of antigen; below a certain dose, it may no longer even recognize some antigens. It seems to develop an especially sluggish response to some tumor cells. Thus, infection and age-related cancers, such as prostate and colon cancer, become more likely. In addition, the immune system becomes more likely to attack healthy cells, which may lead to an increase in rheumatoid arthritis and other autoimmune diseases. However, most autoimmune diseases do not seem to be a function purely of age, and genetic predisposition may also play a role. In any case, the gradual decline of the immune system leaves the body more and more susceptible to a wide variety of diseases, each of which takes its toll on the functioning and vigor of the organism as a whole.
Aging and Psychological Functioning
Research continues into ways to forestall physical aging in the hopes that someday we will discover a way to stay young as long as we live. The crusade against senescence and death is particularly appealing to Americans, who idealize success and are enamored with youth. The sentiments “You’re only as old as you think you are!” and “Age is just a number!” express an optimistic outlook that fits well with our can-do attitude toward life. According to this optimistic picture of later life, both physical and psychological decline can be offset by vigorous exercise and engagement with the world. “Use it or lose it!” seems to be the motto here, a philosophy that has been applied to everything from “sex after 60” to lifelong learning.
No wonder that the strategy called “successful aging” has become the goal of many gerontologists. In part, they wish to reject age-based stereotypes, and in part, they wish to counter the assumption that aging means a rapid decline into frailty and senility (Rowe & Kahn, 1997). They are certainly right to reject such stereotypes. But the idea of successful aging should never be based on denial of real losses in functioning in the last stage of life. The importance of the idea of successful aging is that it encourages older people to optimize the capacities that remain while compensating for inevitable losses (Baltes & Baltes, 1990). The measure of successful aging is life satisfaction and a sense of well-being in the face of decline. Successful aging therefore involves the psychological side of aging, including self-concept, social relationships, social roles, and cognitive processes (Friedman & Ryff, 2012).
Self-Concept and Social Relationships
The way people see themselves has several dimensions, including personality, self-esteem, body image, and social roles. The aspect of self-concept that changes least with age seems to be personality. For instance, an extroverted person, one who enjoys interacting with other people, is likely to remain extroverted from childhood into the final stage of life. An older person who is skeptical or gullible is likely to have been that way all along.
Other aspects of self-concept do tend to change, however. The aging mind is not so much the impetus for change as is the progression of circumstances in which people find themselves. Take body image, for example. Naturally, the image of one’s body changes as hair becomes grayer and skin gets more wrinkled. Self-esteem varies throughout life with one’s successes, whether they are interpersonal, occupational, intellectual, or otherwise.
Social relationships in old age tend to exhibit the most predictable types of change. For one thing, people’s social networks become smaller as time goes on. With retirement, work relationships diminish, if not disappear. An older person may have outlived a great many friends and family members. In addition, it is difficult to add new members to the network if one is no longer engaged in work or wider community life.
Social Roles
Another aspect of self-concept that changes with age has to do with the social roles we occupy. Growing up and growing older, we leave behind earlier roles, such as child, student, employee, parent, and eventually, perhaps, spouse and friend. In the process, whether as an adolescent or a recent retiree, it is natural enough to ask: Who am I? Psychologist Carl Jung described the psychological task of the second half of life as “individuation”—that is, becoming more and more our genuine individual self as opposed to carrying out the social roles required of people in midlife (Chinen, 1989).
Gerontologists have spoken about this late-life transition as a matter of role loss or role discontinuity. In earlier-life transitions, role losses are typically accompanied by new roles that take their place: Ceasing to be a child in one’s family of birth, one grows up and takes on the role of parent. But in old age, some roles, such as those ended by widowhood or retirement, may never be replaced.
From one sociological standpoint, then, old age can be described as a roleless role (Blau, 1981). Once defined in this way, it is a natural step to see aging as a “social problem.” A different perspective is possible, however. Other sociologists look on old age as a period when individuals maintain informal roles that are individually negotiated and perhaps continually redefined and constructed. In other words, the meaning of age, subjectively experienced, would not be decisively determined by the external roles, such as spouse, employee, and parent, that typically shape behavior earlier in the life course. On the contrary, once freed from conventional roles, the development of the self in later life may become a highly individual matter. From a philosophical point of view, old age can actually appear as an unexpected form of “late freedom” (Rosenmayr, 1984).
The importance of the meaning we bring to situations encountered in life has been underscored by several theories of aging. For example, Hans Thomae has developed his cognitive theory of aging based on empirical results of the Bonn Longitudinal Study of Aging (Rudinger & Thomae, 1990). The cognitive theory of aging argues that it is perception of change, rather than actual objective change, that has the most impact on behavior. The same life event—such as retirement—might be perceived by one person as loss and by another as freedom from an oppressive work situation. Cognitive, emotional, and motivational factors shape the way we perceive any event, and adjustment depends on a balance that changes over the life course. Studies of stress and coping in old age reveal individual differences in mastery depending on perception and adaptation.
The subjective experience of meaning is closely related to individual well-being, as Carol Ryff (1989) has argued. She has defined multiple psychological dimensions, including self-acceptance, which may come from reviewing one’s life; positive relations with other people; autonomy and self-determination; mastery of the surrounding environment; beliefs that give purpose to life; and a sense of personal growth and development over the life course. Ryff’s conceptualization gives a new approach to the definition of activity by shifting our attention to the inner dimension of the relationship between ourselves and the world.
But the old theory of disengagement has received some support as well—for example, through the idea of “gerotranscendence,” Lars Tornstam (2005) has suggested that people find the deepest meaning in the last stage of life by overcoming self-centeredness and fear of death in favor of a spiritual focus.
Cognitive Functioning
The search for interpretive meaning in later life underscores the importance of cognitive functioning in old age. Contrary to the popular stereotype, we don’t “lose a million neurons every day” as we grow older. Most people ages 65 and older do not suffer from memory defects or dementia. Among all those ages 65 and older, there are a moderate number—perhaps one in five—who have mild or moderate cognitive impairment. That means the overwhelming majority of older people have very little or no cognitive impairment. Memory deficits are actually quite limited among the large majority of older people. Nevertheless, some thinking processes do decline or change with age. Cognitive skills such as remembering, solving complex problems, paying attention, and processing language are affected by age- and disease-related changes in the brain.
Cognitive functioning is a critical
