• What are the key issues in defining health and illness?

• How is the quality of life assessed?

• What normative age-related changes occur in the immune system?

• What are the developmental trends in chronic and acute diseases?

• What are the key issues in stress across adulthood?


osa is a 72-year-old immigrant from Mexico liv­ing in a small apartment in a large city in the southwestern United States. For most of her life she has been very healthy, but lately she has noticed it is getting harder to get up every morning. In addition, when she gets a cold she takes longer to recover than when she was younger. Rosa wonders whether these problems are typi­cal or whether she is experiencing something unusual.

Each of us has had periods of health and of illness. Most people are like Rosa—healthy for nearly all our lives. In this section, we will tackle the difficult issue of defining health and illness. We will consider quality of life, an increasingly important notion as medical tech­nology keeps people alive longer. We will see how the differences between acute and chronic disease become more important with age. Because our immune sys­tem plays such a central role in health and illness, we will examine key age-related changes in it. Finally, we will consider how stress can affect our health.

Defining Health and Illness

What does the term health mean to you? The total lack of disease? Complete physical, mental, and social well-being? Actually, scientists cannot agree
on a comprehensive definition, largely because the term has been used in so many different contexts (Davies, 2007). Many people now include biological, psychological, sociocultural, spiritual, and environ­mental components; as Davies (2007) puts it, health is an ongoing outcome from the processes of a life lived well.

The World Health Organization defines health as a state of complete physical, mental, and social well-being, and not merely the absence of disease or infirmity (World Health Organization, 2007). Illness is the presence of a physical or mental disease or impairment.

Think for a moment about your health. How would you rate it? Although this question looks sim­ple, how people answer it turns out to be predictive of illness and mortality (Idler & Benyamini, 1997). Why? There are several possibilities (Wolinsky & Tierney, 1998). One is that self-rated health captures more aspects of health than other measures. A sec­ond possibility is that poor self-rated health reflects respondents’ belief that they are on a downward trajectory in functioning. A third is that people’s self-ratings affect their health-related behaviors, which in turn affect health outcomes. Finally, self­rated health may actually represent an assessment of people’s internal and external resources that are available to support health. Research data support all these ideas; a review of more than 30 years of research showed that self-ratings of health are very predictive of future health outcomes (Blazer, 2008).

Self-ratings also tend to be fairly stable over time. Wolinsky and colleagues (2008) followed 998 African Americans aged 49 to 65 for four years, and found that 55% had the same self-rating over time (25% improved and 20% declined). Overall, men rated their health worse than women did. Among the oldest-old, self-rated health is a powerful pre­dictor of mortality across cultures; for example, a two-year study in China showed that self-rated health still predicted mortality even after socio­economic status and health conditions had been accounted for (Chen & Wu, 2008).

However, self-ratings of health do reflect differ­ences in socioeconomic background in terms of how healthy people say they are. For example, indigenous

Australians rate their health as significantly poorer than nonindigenous Australians, mainly due to dif­ferences in economic variables (e. g., access to health care) (Booth & Carroll, 2008).

Overall, given the strong relation between self­rated health and actual health-related outcomes, including one’s own mortality, it should come as no surprise that researchers often include such measures in their studies of older adults. Such measures pro­vide a good proxy (or stand-in) variable for health, avoiding a time-consuming (and possibly costly) assessment of health. This approach works most of the time; as we proceed, times when it doesn’t will be noted.