Cognitive functioning as a predictor of functional disability in later life.

OBJECTIVE The contribution of cognitive functioning on multiple levels of functional disability and mortality over two years as well as individual activities of daily living (ADLs) and instrumental activities of daily living (IADLs) tasks, in a sample of older U.S. adults was examined. METHODS A total of 4,077 U.S. adults (1,493 males and 2,584 females) aged > or =70 years (mean = 76.35 years) from the Second Longitudinal Study of Aging (1997/1998-1999/2000) were examined using an adapted Telephone Interview of Cognitive Status (TICS), ADLs, and IADLs. RESULTS Multivariate logistic regression investigated cognition as a predictor of five mutually exclusive levels of functional disability. People with the lowest level of cognition had greater odds of mortality at follow-up (adjusted odds ratio [AOR] = 2.86, 95% confidence interval [CI] = 1.94-4.20), ADL and IADL disability (AOR = 1.58, 95% CI = 1.15-2.16), ADL disability (AOR = 1.83, 95% CI = 1.27-2.64), or IADL disability (AOR = 1.22, 95% CI = 0.86-1.71) than those who were disability-free. Cognitive functioning was not predictive of individual ADL tasks but was predictive of the IADL tasks of preparing meals, shopping for groceries, managing money, telephone use, light housework, and medications but not heavy housework. CONCLUSION Persons with lower levels of cognitive functioning were more likely to die or become disabled than those with higher levels of cognition. Changes in cognitive functioning might serve as an early indicator of neurologic and medical factors.

[1]  D. Dunlop,et al.  Incidence of functional limitation in older adults: the impact of gender, race, and chronic conditions. , 2002, Archives of physical medicine and rehabilitation.

[2]  U. Sonn,et al.  Cognitive function and functional ability. A cross- sectional and longitudinal study at ages 85 and 95 in a non-demented population , 2001, Aging.

[3]  S. Willis,et al.  Long-term effects of fluid ability training in old-old age , 1990 .

[4]  Edward L. Korn,et al.  Analysis of Health Surveys , 1999 .

[5]  E D Richardson,et al.  Impairments in physical performance and cognitive status as predisposing factors for functional dependence among nondisabled older persons. , 1996, The journals of gerontology. Series A, Biological sciences and medical sciences.

[6]  J. Cummings,et al.  The Montreal Cognitive Assessment, MoCA: A Brief Screening Tool For Mild Cognitive Impairment , 2005, Journal of the American Geriatrics Society.

[7]  Marshal F. Folstein,et al.  The telephone interview for cognitive status , 1988 .

[8]  Denise C. Park,et al.  Cognitive aging and everyday life. , 2000 .

[9]  B. Mulsant,et al.  Somatic Symptoms in Late-Life Anxiety: Treatment Issues , 2005, Journal of geriatric psychiatry and neurology.

[10]  L. Branch,et al.  Assessing physical function in the elderly. , 1987, Clinics in geriatric medicine.

[11]  B. Vellas,et al.  Instrumental activities of daily living as a potential marker of frailty: a study of 7364 community-dwelling elderly women (the EPIDOS study). , 2001, The journals of gerontology. Series A, Biological sciences and medical sciences.

[12]  Michael Witt,et al.  SUDAAN language manual, release 9.0: , 2003 .

[13]  R. Wallace,et al.  Measures of cognitive functioning in the AHEAD Study. , 1997, The journals of gerontology. Series B, Psychological sciences and social sciences.

[14]  Ronald C. Petersen,et al.  Mild cognitive impairment clinical trials , 2003, Nature Reviews Drug Discovery.

[15]  L. Fratiglioni,et al.  Poor mental and physical health differentially contributes to disability in hospitalized geriatric patients of different ages , 2004, International journal of geriatric psychiatry.

[16]  J Ormel,et al.  The assessment of ADL among frail elderly in an interview survey: self-report versus performance-based tests and determinants of discrepancies. , 1996, The journals of gerontology. Series B, Psychological sciences and social sciences.

[17]  J. Robine,et al.  Healthy life expectancy: evaluation of global indicator of change in population health. , 1991, BMJ.

[18]  M. K. James,et al.  The timing of change: patterns in transitions in functional status among elderly persons. , 1998, The journals of gerontology. Series B, Psychological sciences and social sciences.

[19]  J. Hd..  Americans with Disabilities 1991-1992 , 1994 .

[20]  K. Manton,et al.  Changes in the prevalence of chronic disability in the United States black and nonblack population above age 65 from 1982 to 1999 , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[21]  K. Markides,et al.  Cognitive status and incident disability in older Mexican Americans: findings from the Hispanic established population for the epidemiological study of the elderly. , 2004, Ethnicity & disease.

[22]  E. Crimmins,et al.  Further evidence on recent trends in the prevalence and incidence of disability among older Americans from two sources: the LSOA and the NHIS. , 1997, The journals of gerontology. Series B, Psychological sciences and social sciences.

[23]  C. Fabrigoule,et al.  Disability and cognitive impairment in the elderly. , 1997, Disability and rehabilitation.

[24]  M. Silverstein,et al.  Observing the onset of disability in older adults. , 2003, Social science & medicine.

[25]  W. W. Muir,et al.  Regression Diagnostics: Identifying Influential Data and Sources of Collinearity , 1980 .

[26]  J. Ormel,et al.  The impact of physical performance and cognitive status on subsequent ADL disability in low‐functioning older adults , 1998, International journal of geriatric psychiatry.

[27]  J. S. Siegel.  A Generation of Change: A Profile of America's Older Population , 1993 .

[28]  H. Dodge,et al.  Cognitive impairment as a strong predictor of incident disability in specific ADL-IADL tasks among community-dwelling elders: the Azuchi Study. , 2005, The Gerontologist.

[29]  C. Camp,et al.  Memory training in normal and demented elderly populations: the E-I-E-I-O model. , 1993, Experimental aging research.