Among those above age 70, the average number of diseases that each person reports has increased in recent years (17). This increase is because people have survived a number of diseases that once would have been fatal, and they have lived to acquire additional conditions, both potentially fatal and nonfatal, such as arthritis. Thus, older people have more diseases, but less disability, than in the past. Inclusion of indicators of cognitive functioning in nationally representative surveys of the older population has allowed Freedman and colleagues (29) to estimate change in the prevalence of cognitive impairment during a five-year period during the mid 1990s. They estimate very significant reduction.
