Guidepost 1: How is today's older population changing?

• Efforts to combat ageism are making headway, thanks to the visibility of a growing number of active, healthy older adults.
• The proportion of older people in the United States and world populations is greater than ever before and is expected to continue to grow. People over 80 are the fastest-growing age group.
• Today, many older people are healthy, vigorous, and active. Although effects of primary aging may be beyond people's control, they often can avoid effects of secondary aging.
• Specialists in the study of aging sometimes refer to people between ages 65 and 74 as the young old, those over 75 as the old old, and those over 85 as the oldest old. However, these terms may be more useful when used to refer to functional age.

PHYSICAL DEVELOPMENT

Guidepost 2: How has life expectancy changed, and how does it vary?

• Life expectancy has increased dramatically. The longer people live, the longer they are likely to live.
• In general, life expectancy is greater in developed countries than in developing countries, among white Americans than among African Americans, and among women as compared to men.
• Recent gains in life expectancy come largely from progress toward reducing death rates from diseases affecting older people. Further large improvements in life expectancy may depend on whether scientists can learn to modify basic processes of aging.

Guidepost 3: What theories have been advanced for causes of aging, and what does research suggest about possibilities for extending the life span?

• Theories of biological aging fall into two categories: genetic-programming theories and variable-rate, or error theories.
• Research on extension of the life span through genetic manipulation or caloric restriction has challenged the idea of a biological limit to the life span.

Guidepost 4: What physical changes occur during old age, and how do these changes vary among individuals?

• Changes in body systems and organs with age are highly variable and may be results of disease, which in turn may be affected by lifestyle.
• Most body systems generally continue to function fairly well, but the heart becomes more susceptible to disease. Reserve capacity declines.
• Although the brain changes with age, the changes are usually modest. They include loss or shrinkage of nerve cells and a general slowing of responses. However, the brain also seems able to grow new neurons and build new connections late in life.
• Visual and hearing problems may interfere with daily life but often can be corrected. Irreversible damage may result from age-related macular degeneration or glaucoma. Losses in taste and smell may lead to poor nutrition. Training can improve muscular strength, balance, and reaction time. Older adults tend to be susceptible to accidents and falls.
• Many older people are sexually active, though the frequency and intensity of sexual experience are generally lower than for younger adults.

Guidepost 5: What health problems are common in late adulthood, and what factors influence health at that time?

• Most older people are reasonably healthy, especially if they follow a healthy lifestyle. Most do have chronic conditions, but these usually do not greatly limit activities or interfere with daily life. The proportion of older adults with physical disabilities has declined. Still, older adults do need more medical care than younger ones.
• Exercise and diet are important influences on health. Loss of teeth can seriously affect nutrition.

Guidepost 6: What mental and behavioral disorders do some older people experience?

• Most older people are in good mental health. Depression, alcoholism, and many other conditions can be reversed with treatment; others, such as Alzheimer's disease, are irreversible.
• Alzheimer's disease becomes more prevalent with age. It is highly heritable, but diet, exercise, and other lifestyle factors may play a part. Behavioral and drug therapies can slow deterioration. Mild cognitive impairment can be an early sign of the disease, and researchers are attempting to develop tools for early diagnosis.
• Major depressive disorder tends to be underdiagnosed in older adults.

COGNITIVE DEVELOPMENT

Guidepost 7: What gains and losses in cognitive abilities tend to occur in late adulthood, and are there ways to improve older people's cognitive performance?

• Physical and psychological factors that influence older people's performance on intelligence tests may lead to underestimation of their intelligence. Cross-sectional research showing declines in intelligence may reflect cohort differences.
• Measures of fluid and crystallized intelligence show a more encouraging pattern, with crystallized abilities increasing into old age.
• In Baltes' dual-process model, the mechanics of intelligence often decline, but the pragmatics of intelligence may continue to grow.
• A general slowdown in central nervous system functioning may affect the speed of information processing. However, this slowdown may be limited to certain processing tasks and may vary among individuals.
• The Seattle Longitudinal Study found that cognitive functioning in late adulthood is highly variable. Few people decline in all or most areas, and many people improve in some. The engagement hypothesis seeks to explain these differences.
• Although the ability to perform instrumental activities of daily living (IADLs) generally declines with age, ability to solve interpersonal or emotionally charged problems does not.
• Older people show considerable plasticity in cognitive performance and can benefit from training.
• Some aspects of memory, such as sensory memory, semantic and procedural memory, and priming appear nearly as efficient in older adults as in younger people. Other aspects, mainly the capacity of working memory and the ability to recall specific events or recently learned information, are often less efficient.
• Neurological changes, as well as declines in perceptual speed, may account for much of the decline in memory functioning in older adults. However, the brain can compensate for some age-related declines.
• According to studies of metamemory, some older adults may overestimate their memory loss, perhaps because of stereotypes about aging.
• According to Baltes's studies, wisdom is not age-related, but people of all ages give wiser responses to problems affecting their own age group.

Guidepost 8: What educational opportunities can older adults pursue?

• Lifelong learning can keep older people mentally alert.
• Educational programs for older adults are proliferating. Most of these programs have either a practical-social focus or a more serious educational one.
• Older adults learn better when material and methods are geared to the needs of this age group.