Cognitive functioning as a predictor of functional disability in later life.
ABSTRACT 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.
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.
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.
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.
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ABSTRACT: Traffic-related particles induce oxidative stress and may exert adverse effects on central nervous system function, which could manifest as cognitive impairment. We assessed the association between black carbon (BC), a marker of traffic-related air pollution, and cognition in older men. A total of 680 men (mean ± SD, 71 ± 7 years of age) from the U.S. Department of Veterans Affairs Normative Aging Study completed a battery of seven cognitive tests at least once between 1996 and 2007. We assessed long-term exposure to traffic-related air pollution using a validated spatiotemporal land-use regression model for BC. The association between BC and cognition was nonlinear, and we log-transformed BC estimates for all analyses [ln(BC)]. In a multivariable-adjusted model, for each doubling in BC on the natural scale, the odds of having a Mini-Mental State Examination (MMSE) score ≤ 25 was 1.3 times higher [95% confidence interval (CI), 1.1 to 1.6]. In a multivariable-adjusted model for global cognitive function, which combined scores from the remaining six tests, a doubling of BC was associated with a 0.054 SD lower test score (95% CI, -0.103 to -0.006), an effect size similar to that observed with a difference in age of 1.9 years in our data. We found no evidence of heterogeneity by cognitive test. In sensitivity analyses adjusting for past lead exposure, the association with MMSE scores was similar (odds ratio = 1.3; 95% CI, 1.1 to 1.7), but the association with global cognition was somewhat attenuated (-0.038 per doubling in BC; 95% CI, -0.089 to 0.012). Ambient traffic-related air pollution was associated with decreased cognitive function in older men.Environmental Health Perspectives 12/2010; 119(5):682-7. DOI:10.1289/ehp.1002767 · 7.03 Impact Factor
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ABSTRACT: Approximately 25% of individuals with dementia live alone, yet little is known about the cognitive and functional factors that impact detection of impairment. Subjects with dementia (n = 349) from a community study of dementia management were administered the Mini-mental State Examination (MMSE) and were asked to rate their cognitive status. Each participant's knowledgeable informant (KI) was interviewed to provide information about the subject's mental health and levels of cognitive and functional impairment. Subjects with dementia living alone (n = 97, 27.8%) were compared to subjects living with others (n = 252, 72.2%) regarding functional impairment, psychiatric symptoms, cognitive functioning, and dementia recognition. While subjects with dementia living alone had significantly fewer ADL impairments (p < 0.0001) and less cognitive impairment (p < 0.0001) than subjects with dementia who were living with others, nearly half of subjects living alone had two or more IADL impairments. Both knowledgeable informants (p < 0.001) and primary care physicians (p < 0.009) were less likely to detect dementia in subjects living alone, while 77.3% of subjects with dementia living alone rated their cognitive abilities as "good" or "a little worse". Subjects with dementia living alone and those living with others had similar rates of psychosis (p = 0.2792) and depressive symptoms (p = 0.2076). Lack of awareness of cognitive impairment by individuals with dementia living alone as well as their knowledgeable informants and physicians, combined with frequent functional impairment and psychiatric symptoms, heightens risk for adverse outcomes. These findings underscore the need for increased targeted screening for dementia and functional impairment among older persons living alone.International Psychogeriatrics 08/2010; 22(5):778-84. DOI:10.1017/S1041610209991529 · 1.89 Impact Factor
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ABSTRACT: The present study of older adults used structural equation modeling (SEM) to examine the relationships between 3 executive processes underlying executive function (EF) (inhibition, task switching, updating in working memory), and 2 types of instrumental activities of daily living (IADLs) (self-report, performance based). Experimental tasks of executive attention and self-report or performance-based IADL tests were administered to create latent constructs of EF and IADLs. Confirmatory factor analysis (CFA) was used to examine the construct validity of EF and IADLs. This analysis indicated a 3-factor model of inhibition, updating, and task switching and a 2-factor model of self-report and performance-based IADLs. As predicted, when the latent variable relationships were analyzed, executive processes had a significant relationship with performance-based, but not self-report, IADLs. In addition, task switching had a strong and significant relationship with performance-based IADLs. The results of this study uniquely show a direct relationship between executive processes and performance-based IADLs, thus demonstrating the ecological utility of experimental measures of EF to predict daily function. Furthermore, these results point to areas of cognitive training that may strategically impact older adults' performance on daily life activities.Psychology and Aging 06/2010; 25(2):343-55. DOI:10.1037/a0017729 · 2.73 Impact Factor