Trends in the Prevalence and Mortality of Cognitive Impairment in the United States: 1993 to 2004

Alzheimer's & Dementia, Vol. 4, 2008

11 Pages Posted: 20 Nov 2015

See all articles by Kenneth Langa

Kenneth Langa

University of Michigan at Ann Arbor

Eric Larson

University of Washington

Jason Karlawish

University of Pennsylvania

David M. Cutler

Harvard University - Department of Economics; National Bureau of Economic Research (NBER); Harvard University - Harvard Kennedy School (HKS)

Mohammed Kabeto

University of Michigan at Ann Arbor - Medical School

Scott Y. Kim

National Institutes of Health; University of Michigan at Ann Arbor

Allison Rosen

University of Massachusetts Worcester - Medical School

Date Written: 2008

Abstract

Recent medical, demographic, and social trends might have had an important impact on the cognitive health of older adults. To assess the impact of these multiple trends, we compared the prevalence and 2-year mortality of cognitive impairment (CI) consistent with dementia in the United States in 1993 to 1995 and 2002 to 2004. We used data from the Health and Retirement Study (HRS), a nationally representative population-based longitudinal survey of U.S. adults. Individuals aged 70 years or older from the 1993 (N = 7,406) and 2002 (N = 7,104) waves of the HRS were included. CI was determined by using a 35-point cognitive scale for self-respondents and assessments of memory and judgment for respondents represented by a proxy. Mortality was ascertained with HRS data verified by the National Death Index. In 1993, 12.2% of those aged 70 or older had CI compared with 8.7% in 2002 (P < .001). CI was associated with a significantly higher risk of 2-year mortality in both years. The risk of death for those with moderate/severe CI was greater in 2002 compared with 1993 (unadjusted hazard ratio, 4.12 in 2002 vs 3.36 in 1993; P = .08; age- and sex-adjusted hazard ratio, 3.11 in 2002 vs 2.53 in 1993; P = .09). Education was protective against CI, but among those with CI, more education was associated with higher 2-year mortality. These findings support the hypothesis of a compression of cognitive morbidity between 1993 and 2004, with fewer older Americans reaching a threshold of significant CI and a more rapid decline to death among those who did. Societal investment in building and maintaining cognitive reserve through formal education in childhood and continued cognitive stimulation during work and leisure in adulthood might help limit the burden of dementia among the growing number of older adults worldwide.

Suggested Citation

Langa, Kenneth and Larson, Eric and Karlawish, Jason and Cutler, David M. and Kabeto, Mohammed and Kim, Scott Y. and Rosen, Allison, Trends in the Prevalence and Mortality of Cognitive Impairment in the United States: 1993 to 2004 (2008). Alzheimer's & Dementia, Vol. 4, 2008. Available at SSRN: https://ssrn.com/abstract=2692695

Kenneth Langa

University of Michigan at Ann Arbor ( email )

500 S. State Street
Ann Arbor, MI 48109
United States

Eric Larson

University of Washington ( email )

Seattle, WA 98195
United States

Jason Karlawish

University of Pennsylvania ( email )

Philadelphia, PA 19104
United States

David M. Cutler

Harvard University - Department of Economics ( email )

Littauer Center, Room 315A
Cambridge, MA 02138
United States
617-496-5216 (Phone)
617-495-8570 (Fax)

National Bureau of Economic Research (NBER) ( email )

1050 Massachusetts Avenue
Cambridge, MA 02138
United States
617-868-3900 (Phone)
617-868-2742 (Fax)

Harvard University - Harvard Kennedy School (HKS) ( email )

79 John F. Kennedy Street
Cambridge, MA 02138
United States

Mohammed Kabeto

University of Michigan at Ann Arbor - Medical School ( email )

Ann Arbor, MI
United States

Scott Y. Kim (Contact Author)

National Institutes of Health ( email )

Warren G. Magnuson Clinical Center
Bethesda, MD 20895-1156
United States

University of Michigan at Ann Arbor ( email )

500 S. State Street
Ann Arbor, MI 48109
United States

Allison Rosen

University of Massachusetts Worcester - Medical School ( email )

55 Lake Avenue North
Worcester, MA 01655
United States

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