Although aging is a topic that applies to everyone, it tends to be a mysterious process, often leading to more questions than answers upon thoughtful reflection. It may be that we know it when we see it, but little agreement exists in terms of definition, explanation, understanding, or relevancy to oneself.

Old age is typically defined as any age over 65 years, although this number is an arbitrary cutoff. With the increasing life span, additional terminology or definitions have appeared. Gerontologists, professionals who study aging, refer to adults over 65 but under age 75 as the “young-old,” those age 75 to 85 as the “old-old,” and those over age 85 as the “oldest old.” However, aging may be best understood when placed within a cultural context, as life expectancy varies greatly around the world. Today, the life expectancy in most industrialized countries is well over 70 years of age and increasing. Seven percent of the world’s population is currently over the age of 65; by the year 2030, this figure is likely to more than double.

Life expectancy in the United States has increased dramatically over the past two centuries with advances in medicine and public health. Today the average life expectancy at birth is approximately 74 years for men and 80 for women. The “graying of America” has become a popular phrase in reference to the drastic changes occurring in the U.S. population demographics. Although one out of every eight Americans is currently over age 65, with the baby boom cohorts aging, the elderly population is projected to reach 70.3 million in the next decade, making up 20% of the population. Estimates indicate that by 2030, one out of every five Americans will be over age 65, with racial and ethnic diversity continuing to increase with the population expansion.

Historically, the aged or oldest members of a community were held in high esteem and valued for their wisdom and knowledge. However, in modern society, there are many myths and stigmas attached to growing older, leading to what gerontologists identify as ageism. The term ageism refers to prejudice or discrimination against an individual because of age, and it tends to be facilitated though the use of stereotypes to categorize the elderly. Older people are often thought of as weak, fragile, senile, asexual, and incompetent. Research suggests that some stereotypes are so prevalent that they affect older adults’ performance on memory and performance tasks as well as reports of self-esteem.

Regardless of myths, aging is an ongoing process affecting those fortunate enough to avoid the alternative and experience the full life cycle. With people living longer and healthier lives, more focus is being given to the topic of aging than ever before.

Psychosocial Theories of Late Adulthood

Many theories have emerged to explain the psychosocial development of late stages of life. Although there are multiple theories available, the majority fall under one of three categories, depending on the general aspects of adult development focus.

Core Self Theories

Identity theories stem from the concept that adults strive to achieve their full potentials, and that each person must depend on him- or herself to achieve that goal. Much work in this area comes from Erikson’s stages of development; this concept posits that in times of transition, individuals struggle with issues of identity and role confusion. Erikson postulated that in the final stage of life, people work toward integrating their own life experiences with their vision of society and the future.

Core self theories hinge on the idea of optimization of goals though compensation, meaning that individuals both assess their goals and identify how to achieve their goals despite personal difficulties. These theories tend to be supported by behavioral genetics, suggesting that some inherited traits are more apparent later in life. An example would be temperament, which remains constant across the life span.

Stratification Theories

Stratification theories purport that how people are divided into social strata (e.g., age, gender, ethnicity, sexual orientation) influence their access to various options, which can then have an impact throughout the life span. Some theories focus explicitly on the impact that age plays in shrinking an individual’s social sphere, thus leading to social withdrawal. Another theory states that the elderly remain socially active but are forced into withdrawal due to ageism. However, the stratification theories are best viewed through a lens of multiculturalism. Given that cultural values and social categorization are present from birth throughout the life span, they presumably affect life paths.

Dynamic Theories

In contrast, dynamic theorists focus on individuals and the world they inhabit, suggesting there are daily changes in late adulthood. A life of adaptive changes is assumed as people strive to maintain their core selves within the context of a changing body and world. These theories are based on the position of ongoing, nonstop changes in the self and the world, but it is assumed that people will adapt to changes in a way that maintains the core of who they are.

Physical Changes in Aging

The most overt changes of aging may be those that are physical in nature. Much like psychosocial development, physical aging has been explained by various theories, with two basic postulates emerging. Although both focus on the adaptations of the human body, one defines aging as a predetermined, natural part of a fixed genetic plan, with the other examining aging on a cellular level and identifying the cause of aging through interactions with the environment.

Genetic Aging

The genetic theory of aging is based in information about life expectancy, noting that every species seems to have a maximum life span, with this being approximately 120 years for humans. According to genetic explanations of aging, all people inherit genes that allow for survival until middle age or through the reproductive years. Genes causing aging are then activated, with illness and death each occurring in a specific genetic way. Even without the genes for various diseases that occur later in life, there may be several genes that cause aging directly. Some theorize that death could be an adaptive way to make room for a new generation.

Cellular Aging

Theories that emphasize aging at the cellular level state that cell duplication allows for aging as minor errors accumulate over time. Often referred to as damage-based theories, aging is thought to be caused by mutation caused by stresses or toxins or occurring in the processes of cellular repair. Other possible causes of errors on the cellular level may be the presence of oxygen free radicals, deficiencies of the immune system, or telomere shortening when cells no longer reproduce. These cases of imprecise replication, and the cells’ decreased ability to detect and correct them, can result in harmless changes, minor reductions in function, or fatal damage. The processes by which cells are able to repair and replicate themselves are believed to become less successful with age.


Physical appearance may be the most concrete indication of aging. The first outward signs of aging are typically seen in the skin, as aging skin becomes drier, thinner, and less elastic. There may also be an appearance of age spots, blood vessels, and wrinkles in the skin. A change in hair color and texture is a common sign of aging, with hair tending to thin and turn gray and then eventually white.

Changes in body shape and musculature also occur with age as people become shorter in late life due to settling of the vertebrae. Body shape also changes as body fat redistributes and collects in the torso, abdomen, and lower face. Regardless of the fat redistributed, there can be an overall weight loss occurring with age due to loss of muscle and even bone, leaving older people at risk for falls. Remaining as physically active as possible helps aging adults to protect themselves from serious losses of muscle or bone.

Dulling of the Senses

Because our senses allow us to connect with other people and the world around us, these changes can be devastating if the losses are not compensated for. Sensory deficits can limit an older adult’s ability to interact socially and perhaps cause an accelerated process of withdrawal and isolation. Only 10% of the elderly have adequate vision. Although some aging individuals can correct their vision with glasses, a substantial portion suffers serious vision problems due to cataracts, glaucoma, or macular degeneration. Another sensory deficit common in older age is that of hearing loss. One-third of individuals over 60 have hearing loss, with one out of two adults over the age of 80 suffering from poor hearing. For many people this can be helped with the use of hearing aids, but it may be difficult to compensate for if loss is severe.

Sexual Response

Changes in physical appearance and sensory acuity may feed the stereotype of the elderly as asexual. However, research indicates that intimacy and sexuality are an important part of healthy relationships throughout the life span. One age-related physiological change is that of the slowing of the sex response cycle. It may take a man longer to attain an erection, and it may take longer for a woman to attain sufficient vaginal lubrication for intercourse. An erection may not be as firm as it was at a younger age, nor will the vagina have as much elasticity. It may also become more difficult for both men and women to achieve orgasm. However, contrary to popular belief, these changes do not signal the end of a satisfying sex life, and many older adults enjoy intimacy and physical contact throughout the life span.

Common Health Problems Associated With Aging

Poor physical health is not an inevitable consequence of aging. Unfortunately, many illnesses go undetected and untreated because older adults mistakenly blame symptoms on the aging process. Through prevention, early detection, and treatment, many health problems can be avoided during later years of life.

Arthritis, a painful, chronic stiffening of joints, is common in the United States, with over one half of adults over the age of 65 suffering from this disease. Diabetes, caused by blood levels of glucose being too high, can lead to dangerous health problems in older adults, including kidney failure, vision loss, and neuropathy. Although cancer can develop at any age, older adults are also more likely to experience this disease.

Osteoporosis, often considered a “silent” disease because symptoms may not be initially noticed, weakens the bones, increasing risks for a fracture or break. Although osteoporosis is more common in women, many men also encounter weakening bones. In addition, men over the age of 50 may be at risk for prostate problems. Not caused by aging in itself, urinary incontinence, or the loss of bladder control, can range from mild to uncontrollable in older adults.

High blood pressure, or hypertension, is often referred to as the “silent killer” of the elderly due to the lack of identifiable symptoms. However, left unidentified or treated, high blood pressure can lead to stroke, heart disease, and kidney failure. Strokes, the third leading cause of death after heart disease and cancer in the general population, occur when blood is unable to flow to a part of the brain; this causes cells to be damaged or die. In an aging individual, strokes are a leading cause of physical and mental disabilities.

Cognitive Decline

Research consistently supports observations of decrease of memory and speed of thought processing with age. However, there appears to be little agreement on the specific domains or timing of cognitive decline. Although few 80-year-olds would deny change in their cognitive functioning compared to when they were 40, cognitive change is characterized by individual differences. For some people, decline occurs rapidly and appears extreme. For others, decline may be a slow and gradual process or may not appear to occur at all until late life. The dulling of the senses that occurs with aging may have an impact on cognitive processes as the brain may receive distorted sensory input. However, if input reaches the brain, memory can be quite good, although speed of retrieval may be slower due to decreased processing speeds. It seems that cognitive decline in late life is not as extensive or as devastating as was once thought.


Dementia is defined as a chronic decrease in memory in addition to impairment in at least one other area of thought process, including impaired judgment, problem-solving ability, emotional regulation, or language ability. There are more than 70 diseases or circumstances that can cause various forms of dementia, all characterized by forgetfulness and confusion. In general, dementia is a product of damage to the brain and can be reversed less than 5% of the time, depending on the circumstances (e.g., brain tumor or injury, stroke, incorrect medication, or other head injury). Dementia should not be confused with delirium, which is a rapid onset of decreased cognitive ability such as altered consciousness or impaired memory, but which abates with treatment of underlying cause.

The most common form of dementia is due to Alzheimer’s disease. This cognitive decline is not part of the normal aging process but is defined as a gradual loss of memory and personality. Vascular dementia is the next most common type of dementia, leading to cognitive decline through one or a series of strokes. This dementia causes sporadic and progressive loss of cognitive functioning. Some dementias, such as Parkinson’s disease or Huntington’s disease, tend to begin with motor deficits and produce cognitive deficits only in the later stages of the disease process.

An important aspect of the dementia literature addresses the challenges faced by those caring for individuals suffering from dementia. Caregivers are encouraged to seek information and support, given the taxing nature of caregiving for a person with dementia.

Future Directions

Although there is no denying that change occurs over the life span, aging is not synonymous with disease, frailty, decline, or unhappiness. Many older adults would say that they continue to thrive and find meaning in their lives well beyond the age of 65; some would say life didn’t start until they turned 70.

More than ever before, focus is on the process of healthy aging. Contemporary approaches to aging highlight the optimal physical, mental, and social well-being or functioning of older adults, with clear intentions for the quality, and not simply the length, of life continuing to improve. One thing is certain—as long as it continues to occur, aging will be a journey of continued interest and exploration.


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