When Does a Person Become Old?

The traditional designation for old age—65 years—has no basis in biology. Many people are vigorous and active at 65. Others are sick and inactive at 40. Rather, the basis for choosing age 65 is in history. Age 65 was chosen as the age for retirement in Germany, the first nation to establish a retirement program. (In 1889, Bismarck, Germany's Chancellor, first chose age 70, but in 1916, the age was lowered to 65.)

The question as to when a person becomes old can be answered in different ways. Chronologic age is based solely on the passage of time. It is a person's age in years. Chronologic age has limited significance in terms of health. Nonetheless, the likelihood of developing a health problem increases as people age. Because chronologic age helps predict many health problems, it has some legal and financial uses. It is also used to determine eligibility for some programs for older people.

Biological age refers to changes in the body that commonly occur as people age. For example, vision and hearing typically worsen as people age. Because these changes affect some people more than others, some people are biologically old at 40, and others are biologically young at 60 and even older.

Psychologic age is based on how people act and feel. For example, an 80-year-old who works, plans, looks forward to future events, and participates in many activities is considered psychologically young. Such a person is commonly described as "being young at heart."

People often wonder whether what they are experiencing as they age is normal or abnormal. Although people age somewhat differently, many changes occur in almost everyone and are thus considered "normal." However, a more accurate description of these changes is "usual." Usual aging refers to what happens to most people, including disorders that are common among older people. Usual aging does not necessarily mean that the changes are unavoidable or desirable.

Usual aging was once thought to include such unavoidable changes as muscle weakness, slowed movement, loss of balance, and memory loss. Research has shown that many of these common, "normal" changes result from an unhealthy lifestyle or from disorders that can be prevented or treated and reversed, rather than from aging itself. So the question to ask may be whether changes can be avoided rather than whether they are "normal." This question leads to the concept of healthy aging.

Healthy aging refers to a postponement of or reduction in the undesired effects of aging. The goals of healthy aging are maintaining physical and mental health, avoiding disorders, and remaining active and independent. For most people, maintaining general good health requires more effort as they age. Certain healthy habits have been shown to reduce the risk of developing several disorders that commonly occur as people age. These habits include following a nutritious diet, exercising regularly, and staying mentally active. Developing these habits is an important part of healthy aging. The sooner a person develops them, the better. However, it is never too late to begin. In this way, people can have some control over what happens to them as they age.