ABSTRACT
Many epidemiological studies have demonstrated that somatic morbidity and functional incapacity are more frequent in old than in young age (e.g., Bell, Rose, & Damon, 1972; Branch, Katz, Kniepeman, & Papsidero, 1984; Palmore, 1986; Steinhagen-Thiessen & Borchelt, 1993). It has been shown that more than 80% of those who are 65 years of age and older, on the average, have a chronic disease, and many of these have multiple diseases (Fozard, Metter, & Brant, 1990). It has also been well known for a long time that increasing age is associated with an increasing prevalence of diseases that affect cognitive functions (e.g., Brody & Schneider, 1986; Fries & Crapo, 1981; Nolan & Blass, 1992). The increasing health problems in old age most likely contribute to the well-known increase in variability in cognitive performance in old age (Bäckman, Small, Wahlin, & Larsson, 1999). It goes without saying, however, that the interrelations between aging, health, and cognitive functions are complex. Only the first steps have been taken to understand the mechanisms behind these interrelations.
