Ageing or aging (बूढ़ा होना) is the process of becoming older. The term refers especially to human beings, many animals, and fungi, whereas for example bacteria, perennial plants and some simple animals are potentially biologically immortal. In humans, ageing represents the accumulation of changes in a human being over time, encompassing physical, psychological, and social changes. Reaction time, for example, may slow with age, while knowledge of world events and wisdom may expand. The subject of ageing being most interesting, Siddha Spirituality of Swami Hardas Life System appeals to our valuable readers to read this article.
Health Definition (स्वास्थ्य की परिभाषा)
Health is “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.”
Ageing and Health key facts (बूढा होना और स्वास्थ्य प्रमुख तथ्य)
- Between 2015 and 2050, the proportion of the world’s population over 60 years will nearly double from 12% to 22%.
- By 2020, the number of people aged 60 years and older will outnumber children younger than 5 years.
- In 2050, 80% of older people will be living in low- and middle-income countries.
- The pace of population ageing is much faster than in the past.
- All countries face major challenges to ensure that their health and social systems are ready to make the most of this demographic shift.
Today, 125 million people are aged 80 years or older. By 2050, there will be almost 120 million living in China alone, and 434 million people in this age group worldwide, however, 80% of all older people will live in low- and middle-income countries.
Ageing versus immortality (बुढ़ापा बनाम अमरता)
Early life forms on Earth, starting at least 3.7 billion years ago, were single-celled organisms. Such organisms multiply by fission into daughter cells; thus do not age and are innately immortal.
Ageing and mortality of the individual organism became possible with the evolution of sexual reproduction, which occurred with the emergence of the fungal/animal kingdoms approximately a billion years ago, and the evolution of seed-producing plants 320 million years ago.
The sexual organism could henceforth pass on some of its genetic material to produce new individuals and could itself become disposable with respect to the survival of its species. This classic biological idea has however been perturbed recently by the discovery that the bacterium E. coli may split into distinguishable daughter cells, which opens the theoretical possibility of “age classes” among bacteria.
Ageing Effects (बुढा होने के प्रभाव)
Ageing symptoms (बुढा होने के लक्षण)
A number of characteristic ageing symptoms are experienced by a majority or by a significant proportion of humans during their lifetimes, which include:
- Teenagers lose the young child’s ability to hear high-frequency sounds above 20 kHz.
- Wrinkles develop mainly due to photoageing, particularly affecting sun-exposed areas (face).
- After peaking in the mid-20s, female fertility declines.
- After age 30 the mass of a human body is decreased to 70 years and then shows damping oscillations.
- Muscles have reduced the capacity of responding to exercise or injury and loss of muscle mass and strength is common.
- People over 35 years of age are at increased risk of losing strength in the ciliary muscle which leads to difficulty focusing on close objects, or presbyopia.
- Around age 50, hair turns grey.
- Menopause typically occurs between 49 and 52 years of age.
- In the 60–64 age cohort, the incidence of osteoarthritis rises to 53%. Only 20%, however, report disabling osteoarthritis at this age.
- Almost half of the people older than 75 have hearing loss inhibiting spoken communication.
- By age 80, more than half of all Americans either have a cataract or have had cataract surgery.
- Frailty, a syndrome of decreased strength, physical activity, physical performance, and energy, affects 25% of those over 85.
- Atherosclerosis is classified as an ageing disease. It leads to cardiovascular disease e.g. stroke and heart attack, which globally is the most common cause of death.
- Recent evidence suggests that age-related risk of death plateaus after age 105. The maximum human lifespan is suggested to be 115 years.
The oldest reliably recorded human was Jeanne Calment who reportedly died in 1997 at 122, though recent research has disputed this.
Dementia becomes more common with age. About 3% of people between the ages of 65 and 74, 19% between 75 and 84, and nearly half of those over 85 years of age have dementia. The spectrum ranges from mild cognitive impairment to the neurodegenerative diseases of Alzheimer’s disease, cerebrovascular disease, Parkinson’s disease, and Lou Gehrig’s disease.
Memory decline (याददाश्त में गिरावट)
Furthermore, many types of memory decline with ageing, but not semantic memory or general knowledge such as vocabulary definitions, which typically increases or remains steady until late adulthood. Intelligence declines with age, though the rate varies depending on the type and may, in fact, remain steady throughout most of the lifespan, dropping suddenly only as people near the end of their lives.
Visual impairment (दृष्टि क्षीणता)
Age can result in visual impairment, whereby non-verbal communication is reduced, which can lead to isolation and possible depression. Macular degeneration causes vision loss and increases with age, affecting nearly 12% of those above the age of 80. This degeneration is caused by systemic changes in the circulation of waste products and by the growth of abnormal vessels around the retina.
The biological basis of Ageing (बुढा होने के जैविक आधार)
The factors proposed to influence biological ageing fall into two main categories, programmed and damage-related. Programmed factors follow a biological timetable, perhaps one that might be a continuation of the one that regulates childhood growth and development. This regulation would depend on changes in gene expression that affect the systems responsible for maintenance, repair and defense responses.
Damage-related factors include internal and environmental assaults to living organisms that induce cumulative damage at various levels. A third, novel, concept is that ageing is mediated by vicious cycles.
Ageing Programmed factors (बुढा होने के क्रमादेशित कारक)
The rate of ageing varies substantially across different species, and this, to a large extent, is genetically based. For example, numerous perennial plants ranging from strawberries and potatoes to willow trees typically produce clones of themselves by vegetative reproduction and are thus potentially immortal, while annual plants such as wheat and watermelons die each year and reproduce by sexual reproduction.
The oldest animals known so far are 15,000-year-old Antarctic sponges, which can reproduce both sexually and clonally.
In laboratory settings, researchers have demonstrated that selected alterations in specific genes can extend lifespan quite substantially in yeast and roundworms, less so in fruit flies and less again in mice. Some of the targeted genes have homologs across species and in some cases have been associated with human longevity.
DNA methylation (डीएनए मेथिलिकरण)
Horvath hypothesized that DNA methylation age measures the cumulative effect of an epigenetic maintenance system but details are unknown. DNA methylation age of blood predicts all-cause mortality in later life.
Senescent cells (वृद्ध होनेवाली कोशिका)
Restriction of calory (कैलोरी पर प्रतिबंध)
Caloric restriction leads to longer lifespans in various species, an effect that is unclear but probably mediated by the nutrient-sensing function of the mTOR pathway.
mTOR, a protein that inhibits autophagy, has been linked to ageing through the insulin signaling pathway. mTOR functions through nutrient and growth cues leading scientists to believe that dietary restriction and mTOR are related in terms of longevity.
Ras2 gene (रस 2 जीन)
Over-expression of the Ras2 gene increases lifespan in yeast by 30%. A yeast mutant lacking the genes SCH9 and RAS1 has recently been shown to have a tenfold increase in lifespan under conditions of calorie restriction and is the largest increase achieved in any organism.
When telomeres become too short, the cells senesce and die or cease multiplying. The length of telomeres is, therefore, the “molecular clock”, predicted by Hayflick.
The idea that ageing results from an increase in autoantibodies that attack the body’s tissues. A number of diseases associated with ageing, such as atrophic gastritis and Hashimoto’s thyroiditis, are probably autoimmune in this way.
Balancing energy generation and consumption (ऊर्जा उत्पादन और खपत को संतुलित करना)
The cellular balance between energy generation and consumption requires tight regulation during ageing.
Ageing of skin (त्वचा का बुढ़ापा)
Skin aging is caused in part by TGF-β, which reduces the subcutaneous fat that gives skin a pleasant appearance and texture. TGF-β does this by blocking the conversion of dermal fibroblasts into fat cells; with fewer fat cells underneath to provide support, the skin becomes saggy and wrinkled. Subcutaneous fat also produces cathelicidin, which is a peptide that fights bacterial infections.
amage-related factors (बुढा होने के
DNA damage theory of ageing (बुढा होने का डीएनए क्षति सिद्धांत)
Genetic damage – aberrant structural alterations of the DNA, mutations, and epimutations, can cause abnormal gene expression. DNA damage causes the cells to stop dividing or induces apoptosis, often affecting stem cell pools and hence hindering regeneration. However, lifelong studies of mice suggest that most mutations happen during embryonic and childhood development, when cells divide often, as each cell division is a chance for errors in DNA replication.
Genetic instability (आनुवंशिक अस्थिरता)
In heart muscle cells, dogs annually lose approximately 3.3% of the DNA in their heart muscle cells while humans lose approximately 0.6% of their heart muscle DNA each year. These numbers are close to the ratio of the maximum longevities of the two species (120 years vs. 20 years, a 6/1 ratio). The comparative percentage is also similar between the dog and human for yearly DNA loss in the brain and lymphocytes. As stated by lead author, Bernard L. Strehler, “… genetic damage is almost certainly or probably the central cause of ageing.”
Accumulation of waste (कचरे का संचय)
A buildup of waste products in cells presumably interferes with metabolism. This waste accumulates in the cells as small granules, which increase in size as a person ages. The hallmark of ageing yeast cells appears to be an overproduction of certain proteins.
Wear-and-tear theory (पहनने-ओढ़ने का सिद्धांत)
The very general idea that changes associated with ageing are the result of chance damage that accumulates over time.
Accumulation of errors (त्रुटियों का संचय)
The idea that ageing results from chance events that escape proofreading mechanisms, which gradually damages the genetic code.
Cross-linkage (क्रॉस-के संबंध)
The idea that ageing results from the accumulation of cross-linked compounds that interfere with normal cell function.
Free-radical theory (मुक्त-मूलक सिद्धांत)
Damage by free radicals, or more generally reactive oxygen species or oxidative stress, create damage that may give rise to the symptoms we recognize as ageing. Michael Ristow’s group has provided evidence that the effect of calorie restriction may be due to increased formation of free radicals within the mitochondria, causing a secondary induction of increased antioxidant defense capacity.
The mitochondrial theory of ageing (बुढा होने का माइटोकॉन्ड्रियल सिद्धांत)
Free radicals produced by mitochondrial activity damage cellular components, leading to ageing.
DNA oxidation and caloric restriction (डीएनए ऑक्सीकरण और कैलोरी प्रतिबंध)
Caloric restriction reduces 8-OH-dG DNA damage in organs of ageing rats and mice. Thus, the reduction of oxidative DNA damage is associated with a slower rate of ageing and increased lifespan.
How to prevent and delay Ageing (बुढा होने की रोकथाम और देरी कैसे करें)
Lifestyle (जीवन शैली)
No lifespan data exist for humans on a calorie-restricted diet, but several reports support protection from age-related diseases. Two major ongoing studies on rhesus monkeys initially revealed disparate results; while one study, by the University of Wisconsin, showed that caloric restriction does extend lifespan, the second study, by the National Institute on Aging (NIA), found no effects of caloric restriction on longevity. Both studies nevertheless showed improvement in a number of health parameters.
Mediterranean diet (भूमध्य आहार)
The Mediterranean diet is credited with lowering the risk of heart disease and early death. The major contributors to mortality risk reduction appear to be a higher consumption of vegetables, fish, fruits, nuts and monounsaturated fatty acids, i.e. olive oil.
Amount of sleep (नींद की मात्रा)
The amount of sleep has an impact on mortality. People who live the longest report sleeping for six to seven hours each night. Lack of sleep (<5 hours) more than doubles the risk of death from cardiovascular disease, but too much sleep (>9 hours) is associated with a doubling of the risk of death, though not primarily from cardiovascular disease. Sleeping more than 7 to 8 hours per day has been consistently associated with increased mortality, though the cause is probably other factors such as depression and socioeconomic status, which would correlate statistically.
Physical exercise may increase life expectancy. People who participate in moderate to high levels of physical exercise have a lower mortality rate compared to individuals who are not physically active. Moderate levels of exercise have been correlated with preventing aging and improving the quality of life by reducing inflammatory potential.
The majority of the benefits of exercise are achieved with around 3500 metabolic equivalents (MET) minutes per week. For example, climbing stairs 10 minutes, vacuuming 15 minutes, gardening 20 minutes, running 20 minutes, and walking or bicycling for 25 minutes on a daily basis would together achieve about 3000 MET minutes a week.
Chronic stress (चिर तनाव)
A chronically high cortisol level compromises the immune system, causes cardiac damage/arterosclerosis and is associated with facial ageing, and the latter in turn is a marker for increased morbidity and mortality.
A meta-analysis shows that loneliness carries a higher mortality risk than smoking. Stress can be countered by social connection, spirituality, and married life, all of which are associated with longevity.
Medical intervention (चिकित्सा हस्तक्षेप)
Evidence in both animals and humans suggests that resveratrol may be a caloric restriction mimetic. As of 2015, metformin was the understudy for its potential effect on slowing ageing in the worm C.elegans and the cricket. Its effect on otherwise healthy humans is unknown.