: the right to drive a car, which is limited in many countries by a maximum age (usually 70-75 years); the right to occupy certain positions (mainly management positions).

"Successful Aging"

In Western countries these days, the concept of “successful aging” is gaining popularity, which determines how aging should proceed in the best way, using modern advances in medicine and gerontology. The concept can be traced back to the 1950s, but was popularized in the 1987 work of Rowe and Kahn. According to the authors, previous studies of old age have exaggerated the extent to which diseases such as diabetes or osteoporosis, for example, can be attributed to old age, and have criticized research in gerontology for exaggerating the homogeneity of the people studied.

The age composition of a population is usually depicted in the form of age-sex pyramids, in which the proportion of the population at each age is depicted as a function of age. On such pyramids, population aging looks like an increase in the proportion of older people at the top of the pyramid at the expense of young people at the bottom. The aging process, therefore, can be of two types: “aging from below,” or a decrease in fertility, and “aging from above,” or an increase in average life expectancy. In most countries of the world, aging from below is the largest of the two factors, and in post-Soviet countries, including Ukraine, it is the only one. For example, in Ukraine, the aging of the population is partially offset by a drop in life expectancy (from 71 years in 1989 to 68 in 2005), both due to deteriorating health care and increasing social inequality, and due to the spread of the AIDS epidemic. Globally, according to the UN, the percentage of the population over 60 years of age was 8% in 1950, 10% in 2000, and is expected to reach 21% in 2050.

Population aging has a significant impact on society. Older people often prefer to save money instead of spending it on consumer goods. This results in significant deflationary pressure on the economy. Some economists, especially Japanese ones, see advantages in this process, in particular the possibility of introducing automation of production without the threat of increasing unemployment and solving the problem of overpopulation. However, the negative effect is manifested in the system of social security and pensions, which in many countries, mainly in Europe, are financed by taxes on the working part of the population, which is constantly decreasing. In addition, there is a significant impact on education, with both reduced government spending and a deterioration in overall literacy rates due to the reduced ability of an aging population to adapt to rising standards. Thus, controlling the aging population and adapting society to new conditions are the most important tasks of demographic policy.

Attempts to increase life expectancy

The main direction of research in gerontology (the so-called biomedical gerontology) are attempts to increase life expectancy, especially in humans. A marked increase in life expectancy is already underway on a global scale, driven by factors such as general improvements in health care and rising living standards. At the individual level, increasing life expectancy is possible through proper diet, exercise, and avoidance of potentially toxic factors such as smoking. However, all these factors are primarily aimed not at overcoming aging, but only at “random” mortality (the Makeham term in the Gompertz-Makeham law), which already today accounts for a small proportion of mortality in developed countries, and thus this approach has limited potential for increasing life expectancy.

The question of whether life expectancy should be increased is now the subject of much debate at the political level, and the main opposition mainly consists of representatives of certain religious denominations. A number of public (RTD, WTA) and religious (Raelites) organizations actively support work to significantly increase human life expectancy. Under the leadership of Mikhail Batin and Vladimir Anisimov, a comprehensive research program “Science against aging” is being developed.

Psychology of Aging

The most noticeable changes in brain function during aging are the deterioration short term memory and increasing reaction time. Both of these factors limit the possibilities for a normal existence in society and are the subject of a large number of studies. However, if an older person is given more time to complete a particular task that does not require a large amount of current knowledge, older people perform only slightly worse than younger people. For tasks that involve vocabulary, general knowledge, and activities to which a person is accustomed, the decline in productivity with age is virtually unnoticeable.

The question of why a person ages is one of the most pressing today. This is a natural process that leads to a gradual decrease in the adaptive capabilities of the body and the functions of all its organs and systems. Since ancient times, people have tried to understand the essence of this process, slow it down, and achieve immortality. Many of the mysteries of age-related decline have already been solved, but many more remain unsolved.

What is aging

This is a natural biological process of a destructive nature. It gradually leads to disruption of the body’s functioning and its survival in the environment. A decrease in the functioning of all organs and systems leads to a limitation of the overall capabilities of the body, the emergence of age-related chronic diseases and an increased risk of dying.

Historically, the essence of life, senile decline and death is considered not only in a biological, but also in a philosophical aspect. Unlike animals, human degradation and death are associated not only with biological, but also with socio-economic processes, as well as with the preservation of mental abilities.

Factors influencing the rate of decline and life expectancy: heredity, the state of internal organs and systems, socio-economic status and the degree of interest of a person in maintaining vigor and health. Therefore, a person’s biological age does not always coincide with the years he has lived. According to WHO recommendations, the following age categories are distinguished:

• 45 – 59 years – average age;
• 60 – 74 years old – elderly;
• 75 – 90 years old – senile;
• over 90 years old - long-livers.

The science that deals with aging is called gerontology, and the branch of medicine that studies diseases of elderly and senile people is called geriatrics.

Is immortality possible?

The question of why people grow old and die has interested people throughout history. Myths about the philosopher's stone and the Holy Grail have excited man's imagination for centuries, forcing him to look for these sources of immortality and an immortal soul.

The answer to the question of immortality was given by the science of genetics. Scientists have found that genetically, human life is programmed for no more than 150 years. Now science is faced with the task of not only prolonging life, but also improving its quality. Geneticists and geriatricians believe that this is quite possible to achieve.

Why the body ages - scientific theories

The main scientific theories of age-related degradation of the body began to appear starting fromXIX century.

I.I. Mechnikov believed that this process is caused by the accumulation of toxic metabolic products in the body, which leads to a breakdown in communication between cells. According to the theory of A.A. Bogomolets, the causes of human aging are associated with changes in the colloid-chemical state and structure of connective tissue proteins. Theory A.V. Nagorny suggests that the biology of organism degradation is based on the attenuation of self-renewal of the cell cytoplasm. All these theories could not explain the essence of extinction, but served as the basis for further study of the main aspects of aging.

Today the most famous theories of aging of the body are:

1. The theory of accumulation of mutations by the English biologist P. Medawar and antagonistic pleiotropy by D. Williams, developed in the 50s of the last century. They are based on the ability of genes to change (mutate), accumulating these changes throughout life. And since each gene is responsible for several traits (pleiotropy), mutational changes entail changes in human physiology. Mutations can occur both spontaneously (for no reason) and under the influence of various environmental factors (stress, infectious agents, etc.). The mechanism operates at different stages of extinction. When a large number of mutations accumulate, a person dies.
2. Theory related to the toxic effects of free radicals. As a result of chemical reactions to cellular level aggressive molecules with an unpaired electron are formed. Colliding with other molecules, they take the missing electron for themselves, becoming neutral, but destroying other molecules and “infecting” them with their aggressiveness. The causes of human aging are associated with an excess of free radicals. Scientists have identified an enzyme that neutralizes free radicals (superoxide dismutase - SOD), the amount of which determines the rate of age-related degradation. This theory is well founded. But scientists are sure that free radicals are not the only cause of extinction.
3. Theory of apoptosis. According to this theory, in a young organism, all types of cells are renewed quickly and completely replace dead ones (each cell has a mechanism of apoptosis - self-destruction after a certain time). At the stage of extinction, this mechanism fails and there are fewer and fewer newly formed cells in the body than dead ones, which leads to general degradation of the body. Apoptosis can be accelerated when cells are damaged. Thus, when rapidly dividing stem cells (including bone marrow cells) are damaged by radiation, the risk of developing malignant tumors increases.
4. Telomere theory. The essence of the theory: in the nucleus of each cell there are 23 pairs of chromosomes, which are twisted spirals with small tips at the ends - telomeres. According to this theory, telomeres most accurately determine a person’s biological age, since they shorten with each cell division. The shorter the telomeres, the longer the time that separates it from the primary mother cell. This theory is very reliable, but it does not explain why the nerve and muscle cells of a mature organism do not divide, the telomeres in them do not change their level, but the cells age in the same way as all the others.
5. Neuroendocrine theory. With age, the brain gradually loses its functions due to the accumulation of toxic metabolic products. As a result, not only the nervous system suffers, but also the endocrine system, since its center is located in the brain and is regulated by its cortex. A deficiency of hormones that regulate all body functions leads to decline.

Causes and mechanism of aging (video)

What happens in the body

There are biological and calendar (by date of birth) age of a person. Biological age depends on the rate of decline, the physiological state of all organs and systems and the degree of adaptation of the individual in the environment. To determine biological age, you need to conduct a full examination and find out what condition the organs are in and how correctly they function, including how capable they are of adapting to various loads.

The following types of aging are distinguished:

• physiological or natural aging– the body fades away in accordance with the genetic “plan”; this is a slow irreversible process that allows the individual to adapt and lead a decent lifestyle;
• pathological appearance– associated with existing chronic diseases, the addition of age-related diseases or hidden pathological (including genetic) processes; This is premature degradation, it occurs much faster.

The biology of aging is associated with circulatory and metabolic disorders. In old age the walls blood vessels lose their tone, sometimes their lumen narrows (with atherosclerosis). This leads to impaired blood circulation and blood supply various organs and fabrics. The deficiency of nutrients and oxygen that accompanies such disorders leads to changes in cellular metabolism and the appearance of the following changes and accompanying signs of human aging:

• decreased metabolic rate, leading to energy deficiency; symptoms: lethargy, weakness, decreased performance;
• a decrease in the adaptive capabilities of the human body, a sharp decrease in immunity in response to external influences; symptoms: hypothermia, stress, high loads lead to increased morbidity;
• decreased function of the heart muscle (myocardium); the heart has difficulty pumping blood into the vessels; symptoms: shortness of breath during physical activity, and then at rest, the appearance of swelling in the legs;
• disruption of the digestive system; food is not fully digested due to a deficiency of digestive enzymes; disturbance of the tone of intestinal smooth muscles leads to the development of constipation and reabsorption of toxic products from the intestines into the blood;
• metabolic disorders in liver and kidney cells: these processes lead to an increase in the content of toxic substances in the blood; symptoms: increasing weakness, lack of appetite, sometimes slight increase body temperature, attacks of nausea, vomiting;
• reducing the content of hyaluronic acid in tissues, which attracts water; characteristic features: the skin becomes dry, wrinkles form, dry mouth, dry and irritated eyes, dryness in the genital area are bothersome; irritation of the mucous membranes leads to infection, the development of acute and chronic diseases (cystitis, vaginitis, keratitis, etc.);
• impaired blood circulation in the pelvis; this contributes to the development of chronic prostatitis and prostate adenoma in men; symptoms: urinary disorders and pain;
• disturbance of calcium metabolism, it is washed out of the bones and increased levels in the blood; symptoms: bones become brittle, appear frequent fractures; excess calcium in the blood can lead to the development of limb cramps;
• metabolic disorders in cartilage and bone tissue; leads to the development of osteochondrosis and osteoarthrosis - metabolic lesions of the spine and joints
• decreased skeletal muscle tone; characteristic features: posture is disturbed, flabby muscles cannot support the spine; symptoms: signs of osteochondrosis intensify, gait becomes uncertain;
• disruption of the neuroendocrine system; sexual function fades, function decreases thyroid gland; symptoms: due to decreased thyroid function appears excess weight, dryness of the skin increases; disorders of the nervous system lead to a decrease in intelligence; Sexual function decreases and women go through menopause.

Gradual extinction

Natural aging continues for decades. The stages of aging correspond to age categories. It matters at what age a person ages: the process starts immediately after growth stops.

After 30 years

Its first signs can be noticed after 30.

Over the next 15 years, you can see the following changes:

• excess weight appears, which indicates a decrease in energy costs and fat deposition in the form of strategic energy reserves; but if a person leads a healthy lifestyle, from excess fat easy to get rid of;
• the skin becomes drier than it was just a few years ago; upon careful examination, you can see the first emerging wrinkles on the face, which become especially noticeable by the age of 40;
• the reproductive capabilities of men and women are reduced; infertility develops more often; in women over 35 years of age, the risk of miscarriage increases;
• in men, the secretion of male sex hormones gradually decreases, the first disruptions in sex life; but often after 30 years of age, men still have high hormonal activity, which leads to baldness.

45 - 60 years

The next stage is 45 – 60 years:

• the functional abilities of the endocrine system gradually decrease; this leads to external changes (stable weight gain, increased dry skin) and a decrease in reproductive abilities; women's reproductive abilities decline;
• The sexual and reproductive capabilities of men decrease, the first symptoms of damage to the prostate gland and associated urinary disorders appear;
• increasing weight contributes to fatigue and decreased performance;
• the skin becomes dry, wrinkled, and bags under the eyes appear due to a decrease in its tone;
• persons whose work involves constant eye strain develop dry eyes;
• disturbances in the functioning of the cardiovascular system develop: increased blood pressure (BP), severe short-term pain in the heart (attacks of angina pectoris against the background of atherosclerosis);
• closer to 60 years of age, the functions of other organs and systems are disrupted: digestive disorders, cystitis and vaginitis appear in women; in men, urethritis and prostatitis;
• vision is impaired: most people develop farsightedness.

60 – 75 years

How older people age (60 – 75 years):

• the body ages, muscles become thinner; external manifestations: poor posture, signs of osteochondrosis and osteoarthrosis;
• changes in vision and hearing increase; impaired coordination of movements and frequent dizziness appear;
• the functions of digestion, blood circulation, liver and kidneys gradually decrease; but at this age they are not always noticeable;
• osteoporosis develops - bones become fragile due to loss of calcium, frequent fractures are characteristic;
• immunity decreases, the risk of developing tumors and infections increases;
• disturbances in the metabolism of nerve cells leads to a slight decrease in the intellectual level, including memory, especially short-term; A person remembers everything that happened in the past well, but it is difficult to assimilate new knowledge.

75 years and older

Old age (75 – 90 years) and long-livers:

• biological and intellectual decline in elderly people increases slowly, but irreversibly and leads to natural death; the rate of extinction varies from person to person.

Stages of age-related degradation:

• first: maintaining the professional and cultural interests of the individual;
• second: all interests are limited to everyday life;
• third: all conversations come down to health and illness;
• fourth: the circle of communication is sharply limited, the maximum limitation of contacts with the outside world;
• fifth: complete loss of the need for communication and new experiences; life is limited to sleep and food.

What is special about aging women?

The age-related decline of women is closely related to the function of the reproductive system. General, barely noticeable signs of biological decline (slight dry skin and a tendency to gain weight) appear in them after 30 and are easily compensated for proper nutrition, physical activity and proper skin care.

After 40-45 years it begins to change hormonal background women: the function of the hypothalamus-pituitary-ovarian system, which provides hormonal support for reproductive function, decreases.

A deficiency of the female sex hormones estrogen leads to the impossibility of conception. If conception does occur, the risk of miscarriage increases.

After 45–50, many women experience signs of menopause associated with estrogen deficiency:

• violated menstrual cycle: the duration of menstruation is shortened, the intervals between them increase; but sometimes periods can become longer with greater blood loss; sudden cessation of menstruation is rare;
• at 50 – 52 menopause occurs (last menstruation);
• the uterus and ovaries decrease in volume;
• after 60, the tone of the pelvic muscles decreases significantly, which can lead to prolapse and even prolapse of the internal genital organs;
• decreased immunity and thinning of the mucous membranes of the genital organs contribute to the development of infections of the genitourinary organs - vulvovaginitis and cystitis;
• estrogens maintained normal mineral metabolism in a woman’s body; when they are deficient due to leaching of calcium from the bones, osteoporosis and frequent fractures develop;
• Immunity disorders contribute to the development of tumor and autoimmune (with allergies to one’s own tissues) processes.

Sometimes menopause is accompanied by a number of mental, vegetative-vascular and metabolic disorders. In such cases, they speak of climacteric syndrome, the main symptoms of which are:

• mental changes- changeable mood, tearfulness alternating with aggressiveness, bad mood alternating with enthusiasm, increased anxiety etc.;
• vegetative-vascular disorders– a feeling of heat and a rush of blood to the upper half of the body, face and neck; changes in blood pressure, attacks of strong heartbeats and pain in the heart;
• metabolic disorders: dry skin and mucous membranes, development of osteoporosis.

With estrogen deficiency, the vitamin A content and the function of the sebaceous glands of the skin decrease. The skin begins to age quickly.

Socio-economic factors

Factors influencing life expectancy and quality of life include social and economic conditions. It has been established that the higher educational level older people and the better their economic situation, the more prosperous the natural decline proceeds. This is due to better information about healthy way life, the desire to constantly improve the quality of one’s life. It has also been scientifically established that older people with good financial standing have longer telomeres.

Retirement can be a social shock for older people. A sharp transition from high activity to no need to work can be accompanied by significant stress and provoke the development of neuroses, including severe depression.

In such cases, psychology is of great importance: support of old people by relatives, children and grandchildren. Lonely old people will be helped to cope with the situation by being passionate about some activity or creativity. If this does not happen, stress can significantly accelerate the process of degradation and the development of various age-related diseases. Social aging is the acceleration of extinction processes against the backdrop of the lack of a social environment necessary for a normal life.

The aging population is of great importance. There are two types of this process: due to an increase in life expectancy and due to a decrease in fertility. The predominance of the first type is characteristic of a civilized society.

Premature aging

All features of pathological or premature aging are not fully understood. It develops for various reasons, both internal and external. Internal causes include heredity and various chronic diseases. Most often, metabolic diseases accelerate degradation: atherosclerosis, obesity, diabetes mellitus. Against the background of this pathology, it develops new stage: numerous complications that negatively affect metabolism, which affects the rate of decline.

External aspects that contribute to premature decline and shortening of a person’s life include:

• improper inadequate or irregular nutrition;
• sedentary lifestyle;
• bad habits: smoking, abuse of alcohol, psychotropic substances;
• constant overwork and stress;
• psychology of relationships.

Premature aging (progeria) can also be a purely hereditary disease that manifests itself in childhood or in adults. Children with progeria live to an average of 13 years of age. Progeria in adults manifests itself after 30 years; patients rapidly develop all phases of age-related degradation, develop diseases associated with atherosclerosis, malignant tumors, from which they die.

Aging in non-standard conditions

There is no clear evidence that under non-standard conditions aging slows down or accelerates. A NASA study of the aging of twins, one of whom spent a year in space, revealed the following features:

• in a twin who has been in space, the length of telomeres has increased - the surest sign of a halt in degradation;
• some time after landing, the astronaut's telomere length decreased to the same as that of his brother.

So there is no exact evidence of the suspension of extinction processes in space yet, but NASA continues its research.

When asked why people age more slowly during lethargic sleep or in a coma, you can answer like this:

The aging process can be slowed down due to the fact that energy is spent only on maintaining vital functions at rest; the energy saved on social activities allows you to fully cover all the needs of the body; after leaving this state and restoring motor activity, energy costs increase, and the ability to age is restored.

Age-related decline of the body, leading to death, is a genetically determined process that, under certain conditions, can be accelerated or slowed down. All types and patterns of this process have not yet been fully explained, but what is already known gives hope for a significant improvement in the quality of life in old age.

Nothing is eternal. Any organism sooner or later undergoes aging. Unfortunately, this process is irreversible. But the speed at which the body undergoes destructive the impact, after all, depends on each of us. In order to stay healthy longer and look younger than your true age, it is important not only to know the reasons that affect the aging of organs and tissues, but also ways to solve each of the identified problems.
Of course, specialists in the field of cosmetic surgery have advanced far in their research and inventions, but the good news is that there are more accessible and harmless ways to maintain health and beauty.
Before taking specific actions and starting a war against aging, it is necessary to familiarize yourself with a number of reasons that, over time, negatively affect the functioning of the body.

1 . Stress. It has long been no secret to anyone that constant moral stress has an adverse effect on well-being and reduces performance and immunity, significantly increases the risk of cardiovascular diseases. In addition to these disastrous consequences for humans, there is one more thing - premature aging These conclusions were reached by Doctor of Philosophy, professor of psychiatry from Californian Elissa Epel University. hypothesis about premature she carefully checked aging at the cellular level. Her assumption was confirmed.

How to behave.
If you notice that your heart is beating faster or your sweating has increased, take a few measured, deep breaths. And acquire some pleasant hobby for the rest of your life that will reduce constant stress.

2. Drinking alcoholic beverages. There is ample evidence of the harmful effects of alcohol on the body. Of the entire cohort of this type of drink, only red wine is beneficial. Provided that it is used in moderation.

How to behave.
It is beneficial for women to drink one glass of red wine a day, for men - two. According to the study, published in the American Journal of Epidemiology, such a measure will help reduce the risk of death from cardiovascular diseases by a third. But you should not exceed this norm. Excessive use alcohol-containing products leads to strokes, cancers in the liver, chest and throat.

3. Lack of physical activity. Many of us suffer from this deficiency. If not of your own free will, then due to some circumstances. For example, due to sedentary work. William Evans, PhD, professor of geriatric medicine, nutrition and physiology at the University of Arkansas, believes that even a few minutes of physical activity per hour can improve well-being. stabilize weight, cope with stress and slow down the aging process.

How to behave.
The most important thing is to find the strength to increase your level of physical activity. If you don't have time to visit the gym or swimming pool, train yourself to climb the stairs to the floor. Gradually increase the load. The best option is hour and a half walking five times a week.

4 . Eating large amounts of saturated fat. Saturated fats enter the human body along with delicious chicken, meat, milk and butter. Their excessive consumption leads to increased cholesterol levels, which sooner or later leads to heart disease.

How to behave.
The most ideal option in this case is the kitchen. Mediterranean with lots of seafood. Peanut and olive oils, safflower, and canola should be included in your usual diet. The main task remains to reduce the consumption of saturated fat to the optimal level, which is equal to ten percent of the total calories consumed.

5 . Tobacco smoking. Recognized leader among causes of mortality. About five million people on the planet die every year due to smoking. The life of a smoker is on average thirteen years shorter than the life of a non-smoker. These are the statistics in developed countries.

How to behave. To reduce the risk of cancer and premature wrinkles, you need to stop smoking. The dose of nicotine obtained in this way can be replaced with nicotine contained in other sources. These include special patches and chewing gum. Over the past decade, more than a hundred studies have been conducted, the results of which show that these substitutes double the likelihood of quitting smoking.

6. Bad ecology . Polluted and dusty air can cause dry and burning eyes, coughing, asthmatic attacks and respiratory diseases.

How to behave.
Unfortunately, you will not be able to change the level of ecology on your own. It is necessary to travel outside the city as often as possible, to walk through a coniferous or deciduous forest.

7. Prolonged exposure to the sun. Nowadays, skin cancer is a fairly common disease, which has its own incurable forms. For example, melanoma.

How to behave.
You should not go outside during lunch, when the sun burns especially strongly with its rays at right angles. In addition, you need to constantly use sun protection creams that suit your skin type. This will not only reduce the risk of skin cancer, but also get rid of dryness and wrinkles.

8 . Lack of healthy sleep. Lack of healthy and adequate sleep leads to poor health, obesity, high blood pressure, diabetes and even problems with remembering any material. These unfavorable changes are happening to people not only the elderly, they also affect young people.

How to behave.
Sleep eight hours a night. Preferably always at the same time. A consistent sleep pattern will help get rid of many health problems and restore your blooming appearance.

9 . Excess weight. Excessive body weight is the root cause of many diseases. Due to obesity, the cardiovascular system often suffers, and cancer or diabetes mellitus are no less common.

How to behave.
Create an optimal diet for yourself, with which you can eventually adjust weight . This does not have to be a debilitating diet. The presence of all vitamins and minerals in food is important. It is important to adhere to this diet constantly. This event is lifelong and has no deadline. In order to properly develop your menu, which will take into account all the necessary needs of the body, you can visit a nutritionist. To normalize body weight, physical exercise is no less important.

10 . Excessive sugar consumption. Lack of moderation in the consumption of sweets leads to the most unfavorable consequences. This includes weight gain, dental disease, and diabetes.

How to behave.
It is necessary to minimize the consumption of sugar. If you really want something sweet, allow yourself a couple of spoons of honey or eat sweet fruits. Try eliminating foods high in sugar from your diet.

It is impossible to turn back the clock, but each of us can slow down the movement of the hands. Listen to your body and the recommendations of specialists.

Old age or aging- an inevitable process, the essence of which boils down to the appearance of signs of fatigue of both individual organs and tissues and the body as a whole. Old age is the final stage of individual development of the body in our world. The beginning of it in a person is conventionally considered to be after 75 years of age - this is the so-called physiological old age. But even in this state, mental and physical strength, a certain capacity for work, social or social activity and interest in the world around us can be maintained. The aging process does not begin in different organs and tissues at the same time and proceeds with different intensities. In many ways, the intensity of aging depends on the innate, genetically determined properties of tissues.

Many families are known whose members are distinguished by enviable longevity, showing no signs of memory, mental or physical impairment until 80 - 90 years or more. Conversely, there are short-lived families whose members live 35 - 55 years.

It turned out that the lifespan of animals and humans directly depends on the innate activity of the enzyme superoxide dismutase (SOD). Unfortunately, the activity of this enzyme cannot be regulated from the outside, since it is genetically programmed. However, SOD accounts for only 70% of the work to neutralize dangerous oxygen radicals.

The remaining 30% comes from so-called antioxidants, the level of which can be regulated using biologically active drugs. These include vitamins E, beta-carotene, trace elements zinc and selenium and others.

By adding these components to our food, we can control the activity of 1/3 of the free radical processes that limit the rate of aging of our body.

Understanding the patterns of aging is very important. From the modern standpoint of natural science, this is a gradual decrease in the adaptive capabilities of the body.

It is impossible to accurately diagnose the onset of aging - it begins covertly and affects not the entire body, but the most vulnerable organ or system.

And if at first the changes caused by aging practically do not disrupt the process of adaptation of the body to sharply changing living conditions, then later, with more pronounced age-related changes, the body adapts to such tests with more and more difficulty.

First of all, the aging process affects the cardiovascular and nervous systems. The deposition of cholesterol in blood vessels during the aging process leads to a gradual loss of adequate blood supply to the cells of various organs and tissues. nutrients and removal of waste metabolites (slags) from cells.

The functioning of organs is disrupted. The liver is less able to cleanse the blood of water-soluble toxins, which leads to the abundant appearance of pigmented age spots on the skin. The kidneys do not filter the blood effectively enough, as a result of which uric acid, residual nitrogen and other intermediate metabolic products accumulate in the blood, the increased concentration of which begins to inhibit primary metabolic processes and inhibit cellular respiration.

The nervous system, which consumes the most energy and needs an uninterrupted supply of oxygen, glucose, calcium and other nutrients, is very sensitive to the accumulation of toxins in the body.

In old people, due to the deterioration of the activity of nervous processes, initiative, efficiency, and attention decrease to one degree or another, the ability to switch from one type of activity to another becomes difficult, emotional instability develops, and sleep is disturbed.

Significant changes are taking place in the sphere of the psyche. With aging, there is a deterioration in character, the appearance of depression, feelings of loneliness and anxiety, thoughts of the worthlessness and meaninglessness of life, fear of the future arises, and people often become extremely stingy or callous.

With age, the capabilities of the body's defenses change, the activity of the immune system, which protects the body from infections, from cancerous degeneration of cells, and contributes to the rapid restoration of damaged organs, decreases.

If the aging of the organism cannot currently be prevented, then the time of its appearance and the rate at which it affects the entire organism can, within certain limits, be regulated. Modern scientists have set out to turn old age not into a painful, long 20-25 year period full of illnesses and suffering, but into a beautiful segment of our journey, full of life wisdom, dedicated to grandchildren and great-grandchildren, family affairs and understanding the depths of existence.

How does aging occur?

The outer side of aging shows up sooner than we think.

First stage characterized by changes in a person's character. Those around him begin to notice his inattention, inability to concentrate, rapid fatigue from monotonous actions, difficulty falling asleep, unexpected emotional ups and downs, irritability, tearfulness and aggressiveness, bad mood, depression, insomnia, the appearance of unaccountable fear, memory disorders.

Second phase is already reflected in a person’s appearance. At the same time, the structure of the skin, hair, and nails changes.

Due to the decrease in collagen cells, the elasticity of the skin deteriorates, dryness and flaking appear, wrinkles, age spots, and irritation appear. The skin becomes thinner because the balance between new growing skin epithelial cells and dying old cells is disrupted, causing the growth of new cells to slow down and the content of dying skin cells to increase.

A similar process occurs in hair. Due to insufficient intake of minerals and vitamins into the body, hair changes its structure, becomes brittle, thin, dull, changes color - gray hair appears. Men often experience baldness, women often experience sparse hair growth and split ends.

Third stage- Aging is associated with changes in figure. Many people become uncharacteristically overweight, their waistline disappears, and their fat mass increases. And if it only affected the deterioration of the figure. Obesity is a sign that the aging process has picked up speed.

At the same time, many negative changes occur in the body, the activity of absolutely all organs and systems is disrupted, including bone tissue, especially the spine, which cannot withstand such weight and begins to deform.

With spinal deformation, the proper functioning of the entire body is disrupted. It is then that all the characteristic diseases of old age appear on the scene.

But do not think that old age is determined by your passport age; your passport age of thirty years is just a signal that you now need to pay attention to yourself. Special attention. Some people notice signs of aging after they are twenty-five, while others notice them after they are forty-five.

According to many scientists, the main cause of aging (degeneration of the body) lies deep in the genetic material of the cell - DNA. The essence of this theory is that damage to the DNA of cells caused by the oxidation process accumulates with age. This leads to the development of degenerative diseases of aging: cancer, immune disorders, cardiovascular pathology, brain and nervous system dysfunction, mental degradation, acquired diabetes mellitus, arthritis.