Vascular burden as a substrate for higher-level gait disorders in older adults. A review of brain mapping literature

Vascular brain burden, evaluated as white matter hyperintensities (WMH), may explain in part the higher-level gait disorders found in older adults. However, the magnitude and location of WMH as a determinant of higher-level gait disorders remain unknown. The purpose of this review was to determine if the magnitude and distribution of WMH would be associated with the presence of gait disorders in older adults. Medline was searched using the following keywords: "gait", "gait disorders, neurologic", "walking", "cerebrovascular disorders", "leukoaraiosis", "leukoencephalopathies" and "aged". Additional references were reviewed from the bibliographies, and from citation searches on key articles. Observational studies, without language restriction, published between 1995-2011 and exploring simultaneously WMH on MRI and gait performance were selected. Twenty-one studies met the selection criteria. The number of participants per study ranged from 14 to 3301 (35% to 75% female). The total WMH burden was associated with gait disorders in all studies. The largest WMH fractions associated with gait disorders were found in the frontal lobe, the centrum semiovale, the posterior limb of internal capsule, the genu and the splenium of corpus callosum. Gait velocity, stride length and step width were the gait parameters most commonly affected in the presence of WMH. The brain mapping literature supports the hypothesis that a high WMH burden is associated with gait disorders in the course of aging. This could give rise to new strategies for the prevention of higher-level gait disorders and falls in the elderly based on the management of cerebrovascular disease

Analysis of equilibrium states of Markov solutions to the 3D Navier-Stokes equations driven by additive noise

We prove that every Markov solution to the three dimensional Navier-Stokes equation with periodic boundary conditions driven by additive Gaussian noise is uniquely ergodic. The convergence to the (unique) invariant measure is exponentially fast. Moreover, we give a well-posedness criterion for the equations in terms of invariant measures. We also analyse the energy balance and identify the term which ensures equality in the balance.Comment: 32 page

Nutrient Biomarker Patterns, Cognitive Function, and Mri Measures of Brain Aging

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Spatio-temporal gait analysis based on human-smart rollator interaction

The ability to walk is typically related to several biomechanical components that are involved in the gait cycle (or stride), including free mobility of joints, particularly in the legs; coordination of muscle activity in terms of timing and intensity; and normal sensory input, such as vision and vestibular system. As people age, they tend to slow their gait speed, and their balance is also affected. Also, the retirement from the working life and the consequent reduction of physical and social activity contribute to the increased incidence of falls in older adults. Moreover, older adults suffer different kinds of cognitive decline, such as dementia or attention problems, which also accentuate gait disorders and its consequences. In this paper we present a methodology for gait identification using the on-board sensors of a smart rollator: the i-Walker. This technique provides the number of steps performed in walking exercises, as well as the time and distance travelled for each stride. It also allows to extract spatio-temporal metrics used in medical gait analysis from the interpretation of the interaction between the individual and the i-Walker. In addition, two metrics to assess users’ driving skills, laterality and directivity, are proposed.Peer ReviewedPostprint (author's final draft

Motor phenotype of decline in cognitive performance among community-dwellers without dementia: Population-based study and meta-analysis

Background: Decline in cognitive performance is associated with gait deterioration. Our objectives were: 1) to determine, from an original study in older community-dwellers without diagnosis of dementia, which gait parameters, among slower gait speed, higher stride time variability (STV) and Timed Up & Go test (TUG) delta time, were most strongly associated with lower performance in two cognitive domains (i.e., episodic memory and executive function); and 2) to quantitatively synthesize, with a systematic review and meta-analysis, the association between gait performance and cognitive decline (i.e., mild cognitive impairment (MCI) and dementia). Methods: Based on a cross-sectional design, 934 older community-dwellers without dementia (mean6standard deviation, 70.3 64.9years; 52.1% female) were recruited. A score at 5 on the Short Mini-Mental State Examination defined low episodic memory performance. Low executive performance was defined by clock-drawing test errors. STV and gait speed were measured using GAITRite system. TUG delta time was calculated as the difference between the times needed to perform and to imagine the TUG. Then, a systematic Medline search was conducted in November 2013 using the Medical Subject Heading terms "Delirium," "Dementia," "Amnestic," "Cognitive disorders" combined with "Gait" OR "Gait disorders, Neurologic" and "Variability." Findings: A total of 294 (31.5%) participants presented decline in cognitive performance. Higher STV, higher TUG delta time, and slower gait speed were associated with decline in episodic memory and executive performances (all P-values <0.001). The highest magnitude of association was found for higher STV (effect size = -0.74 [95% Confidence Interval (CI): -1.05;- 0.43], among participants combining of decline in episodic memory and in executive performances). Meta-analysis underscored that higher STV represented a gait biomarker in patients with MCI (effect size = 0.48 [95% CI: 0.30;0.65]) and dementia (effect size = 1.06 [95% CI: 0.40;1.72]). Conclusion: Higher STV appears to be a motor phenotype of cognitive decline. © 2014 Beauchet et al

Association of executive function impairment, history of falls and physical performance in older adults: A cross-sectional population-based study in Eastern France

To estimate: 1) the association between executive function (EF) impairment and falls; and 2) the association of EF impairment on tests of physical function used in the evaluation of fall risk.Cross-sectional study. Thirteen health examination centres in Eastern France. Four thousand four hundred and eighty one community-dwelling older adults without dementia aged 65 to 97 years (mean age 71.8 +/- 5.4, women 47.6%). Participants underwent a comprehensive medical assessment that included evaluations of EF using the Clock Drawing Test and of physical performance using the Timed Up &amp; Go Test (TUG). Analysis used multivariable modified Poisson regression to evaluate the association between impaired EF and each of the fall outcomes (any fall, recurrent falls, fall-related injuries). Multivariable linear regression was used to evaluate the association between EF impairment and performance on the TUG and grip strength. EF impairment, assessed using the clock drawing test, was present in 24.9% of participants. EF impairment was independently associated with an increased risk of any fall (RR=1.13, 95% CI (1.03, 1.25)) and major soft tissue fall-related injury (RR= 2.42, 95% CI (1.47, 4.00)). Additionally, EF impairment was associated with worse performance on the TUG (p &lt; 0.0001). EF impairment among older adults without dementia was highly prevalent and was independently associated with an increased risk for falls, fall-related injuries and with decreased physical function. The use of the Clock Drawing Test is an easy to administer measure of EF that can be used routinely in comprehensive fall risk evaluations

Association Between Serum 25-Hydroxyvitamin D Concentration and Optic Chiasm Volume

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Vitamin D concentration and lateral cerebral ventricle volume in older adults

Scope Vitamin D deficiency is associated with an enlargement of the lateral cerebral ventricles in rodents. The effect of low serum 25-hydroxyvitamin D (25OHD) on lateral cerebral ventricle volume has not been studied yet in humans. The purpose of this cross-sectional study was to determine whether vitamin D deficiency was associated with greater lateral cerebral ventricle volume in older adults. Methods and results Ninety-two Caucasian community-dwellers with no clinical hydrocephalus (mean, 72.2 +/- 6.2 years; 46.7% female) were divided into two groups according to serum 25OHD concentration (deficiency &lt;= 50 nmol/L; normal &gt; 50 nmol/L). Cerebral ventricular volume was quantified using semi-automated software from three-dimensional T1-weighted MRI. Age, gender, body mass index, blood pressure, education level, Mini-Mental State Examination, white matter lesions, and serum calcium concentrations were used as covariates. There was an inverse linear association between 25OHD concentration and ventricular volume (p = 0.049). Compared to individuals with normal 25OHD, those with 25OHD deficiency (n = 33) had 28% larger lateral ventricles (46.9 +/- 26.8 mL versus 36.6 +/- 16.4 mL, p = 0.026). Vitamin D deficiency was associated with an increase in ventricular volume (adjusted beta = 16.55, p = 0.023). The ventricular enlargement involved ventricle bodies (p = 0.025) but not temporal horns (p = 0.112). Conclusion Serum 25OHD deficiency was associated with larger lateral cerebral ventricles. These findings provide a scientific base for vitamin D replacement trials

Higher Serum Vitamin D Concentration Is Associated with Better Balance in Older Adults with Supra-Optimal Vitamin D Status

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Vascular Burden Predicts Gait, Mood, and Executive Function Disturbances in Older Adults with Mild Cognitive Impairment: Results from the Gait and Brain Study

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