Associations between Mobility, Cognition, and Brain Structure in Healthy Older Adults.

Mobility limitations lead to a cascade of adverse events in old age, yet the neural and cognitive correlates of mobility performance in older adults remain poorly understood. In a sample of 387 adults (mean age 69.0 ± 5.1 years), we tested the relationship between mobility measures, cognitive assessments, and MRI markers of brain structure. Mobility was assessed in 2007-2009, using gait, balance and chair-stands tests. In 2012-2015, cognitive testing assessed executive function, memory and processing-speed; gray matter volumes (GMV) were examined using voxel-based morphometry, and white matter microstructure was assessed using tract-based spatial statistics of fractional anisotropy, axial diffusivity (AD), and radial diffusivity (RD). All mobility measures were positively associated with processing-speed. Faster walking speed was also correlated with higher executive function, while memory was not associated with any mobility measure. Increased GMV within the cerebellum, basal ganglia, post-central gyrus, and superior parietal lobe was associated with better mobility. In addition, better performance on the chair-stands test was correlated with decreased RD and AD. Overall, our results indicate that, even in non-clinical populations, mobility measures can be sensitive to sub-clinical variance in cognition and brain structures

Associations between Mobility, Cognition, and Brain Structure in Healthy Older Adults

Mobility limitations lead to a cascade of adverse events in old age, yet the neural and cognitive correlates of mobility performance in older adults remain poorly understood. In a sample of 387 adults (mean age 69.0 ± 5.1 years), we tested the relationship between mobility measures, cognitive assessments, and MRI markers of brain structure. Mobility was assessed in 2007–2009, using gait, balance and chair-stands tests. In 2012–2015, cognitive testing assessed executive function, memory and processing-speed; gray matter volumes (GMV) were examined using voxel-based morphometry, and white matter microstructure was assessed using tract-based spatial statistics of fractional anisotropy, axial diffusivity (AD), and radial diffusivity (RD). All mobility measures were positively associated with processing-speed. Faster walking speed was also correlated with higher executive function, while memory was not associated with any mobility measure. Increased GMV within the cerebellum, basal ganglia, post-central gyrus, and superior parietal lobe was associated with better mobility. In addition, better performance on the chair-stands test was correlated with decreased RD and AD. Overall, our results indicate that, even in non-clinical populations, mobility measures can be sensitive to sub-clinical variance in cognition and brain structures

The effects of an aerobic training intervention on cognition, grey matter volumes and white matter microstructure

While there is strong evidence from observational studies that physical activity is associated with reduced risk of cognitive decline and dementia, the extent to which aerobic training interventions impact on cognitive health and brain structure remains subject to debate. In a pilot study of 46 healthy older adults (66.6 years ± 5.2 years, 63% female), we compared the effects of a twelve-week aerobic training programme to a waitlist control condition on cardiorespiratory fitness, cognition and magnetic resonance imaging (MRI) outcomes. Cardiorespiratory fitness was assessed by VO2 max testing. Cognitive assessments spanned executive function, memory and processing speed. Structural MRI analysis included examination of hippocampal volume, and voxel-wise assessment of grey matter volumes using voxel-based morphometry. Diffusion tensor imaging analysis of fractional anisotropy, axial diffusivity and radial diffusivity was performed using tract-based spatial statistics. While the intervention successfully increased cardiorespiratory fitness, there was no evidence that the aerobic training programme led to changes in cognitive functioning or measures of brain structure in older adults. Interventions that are longer lasting, multi-factorial, or targeted at specific high-risk populations, may yield more encouraging results

Cognition and mobility show a global association in middle- and late-adulthood: Analyses from the Canadian Longitudinal Study on Aging

Background: Given our aging population, there’s great interest in identifying modifiable risk factors for cognitive decline. Studies have highlighted the relationship between aspects of mobility and cognitive processes. However, cognition and mobility are both multifaceted concepts and their interrelationships remain to be well defined. Research question: Here, we firstly aimed to replicate cross-sectional associations between objective measures of mobility and cognition. Second, we tested whether these associations remained after the consideration of multiple age-related confounders. Finally, to test the hypothesis that the association between mobility and cognition is stronger in older adults, we examined the moderating effect of age in the association between mobility and cognition. Methods: In the Canadian Longitudinal Study on Aging, 28,808 community-dwelling adults (aged 45–87; 51% female) completed mobility (gait, balance and chair stands) and cognitive (memory, executive function and processing speed) assessments. General linear models were used to examine mobility-cognition relationships and the moderating effect of age. Results: Cognitive measures were significantly associated with mobility measures (all p < 0.001). Further, age significantly moderated the mobility-cognition relationship, with the strength of the associations generally increasing with age. Significance: All cognitive measures were related to indices of mobility, suggesting a global association. In our moderation analyses, the mobility-cognition relationship often increased with age. However, the small effect sizes observed suggest that mobility is, in isolation, not a strong correlate of cognitive performance in middle and late-adulthood

Association between gait and cognition in an elderly population based sample

Background. Gait is thought to have a cognitive component, but the current evidence in healthy elderly is mixed. We studied the association between multiple gait and cognitive measures in a cohort of older people. Methods. 178 cognitively healthy participants from the Whitehall II Imaging Sub-study had a detailed clinical and neuropsychological assessment, as well as a MRI scan. Spatiotemporal and variability gait measures were derived from two 10m walks at self-selected speed. We did a linear regression analysis, entering potential confounders with backwards elimination of variables with p≥0.1.The remaining variables were then entered into a second regression before doing a stepwise analysis of cognitive measures, entering variables with p<0.05 and removing those with p≥0.1. Results. Amongst absolute gait measures, only greater stride length was associated with better performance in the TMT A and the BNT. The STV was associated with performance in the TMT A. Age was associated with poorer walking speed and stride time, female sex with shorter strides and stride time, as well as shorter doubles stance. Length of full-time education was associated with faster walking speed and shorter stride time, and a history of muscular-skeletal disease with slower walking speed, shorter stride length and longer stride time. Interestingly, volume of WMH in FLAIR MRI images did not contribute independently to any of the gait variables. Conclusions. No strong relationship between gait and non-motor cognition was observed in a cognitively healthy, high functioning sample of elderly. Nevertheless we find some relationships with spatial, but not temporal gait which warrant further investigation. WMH made no independent contribution to gait

A community-based physical activity intervention to prevent mobility-related disability for retired older people (REtirement in ACTion (REACT)): Study protocol for a randomised controlled trial

© 2018 The Author(s). Background: The REtirement in ACTion (REACT) study is a multi-centre, pragmatic, two-arm, parallel-group randomised controlled trial (RCT) with an internal pilot phase. It aims to test the effectiveness and cost-effectiveness of a community, group-based physical activity intervention for reducing, or reversing, the progression of functional limitations in older people who are at high risk of mobility-related disability. Methods/design: A sample of 768 sedentary, community-dwelling, older people aged 65 years and over with functional limitations, but who are still ambulatory (scores between 4 and 9 out of 12 in the Short Physical Performance Battery test (SPPB)) will be randomised to receive either the REACT intervention, delivered over a period of 12 months by trained facilitators, or a minimal control intervention. The REACT study incorporates comprehensive process and economic evaluation and a nested sub-study which will test the hypothesis that the REACT intervention will slow the rate of brain atrophy and of decline in cognitive function assessed using magnetic resonance imaging (MRI). Outcome data will be collected at baseline, 6, 12 and 24 months for the main study, with MRI sub-study data collected at baseline, 6 and 12 months. The primary outcome analysis (SPPB score at 24 months) will be undertaken blinded to group allocation. Primary comparative analyses will be on an intention-to-treat (ITT) basis with due emphasis placed on confidence intervals. Discussion: REACT represents the first large-scale, pragmatic, community-based trial in the UK to target the non-disabled but high-risk segment of the older population with an intervention to reduce mobility-related disability. A programme that can successfully engage this population in sufficient activity to improve strength, aerobic capacity, coordination and balance would have a major impact on sustaining health and independence. REACT is also the first study of its kind to conduct a full economic and comprehensive process evaluation alongside the RCT. If effective and cost-effective, the REACT intervention has strong potential to be implemented widely in the UK and elsewhere

Characterising the relationship between mobility, cognition and brain structure in healthy older adults

With a rapidly growing older population, understanding factors that contribute to healthy ageing is a public health priority – and one such factor is mobility. Using cognitive assessments and magnetic resonance imaging (MRI), this thesis aimed to characterise the associations between mobility and the ageing brain. First, a systematic review and meta-analysis of the literature was conducted to examine the relationship between different domains of cognition (memory, executive function and processing speed) and mobility (gait, balance and lower-extremity function). The reviewed evidence suggested that reduced mobility was correlated with lower cognitive function in older adults, although notable variability was observed between studies. To address the gaps identified by the review, I examined mobility-cognition associations in the Canadian Longitudinal Study on Ageing. Findings supported the hypothesis that poor mobility is associated with poor cognition, and indicated that this relationship is not domain-specific. In addition, I found that controlling for a variety of age-related confounders did not nullify the mobility-cognition association. Less is known about the neural correlates of poor mobility. To examine which brain structures are associated with mobility, voxel-based-morphometry and diffusion tensor imaging outcomes were correlated with mobility measures in a sample of older adults from the Whitehall II cohort. Our findings indicated that older adults with poor mobility tend to have lower grey matter volume and reduced white matter microstructure. Since mobility relates to brain structure and function, it is plausible that improving mobility may lead to cognitive and structural benefits. To test this, I examined the effects of a physical activity intervention in a sub-sample recruited from the Retirement in Action study. In a between-group comparison of change over 6-months, we did not find evidence that physical activity modified cognitive or MRI outcomes. The evidence presented in this thesis supports the hypothesis that mobility is positively associated with cognition and brain structure in healthy older adults. Contrary to predictions, however, we did not observe exercise-induced effects in brain structure or function.</p

Characterising the relationship between mobility, cognition and brain structure in healthy older adults

With a rapidly growing older population, understanding factors that contribute to healthy ageing is a public health priority â and one such factor is mobility. Using cognitive assessments and magnetic resonance imaging (MRI), this thesis aimed to characterise the associations between mobility and the ageing brain. First, a systematic review and meta-analysis of the literature was conducted to examine the relationship between different domains of cognition (memory, executive function and processing speed) and mobility (gait, balance and lower-extremity function). The reviewed evidence suggested that reduced mobility was correlated with lower cognitive function in older adults, although notable variability was observed between studies. To address the gaps identified by the review, I examined mobility-cognition associations in the Canadian Longitudinal Study on Ageing. Findings supported the hypothesis that poor mobility is associated with poor cognition, and indicated that this relationship is not domain-specific. In addition, I found that controlling for a variety of age-related confounders did not nullify the mobility-cognition association. Less is known about the neural correlates of poor mobility. To examine which brain structures are associated with mobility, voxel-based-morphometry and diffusion tensor imaging outcomes were correlated with mobility measures in a sample of older adults from the Whitehall II cohort. Our findings indicated that older adults with poor mobility tend to have lower grey matter volume and reduced white matter microstructure. Since mobility relates to brain structure and function, it is plausible that improving mobility may lead to cognitive and structural benefits. To test this, I examined the effects of a physical activity intervention in a sub-sample recruited from the Retirement in Action study. In a between-group comparison of change over 6-months, we did not find evidence that physical activity modified cognitive or MRI outcomes. The evidence presented in this thesis supports the hypothesis that mobility is positively associated with cognition and brain structure in healthy older adults. Contrary to predictions, however, we did not observe exercise-induced effects in brain structure or function.</p

Right-left asymmetry in corticospinal tract microstructure and dexterity are uncoupled in late adulthood

Ageing leads to a decline in white matter microstructure and dexterous function of the hand. In adolescents, it has previously been shown that the degree of right-left asymmetry in the corticospinal tract (CST) is linearly related with right-left asymmetry in dexterity. Here, we tested whether this association is also expressed in older adults. Participants completed a simple circle drawing task with their right and left hand as a measure of dexterity and underwent whole-brain diffusion weighted imaging at 3 Tesla (n = 199; aged 60–72 years). Fractional anisotropy and mean diffusivity of right and left CST were extracted from a manually defined region-of-interest. Linear regression analyses were computed to replicate the analyses in adolescents. Frequentist analyses were complemented with a Bayesian analytical framework. Outcome measures were compared with those previously reported in adolescents (aged 11–16 years). Asymmetries in white matter microstructure of the CST were evident and comparable to the degree of lateralisation observed in adolescence. Similarly, asymmetries in dexterity were evident, but to a lesser degree than in adolescents. Unlike in adolescents, we found no evidence of a linear relationship between asymmetries in CST microstructure and dexterity. Complementary Bayesian regression analysis provided moderate evidence in favour of the null hypothesis, pointing towards a lack of association between the structural and functional measures of right-left asymmetry. Our findings are compatible with the notion that, by late adulthood, a diverging impact of age on white matter structure and dexterous hand function dilutes the structure-function relationship between CST microstructure and manual proficiency that has been reported in adolescents

Is Fall Risk Systematically Evaluated in Memory Clinics? A National Survey of Practice in France

International audienceBackground: Falls are a major health problem in older persons but are still under-diagnosed and challenging to prevent. Current guidelines do not target high-risk populations, especially people living with dementia. In France, people with neurocognitive disorders are mainly referred to memory clinics (MCs). Objective: We aimed to survey the routine practice of physicians working in MCs regarding fall risk assessment. Methods: We conducted a cross-sectional survey in France from January to May 2019 among physicians working in MCs, through an anonymous online questionnaire: twenty-seven questions about the physician’s background and their practice of fall risk assessment, especially use of clinical and paraclinical tools. We compared the results according to the age and the specialty of the physician. Results: We obtained 171 responses with a majority of women (60%) and geriatricians (78%). All age classes and all French regions were represented. Most of respondents (98.8%) stated that they address gait and/or falls in outpatient clinic and 95.9%in day hospitals. When asked about how they assess fall risk, fall history (83%) and gait examination (68.4%) were the most widely used, while orthostatic hypotension (24%) and clinical standardized tests (25.7%) were less common. Among standardized tests, One-leg Balance, Timed Up and Go Test, and gait speed measurements were the most used. Geriatricians had more complete fall risk assessment than neurologists (e.g., 56%versus 13%for use of standardized tests, p < 0.0001). Conclusion: Almost all physicians addressed the question of fall in MC, but practices are widely heterogeneous. Further investigations are needed to standardize fall risk assessment in MCs