Cortical control of gait in aging is bilateral, widespread, and dependent on the integrity of both gray and white matter.

This research examined the influence of prior group collaboration on later individual recall. We considered the negative effects of retrieval disruption and the potentially positive effects of re-exposure to additional items during group recall in the context of three hypotheses: the individual-strategy hypothesis, the combined-strategy hypothesis, and the group-strategy hypothesis. After a study phase and a brief delay, participants completed three successive recall trials in four different recall sequence conditions: III (individual-individual-individual), ICI (individual-collaborative-individual), CII (collaborative-individual-individual), and CCI (collaborative-collaborative-individual). Results show that repeated group recalls (CCI), and securing individual retrieval organisation prior to group recall (ICI), benefit later individual recall more than repeated individual recalls (III). These findings support the group-strategy hypothesis and the individual-strategy hypothesis, and have important implications for group versus individual learning practices in educational settings.

Background Poor gait performance predicts risk of developing dementia. No structured critical evaluation has been conducted to study this association yet. The aim of this meta-analysis was to systematically examine the association of poor gait performance with incidence of dementia. Methods An English and French Medline search was conducted in June 2015, with no limit of date, using the medical subject headings terms “Gait” OR “Gait Disorders, Neurologic” OR “Gait Apraxia” OR “Gait Ataxia” AND “Dementia” OR “Frontotemporal Dementia” OR “Dementia, Multi-Infarct” OR “Dementia, Vascular” OR “Alzheimer Disease” OR “Lewy Body Disease” OR “Frontotemporal Dementia With Motor Neuron Disease” (Supplementary Concept). Poor gait performance was defined by standardized tests of walking, and dementia was diagnosed according to international consensus criteria. Four etiologies of dementia were identified: any dementia, Alzheimer disease (AD), vascular dementia (VaD), and non-AD (ie, pooling VaD, mixed dementias, and other dementias). Fixed effects meta-analyses were performed on the estimates in order to generate summary values. Results Of the 796 identified abstracts, 12 (1.5%) were included in this systematic review and meta-analysis. Poor gait performance predicted dementia [pooled hazard ratio (HR) combined with relative risk and odds ratio = 1.53 with P < .001 for any dementia, pooled HR = 1.79 with P < .001 for VaD, HR = 1.89 with P value < .001 for non-AD]. Findings were weaker for predicting AD (HR = 1.03 with P value = .004). Conclusions This meta-analysis provides evidence that poor gait performance predicts dementia. This association depends on the type of dementia; poor gait performance is a stronger predictor of non-AD dementias than AD.

Background The differences in gait abnormalities from the earliest to the latter stages of dementia and in the different subtypes of dementia have not been fully examined. This study aims to compare spatio-temporal gait parameters in cognitively healthy individuals, patients with amnestic (aMCI) and non-amnestic (naMCI) MCI, and patients with mild and moderate stages of Alzheimer’s disease (AD) and non-Alzheimer’s disease (non-AD). Methods Based on a cross-sectional design, 1719 participants (77.4±7.3 years, 53.9% female) were recruited from cohorts from seven countries participating in the “Gait, cOgnitiOn & Decline” initiative. Mean values and coefficients of variation of spatio-temporal gait parameters were measured during normal pace walking with the GAITRite system at all sites. Results Performance of spatio-temporal gait parameters declined in parallel to the stage of cognitive decline from MCI status to moderate dementia. Gait parameters of patients with naMCI were more disturbed compared to patients with aMCI, and MCI subgroups performed better than demented patients. Patients with non-AD dementia had worse gait performance than those with AD dementia. This degradation of the gait parameters was similar between mean values and coefficients of variation of spatio-temporal gait parameters in the earliest stages of cognitive decline, but different in the most advanced stages, especially in the non-AD subtypes. Conclusions Spatio-temporal gait parameters were more disturbed in the advanced stages of dementia, and more affected in the non-AD dementias than in AD. These findings suggest that quantitative gait parameters could be used as a surrogate marker for improving the diagnosis of dementia.

Gait decline is common among older adults and is a risk factor for adverse outcomes. Poor gait performance in dual-task conditions, such as walking while performing a secondary cognitive interference task, is associated with increased risk of frailty, disability, and death. Yet, the functional neural substrates that support locomotion are not well established. We examined the functional connectivity associated with gait velocity in single- (normal pace walking) and dual-task (walking while talking) conditions using resting-state functional Magnetic Resonance Imaging (fMRI). We acquired 6 minutes of resting-state fMRI data in 30 cognitively healthy older adults. Independent components analyses were performed to separate resting-state fMRI data into group-level statistically independent spatial components that correlated with gait velocity in single- and dual-task conditions. Gait velocity in both task conditions was associated with similar functional connectivity in sensorimotor, visual, vestibular, and left fronto-parietal cortical areas. Compared to gait velocity in the single-task condition, the networks associated with gait velocity in the dual-task condition were associated with greater functional connectivity in supplementary motor and prefrontal regions. Our findings show that there are partially overlapping functional networks associated with single- and dual-task walking conditions. These initial findings encourage the future use of resting-state fMRI as tool in developing a comprehensive understanding of age-related mobility impairments.

No abstract

Objectives Falls are highly prevalent in individuals with cognitive decline. The complex relationship between falls and cognitive decline (including both subtype and severity of dementia) and the influence of gait disorders have not been studied. This study aimed to examine the association between the subtype (Alzheimer disease [AD] versus non-AD) and the severity (from preclinical to moderate dementia) of cognitive impairment and falls, and to establish an association between falls and gait parameters during the course of dementia. Design Multicenter cross-sectional study. Setting “Gait, cOgnitiOn & Decline” (GOOD) initiative. Participants A total of 2496 older adults (76.6 ± 7.6 years; 55.0% women) were included in this study (1161 cognitively healthy individuals [CHI], 529 patients with mild cognitive impairment [MCI], 456 patients with mild dementia, and 350 with moderate dementia) from 7 countries. Measurements Falls history was collected retrospectively at baseline in each study. Gait speed and stride time variability were recorded at usual walking pace with the GAITRite system. Results The prevalence of individuals who fall was 50% in AD and 64% in non-AD; whereas it was 25% in CHIs. Only mild and moderate non-AD dementia were associated with an increased risk for falls in comparison with CHI. Higher stride time variability was associated with falls in older adults without dementia (CHI and each MCI subgroup) and mild non-AD dementia, whereas lower gait speed was associated with falls in all participant groups, except in mild AD dementia. When gait speed was adjusted for, higher stride time variability was associated with falls only in CHIs (odds ratio 1.14; P = .012), but not in MCI or in patients with dementia. Conclusions These findings suggest that non-AD, but not AD dementia, is associated with increased falls in comparison with CHIs. The association between gait parameters and falls also differs across cognitive status, suggesting different mechanisms leading to falls in older individuals with dementia in comparison with CHIs who fall.

Cognition is important for locomotion and gait decline increases the risk for morbidity, mortality, cognitive decline, and dementia. Yet, the neural correlates of gait are not well established, because most neuroimaging methods cannot image the brain during locomotion. Imagined gait protocols overcome this limitation. This study examined the behavioral and neural correlates of a new imagined gait protocol that involved imagined walking (iW), imagined talking (iT), and imagined walking-while-talking (iWWT). In Experiment 1, 82 cognitively-healthy older adults (M = 80.45) walked (W), iW, walked while talking (WWT) and iWWT. Real and imagined walking task times were strongly correlated, particularly real and imagined dual-task times (WWT and iWWT). In Experiment 2, 33 cognitively-healthy older adults (M = 73.03) iW, iT, and iWWT during functional Magnetic Resonance Imaging. A multivariate Ordinal Trend (OrT) Covariance analysis identified a pattern of brain regions that: 1) varied as a function of imagery task difficulty (iW, iT and iWWT), 2) involved cerebellar, precuneus, supplementary motor and other prefrontal regions, and 3) were associated with kinesthetic imagery ratings and behavioral performance during actual WWT. This is the first study to compare the behavioral and neural correlates of imagined gait in single and dual-task situations, an issue that is particularly relevant to elderly populations. These initial findings encourage further research and development of this imagined gait protocol as a tool for improving gait and cognition among the elderly.