One in five noninstitutionalized people aged 70 years or older in the United States needs help with one or more activities of daily living (ADLs), such as bathing, using the toilet, dressing, eating, walking, or transferring from a bed to a chair. A new study reveals that functionally independent elderly people, who are either cognitively impaired or depressed, are at substantially increased risk of becoming dependent and needing help with ADLs compared with elderly people who don't have these problems. However, only cognitive impairment is a risk factor for further functional decline among elderly men and women who are already dependent for help in ADLs.
Cognitive impairment and depressive symptoms may lead to an erosion of the physical skills needed to maintain functional independence. They also may lessen resistance to acute stressors such as hospitalization that often accelerate functional decline in older people, explains Kenneth E. Covinsky, M.D., M.P.H. In a study that was supported in part by the Agency for Healthcare Research and Quality (K02 HS00006), Dr. Covinsky and colleagues at the University of California, San Francisco, interviewed 5,697 elderly people (mean age 77 years) in 1993 and 1995.
The researchers measured participants' baseline functional dependence, cognitive ability, and number of depressive symptoms. They then compared the risk of functional decline among those with depressive symptoms, cognitive impairment, or both with the risk of decline among elderly people with neither problem.
Among those who were independent in all ADLs at baseline, the relative risk of 2-year functional decline doubled for those with cognitive impairment and/or depressive symptoms. For those who were dependent in one or more ADLs at baseline, the risk of 2-year functional decline doubled for those with cognitive impairment, rose significantly for those with both problems, but declined by nearly half for those with depressive symptoms alone. Depression, unlike cognitive impairment, tends to improve over time, especially with effective treatment, notes Dr. Covinsky.
More details are in "Cognitive impairment, depressive symptoms, and functional decline in older people," by Kala M. Mehta, D.Sc., Kristine Yaffe, M.D., and Dr. Covinsky, in the June 2002 Journal of the American Geriatrics Society 50, pp. 1045-1050.