Black elders have a greater frequency of functional decline than do white elders. The impact of cognitive function on explaining black-white disparities in functional decline has not been extensively explored.
To compare the extent to which different risk domains (comorbidity, smoking, socioeconomic status (SES), self-rated health, and cognitive function) explain more frequent functional decline in black elders, we studied 779 black and 4892 white community-dwelling adults aged 70 and older from the Assets and Health Dynamics Among the Oldest Old (AHEAD), a population-based cohort study begun in 1993. Our primary outcome was worse functional status at 2 years than at baseline. We used logistic regression to compare the unadjusted with the adjusted black-white odds ratios (ORs) after adjusting for each risk domain.
At baseline black participants aged 70-79 had higher rates of smoking, diabetes, and hypertension; lower SES; and worse cognitive function than did white participants (p <.05 for all). The mean cognitive score was 15.7 in black and 21.8 in white participants (p <.01). Black participants had a higher frequency of 2-year functional decline than did white participants (10.9% vs 4.7%; OR = 2.61, 95% confidence interval [CI], 1.69-4.03 adjusted for age and sex). Adjustment for comorbidity and smoking did not significantly change the black-white OR, whereas self-rated health and SES accounted for about half the risk. Adjustment for cognitive function accounted for nearly all the associated decline (OR = 1.10, 95% CI, 0.67-1.79). Among participants aged 80 and over, those who were black had significantly lower risk for functional decline after adjustment for cognitive function (OR = 0.61, 95% CI, 0.38-0.96 vs OR = 1.08, 95% CI, 0.70-1.66 adjusted for age and sex only).
Cognitive function mediated the higher frequency of functional decline among black elders. Efforts to understand cognitive function may enhance our understanding of black-white disparities in health outcomes.
"For example, Suthers et al.  investigated the link between life expectancy and cognitive impairment. Moody-Ayers et al.  examined the effect of cognitive functioning on functional decline. Not often considered in past research was the factor structure underlying the cognitive measures. "
[Show abstract][Hide abstract] ABSTRACT: Using cognitive data from the Health and Retirement Study and Asset Health Dynamics Among the Oldest Old studies that were collected between 1992 and 2004, McArdle and colleagues (2007) found that a two-factor model (episodic memory and mental status) fit better than a one-factor model. The question that was addressed in the present study was whether these results would replicate in newer cohorts of data, collected between 2006 and 2010. We also tested age, education, and gender as predictors of the identified factors. Results confirm that a two-factor structure fits better than the single-factor model in the newer cohorts. Differential predictors were also observed.
Journal of aging research 05/2014; 2014:798514. DOI:10.1155/2014/798514
"Foremost, this study provides further evidence that executive functioning contributes not only to ADL disability onset, but also to declines in physical performance, an early indicator of disability, in African American older adults [1, 17, 39]. Executive functioning accounted for a small, yet significant, proportion of variance in physical performance, and our findings suggest that performance of basic physical tasks included in the SPPB involve executive processes such as inhibition and mental flexibility. "
[Show abstract][Hide abstract] ABSTRACT: An older adult's ability to perform physical tasks is predictive of disability onset and is associated with declines in cognition. Risk factors for physical performance declines among African Americans, a group with the highest rates of disability, remain understudied. This study sought to identify demographic, health, and cognitive factors associated with lower-extremity physical performance in a sample of 106 African American women ages 56 to 91. After controlling for global cognitive functioning (Mini Mental State Exam), physical performance was associated with executive functioning (Stroop Color/Word), but not visuospatial construction (WASI Block Design) or processing speed (Trail Making Test, Part A). Executive functioning remained associated with physical performance after entry of demographic variables, exercise, depression, disease burden, and body mass index (BMI). Age, and BMI were also significant in this model. Executive functioning, age and BMI are associated with lower-extremity physical performance among older African American women.
Journal of aging research 02/2011; 2011:578609. DOI:10.4061/2011/578609
"Comorbidity indexes adjusted for clinical disease severity (e.g., Cumulative Illness Rating Scale; Extermann, 2000 ) could be a solution for this issue; however, medical records data used to calculate these indexes are unlikely to be available in nonclinical studies. Previous research suggests that quality of education received by older cohorts or cumulative disadvantage associated with lower education attainment may affect race differences in cognitive performance and disability above and beyond years of formal education ( Farmer & Ferraro, 2005 ; Manly et al., 1998 ; Mendes de Leon et al., 1997 ; Moody-Ayers et al., 2005 ; Sachs-Ericsson & Blazer, 2005 ). Although these unmeasured infl uences could underlie the nonsignifi cant effects of cognitive performance on ADL disability in African Americans, it appears they did not affect the relationship between RPA and cognitive performance . "
[Show abstract][Hide abstract] ABSTRACT: This study examined if reported physical activity has beneficial outcomes on disability through cognitive performance-mediated effects and if these mediation effects are comparable for White and African American elders. Longitudinal data from the Assets and Health Dynamics among the Oldest Old study (N = 4,472) are used to test mediation in multilevel models. During the 7-year follow-up, cognitive performance mediated the effects of reported physical activity on disability in the entire sample and in Whites but not in African Americans. Our results indicate that reported physical activity may delay the disability development through improvement in cognitive performance. Unmeasured education and comorbidity influences may have obscured the mediation effects in African Americans. Reported physical activity plays a key role in the independence of older adults and should be particularly promoted in African Americans and during the entire life course.
The Journals of Gerontology Series B Psychological Sciences and Social Sciences 03/2009; 64(1):4-13. DOI:10.1093/geronb/gbn030 · 3.21 Impact Factor
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