Department of Internal Medicine, Section on Gerontology and Geriatric Medicine, Claude D. Pepper Older Americans Independence Center, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
Emerging evidence indicates an association between cognitive function and physical performance in late life. This study examines the relationship between cognitive function and subsequent gait speed decline among high-functioning older adults.
Measures of global cognitive function (Modified Mini Mental State Examination [3MS]) and executive control function (ECF) (a clock drawing task [CLOX 1] and the 15-item Executive Interview [EXIT 15]) were obtained in the Health, Aging, and Body Composition Study in 1999-2000. Gait-speed (meters/second) was assessed over 20 meters at usual pace. Using a mixed model, we assessed the relationship between baseline cognitive function and gait-speed change over 3 years.
Two thousand, three hundred forty-nine older adults (mean age 75.6 +/- 2.9 years) completed the assessments. After adjustment for baseline gait speed, a 1-standard-deviation (SD) lower performance on each cognitive test was associated with greater gait-speed decline over 3 years: 0.016 m/s for the 3MS (SD = 8.1), 0.009 m/s for CLOX 1 (SD = 2.4), and 0.012 m/s for EXIT 15 (SD = 4.1) (p <.0005 for all). After adjustment for comorbidities, the effect size was attenuated for 3MS and CLOX 1, and the association for EXIT 15 was no longer significant. Depression score was most strongly associated with the EXIT 15 effect reduction.
Global and executive cognitive functions predict declines in gait speed. The association of ECF with gait speed decline is attenuated by comorbid conditions, particularly depression. Elucidation of the mechanisms underlying these associations may point to new pathways for the treatment of physical decline associated with diminished cognitive function.
"In a prospective study, the rate of falls increases with each unit decrease in the MMSE score, and such an increase in fall incidence is evident down to an MMSE score of 22 out of 30 (Gleason et al., 2009). Another prospective study showed that older adults with poorer global cognition and executive functions are associated with a greater decline in gait speed over the following 3 years, which is modulated by depression (Atkinson et al., 2007). Furthermore, older adults with MMSE scores greater than 19 in baseline assessment experience fewer falls after multifactorial interventions designed to reduce their incidence, but such a benefit is not observed in those with low MMSE scores (Jensen et al., 2003). "
[Show abstract][Hide abstract] ABSTRACT: Falls, a common cause of injury among older adults, have become increasingly prevalent. As the world's population ages, the increase in-and the prevalence of-falls among older people makes this a serious and compelling societal and healthcare issue. Physical weakness is a critical predictor in falling. While considerable research has examined this relationship, comprehensive reviews of neuropsychological predictors of falls have been lacking. In this paper, we examine and discuss current studies of the neuropsychological predictors of falls in older adults, as related to sporting and non-sporting contexts. By integrating the existing evidence, we propose that brain aging is an important precursor of the increased risk of falls in older adults. Brain aging disrupts the neural integrity of motor outputs and reduces neuropsychological abilities. Older adults may shift from unconscious movement control to more conscious or attentive motor control. Increased understanding of the causes of falls will afford opportunities to reduce their incidence, reduce consequent injuries, improve overall well-being and quality of life, and possibly to prolong life.
"Gait speed during NW has been shown to be related to cognitive decline , MCI , and risk of dementia , while impaired cognitive functions have been shown to be related to a decline in normal gait speed [9,11,13]. The majority of studies investigating this relationship have focused on normal gait speed and processing speed  or executive function [9,13], and have confirmed the relationship in older adults. Consistent with our results in MCI participants, McGough et al. have reported that physical performance is associated with executive function after adjusting for age, sex, and age-related factors in sedentary older adults with aMCI . "
[Show abstract][Hide abstract] ABSTRACT: Gait ability and cognitive function are interrelated during both normal walking (NW) and dual-task walking (DTW), and gait ability is thus adversely affected by cognitive impairment in both situations. However, this association is insufficiently understood in people with mild cognitive impairment (MCI). Here, we conducted a study with MCI participants, to examine whether the association depends on walking conditions and MCI subtypes.
We classified 389 elderly adults into amnestic MCI (n = 191) and non-amnestic MCI (n = 198), assessed their cognitive functions, and administered gait experiments under NW and DTW conditions. Gait ability was defined as gait speed. Five aspects of cognitive function were assessed: processing speed, executive function, working memory, verbal memory, and visual memory.
Regression analysis adjusted for covariates showed a significant association between cognitive functions and gait speed. Processing speed and executive function correlated with gait speed during both NW and DTW (p < .05). Gait speed during DTW was also significantly associated with working memory (p < .001). Visual memory was associated during NW and DTW, particularly for amnestic MCI participants (p < .05).
Our findings support the idea that the association between gait speed and cognitive function depends on walking condition and MCI subtypes. Additional studies are necessary to determine the neural basis for the disruption in gait control in older adults with MCI.
"First, walking is often viewed as a rhythmic, simple motor task, but among older adults, it has been shown to draw upon higher-level resources, including executive function (Hausdorff et al. 2005). As a complex motor task, walking may be regulated by neural networks that draw on cognitive resources (Atkinson et al. 2007; Cocchini et al. 2004; Fitzpatrick et al. 2007; Inzitari et al. 2007; Rosano et al. 2005; Sheridan et al. 2003; Soumare et al. 2009b). Lead has been found to be associated with worse cognitive function in adults, which may explain part of the association with walking speed (Bandeen-Roche et al. 2009; Shih et al. 2006, 2007; Weisskopf et al. 2007; Weuve et al. 2009). "
[Show abstract][Hide abstract] ABSTRACT: Background: Walking speed is a simple and reliable measure of motor function that is negatively associated with adverse health events in older people, including falls, disability, hospital admissions, and mortality. Lead has adverse affects on human health, particularly on the vascular and neurological systems.
Objective: We explored the hypothesis that lead is associated with slower walking speed.
Methods: We used U.S. National Health and Nutrition Examination Survey (NHANES) cross-sectional data from 1999–2002. The time to walk 20 ft (walking speed) was measured among 1,795 men and 1,798 women ≥ 50 years of age. The association between walking speed and quintiles of blood lead concentration was estimated separately in men and women using linear regression models adjusted for age, education, ethnicity, alcohol use, smoking status, height, and waist circumference.
Results: Mean blood lead concentrations and walking speeds were 2.17 μg/dL and 3.31 ft/sec in women, and 3.18 μg/dL and 3.47 ft/sec in men, respectively. Among women, walking speed decreased with increasing quintiles of blood lead, resulting in an estimated mean value that was 0.11 ft/sec slower (95% CI: –0.19, –0.04; p-trend = 0.005) for women with blood lead concentrations in the highest versus lowest quintile. In contrast, lead was not associated with walking speed in men.
Conclusion: Blood lead concentration was associated with decreased walking speed in women, but not in men. Our results contribute to the growing evidence that lead exposure, even at low levels, is detrimental to public health.
Environmental Health Perspectives 04/2013; 121(6). DOI:10.1289/ehp.1205918 · 7.98 Impact Factor
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