Let's postpone aging for later
Man has managed to postpone his biological aging for a decade. This conclusion, first formulated in 1994 in the article Longer Life Expectation? Evidence from Sweden of Reductions in Mortality Rates at Advanced Ages: James Vaupel, Hans Lundstrom // Studies in the Economics of Aging (ed. Wise, D. A.) 79–104 (Univ. Chicago Press, 1994) and has since been repeatedly confirmed, is a fundamental discovery in the field of the biology of human aging, which is extremely important for individuals, society and the economy. Interestingly, the rate of age-related degradation of the body is constant for different individuals and does not change with time. Apparently, modern man retains good health longer, which contributes to the postponement of his death. The results of the work done by demographers, epidemiologists and other specialists in the field of biomedicine indicate that in the future humanity is waiting for further progress in shifting the limits of life expectancy (with good health) to even more advanced years.
The discovery of the possibility of postponing human death and the evidence published after 1994 finally resolved the millennial dispute about the possibility of prolonging life. All the evidence suggests that biological aging of a person is inevitable, but the process of its development is quite flexible. The reason for postponing a person's death is an improvement in health, not revolutionary achievements that slow down the aging process. There is also information according to which the age at which the degradation of the human body begins has also increased in recent years, but these data are contradictory, which is partly due to the complexity of determining and assessing the degree of degradation. The future of humanity in this aspect is unknown, but there is every reason to assume that modern young people have very long lives ahead. If progress in reducing human mortality continues to develop at the same rate, most children born in developed countries after 2000 will live to the next century. An increase in life expectancy will change a person's approach to using the time allotted to him and will require a revision of strategies governing employment, retirement, education, health care and other spheres of human life and activity.
Oddly enough, genetic factors have very little effect on the life expectancy of an individual. The longevity of modern people is mainly due to the improvement of the quality of medical care, standard of living, education, proper nutrition and the popularity of a healthy lifestyle. However, in the future, the improvement of the health of older people, at least in part, will be due to methods developed based on the results of a detailed study of human genetics and the causes of aging.
Postponement of deathThe hypothesis of postponing the death of elderly people was proposed about twenty years ago on the basis of data on a progressive decrease in the mortality rate and the existence of a number of specific populations, such as the population of the high priests of the Mormon Church.
The first convincing evidence of this hypothesis was obtained as a result of the analysis of data on the dynamics of the mortality rate in Sweden. In this country, the systematic collection of demographic data began in the 1750s, and since 1861, the data collection system has been working almost flawlessly.
The results of two more studies, also published in 1994, confirmed the fact of postponing the age of death of older people in other economically developed countries. Since then, a number of proofs of a further increase in this indicator have already been obtained. A side effect of this phenomenon has been the rapid growth in the number of people who have reached the age of 100.
These data confused demographers and actuaries (specialists analyzing statistical data and predicting mortality trends), most of whom believed that the average life expectancy of a person had almost reached its upper limit. They argued their belief with theoretical calculations, as well as the results of analyzing a huge amount of data on mortality trends, which, however, did not apply to the mortality of people over 85 years old. The decrease in the mortality rate was obvious, but experts were of the opinion that a further decrease in this indicator is unlikely. Such pessimism was due to their inability to imagine the scale of possible achievements in the field of increasing life expectancy and was supported by their one-sided understanding of the theory of aging.
In particular, they adhered to the widespread opinion that there is only one cause of death in old age - old age as such – and that it is inevitable. This theory is rooted in the hypothesis proposed by Aristotle about the difference between premature death and death from old age and leads to the conclusion that each species is characterized by a certain maximum life expectancy. Other scientists, ranging from the ancient physician Galen (the end of the second century AD) and ending with the luminaries of our time, proved the ability of a low-calorie diet to prolong life, and also offered numerous hypotheses concerning the secrets of longevity. Evolutionary biologists have argued that biological aging of multicellular organisms is inevitable, but the speed of its development can be influenced by various interventions, including genetic ones. As a result, demographers and actuaries came to the correct conclusion that in the near future we will not be able to enjoy the results of such interventions. In addition, many experts on human aging believe that reducing mortality at a young age will lead to an increase in the life expectancy of sickly individuals, which, in turn, will make it difficult to further reduce morbidity and mortality later in life.
The idea of the inevitability of death as a result of biological aging and the maximum life expectancy specific to each species was refuted by two parallel papers, the results of which were published in 1992 in the journal Science (Curtsinger, J. W., Fukui, H. H., Townsend, D. R. & Vaupel, J. W. Demography of genotypes: failure of the limited life-span paradigm in Drosophila melanogaster, and Carey, J. R., Liedo, P., Orozco, D. & Vaupel, J. W. Slowing of mortality rates at older ages in large medfly cohorts). An analysis of demographic data concerning identical twins born in Denmark since 1870 has not confirmed the existence of a maximum life expectancy at birth. Only 25% of variations in adult life expectancy are due to genetic characteristics. This indicator increases somewhat as a person ages, but even in old age it has only a moderate effect.
Attempts to identify the main "longevity genes" of a person have not been crowned with great success. The results of several studies have shown the ability of two variants of the apolipoprotein E gene to reduce or increase, respectively, the risk of death in old age by 1.1 and 1.2 times compared with the risk for people with the usual variant of this gene. None of the many genes that are considered to be associated with life expectancy has a more pronounced effect. All functioning genes of all organisms are directly or indirectly involved in the processes of reproduction and/or survival. The theory of evolution, as well as the results of a number of empirical studies, suggest that gene variants that significantly increase life expectancy are most likely rarely found in natural conditions due to the associated decrease in fertility. Researchers have sought to increase the life expectancy (in some cases very significantly) of nematodes Caenorhabditis elegans by manipulating hundreds of genes. The identification of the first of these genes, age-1, was a huge achievement that completely changed the way experts look at the genetics of aging. Apparently, each of the polymorphisms of hundreds, and possibly thousands of genetic loci makes a small contribution to the formation of the risks of death and the development of degenerative diseases of old age.
The main achievement of the developing field of biodemography was the proof of the need to revise the theory of the inevitability of biological aging of multicellular organisms with additions to it concerning the existence of a wide range of aging models. The results of work in laboratory and field conditions confirm the fact that for some species at certain stages of adult life, the mortality rate may decrease with age, and changes in diet and other external factors, as well as genetic changes, can significantly change the age trajectories of survival.
Delayed decrepitude
Unlike the age at the time of death, the level of health is very difficult to assess. Assessment of the health status of the population, usually based on the results of systematic surveys, is often hampered by poor attendance of participants, especially those with poor health. Demographers and epidemiologists have begun to collect information confirming the postponement of the onset of biological aging of a person by registering various health indicators, but the emerging picture is much less clear and more contradictory, especially with regard to individuals over the age of 85, than indisputable statistics on mortality. Mortality from various diseases is reduced due to the emergence of more effective methods of treatment, and the incidence can increase not only by increasing the number of cases, but also by increasing the effectiveness of diagnosis.
The incidence of the elderly is increasing over time, which is partly due to earlier diagnosis of diseases such as type 2 diabetes, hypertension and some types of cancer. Recently, the incidence of heart disease has also increased, while the elderly are more likely to suffer from complex pathologies.
The degree of disability is usually assessed from the words of a patient who independently notes the limitations of his abilities when performing routine procedures such as dressing, bathing, shopping, etc. An increasing amount of data indicates a possible decrease in the overall level of disability, reflecting an improvement in the quality of medical care and an increase in the age of biological aging. At the same time, the results of a number of studies indicate an increase in this indicator.
Healthy life expectancy – the number of years during which people maintain good (self-assessment) health is increasing in most countries of the world. The direction of trends in the number of years lived with varying degrees of disability depends on the severity of disability (for particularly severe cases, a decrease is characteristic, and for lighter cases, an increase in the number of years) and vary significantly depending on the country.
The amount of information concerning the improvement of morbidity and healthy life expectancy over the age of 85 is very limited. However, significant improvements in the 1990s were observed, at least in the UK and at least in terms of disability. In Denmark, data on the health status of people over the age of 100, born in the period from 1895 to 1896, are comparable with data on the health status of the corresponding population born in 1905. At the same time, the second cohort of examined patients is 50% larger than the first, mainly due to an increase in the survival rate of people aged 80-100 years. However, the levels of physical and mental health of both cohorts practically do not differ.
There are three health conditions: a person can be healthy, sick or dead. Assuming that the state of the disease is better than death, an increase in the level of general morbidity among the elderly can be considered a positive trend. There are two variants of the condition of the disease: chronic illness with disability and disability. Effective measures of rehabilitation of sick people do not reduce the incidence rate, but reduce the level of disability. The study of which countries are implementing the most effective measures aimed at minimizing disability, and the nature of these measures can serve an invaluable service to all mankind.
Indirect data analysis is also quite informative. Most types of morbidity and disability, including heart disease and dementia, increase mortality. Thus, if it is not possible to delay the development of diseases in people over the age of 85, then we will not have to talk about reducing mortality at this age. In the short term, as well as depending on the studied indicator of health status in the final result, parallel processes of saving lives and improving health status may lead to an increase or decrease in the levels of morbidity and disability. This dynamic explains why, in some cases, the improvement in the health of older people occurs against the background of a slow decline in mortality (for example, in the USA and Denmark in the 1980s and 1990s), and the deterioration - against the background of a faster decline in mortality (for example, in Sweden and, especially, in Japan during the last decades). In the long term, however, improving the health of elderly people can ensure a gradual increase in survival rates. This hypothesis is plausible enough, but not supported by convincing evidence.
As one generation ages, the relative number of women in the population gradually increases. As a rule, more boys are born, but despite the higher level of male mortality, by the age of 80 there are only two men for three women (according to Swedish statistics), and by the age of 100 this ratio reaches 6:1. However, older men are generally in better health than their peers. The mechanisms of this paradox are currently unclear. Men often assess their health status better than it actually is and are less likely than women to seek medical help, while women with poor health live longer than men. Men are also more prone to reckless behavior, which can partly be explained by genetic factors that are based on differences in the reproductive capabilities of men and women.
Postponement does not mean slowing downBiological aging is triggered by a total imbalance between the amount of damage accumulating in the body and the rate of their recovery.
Reducing the level of damage (for example, by improving living conditions and preventing diseases) and stimulating their recovery (for example, through medical interventions) are two fundamental mechanisms for improving health. It is logical to assume that the result of the action of these mechanisms will be a slowdown in the processes of degeneration of the body. However, the existing data indicate that in reality there is not a slowdown, but a delay in the launch of these processes. For example, mortality rates and other health indicators that previously corresponded to the 70-year-old age are now more typical for the 80-year-old. This statement is supported by the results of a number of demographic and epidemiological studies, as well as works using animals. However, the most impressive data were obtained when studying a population of people over the age of 110 years.
Very often, the stated age of centenarians does not correspond to reality, therefore, to confirm their age, it is necessary to find authentic official birth records. The results of a scrupulously conducted study showed that for people whose actual age is 110-114 years, the probability of dying in each subsequent year is stable and equal to 50%. The results of scattered observations on the mortality of people who have reached the age of 110 do not contradict these data. Apparently, at this age, the rate of degradation of the human body remains constant.
Reasons for postponement in the past and futureThe main factors contributing to the postponement of biological aging of a person are well-being and medicine.
Well-being plays an extremely important role, as comfortable housing, good clothes, good nutrition and the opportunity to have a good time have a positive effect on the health of the elderly. We should also not forget that medical care may require financial costs. At the same time, there are more educated people in rich countries, who, as a rule, lead a healthier lifestyle. In addition, rich countries can allocate more funds to biomedical research. Medical methods of treatment, surgical interventions and preventive measures are especially important for the elderly, weakened by biological aging of the body. Well-being and medicine are interdependent factors, as well-being provides more opportunities for treatment, education and research, and healthier populations, in turn, are more productive and well-off. The average life expectancy of the population of two countries with the same per capita income may differ; at the same time, countries with different living standards may have the same life expectancy of the population.
The difference in the duration of a healthy life of people from the average values is also determined by a variety of additional factors interacting with each other. Despite intensive study of the issue, the roles of family composition, social ties, obesity and other factors are largely unclear. For example, there is disagreement about the relative importance of impacts occurring in the early and late stages of life. On the one hand, a number of factors that influence the periods of intrauterine development and childhood, including the season of birth, have serious consequences on the state of health in old age. For example, Europeans of the 1900 generation who were born in November and lived to the age of 50 lived on average a few months longer than their peers born in May. Information about the impact of hunger on life expectancy is ambiguous, and the presence of a twin(s) does not seem to have long-term effects. On the other hand, it is known that smoking in adulthood has a serious impact on health even decades after giving up a bad habit. It is also obvious that events that play an important role at later stages of life, such as new medical advances or economic growth, are the main determinants of success in reducing mortality among older people. An impressive example of this pattern is the unification of Germany, after which the mortality rate of elderly and very old people living in the former East Germany began to decline rapidly and soon almost equaled the mortality rate in the former West Germany.
Smoking, an immobile lifestyle and excess weight leave almost no chance for a person to live to a ripe old age. In modern conditions, a healthy lifestyle increases the chance of meeting the 100th anniversary by only a few percent, however, it should be remembered that a century ago this chance was still two times less. At the same time, experts say that about half of modern children currently living in countries with high life expectancy will live to 100 years. A critical factor that ensures a relatively long life (compared to the life expectancy of contemporaries) is the behavior of an individual, but the overall level of longevity of the population determines the well-being and level of medical care.
Further postponement of biological aging of a person depends on progress in improving the health of not only the elderly, but also young people. Of great importance is the implementation of measures aimed at improving living and working conditions and combating unhealthy habits and inclinations (smoking, alcohol abuse, overeating, sedentary lifestyle, etc.), as well as increasing the availability of high-quality medical services.
To increase the average life expectancy to 100 years, humanity needs information. Recent scientific achievements indicate that the effectiveness of prevention and treatment of cardiovascular and oncological diseases will significantly increase in the future. Biological aging is associated with two serious problems: impaired cognitive function and decreased sensitivity of all sensory organs, progress in overcoming which can significantly improve the quality of life of older people. Further study of human genetics and other organisms over time will not only generally increase the level of understanding of the mechanisms leading to biological aging, but will also allow individualizing therapeutic and preventive approaches. The study of the mechanisms of action of a low-calorie diet and other non-genetic interventions can also result in the development of strategies to delay human aging. The developing field of regenerative medicine shows great hopes that in the coming decades a person will learn to rejuvenate various organs and tissues. The development of nanotechnology can also play a role in the fight against biological aging of humans.
Forecasts and consequences of increasing life expectancyDemographers usually predict future mortality rates by extrapolating previously observed trends, sometimes making adjustments to reflect the most likely changes in these trends.
The future may bring catastrophes (epidemics, wars, economic crises, etc.) or breakthroughs (possibly preventing biological aging), but both catastrophes and breakthroughs have happened in the past. Over the past 170 years, in the countries with the highest average life expectancy, such events did not affect the growth of this indicator, which continued at a rate of 2.5 years per decade or six hours per day.
Slowing down the rate of increase in the death rate as people age would significantly slow down biological aging. For example, for modern Swedish women, a twofold decrease in the annual probability of death after 50 years would mean an increase in life expectancy to 84-90 years, while a twofold decrease in the rate of mortality growth after 50 years would increase this indicator to 118 years. This perspective inspired experts on aging to "change the strategy", consisting in the transition from the study of individual diseases to a systematic fight against aging as such.
If young people are sure that they will live at least a hundred years and that they are guaranteed good physical and mental health until the age of 90-95, they will probably manage their allotted time differently than most of our contemporaries do. Having several additional decades at their disposal will allow people to combine education, work, parenting and active recreation more effectively, rather than spending the most productive years of their lives on work and career, forgetting about the importance of creating a full-fledged family.
The prospectsBefore the discovery of the possibility of postponing biological aging of a person, the efforts of geriatricians were regarded as commendable, but, for the most part, futile attempts to alleviate the fate of those doomed to death.
However, today geriatrics, as a specialty, is becoming increasingly attractive. Similarly, the previously unpromising study of the mechanisms of aging has now transformed into an actively developing scientific direction.
The demography of aging, in particular, has become one of the most exciting areas of demography. Demography based on mathematical data processing is of interest not only for politicians, but also for society. It is closely interrelated with both biological and social sciences, and also plays an important role in expanding human knowledge about the mechanisms of aging.
Most politicians understand that the world's population is aging, but they are not fully aware of the rapidity of this process, its social and economic consequences and the inevitability of changing the principles of health care. The phenomenon of postponing biological aging is not discovered as a result of laboratory studies or clinical studies, therefore, specialists in the medical and biological profile are also not fully aware of the possibility of increasing life expectancy. However, the possibility of delaying human biological aging is a proven fact that should inspire future research in the field of gerontology, the work of geriatricians and political reforms.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on Nature: James W. Vaupel, Biodemography of human aging.
31.05.2010