The world is aging, and the number of older people is growing worldwide. So we will dedicate this article to human life expectancy and longevity.
In a developed country, a person who reaches the age of 70 has only a 2% chance of dying in the next 12 months, and people who are 50 years old today have a 50% chance of dying to reach 95 years old. In the world, it has gained more than 30 years of life expectancy in recent decades.
We are witnessing a new age, a new stage in life. The new longevity.
The new steps bring profound social and institutional changes, and our institutions are still managed in ways that are too rigid for the way of life of the 21st century. A third of our existence is lived in what is called “retirement.”
Steps such as childhood and adolescence and new longevity today are now social constructs that condition new needs, new capabilities, new markets, or new challenges. However, its consequences are real and based on facts which, in the case of the new longevity, are the following.
The number of older people in the world is increasing. In China alone, there are more people over 60 than the entire population of Russia, with more than 140 million older Chinese people. In many parts of Europe, there are more wheelchairs than baby carriages, and in Japan, more diapers are sold for adults than for children.
Not only are there more seniors, but life has been extended, and today we live more years and in a much healthier way, as never before in the history of mankind.
Not only is the change occurring in quantitative terms but also qualitatively. New roles define this new longevity and help to understand the extent of its influence. This change is observed among seniors who vote, consume, produce, and provide services.
It is a fact that this new longevity is lived with a new intensity. Every day, we meet people who decide to finish their first marathon, travel the world or take on new personal horizons.
Today, the elderly are a more educated generation, which allows them to learn, to know each other, change their lifestyle, and, above all, to question the established canons. Retirement has ceased to be a supposed recreation phase to become another re-creation.
I – Life Expectancy and Longevity Have Increased by 5 Years Since 2000, but Health Inequalities Persist
As shown by the World Health Statistics presented by the WHO World Health Observatory in May 2016, life expectancy has made spectacular progress, even though significant inequalities persist in the same country and from one country to another.
Life expectancy and longevity increased by 5 years between 2000 and 2015, the fastest increase since the 1960s. These advances reverse the declines recorded during the 1990s when life expectancy was reduced in the 1990s. Africa because of the AIDS epidemic and in Eastern Europe as a result of the collapse of the Soviet Union.
The largest increase was recorded in the WHO African Region. Life expectancy increased by 9.4 years to 60 years, mainly because of improved child survival, progress in malaria control, and scaling up access to antiretroviral drugs for HIV treatment.
*** Life Expectancy and Longevity Differs by Place of Birth
Globally, the life expectancy and longevity of children born in 2015 was 71.4 years (73.8 years for girls and 69.1 years for boys), but the perspectives of each child depend on the place of birth. The report states that newborns in 29 countries – all with high incomes – have an average life expectancy of 80 years or more, while newborns in 22 other countries – all located in sub-Saharan Africa – have an average life expectancy of less than 60 years.
Japanese women, whose lives last, on average, 86.8 years, have the greatest longevity. In the case of men, it is in Switzerland that they live the longest, with an average of 81.3 years. The population of Sierra Leone has the lowest life expectancy and longevity in the world for both sexes: 50.8 years for women and 49.3 years for men.
Life expectancy in good health, which measures the years of good health expected for a child born in 2015, is 63.1 years worldwide (64.6 years for women and 61.5 years for men).
This year’s Global Health Statistics compiles the most recent data on the health-related goals of the Sustainable Development Goals (SDGs), adopted by the UN General Assembly in September 2015. The report highlights important gaps in the data that will need to be corrected to track progress toward the health-related SDGs reliably.
For example, an estimated 53% of deaths worldwide are unrecorded, although several countries (including Brazil, China, the Islamic Republic of Iran, South Africa, and Turkey) have made progress in this area.
*** Africa and the Eastern Mediterranean Are Far From Reaching Universal Health Coverage
While the Millennium Development Goals focused on a limited set of health goals for specific diseases by 2015, the Sustainable Development Goals targeted 2030 and were much broader in scope. For example, the Sustainable Development Goals include a general health goal of “Ensuring healthy living and promoting the well-being of all at all ages” and calling for universal health coverage.
This year’s World Health Statistics show that many countries are still far from achieving universal health coverage, measured by an index of access to 16 essential services, particularly in Africa and the Eastern Mediterranean. In addition, a significant number of service users face catastrophic health costs, defined as direct health costs exceeding 25% of total household economic expenditures.
The report collects data that illustrates inequities in access to health services in the same country, that is, between the poorest residents of a given country and the national average for a range of health services reproductive, mother, and child.
Of the few countries for which recent data are available, Swaziland, Costa Rica, Maldives, Thailand, Uzbekistan, Jordan, and Mongolia lead in their respective regions in terms of the most equal to reproductive health services for mothers, newborns, and children.
II – The Brain During Childhood Can Reveal How It Will Grow Old
A study by a team of specialists from the University of Edinburgh, Scotland, published in Science News in August 2016, showed a connection between the brain during childhood and longevity. The breakthrough opens the possibility of knowing what the degenerative process looks like at the cognitive level.
In childhood, the neurons establish a series of connections in a strict order, which makes it possible to obtain a firm brain. This process, at an advanced age, would be reproduced, but the opposite and most striking is that some cells would be involved in both phenomena.
Children and the elderly are the two most distant age groups. Some are at the beginning of the journey that life involves. The others are approaching, even against their will, an inexorable end. However, even if it seems absurd, the last years of life can be traced back to the first.
From the third week of gestation, when the human brain makes its appearance, it is only a tiny patch of indistinct cells. This initial macula then develops at an intense pace during the first years of life, when each cell assumes a specific function to develop. On the other hand, nerve cells migrate to their final destinations and establish the most relevant neural connections that give rise to, for example, memory, emotions, and thought.
Between 1932 and 1947, almost all 11-year-old Scottish children sat for an intelligence test without knowing they would be the key to much later scientific discovery. In 1999, a team of scientists contacted the people examined at the time. The result was the formation of a group of more than 1,000 people aged 80 to 95 years.
After a thorough study of each of the members of the group, it was detected that people with a high level of intelligence at age 11 probably had better cognitive abilities in old age, which would give them the possibility of predicting the brain potentially very early.
Despite the apparent natural link between childhood and old age, researchers immediately took into account the factors that can influence neuronal development: genetics, daily habits, and the level of sociability of participants.
The way the brain is constructed includes white matter, which is an extension of the tissue that connects distant regions of the brain and allows for rapid communication between them. In study participants with greater white matter in good health, better results in brain function tests were recorded by magnetic resonances.
In addition, Scottish researchers have found it appropriate to add that there are neural pathways whose development takes decades, some up to about 30 years. Among the regions that are progressing more slowly are those that monitor the typical weaknesses of adolescence, such as reactions and impulse judgments, which are, according to other studies, the primary function of declining old age.
A quarter of the way the brain assimilates old age is due to a genetic problem inherited. The rest is largely due to the incorporation of habits that have a significant influence on the maintenance of lucidity in the elderly.
The study found worse results in brain tests for participants who were still smoking at age 70. Interestingly, there was no difference between former smokers and those who had never been in contact with cigarettes.
It is known that what is good for heart-healthy eating, physical activity, and non-smoking – is also beneficial for the brain as it reduces the risk of vascular disease.
The level of sociability also plays a key role. A healthy brain depends on others to stay active and reduce the risk of serious disabilities, such as dementia, in the elderly.
The researchers concluded by recommending that there is an urgent need to promote healthy aging in the state, which offers the opportunity to access education and leisure activities. For example, musical training or learning a second language, as well as incorporating appropriate habits that play a fundamental role.
According to a report presented by researchers at the University of Edinburgh and published in the British Medical Journal in January 2016, people with high IQs are more likely to live longer.
The researchers analyzed data from the Scottish Mental Survey, in which more than 2,000 people were assessed at age 11 and followed until death.
Even taking into account factors such as economic status and level of employment, smarter children ended up living longer than those with low IQs.
Subjects who died before January 1, 1997, had a significantly lower mean IQ at age 11 than those alive. The data show that high mental ability at the end of childhood reduces the risk of death up to age 76.
The authors of the study found that people with high IQs were more likely to quit after their negative health effects were known in the 1950s.
A high IQ could be an indicator of an effective nervous system. Alternatively, genes may contribute to the relationship between IQ and longevity.
Talking about intelligence is a complex scientific field, especially since an IQ score does not necessarily represent intelligence and can be affected by social class, educational norms, and other cultural factors.
IV – An X Chromosome, the Secret of Female Longevity
The report, presented by the University of California at San Francisco and published in the March 2019 scientific journal Aging Cell, attributes to the second X chromosome that women have, compared to men, the possible cause of their longevity and other physiological benefits.
On the basis of experiments on mice, scientists analyzed the effects of the presence of two X chromosomes in female mammals compared to males with only one X and one Y.
Unlike the biological richness of the female X chromosome, the male Y contains only a few genes different from those that create secondary sex characteristics such as male genitalia and facial hair and are not necessary for survival.
The researchers compared laboratory mice with four different combinations of chromosomes and gonads (male and female gamete-forming organs), both found in nature – XX in the ovaries and XY in the testes – and two others created in the laboratory.
When manipulating a gene, the combinations are responsible for XX chromosomes implanted in the testes and XY chromosomes in the ovaries. The mice were genetically identical, except for their sex chromosomes, but everything else, including the environment, was identical.
The longest lifespan was achieved in mice with XX chromosomes in their ovaries, which exceeded the average life of 21 months and even reached 30 months. Genes XX implanted in the gonads prevented the premature death of animals but only prolonged their lives by one or two months.
The human Y chromosome has few brain genes and is not essential for survival, the study said. The second X chromosome contains many genes related to the brain and is crucial for survival.
V – More Neurons, Greater Longevity
Researchers at Vanderbilt University in Tennessee, in their work published in October 2018 by The Journal of Comparative Neurology Research in Systems Neuroscience, argue that long-term living will depend on the number of neurons present in the cerebral cortex.
After comparing the longevity of more than 700 endothermic species, or warmblood, with the number of cortical neuronal cells in their brain, it was concluded that the higher the number of these neurons, the greater their durability. This would explain why cockatoos have survived rats for over 50 years, despite a similar body size.
Humans are no exception to this rule because the data shows that we grow, age, and die at the speed that suits us based on the number of neurons in our cortex. This contradicts the idea that we live longer as a result of an unusually long childhood that stunts sexual maturation and aging. The differences in longevity compared to other primates, therefore, lie in the cerebral cortex.
What is the relationship between the number of neurons and life expectancy? Over time, the body accumulates errors that interfere with proper cell function. Researchers speculate that neuronal damage in the cerebral cortex may affect processes such as cognition or the regulation of the body, a fact that could eventually lead to death. Therefore, life would only be possible if there were enough cortical neurons to maintain vital functions.
As a result, the study encourages us to take good care of our brains by conducting activities that maintain neuronal function in good condition, as our life expectancy and longevity will depend on the health of these cells.
VI – A Longevity Hormone Stimulates Memory and Protects Against Aging of the Brain
Scientists at the University of California in the United States conducted a study published in Cell Reports in August 2017, in which they showed that a single injection of a fragment of the Klotho longevity hormone into young and elderly improved spatial memory and connections between neurons of the hippocampus were strengthened rapidly, these cognitive benefits lasted several weeks.
However, it has not been known to date whether the short-term treatment of klotho could rapidly increase brain function. Therefore, scientists treated mice with injections of the α-klotho protein fragment (aKL-F), which resembles the secreted form of the hormone.
With this, the young mice that received daily aKL-F treatment for four days showed spatial learning and better memory performance during the test called ‘Morris water maze’, in which the ability to find and to memorize the location of a hidden platform submerged in a puddle.
On the other hand, aged mice given a single injection of aKL-F had better spatial memory and working performance two days later. In addition, additional experiments demonstrated that aKL-F treatment for several days counteracted motor and cognitive deficits in mice designed to produce high levels of a pathogenic protein called synuclein, which contributes to Parkinson’s and Alzheimer’s disease.
In addition, during the same period in which aKL-F increased cognition, NMDA receptor signaling of glutamate was also increased and, as a result, reinforced connections between neurons in a region of the brain called the hippocampus, which plays a critical role in learning and memory.
Scientists have found that short-term treatment with klotho helps to combat cognitive and motor deficits in mice with diseased brains, hence improving brain function throughout life, which would represent a new therapeutic strategy to increase resistance to neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
Age, chronic stress, cognitive aging, and neurodegenerative diseases lead to a decrease in klotho levels, making this study a very important discovery as it protects the brain from dysfunction. A longevity hormone stimulates memory and protects against the aging of the brain.
The researchers believe that klotho augmentation in humans could be an effective treatment for improving brain resilience.