The dictionary defines disease as any unhealthy condition.  The National Institute of Child Health and Human Development defines the aging process as a natural continuation of the developmental cycle, which begins long before one normally considers themselves old, or even middle-aged, and proceeds to affect the ability of the body to fight the stressful elements of the environment.
In health the "steady state" mechanism, repairs and replaces body tissue.  Other organs and tissues take up the work of worn out body parts.  In age, the "steady state" mechanism begins to wear out, and there is no system to repair it.  Repair and growth of new tissue slow down.  Healing is slow and often incomplete.
Our bodies are made up of cells, they are born, reproduce, age, and ultimately die.  In reproducing they make copies of themselves; as we age, these copies differ from their predecessors in various ways, each way being a disease in itself.  In other words, old age is like a collection of degenerative diseases.
Diseases are called degenerative, because they each involve the degenerative breakdown of millions of different body cells, which add up to the breakdown of the whole person as well.
The degenerative process of aging occur whether the organism is subject to disease or not, and are primarily the result of cell loses throughout the body.  Progressive loss of body cells is thought to be due to a decline in the body's capacity of self repair and reproduction.
If this conclusion is made, then how do we account for old people who are quite healthy, and how will we know whether the characteristics of the sick old people result from their advance age, illness, or from the interaction of both?
In order to uncover the physiological changes which occur with age alone, it is necessary to separate out those changes which are primarily caused by disease.  The following study will make two important points in regards to what changes occur with aging in the absence of disease:  (1) Many of the changes usually attributed to aging are better seen as the result of disease, and (2) even in the absence of disease there are important changes in physiological functioning with age, although there is far less impairment than is commonly observed.

How one regards senescence is influenced by the individuals hopes, orientation toward life, and philosophy.  Ana Aslan, the Romanian procaine therapist, said that she looked upon old age as virtually the same as disease. "I cannot agree with this assimilation of the two,"commented Simone de Beauvior in her book on old age, "disease is contingent, whereas aging is the law of life."  On the other had, Carl Eisdorfer, who has served as director of the Center for the Study of Aging and Human Development at Duke University says, "There is no necessary relationship between aging and disease".
Most people expect their bodies to degenerate automatically with age and develop such frightening disease as arthritis, cataracts and heart attacks.  But these disease are not caused by growing old.  The damage is caused by persistent strain to an  organ, or bad nutrition. There are probably no diseases caused by growing old.  Diseases associated with old age are simply ones which require decades to develop and don't usually show up in young people.  There  is nothing about old age  which necessitates poor health.
Peak health begins to decline when the body process called anabolism (cell growth)  is overtaken by the opposite process, catabolism (cell death).  Cells have been dying since birth but in our late 20's they start dying faster than they are replaced.
Riley, Foner, and associates (1968), in their review of the research on aging, point out that older persons are less often afflicted with acute diseases (such as infectious diseases) and are more often afflicted with chronic diseases. They are also more likely to suffer disability restrictions because of their health than young persons.
Arthritis and rheumatism, heart conditions, and high blood pressure are the most prevalent chronic diseases afflicting persons age 45, and they increase in prevalence with age.
As people age an increasing percentage exhibit disease so that by age 65 four out of five people are burdened with a chronic condition and about one in three suffers from three or more chronic condition.
Heart disease is far and away the most dangerous and most widespread of the degenerative diseases.  Like other degenerative diseases, heart disease is ordinarily present for a long time in the body before drastic symptoms appear.  
In fact, in our  country, heart disease often begins in the early twenties, growing worse as the years pass until finally the inevitable heart attack strikes.  For most people the first attack does not come until the fifties or sixties.  But for thousands of people every year, the first attack comes in the twenties.  Occasionally even a person in their teens may experience a fatal heart attack.
Illness and disease often occur in individuals who have experienced a series of  psychologically stressful events, a fact particularly pertinent to an understanding of illness in old age.  It appears to be stressful events, not age per se, that are the critical factors.  To the extent that the effects of such events can be ameliorated by education, counseling, and the provision of various intervention programs that provide social supports, patterns of aging can be altered and improved.
The effects of aging and disease are so intricately crossed that it is difficult to separate them.  Nonetheless, it is imperative to distinguish the two.  If they are not distinguished, it can be easily concluded that aging and disease are the same.
Life Styles and Aging  
By changing our life styles we may add to the possibility of an increased life span.  The evidence of this increase is overwhelming when comparing the life style of the U.S. with a tiny  segment of people living in Russia.  In the United States today the average age is around 72 for both male and female.  In the Republics of Georgia, Azerbaijan and in the Cauacaus region of the Soviet Union, an estimated 4,500 to 5,000 people are over 100.  Nearly 50 out of every 100,000 people in that part of the world live to celebrate their 100th birthday and many do not stop at 100.  The oldest Russian is reported to be a healthy, hearty 168 years old.  By comparison, only three in 100,000 reach 100, and very few go much beyond.
These Soviet centenarians are not alone.  Two other societies are also blessed by the miracle of a long, vigorous life.  The Pakistani Hunzas live high in the sky in the Karakoram Range of the Himalayas.  The true number of centenarians in the Hunzan society is not known.  However, there is one well substantiated fact about the Hanas.  According to the UNESCO, they are the only totally cancer free people in the world.  
The Vilcabambans of the Ecuasorian Andes live thousands of miles from the Pakistani Hunzas and the Soviet Georgians, yet they too seem to share the secret of long life.  Their population is small, only 819,but at last count at least nine of their number exceeded 100 years of age.  And their ages were certain, since detailed birth records, kept in the local church, provided proof.
Why do these people live so much longer that the average American?  The reasons are enumerated as follows:
1. The diets of all the long lived people are well stocked with fresh fruits, vegetables, nuts and grains, which provide a balanced complement of necessary vitamins and minerals as adding needed fiber to the diet.  Among the Hunsas, Vilcabambans and long lived Soviets, intestinal diseases ranging from hemorrhoids to cancer occur much less frequently than they do here, possible because of the high fiber content of their diet.
2.  Vigorous, physically demanding work is a way of life.  They begin their long days of physical labor as children and never seem to stop.
3. All these long lived people come from mountainous regions.  They carry out their chores at elevations of 5000 to 12,000 feet above sea level.  Oxygen poor  and of course, pollution free air.
4. To a great extent, they are separated from the pressures and worries of civilization.
5. Good family genes.
It is clear that diet, insulation from pressures and pollution, clean mountain air, daily hard physical work, and good genes, are a contributing factor to long life.
Exercising and Aging  
Exercise is extremely important in extending youthful vitality, though there is no scientific evidence to prove that it significantly extends total life span.  The life extending benefits of exercise most likely result from a reduction in the incidences of certain degenerative diseases rather than from any direct modification of the aging process itself.
Older people who develop good exercise habits enjoy better sleep.  There is good reason to believe that proper sleep can forestall the aging process. Sleep, profound and untroubled, may be regarded as the means whereby  daily accumulations of toxic products are eliminated from the body.  Such perfect sleep, however, becomes rare as the individual ages.  The sleep of the aged is notoriously shallow and easily broken.  Therefore, toxins normally removed by sleep are less adequately eliminated as a person grows older, this in turn affects the quality of sleep, so that a vicious circle develops, resulting in further accumulation of the toxins.
It has been recognized for many years that the facial and neck muscles like those of the rest of the body, can improve in tonicity by exercise practiced over time and on a consistent basis.  It has also been recognized that exercising the jaw muscles and other facial muscles will have a tendency to decrease fat beneath the facial skin.  Consequently, exercising facial muscles have a tendency to actually improve the appearance of a persons face and neck by  decreasing fat in these areas.  Even more so it has been found that the muscles which are strained by movement of the jaw when properly exercised, will decrease wrinkles around the eyes, due to the fact that it will cause a conditioning of the skin around the eyes.
Diet And Aging  
Genetics and living experience determines the bodies weak points and when affected these areas will begin to break down.  Disease and trauma have an effect on the break down of the body also.  Medicine has attempted to show that diet plays a major role in the breakdown of the body systems.  But all that researchers know for sure is that normal nutrition make a healthy body last longer than an unhealthy one.
The only way our bodies can get all the nutrients that are needed to run smoothly is to extract these nutrients from food.  The nutrients found in our foods are composed of vitamins, minerals, amino acids, carbohydrates, and fats.  To understand more fully the value of the ingredients in food certain observations should be made.  The first is that all the nutrients in food are chemicals.  The second observation is that our body is a gigantic collection of living cells.  These cell are born, and they have a natural life span.  Our bodies can be healthy if, and only if, the cells that comprise them are healthy.  What makes a human being healthy is the health of all the trillions of living cells making up the body.
The best way, according to Dr. Frank, to maintain health and to restore damaged health is to provide energy giving nutrients from outside the body.  Among the most essential nutrients are the nucleic acids.  DNA (deoxyribonucleic acid), and RNA ribonucleic acid), which have received virtually no serious medical attention and which are slowly, tragically disappearing from our diets.  Sardines and similar foods have the energy ensuring nutrients, which provide the kind of energy the cells need to create it's own high quality RNA and DNA and to repair the body's damaged nucleic acids.  A young cell can normally repair this damage because it has the needed energy.  The older cell needs help to slow down or reserve the aging process and combat the degenerative diseases that are the unwelcome companions of old age.
The diet is not the final answer, nor are the more powerful nucleic acid extracts.  But clearly they suggest where to look for the single line of attack.  It lies in the neglected area of nutrition, of nourishing the body so that the cells will have the energy to repair themselves.
The greatest hope for increasing life spans can be offered if nutrition from the time of prenatal development to old age is continuously of the highest quality.
Our environment is loaded with pollutants which is unquestionably the fastest growing health menace.  All environmental factors affect disease processes and  may also have some direct influence on the rate of biological aging.  We all inhale some DDT or other pesticides.  Pesticides are present in our foods.  What is their effect  on the aging process?  Well, they certainly don't extend insect life and can produce sterility in birds and other vertebrates.  Skin is the largest organ of the human body.  It is an organ of the body because it performs many essential functions.  Perspiration is given off through the skin.  The skin also helps the body regulate its own temperature.
Skin begins to age at about forty with most people.  As a result of the aging process the skin becomes progressively drier and lose its plumb succulent look, it also begins to lose its elasticity.  This is especially in evidence on the hands, forehead, the eyes, cheeks, and around the mouth.  The ability of the skin to retain water is lost.  Layers of fat directly underneath the skin gradually change and are no longer uniform, causing skin shrinkage and wrinkles.  In addition, there is an extreme loss of subcutaneous fat which causes skin folds to develop in the upper body area, particularly around the neck.
The changes that occur with aging in the skin and subcutaneous tissues are largely responsible for the alterations in external appearance.  As mentioned above, the skin becomes inelastic, dry, and wrinkled.  Minute hemorrhages resulting in the familiar black and blue spots and marking on the skin.  Warts frequently alters the appearance of the face, scalp, and trunk.  Fissures often develop about the mouth, the hair ultimately turn gray and aside from inherited baldness, there is a progressive loss of hair from the frontal and vertical areas of the scalp in men, and a general thinning of the hair in women.  The structural changes responsible for the foregoing consists of an atrophy of the epidermal layer except for the focal areas of hyperkeratosis (excessive deposit of callus).  The latter can be considered premalignant lesions in the sense that malignant tumors, most often basal cell carcinomas, develop at such sites.  
The dermis under goes basophilic degeneration which involves degenerative changes in both collagen and elastic fibers.  The skin adnexal structured (the sweat glands), and sebaceous glands and their hair follicles, undergo atrophy, and there is also atrophy of the subcutaneous tissues. It is not difficult, therefore, to match these structural changes with changes in appearance of the skin.  The fissuring is due to atrophy of the epidermal layer.  The wrinkling and loss of resiliency can be attributed to changes in collagen and elastic, and the dryness to loss of sweat glands.  The secretion of the sebaceous glands contains a factor which protects against hyperkeratotic changes, and loss of this substance permits the development of these tumors.  Atrophy of the hair follicles account for balding.  The loss of subcutaneous tissue is particularly important since the layer affords both an insulating layer and a cushioning against trauma.  The former may be responsible, in part for the inability of old people to regulate body temperature, and the latter to the development of dicubitus ulcers (skin sores) at points of pressure.
The sebaceous glands are not visibly affected by the sun damage.  The dry condition evident on sun affected skin is caused by damage to the epidermis which further results in decreased functioning of the various sebaceous and endocrine glands. Exposure to sunlight is a very large factor in the premature aging of the skin.  Pigmentation will affect this, however, the olive skinned individual will resists the effects of aging for some time.  But even he/she is vulnerable.  Over the years the sun affected skin becomes thinner, darker, and wrinkles appear.  In the light skinned person, whose sunning is pretty well restricted to summer, this aging process begins to show up in the mid-forties until, by the mid-sixties, it is very pronounced.  
Those individuals who are exposed to the sun on a regular year round basis begin to show the effects even sooner.
The concept of  relating decline in physiological function with advancing age has received little attention, and the information which is available is of questionable value because of deficiencies in the design of experiments and lack of long term support to engage in effective longitudinal studies.  However, while important problems of definition remain to be settled, we do have a large body of descriptive information on changes that come with age.  The details may help construct a realistic picture of aging and the degenerative process.
Compiled by
Dr Farhana Islam Biswas