Impact of white matter lesions on physical functioning and fall risk in older people: a systematic review

Neuroimaging Correlates of 3 Distinct Physical-Cognitive Phenotypes in Cognitively Normal Older Adults: The Gothenburg H70 Cohort Study

BACKGROUND AND OBJECTIVES

Individuals aged 70 and older frequently experience an increased risk of deficits in both physical and cognitive functions. However, the natural progression and interrelationship of these deficits, as well as their neurologic correlates, remain unclear. We aimed to classify the data-driven physical-cognitive phenotypes and then investigate their associations with neuroimaging markers.

METHODS

This cross-sectional study included 70-year-old participants from the Gothenburg H70 Birth Cohort (2014-2016). Based on physical performance (grip strength, balance, walking speed, and chair stand) and cognitive measures (episodic memory, perceptual speed, executive function, verbal fluency, and visuospatial abilities), we applied latent class analysis to identify physical-cognitive phenotypes. Based on the brain MRI measurements, 3 groups of neuroimaging markers were involved-neurodegeneration, cerebral small vessel disease (cSVD), and microstructural white matter (WM) integrity. We performed multinomial logistic regressions to examine the differences between the physical-cognitive phenotypes.

RESULTS

In total, 1,140 participants (female: 53.3%) without dementia and disability were included in the study, with 721 (female: 52.2%) undergoing MRI scans. Three physical-cognitive phenotypes were identified: an "optimal" group characterized by high performance in both physical and cognitive functions, an "intermediate" group showing a slight reduction in both domains, and a "physical deficit" group marked by a significant reduction in physical performance. Compared with the optimal group, the other 2 groups were more likely to present with vascular risk factors. The physical deficit group had higher odds of experiencing depression compared with the intermediate group (adjusted odds ratio [aOR] 2.9, 95% CI 1.4-5.9). Compared with the optimal group, the odds of presenting all 3 severe neuroimaging markers were higher in both the intermediate (aOR 3.4, 95% CI 1.5-7.9) and physical deficit (aOR 10.3, 95% CI 2.4-45.0) groups.

DISCUSSION

This study highlights the variability in physical and cognitive performance among older adults and suggests that neuroimaging markers of neurodegeneration, cSVD, and microstructural WM integrity may account for these variations. Our findings indicate the potential for developing group-based strategies to prevent and manage age-related functional decline. Further research with larger sample sizes is needed to deepen our understanding of physical-cognitive decline patterns.

Clinical Phenotypes Associated With Cerebral Small Vessel Disease: A Study of 45,013 UK Biobank Participants

BACKGROUND AND OBJECTIVES

Cerebral small vessel disease (cSVD) is the most common pathology underlying vascular cognitive impairment. Although other clinical features of cSVD are increasingly recognized, it is likely that certain symptoms are being overlooked. A comprehensive description of cSVD associations with clinical phenotypes at scale is lacking. The objective of this study was to conduct a large-scale, hypothesis-free study of associations between cSVD and clinical phenotypes in UK Biobank (UKB).

METHODS

We included participants from the UKB imaging study who had available information on total volume of white matter hyperintensities (WMHs), the most common cSVD neuroimaging feature. We included various UKB variables describing clinical phenotypes, defined as observable signs and symptoms of individuals with concurrent neuroimaging evidence of cSVD. We conducted a phenome scan using the open-source PHESANT software package. Total volume of WMHs was introduced as the independent variable and clinical phenotypes as the dependent variables in the regression model. The association of each phenotype with total volume of WMHs was tested using one of several regression analyses (all age at recruitment and sex-adjusted). All associations were corrected for multiple comparisons using the false discovery rate (FDR) correction method.

RESULTS

We included 45,013 participants in the analysis (mean age = 54.97 years, SD = 7.55). We confirm previously reported associations with depression (odds ratio [OR] = 1.07 [95% CI 1.05-1.10]), apathy (OR = 1.11 [95% CI 1.08-1.14]), falls (OR = 1.11 [95% CI 1.09-1.13]), respiratory problems (OR = 1.14 [95% CI 1.04-1.25]), and sleep disturbance (OR = 1.07 [95% CI 1.04-1.09], all FDR-adjusted p < 0.001). We further identified associations with all-cause dental issues (OR = 0.94 [95% CI 0.96-0.92]), hearing problems (OR = 1.06 [95% CI 1.03-1.08]), and eye problems (OR = 0.93 [95% CI 0.91-0.95], all FDR-adjusted p < 0.001).

DISCUSSION

Our findings suggest that presence of cSVD associates with concurrent clinical phenotypes across several body systems. We have corroborated established associations of cSVD and present novel ones. While our results do not provide causality or direction of association because of the cross-sectional nature of our study, they support the need for a more holistic view of cSVD in research, practice, and policy.

Leukoaraiosis: Epidemiology, Imaging, Risk Factors, and Management of Age-Related Cerebral White Matter Hyperintensities

Leukoaraiosis (LA) manifests as cerebral white matter hyperintensities on T2-weighted magnetic resonance imaging scans and corresponds to white matter lesions or abnormalities in brain tissue. Clinically, it is generally detected in the early 40s and is highly prevalent globally in individuals aged >60 years. From the imaging perspective, LA can present as several heterogeneous forms, including punctate and patchy lesions in deep or subcortical white matter; lesions with periventricular caps, a pencil-thin lining, and smooth halo; as well as irregular lesions, which are not always benign. Given its potential of having deleterious effects on normal brain function and the resulting increase in public health burden, considerable effort has been focused on investigating the associations between various risk factors and LA risk, and developing its associated clinical interventions. However, study results have been inconsistent, most likely due to potential differences in study designs, neuroimaging methods, and sample sizes as well as the inherent neuroimaging heterogeneity and multi-factorial nature of LA. In this article, we provided an overview of LA and summarized the current knowledge regarding its epidemiology, neuroimaging classification, pathological characteristics, risk factors, and potential intervention strategies.

Sex Differences in the Role of Multimorbidity on Poststroke Disability: The Taiwan Stroke Registry

BACKGROUND AND OBJECTIVES

Multimorbidity is common in patients who experience stroke. Less is known about the effect of specific multimorbidity patterns on long-term disability in patients with stroke. Furthermore, given the increased poststroke disability frequently seen in female vs male patients, it is unknown whether multimorbidity has a similar association with disability in both sexes. We assessed whether specific multimorbidity clusters were associated with greater long-term poststroke disability burden overall and by sex.

METHODS

In the Taiwan Stroke Registry, an ongoing nationwide prospective registry, patients with first-ever ischemic stroke were enrolled; this analysis is restricted to those individuals surviving to at least 6 months poststroke. Using a hierarchical clustering approach, clusters of prestroke multimorbidity were generated based on 16 risk factors; the algorithm identified 5 distinct clusters. The association between clusters and 12-month poststroke disability, defined using the modified Rankin Scale (mRS), was determined using logistic regression models, with additional models stratified by sex. The longitudinal association between multimorbidity and functional status change was assessed using mixed-effects models.

RESULTS

Nine-thousand eight hundred eighteen patients with first-ever ischemic stroke were included. The cluster with no risk factors was the reference, "healthier" risk group (N = 1,373). Patients with a cluster profile of diabetes, peripheral artery disease (PAD), and chronic kidney disease (CKD) (N = 1882) had significantly greater disability (mRS ≥ 3) at 1 month (OR [95% CI] = 1.36 [1.13-1.63]), 3 months (OR [95% CI] = 1.27 [1.04-1.55]), and 6 months (OR [95% CI] = 1.30 [1.06-1.59]) but not at 12 months (OR [95% CI] = 1.16 [0.95-1.42]) than patients with a healthier risk factor profile. In the sex-stratified analysis, the associations with this risk cluster remained consistent in male patients (OR [95% CI] = 1.42 [1.06-1.89]) at 12 months, who also had a higher comorbidity burden, but not in female patients (OR [95% CI] = 0.95 [0.71-1.26]), who had higher proportions of severe strokes and severe disability (p-interaction = 0.04).

DISCUSSION

Taiwanese patients with multimorbidity, specifically the concurrent presence of diabetes, PAD, and CKD, had higher odds of a worse functional outcome in the first 6 months poststroke. Clusters of multimorbidity may be less informative for long-term disability in female patients. Further studies should evaluate other mechanisms for worse disability in female patients poststroke.

Differential sensitivity of intraindividual variability dispersion and global cognition in the prediction of functional outcomes and mortality in precariously housed and homeless adults

OBJECTIVE

To examine cognitive intraindividual variability (IIV) dispersion as a predictor of everyday functioning and mortality in persons who are homeless or precariously housed.

METHOD

Participants were 407 community-dwelling adults, followed for up to 13 years. Neurocognition was assessed at baseline and IIV dispersion was derived using a battery of standardized tests. Functional outcomes (social, physical) were obtained at baseline and last follow-up. Mortality was confirmed with Coroner's reports and hospital records (N  = 103 deaths). Linear regressions were used to predict current social and physical functioning from IIV dispersion. Repeated measures Analysis of Covariance were used to predict long-term change in functioning. Cox regression models examined the relation between IIV dispersion and mortality. Covariates included global cognition (i.e. mean-level performance), age, education, and physical comorbidities.

RESULTS

Higher IIV dispersion predicted poorer current physical functioning (B = -0.46 p = .010), while higher global cognition predicted better current (B  = 0.21, p = .015) and change in social functioning over a period of up to 13 years (F  = 4.23, p = .040). Global cognition, but not IIV dispersion, predicted mortality in individuals under 55 years old (HR = 0.50, p = .013).

CONCLUSIONS

Our findings suggest that indices of neurocognitive functioning (i.e. IIV dispersion and global cognition) may be differentially related to discrete dimensions of functional outcomes in an at-risk population. IIV dispersion may be a complimentary marker of emergent physical health dysfunction in precariously housed adults and may be best used in conjunction with traditional neuropsychological indices.

Image Findings as Predictors of Fall Risk in Patients with Cerebrovascular Disease

This study examined computed tomography findings in patients with cerebrovascular disease and determined predictors for falls. Images of the head were divided into 13 regions, and the relationships between computed tomography findings and the presence or absence of falls were investigated. A total of 138 patients with cerebrovascular disease (66% men, aged 73.8 ± 9.6 years) were included. A comparison between the fall and non-fall groups revealed a significant difference in the total functional independence measure scores and imaging findings at admission. Logistic regression analysis showed that the thalamus (p < 0.001), periventricular lucency (p < 0.001), lateral hemisphere room enlargement (p < 0.05), and age (p < 0.05) were related to the presence or absence of falls. For the 42 patients with cerebral hemorrhage, the thalamus (p < 0.01), periventricular lucency (p < 0.05), lateral ventricle vicinity (p < 0.05), and posterior limb of the internal capsule (p < 0.05) were extracted as factors related to the presence or absence of falls. For the 96 patients with cerebral infarction, the thalamus (p < 0.001), periventricular lucency (p < 0.01), and anterior limb of the internal capsule (p < 0.05) were extracted as factors related to the presence or absence of falls. This study found a relationship between the thalamus, lateral ventricle enlargement, periventricular lucency, and falls. Fall prognosis can potentially be predicted from computed tomography findings at admission.

Evaluation of balance and executive function relationships in older individuals

BACKGROUND

Executive function is an important cognitive factor in gait and balance control. Weakening of balance system components and executive functions due to aging may affect walking and balance and increase the risk of falling.

AIMS

The present study aimed to investigate the relationship between balance and executive function in older individuals and the contributions of physical activity and depression to this relationship.

METHODS

A total of 84 healthy individuals aged 60 and over were included in the study. In the study, the Timed Up and Go Test (TUG), Mini Balance Evaluation Systems Test (Mini-BESTest), Digit Symbol Substitution Test (DSST), Trail Making Test A and B (TMT A and TMT B), Physical Activity Scale for the Elderly (PASE), and Geriatric Depression Scale (GDS) were applied.

RESULTS

The Mini-BESTest and TUG correlated with DSST, TMT A, and TMT B. GDS was correlated with TUG. PASE was correlated with Mini-BESTest and TUG. Executive functions differed according to education level; DSST, TMT B, and GDS were effective in fall history.

DISCUSSION

There was a significant relationship between balance and executive function. It was found that balance and walking speed increased as executive function skills increased. Depression and physical activity are associated with balance and gait speed.

CONCLUSIONS

Balance and executive functions are related to each other, and physical activity and depression contribute to this relationship. In order to protect against the negative effects of aging, cognitive and physical training can be performed to prevent balance and executive function declines.

Walking energetics and white matter hyperintensities in mid-to-late adulthood

INTRODUCTION

White matter hyperintensities (WMHs) increase with age and contribute to cognitive and motor function decline. Energy costs for mobility worsen with age, as the energetic cost of walking increases and energetic capacity declines. We examined the cross-sectional associations of multiple measures of walking energetics with WMHs in mid- to late-aged adults.

METHODS

A total of 601 cognitively unimpaired adults (mean age 66.9 ± 15.3 years, 54% women) underwent brain magnetic resonance imaging scans and completed standardized slow- and peak-paced walking assessments with metabolic measurement (V̇O2). T1-weighted scans and fluid-attenuated inversion recovery images were used to quantify WMHs. Separate multivariable linear regression models examined associations adjusted for covariates.

RESULTS

Lower slow-paced V̇O2 (B = 0.07; P = 0.030), higher peak-paced V̇O2 (B = -0.10; P = 0.007), and lower cost-to-capacity ratio (B = .12; P < 0.0001) were all associated with lower WMH volumes.

DISCUSSION

The cost-to-capacity ratio, which describes the percentage of capacity required for ambulation, was the walking energetic measure most strongly associated with WMHs.

Exploring the relationship between frailty and executive dysfunction: the role of frontal white matter hyperintensities

Introduction

Frailty is a geriatric syndrome frequently associated with executive dysfunction and white matter hyperintensities (WMH). But the relation between executive dysfunction and brain changes is poorly understood in frail subjects. Our hypothesis is that frontal-WMH mediates the association between frailty and executive dysfunction.

Methods

A convenience sample of 113 subjects older than 65 years without dementia was studied with neuropsychological test, a structured clinical interview, physical examination and brain MRI. They were classified as robust or pre-frail and frail using the frailty phenotype score (0-5). The frontal WMH (F-WMH) were manually graduated (0-6) using the "Age-Related White Matter Changes score" from FLAIR sequences at a 3 Tesla brain MRI. A mediation analysis was done for testing whether F-WMH could act as a link factor between frailty phenotype score and executive dysfunction.

Results

The group's mean age was 74 ± 6 years, subjects with higher frailty score had more depressive symptoms and worse performance in executive function tests. A regression analysis that explained 52% of the variability in executive functions, revealed a significant direct effect of frailty score (Standardized βcoeff [95% CI] -0.201, [-0.319, -0.049], and F-WMH (-0.152[-0.269, -0.009]) on executive functions, while the F-WMH showed a small partial mediation effect between frailty and executive functions (-0.0395, [-0.09, -0.004]).

Discussion

Frontal matter hyperintensities had a small mediation effect on the association between frailty and executive dysfunction, suggesting that other neuropathological and neurofunctional changes might also be associated with executive dysfunction in frail subjects.

Resistance Training Maintains White Matter and Physical Function in Older Women with Cerebral Small Vessel Disease: An Exploratory Analysis of a Randomized Controlled Trial

Background

As the aging population grows, there is an increasing need to develop accessible interventions against risk factors for cognitive impairment and dementia, such as cerebral small vessel disease (CSVD). The progression of white matter hyperintensities (WMHs), a key hallmark of CSVD, can be slowed by resistance training (RT). We hypothesize RT preserves white matter integrity and that this preservation is associated with improved cognitive and physical function.

Objective

To determine if RT preserves regional white matter integrity and if any changes are associated with cognitive and physical outcomes.

Methods

Using magnetic resonance imaging data from a 12-month randomized controlled trial, we compared the effects of a twice-weekly 60-minute RT intervention versus active control on T1-weighted over T2-weighted ratio (T1w/T2w; a non-invasive proxy measure of white matter integrity) in a subset of study participants (N = 21 females, mean age = 69.7 years). We also examined the association between changes in T1w/T2w with two key outcomes of the parent study: (1) selective attention and conflict resolution, and (2) peak muscle power.

Results

Compared with an active control group, RT increased T1w/T2w in the external capsule (p = 0.024) and posterior thalamic radiations (p = 0.013) to a greater degree. Increased T1w/T2w in the external capsule was associated with an increase in peak muscle power (p = 0.043) in the RT group.

Conclusion

By maintaining white matter integrity, RT may be a promising intervention to counteract the pathological changes that accompany CSVD, while improving functional outcomes such as muscle power.

Characteristics and Clinical Implication of White Matter Lesions in Patients With Adult Moyamoya Disease

BACKGROUND AND OBJECTIVES

White matter hyperintensities (WMHs) are reportedly increased in moyamoya disease (MMD); however, their clinical importance is not well-established owing to their pathophysiologic heterogeneity by distribution. This study aimed to evaluate the burden and pattern of WMHs and its clinical implications in the MMD trajectory.

METHODS

Adult patients with MMD without significant structural lesions were 1:1 propensity score-matched with healthy controls for sex and vascular risk factors. The total, periventricular, and subcortical WMH volumes were segmented and quantified fully automatically. WMH volumes were detrended by age and compared between the 2 groups. MMD severity based on Suzuki stage and future ischemic events were assessed for their association with WMH volumes.

RESULTS

A total of 161 pairs of patients with MMD and controls were analyzed. MMD significantly correlated with increased total WMH volume (B [standard error], 0.126 [0.030]; p < 0.001), periventricular WMH volume (0.114 [0.027]; p < 0.001), and periventricular-to-subcortical ratio (0.090 [0.034]; p = 0.009). In the MMD subgroup (n = 187), advanced MMD had an independent association with the total WMH volume (0.120 [0.035]; p < 0.001), periventricular WMH volume (0.110 [0.031]; p < 0.001), and periventricular-to-subcortical ratio (0.139 [0.038]; p < 0.001). Periventricular WMH volume (adjusted hazard ratio [95% confidence interval], 5.12 [1.26-20.79]) and periventricular-to-subcortical ratio (3.80 [1.51-9.56]) were associated with future ischemic events in patients with medically followed up MMD. However, no demonstrable association was found between subcortical WMH volume and MMD, MMD severity, or future ischemic events.

DISCUSSION

Periventricular WMHs, but not subcortical WMHs, may represent the main pathophysiology of MMD. Periventricular WMHs may be used as a marker for ischemic vulnerability in patients with MMD.

Association of gait speed with regional brain volumes and risk of dementia in older Japanese: The Hisayama study

BACKGROUND

To investigate the association of gait speed with regional brain volumes and the risk of incident dementia.

METHODS

A total of 1112 dementia-free Japanese residents aged ≥65 years who underwent brain magnetic resonance imaging were followed for 5.0 years (median). The participants were classified into the age- and sex-specific quartile levels of maximum gait speed. Regional gray matter volumes (GMV) and white matter hyperintensities volumes (WMHV) were measured by applying voxel-based morphometry methods. The cross-sectional association of maximum gait speed with regional GMV was examined using an analysis of covariance. We also estimated the association between maximum gait speed level and the risk of developing dementia using a Cox proportional hazards model. Mediation analyses were conducted to determine the contribution of regional brain volumes to the association between maximum gait speed and dementia.

RESULTS

Lower maximum gait speed was significantly associated with lower GMV of the total brain, frontal lobe, temporal lobe, cingulate gyrus, insula, hippocampus, amygdala, basal ganglia, thalamus, and cerebellum, and increased WMHV at baseline. During the follow-up, 108 participants developed dementia. The incidence rate of all dementias increased significantly with decreasing maximum gait speed after adjusting for potential confounders (P for trend = 0.03). The mediating effects of the GMV of the hippocampus, GMV of the insula, and WMHV were significant.

CONCLUSIONS

Lower maximum gait speed was significantly associated with an increased risk of dementia. Reduced GMV of the hippocampus or insula, and an increase in WMHV was likely to be involved in this association.

The Ties That Bind: Glial Transplantation in White Matter Ischemia and Vascular Dementia

White matter injury is a progressive vascular disease that leads to neurological deficits and vascular dementia. It comprises up to 30% of all diagnosed strokes, though up to ten times as many events go undiagnosed in early stages. There are several pathologies that can lead to white matter injury. While some studies suggest that white matter injury starts as small infarcts in deep penetrating blood vessels in the brain, others point to the breakdown of endothelial function or the blood-brain barrier as the primary cause of the disease. Whether due to local endothelial or BBB dysfunction, or to local small infarcts (or a combination), white matter injury progresses, accumulates, and expands from preexisting lesions into adjacent white matter to produce motor and cognitive deficits that present as vascular dementia in the elderly. Vascular dementia is the second leading cause of dementia, and white matter injury-attributed vascular dementia represents 40% of all diagnosed dementias and aggravates Alzheimer's pathology. Despite the advances in the last 15 years, there are few animal models of progressive subcortical white matter injury or vascular dementia. This review will discuss recent progress in animal modeling of white matter injury and the emerging principles to enhance glial function as a means of promoting repair and recovery.

Association of covert brain infarcts and white matter hyperintensities with risk of hip fracture in older adults: the Cardiovascular Health Study

Covert brain infarcts and white matter hyperintensities (WMHs), incidental markers of brain microvascular disease commonly seen on brain MRIs in older adults, have been associated with falls and lower bone mineral density. We found covert infarcts and WMHs may also be associated with an increased risk of future hip fracture.

INTRODUCTION

To determine whether covert infarcts and white matter hyperintensities (WMHs) are associated with increased risk of incident hip fracture.

METHODS

A prospective cohort of 3373 community-dwelling adults aged ≥ 65 years enrolled in the Cardiovascular Health Study with a brain MRI (1992-1993) was analyzed. Covert infarcts were categorized by number of infarcts and largest infarct size. WMH burden was assessed by radiologists and graded qualitatively from 0 (no WMHs) to 9 (extensive).

RESULTS

Participants had 465 incident hip fractures during a mean follow-up of 12.8 years. The demographic-adjusted hazard of incident hip fracture was 32% higher among participants with ≥ 1 covert infarct compared to those without infarcts (hazard ratio (HR) 1.32; 95% CI, 1.08-1.62). The hazard of incident hip fracture was similar after further adjustment for medications and medical history (HR = 1.34; 95% CI, 1.08-1.65), but attenuated following additional adjustment for functional status, frailty, and falls (HR = 1.25; 95% CI, 0.99-1.57). Fully adjusted hazard of incident hip fracture per increase in infarct number was 1.10 (95% CI, 0.98-1.23); risk in individuals whose largest infarct was ≥ 20 mm versus 3 to < 20 mm was similar. Compared with WMH grades 0-1, the demographic-adjusted hazard of hip fracture was 1.34 (95% CI, 1.09-1.66) and 1.83 (95% CI, 1.37-2.46), respectively, for WMH grades 2-3 and 4-9. The hazard was similar following adjustment for medications and medical history (grades 2-3: HR = 1.32; 95% CI, 1.05-1.64; grades 4-9: HR = 1.69; 95% CI, 1.23-2.30), but attenuated following additional adjustment for functional status, frailty, and falls (grades 2-3: HR = 1.24; 95% CI, 0.98-1.56; grades 4-9: HR = 1.34; 95% CI, 0.95-1.90).

CONCLUSION

Older, community-dwelling adults with covert infarcts or WMHs may be at increased risk of hip fracture.

A Systematic Review Exploring the Theories Underlying the Improvement of Balance and Reduction in Falls Following Dual-Task Training among Older Adults

BACKGROUND

Balance impairment causes frequent falls in older adults, and preventing falls remains challenging. Dual-task (DT) training reduces falls by improving balance, but the precise theory is not fully understood. This review aims to explore the theories underlying the effectiveness of DT in improving balance and reducing falls in older adults.

METHODS

Eleven electronic databases were searched from database inception to June 2022. Two reviewers independently performed study screening and data extraction. The risk of bias (RoB) in the included studies was assessed using the Cochrane Collaboration RoB 2 tool.

RESULTS

The searches yielded 1478 citations, of which 30 studies met the inclusion criteria and were included in the review. Twenty-two of the 30 included studies utilized the motor-cognitive type of DT for training, while six used motor-motor and two utilized cognitive-cognitive DT. The included studies reported 20 different theories to explain the effectiveness of DT for improving balance and reducing falls in older adults. The predominant theory identified in the included studies was attention theory (n = 14). Overall, 26 studies reported improved balance and five studies found a reduction in fall incidence following DT training. Balance and falls improved significantly in 15 motor-cognitive DT intervention studies.

CONCLUSION

Attention shifting between two tasks is reported to occur following DT training. Motor-cognitive DT training improves balance and reduces fall incidence in older adults by shifting attention based on the difficulty and priority of a task from the motor to the cognitive task.

The association between white matter hyperintensity volume and cognitive/physical decline in older people with dementia: A one-year longitudinal study

OBJECTIVES

Understanding the relationship between white matter hyperintensities (WMHs) and cognitive and physical decline in people with dementia will assist in determining potential treatment strategies. Currently there is conflicting evidence describing the association between WMHs and cognitive decline and, WMHs association with declines in objective measures of physical function have not been examined. We examined the relationship between baseline WMH volume and physical/cognitive decline over one-year in older people with dementia.

METHODS

Twenty-six community-dwelling older people with dementia (mean age = 81 ± 8 years; 35% female) were assessed at baseline and follow-up (one-year) using the Addenbrooke's Cognitive Examination-Revised (including verbal fluency), Trail Making Test A, the Physiological Profile Assessment (PPA), timed-up-and-go (TUG) and gait speed. WMH volumes were quantified using a fully automated segmentation toolbox, UBO Detector.

RESULTS

In analyses adjusted for baseline performance, higher baseline WMH volume was associated with decline in executive function (verbal fluency), sensorimotor function (PPA) and mobility (TUG). Executive function (semantic/category fluency) was the only domain association that withstood adjustment for age, and additionally hippocampal volume.

CONCLUSIONS

In unadjusted analyses, WMH volume was associated with one-year declines in cognitive and physical function in older people with dementia. The association with executive function decline withstood adjustment for age. More research is needed to confirm these findings and explore whether vascular risk reduction strategies can reduce WMH volume and associated cognitive and physical impairments in this group.

Gait in Cerebral Amyloid Angiopathy

Background Gait is a complex task requiring coordinated efforts of multiple brain networks. To date, there is little evidence on whether gait is altered in cerebral amyloid angiopathy (CAA). We aimed to identify impairments in gait performance and associations between gait impairment and neuroimaging markers of CAA, cognition, and falls. Methods and Results Gait was assessed using the Zeno Walkway during preferred pace and dual task walks, and grouped into gait domains (Rhythm, Pace, Postural Control, and Variability). Participants underwent neuropsychological testing and neuroimaging. Falls and fear of falling were assessed through self-report questionnaires. Gait domain scores were standardized and analyzed using linear regression adjusting for age, sex, height, and other covariates. Participants were patients with CAA (n=29), Alzheimer disease with mild dementia (n=16), mild cognitive impairment (n=24), and normal elderly controls (n=47). CAA and Alzheimer disease had similarly impaired Rhythm, Pace, and Variability, and higher dual task cost than normal controls or mild cognitive impairment. Higher Pace score was associated with better global cognition, processing speed, and memory. Gait measures were not correlated with microbleed count or white matter hyperintensity volume. Number of falls was not associated with gait domain scores, but participants with low fear of falling had higher Pace (odds ratio [OR], 2.61 [95% CI, 1.59-4.29]) and lower Variability (OR, 1.64 [95% CI, 1.10-2.44]). Conclusions CAA is associated with slower walking, abnormal rhythm, and greater gait variability than in healthy controls. Future research is needed to identify the mechanisms underlying gait impairments in CAA, and whether they predict future falls.

Weight for It: Resistance Training Mitigates White Matter Hyperintensity-Related Disruption to Functional Networks in Older Females

Background: White matter hyperintensities (WMH) are associated with impaired cognition and increased falls risk. Resistance training (RT) is a promising intervention to reduce WMH progression, improve executive functions, and reduce falls. However, the underlying neurobiological process by which RT improves executive functions and falls risk remain unclear. We hypothesized that: 1) RT reduces the level of WMH-related disruption to functional networks; and 2) reduced disruption to the sensorimotor and attention networks will be associated with improved executive function and reduced falls risk. Objective: Investigate the impact of 52 weeks of RT on WMH-related disruption to functional networks. Methods: Thirty-two older females (65–75 years) were included in this exploratory analysis of a 52-week randomized controlled trial. Participants received either twice-weekly RT or balance and tone training (control). We used lesion network mapping to assess changes in WMH-related disruption to the sensorimotor, dorsal attention, and ventral attention networks. Executive function was measured using the Stroop Colour-Word Test. Falls risk was assessed using the Physiological Profile Assessment (PPA) and the foam sway test. Results: RT significantly reduced the level of WMH-related disruption to the sensorimotor network (p = 0.005). Reduced disruption to the dorsal attention network was associated with improvements in Stroop performance (r = 0.527, p = 0.030). Reduced disruption to the ventral attention network was associated with reduced PPA score (r = 0.485, p = 0.049) Conclusion: RT may be a promising intervention to mitigate WMH-related disruption to the sensorimotor network. Additionally, reducing disruption to the dorsal and ventral attention networks may contribute to improved executive function and reduced falls risk respectively.

Effects of a 12-Week Periodized Resistance Training Program on Resting Brain Activity and Cerebrovascular Function: A Nonrandomized Pilot Trial

Resistance training is a promising strategy to promote healthy cognitive aging; however, the brain mechanisms by which resistance training benefits cognition have yet to be determined. Here, we examined the effects of a 12-week resistance training program on resting brain activity and cerebrovascular function in 20 healthy older adults (14 females, mean age 69.1 years). In this single group clinical trial, multimodal 3 T magnetic resonance imaging was performed at 3 time points: baseline (preceding a 12-week control period), pre-intervention, and post-intervention. Along with significant improvements in fluid cognition (d = 1.27), 4 significant voxelwise clusters were identified for decreases in resting brain activity after the intervention (Cerebellum, Right Middle Temporal Gyrus, Left Inferior Parietal Lobule, and Right Inferior Parietal Lobule), but none were identified for changes in resting cerebral blood flow. Using a separate region of interest approach, we provide estimates for improved cerebral blood flow, compared with declines over the initial control period, in regions associated with cognitive impairment, such as hippocampal blood flow (d = 0.40), and posterior cingulate blood flow (d = 0.61). Finally, resistance training had a small countermeasure effect on the age-related progression of white matter lesion volume (rank-biserial = -0.22), a biomarker of cerebrovascular disease. These proof-of-concept data support larger trials to determine whether resistance training can attenuate or even reverse salient neurodegenerative processes.

Detection of subtle white matter lesions in MRI through texture feature extraction and boundary delineation using an embedded clustering strategy

White matter lesions (WML) underlie multiple brain disorders, and automatic WML segmentation is crucial to evaluate the natural disease course and effectiveness of clinical interventions, including drug discovery. Although recent research has achieved tremendous progress in WML segmentation, accurate detection of subtle WML present early in the disease course remains particularly challenging. Here we propose an approach to automatic WML segmentation of mild WML loads using an intensity standardisation technique, gray level co-occurrence matrix (GLCM) embedded clustering technique, and random forest (RF) classifier to extract texture features and identify morphology specific to true WML. We precisely define their boundaries through a local outlier factor (LOF) algorithm that identifies edge pixels by local density deviation relative to its neighbors. The automated approach was validated on 32 human subjects, demonstrating strong agreement and correlation (excluding one outlier) with manual delineation by a neuroradiologist through Intra-Class Correlation (ICC = 0.881, 95% CI 0.769, 0.941) and Pearson correlation (r = 0.895, p-value < 0.001), respectively, and outperforming three leading algorithms (Trimmed Mean Outlier Detection, Lesion Prediction Algorithm, and SALEM-LS) in five of the six established key metrics defined in the MICCAI Grand Challenge. By facilitating more accurate segmentation of subtle WML, this approach may enable earlier diagnosis and intervention.

Functional Abilities of an International Post-Stroke Population: Standard Assessment of Global Everyday Activities (SAGEA) Scale

BACKGROUND AND OBJECTIVES

Function is an important outcome after stroke; traditional assessments may not capture functional deficits important to patients. We examined the validity of the Standard Assessment of Global Everyday Activities (SAGEA), a patient-reported outcome that assesses activities important to patients and for use in international clinical trials.

METHODS

The NAVIGATE-ESUS trial evaluated rivaroxaban compared to aspirin in preventing recurrent stroke in 7213 participants. The Modified Rankin Scale (mRS), the National Institutes of Health Stroke Scale (NIHSS), and the SAGEA were collected at entry. Chi square tests were used to compare proportions and Spearman rank correlations were used to compare between measures. SAGEA was compared to the Modified Frailty Index (MFI) and the occurrence of infarct to examine criterion validity RESULTS: Participants were 67 years, 2/3 were male, and at baseline 30% had no disability and 58% had slight disability according to mRS scores. SAGEA was weakly correlated with the mRS (r=0.37), the NIHSS (r=0.29) and the MFI (r=0.30). Of the 2154 with an mRS score of 0, 61% reported difficulty on the SAGEA. The largest discrepancies between SAGEA and other measures were because of cognitive functional deficits detected by the SAGEA that were not identified on other assessments. A larger number of MRI identified infarcts (acute and covert) were associated with a higher SAGEA score (p=0.007).

CONCLUSIONS

The SAGEA is a simple, globally applicable measure of cognitive and functional abilities that identifies issues that other commonly used assessments of disability and function do not capture.

Protection of ischemic white matter and oligodendrocytes in mice by 3K3A-activated protein C

Subcortical white matter (WM) stroke accounts for 25% of all strokes and is the second leading cause of dementia. Despite such clinical importance, we still do not have an effective treatment for ischemic WM stroke, and the mechanisms of WM postischemic neuroprotection remain elusive. 3K3A-activated protein C (APC) is a signaling-selective analogue of endogenous blood protease APC that is currently in development as a neuroprotectant for ischemic stroke patients. Here, we show that 3K3A-APC protects WM tracts and oligodendrocytes from ischemic injury in the corpus callosum in middle-aged mice by activating protease-activated receptor 1 (PAR1) and PAR3. We show that PAR1 and PAR3 were also required for 3K3A-APC's suppression of post-WM stroke microglia and astrocyte responses and overall improvement in neuropathologic and functional outcomes. Our data provide new insights into the neuroprotective APC pathway in the WM and illustrate 3K3A-APC's potential for treating WM stroke in humans, possibly including multiple WM strokes that result in vascular dementia.

Cerebral small vessel disease, cardiovascular risk factors, and future walking speed in old age: a population-based cohort study

Background

The purpose of this study was to examine the associations between combined and individual cerebral small vessel disease (cSVD) markers on future walking speed over 9 years; and to explore whether these associations varied by the presence of cardiovascular risk factors (CRFs).

Methods

This population-based cohort study included 331 adults, aged ≥60 years, without limitation in walking speed (≥0.8 m/s). At baseline, cSVD markers, including white matter hyperintensities (WMH), lacunes, and perivascular spaces (PVS), were assessed on magnetic resonance imaging. The modifiable CRFs (physical inactivity, heavy alcohol consumption, smoking, hypertension, high total cholesterol, diabetes, and overweight/obese) were combined into a score. The association between baseline cSVD markers and the decline in walking speed was examined using linear mixed-effects models, whereas Cox proportional hazards models were used to estimate the association with walking speed limitation (defined as < 0.8 m/s) over the follow-up.

Results

Over the follow-up period, 76 (23.0%) persons developed walking speed limitation. Participants in the highest tertile of the combined cSVD marker score had a hazard ratio (HR) of 3.78 (95% confidence interval [CI] 1.70-8.45) for walking speed limitation compared with people in the lowest score tertile, even after adjusting for socio-demographics, CRFs, cognitive function, and chronic conditions. When investigating the cSVD markers individually, having the highest burden of WMH was associated with a significantly faster decline in walking speed (β coefficient − 0.020; 95% CI -0.035-0.004) and a greater HR of walking speed limitation (HR 2.78; 95% CI 1.31-5.89) compared with having the lowest WMH burden. Similar results were obtained for the highest tertile of PVS (HR 2.13; 95% CI 1.04-4.36). Lacunes were associated with walking speed limitation, but only in men. Having ≥4 CRFs and high WMH volume simultaneously, showed a greater risk of walking speed limitation compared with having ≥4 CRFs and low WMH burden. CRFs did not modify the associations between lacunes or PVS and walking speed.

Conclusions

Combined cSVD markers strongly predict walking speed limitation in healthy older adults, independent of cognitive function, with WMH and PVS being the strongest contributors. Improving cardiovascular health may help to mitigate the negative effects of WMH on future walking speed.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02529-6.

Participation in cognitive activities is associated with foot reaction time and gait speed in older adults

BACKGROUND

Given the evidence of the links between cognition and mobility, participation in cognitive activities may benefit neuromotor performance and mobility in older adults.

AIMS

To examine the association between participation in cognitive activities and foot reaction time (RT) and gait speed in community-dwelling older adults.

METHODS

The MOBILIZE Boston Study II (MBSII) re-enrolled 354 community-dwelling older adults aged ≥ 70 years from the original MBS cohort. Of these, 310 completed the performance testing and we excluded three participants who had Parkinson's disease. Cognitive Activities Scale (CAS) assessed participation in 17 cognitive activities. Simple and Choice foot RT (SRT, CRT, msec) and gait speed (m/s) were measured using a sensored GAITRite® gait mat.

RESULTS

The average age of the 307 participants was 84 years; 79% were white and 65% were women. The average CAS score was 25.5 ± 11.7, indicating participation in approximately 26 activities per week on average. The average foot SRT was 245 ± 57msec and average CRT was 323 ± 85msec. Usual-paced gait speed was 0.9 ± 0.3 m/s on average. More frequent participation in cognitive activities was associated with shorter SRT (β = - 0.759, p = 0.015) and CRT (β = - 1.125, p = 0.013), and faster gait speed (β = 0.003, p = 0.026), after adjusting for potential confounders.

DISCUSSION

Participation in cognitively stimulating activities may be beneficial for neuromotor performance and mobility in older adults.

CONCLUSIONS

Prospective and intervention studies are needed to determine whether participation in cognitive activities may prevent mobility decline over time, and thus reduce fall risk.

Mind the gaps: functional networks disrupted by white matter hyperintensities are associated with greater falls risk

White matter hyperintensities (WMH) are associated with greater falls risk and slow gait speed. Whether these deficits are caused by the disruption of large-scale functional networks remains inconclusive. Further, physical activity moderates the association between WMHs and falls, but whether this extends to the disruption of functional networks remains unknown. One hundred and sixty-four adults (>55 years old) were included in this study. Using lesion network mapping, we identified significant correlations between the percentage of WMH-related disruption of the dorsal attention network and Physiological Profile Assessment (PPA) score (r = 0.24, p < 0.01); and between disruption of both the sensorimotor (r = 0.23, p < 0.01) and ventral attention networks (r = 0.21, p = 0.01) with foam sway. There were no significant associations with floor sway or gait speed. Physical activity moderated the association between the dorsal attention network and PPA score (p = 0.045). Thus, future research should investigate whether physical activity should be recommended in the clinical management of older adults with cerebral small vessel disease.

Imaging-based indices of Neuropathology and gait speed decline in older adults: the atherosclerosis risk in communities study

Imaging markers of cerebrovascular disease and Alzheimer's disease (AD) are implicated in mobility impairment in older adults, but few studies have examined these relationships longitudinally in a racially-diverse population-based sample. At Visit 5 (2011-13) of the ARIC Study, 1859 participants had usual pace gait speed (cm/s) assessed and brain MRI (mean age = 76.3, 28.5% Black) and PET (n = 343; mean age = 75.9, 42.6% Black) measures including total/regional brain volume (cm3), white matter hyperintensities (WMH; cm3), infarcts (present/absent), microbleeds (count) and global beta-amyloid (Aβ). Participants returned at Visit 6 (n = 1264, 2016-17) and Visit 7 (n = 1108, 2018-19) for follow-up gait speed assessments. We used linear regression to estimate effects of baseline infarct presence, higher microbleed count, and a one interquartile range (IQR) poorer measures of continuous predictors (-1 IQR total brain volume, temporal-parietal lobe meta region of interest(ROI); +1 IQR WMH volume, global Aβ SUVR) on cross-sectional gait speed and change in gait speed adjusting for age, sex, education, study site, APOE e4, estimated intracranial volume, BMI, and cardiovascular risk factors. Cross-sectionally, slower gait speed outcome was associated with higher WMH volume, -3.38 cm/s (95%CI:-4.71, -2.04), infarct presence, -5.60 cm/s (-7.69, -3.51), microbleed count, -2.20 cm/s (-3.20, -0.91), smaller total brain volume, -9.26 cm/s (-12.1, -6.43), and smaller temporal-parietal lobe ROI -6.28 cm/s (-8.28, -4.28). Longitudinally, faster gait speed outcome decline was associated with higher WMH volume, -0.27 cm/s/year, (-0.51, -0.03) and higher global Aβ SUVR, -0.62 cm/s/year (-1.20, -0.03). Both cerebrovascular and AD pathology may contribute to mobility decline commonly seen with aging.

Cognitive and Motor Cortical Activity During Cognitively Demanding Stepping Tasks in Older People at Low and High Risk of Falling

Background: Choice stepping reaction time tasks are underpinned by neuropsychological, sensorimotor, and balance systems and therefore offer good indices of fall risk and physical and cognitive frailty. However, little is known of the neural mechanisms for impaired stepping and associated fall risk in older people. We investigated cognitive and motor cortical activity during cognitively demanding stepping reaction time tasks using functional near-infrared spectroscopy (fNIRS) in older people at low and high fall risk.

Methods: Ninety-five older adults [mean (SD) 71.4 (4.9) years, 23 men] were categorized as low or high fall risk [based on 12-month fall history (≥2 falls) and/or Physiological Profile Assessment fall risk score ≥1]. Participants performed a choice stepping reaction time test and a more cognitively demanding Stroop stepping task on a computerized step mat. Cortical activity in cognitive [dorsolateral prefrontal cortex (DLPFC)] and motor (supplementary motor area and premotor cortex) regions was recorded using fNIRS. Stepping performance and cortical activity were contrasted between the groups and between the choice and Stroop stepping conditions.

Results: Compared with the low fall risk group (n = 71), the high fall risk group (n = 24) exhibited significantly greater DLPFC activity and increased intra-individual variability in stepping response time during the Stroop stepping task. The high fall risk group DLPFC activity was greater during the performance of Stroop stepping task in comparison with choice stepping reaction time. Regardless of group, the Stroop stepping task elicited increased cortical activity in the supplementary motor area and premotor cortex together with increased mean and intra-individual variability of stepping response times.

Conclusions: Older people at high fall risk exhibited increased DLPFC activity and stepping response time variability when completing a cognitively demanding stepping test compared with those at low fall risk and to a simpler choice-stepping reaction time test. This increased hemodynamic response might comprise a compensatory process for postural control deficits and/or reflect a degree of DLPFC neural inefficiency in people with increased fall risk.

What does hand motor function tell us about our aging brain in association with WMH?

Background

White matter hyperintensities (WMH) are a common cerebral finding in older people. WMH are usually asymptomatic, but excessive WMH are associated with cognitive decline and dementia. WMH are also among the neurological findings most consistently associated with declining motor performance in healthy ageing.

Aims

To determine if WMH load is associated with simple and complex motor movements in dominant and non-dominant hands in cognitively intact older subjects.

Methods

Hand motor performance was assessed with the Purdue Pegboard and Finger-tapping tests on 44 healthy right-handed participants, mean age 70.9 years (range 59–84 years). Participants also underwent magnetic resonance (MR) imaging, which were used to quantify WMH volume. The effect of WMH on the motor parameters was assessed via mediation analyses.

Results

WMH load increased significantly with age, while the motor scores decreased significantly with age. WMH load mediated only the relationship between age and left-hand pegboard scores.

Discussion

WMH mediated only the more complex Purdue Pegboard task for the non-dominant hand. This is likely because complex movements in the non-dominant hand recruit a larger cerebral network, which is more vulnerable to WMH.

Conclusions

Complex hand movements in the non-dominant hand are mediated by WMH. Subtle loss of motor movements of non-dominant hand might predict future excessive white matter atrophy.

Sweat the Fall Stuff: Physical Activity Moderates the Association of White Matter Hyperintensities With Falls Risk in Older Adults

Background: Falls in older adults are a major public health problem. White matter hyperintensities (WMHs) are highly prevalent in older adults and are a risk factor for falls. In the absence of a cure for WMHs, identifying potential strategies to counteract the risk of WMHs on falls are of great importance. Physical activity (PA) is a promising countermeasure to reduce both WMHs and falls risk. However, no study has yet investigated whether PA attenuates the association of WMHs with falls risk. We hypothesized that PA moderates the association between WMHs and falls risk.

Methods: Seventy-six community-dwelling older adults aged 70–80 years old were included in this cross-sectional study. We indexed PA using the Physical Activity Score for the Elderly (PASE) Questionnaire. Falls risk was assessed using the Physiological Profile Assessment (PPA), and WMH volume (mm³) was determined by an experienced radiologist on T2-weighted and PD-weighted MRI scans. We first examined the independent associations of WMH volume and PASE score with PPA. Subsequently, we examined whether PASE moderated the relationship between WMH volume and PPA. We plotted simple slopes to interpret the interaction effects. Age, sex, and Montreal Cognitive Assessment (MoCA) score were included as covariates in all models.

Results: Participants had a mean age of 74 years (SD = 3 years) and 54 (74%) were female. Forty-nine participants (66%) had a Fazekas score of 1, 19 (26%) had a score of 2, and 6 (8%) a score of 3. Both PASE (β = −0.26 ± 0.11; p = 0.022) and WMH volume (β = 0.23 ± 0.11; p = 0.043) were each independently associated with PPA score. The interaction model indicated that PASE score moderated the association between WMH volume and PPA (β = −0.27 ± 0.12; p = 0.030), whereby higher PASE score attenuated the association between WMHs and falls risk.

Conclusion: PA is an important moderator of falls risk. Importantly, older adults with WMH can reduce their risk of falls by increasing their PA.

The association between white matter hyperintensity volume and gait performance under single and dual task conditions in older people with dementia: A cross-sectional study

BACKGROUND

Understanding the relationship between white matter hyperintensities (WMHs) and gait may assist in understanding the central control of gait and determining treatment modalities. These relationships are yet to be realized in older people with dementia.

OBJECTIVE

To examine the association between WMH volume and gait under single-task and dual task (DT) conditions in people with dementia.

METHODS

Twenty-eight community-dwelling older people with dementia (median age=83 years; [IQR=77-86]; 36% female) had timed gait speed assessed at usual pace. Gait (speed, stride length, cadence) was assessed using the GAITRite® mat under three conditions (n = 18/28): a) single-task, b) functional DT: carrying a glass of water and c) cognitive DT: counting backwards from 30. WMH volumes were quantified using a fully automated segmentation toolbox.

RESULTS

Total, temporal and parietal WMH volumes were negatively correlated with timed and functional DT gait speed, and with stride length under single-task, functional DT and cognitive DT conditions. Frontal WMH volumes were negatively correlated with timed gait speed and stride length under single-task and functional DT conditions. Participants with higher total WMH burden had significantly slower timed and functional DT gait speed and reduced stride length under single-task, functional DT and cognitive DT conditions compared to participants with lower WMH burden.

CONCLUSIONS

WMH volume was associated with slower gait speed and reduced stride length, but not cadence, under single-task and DT conditions in people with dementia. Further research is needed to confirm these findings and determine whether vascular risk management can improve gait in older people with dementia.

Reshaping the path of vascular cognitive impairment with resistance training: a study protocol for a randomized controlled trial

Background

Subcortical ischemic vascular cognitive impairment (SIVCI) is the most common form of vascular cognitive impairment. Importantly, SIVCI is considered the most treatable form of cognitive impairment in older adults, due to its modifiable risk factors such as hypertension, diabetes mellitus, and hypercholesterolemia. Exercise training is a promising intervention to delay the progression of SIVCI, as it actively targets these cardiometabolic risk factors. Despite the demonstrated benefits of resistance training on cognitive function and emerging evidence suggesting resistance training may reduce the progression of white matter hyperintensities (WMHs), research on SIVCI has predominantly focused on the use of aerobic exercise. Thus, the primary aim of this proof-of-concept randomized controlled trial is to investigate the efficacy of a 12-month, twice-weekly progressive resistance training program on cognitive function and WMH progression in adults with SIVCI. We will also assess the efficiency of the intervention.

Methods

Eighty-eight community-dwelling adults, aged > 55 years, with SIVCI from metropolitan Vancouver will be recruited to participate in this study. SIVCI will be determined by the presence of cognitive impairment (Montreal Cognitive Assessment < 26) and cerebral small vessel disease using computed tomography or magnetic resonance imaging. Participants will be randomly allocated to a twice-weekly exercise program of (1) progressive resistance training or (2) balance and tone training (i.e., active control). The primary outcomes are cognitive function measured by the Alzheimer’s Disease Assessment Scale-Cognitive-Plus (ADAS-Cog-13 with additional cognitive tests) and WMH progression.

Discussion

The burden of SIVCI is immense, and to our knowledge, this will be the first study to quantify the effect of progressive resistance training on cognitive function and WMH progression among adults with SIVCI. Slowing the rate of cognitive decline and WMH progression could preserve functional independence and quality of life. This could lead to reduced health care costs and avoidance of early institutional care.

Trial registration

ClinicalTrials.gov NCT02669394. Registered on February 1, 2016

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05156-1.

Automatic segmentation of white matter hyperintensities from brain magnetic resonance images in the era of deep learning and big data - A systematic review

BACKGROUND

White matter hyperintensities (WMH), of presumed vascular origin, are visible and quantifiable neuroradiological markers of brain parenchymal change. These changes may range from damage secondary to inflammation and other neurological conditions, through to healthy ageing. Fully automatic WMH quantification methods are promising, but still, traditional semi-automatic methods seem to be preferred in clinical research. We systematically reviewed the literature for fully automatic methods developed in the last five years, to assess what are considered state-of-the-art techniques, as well as trends in the analysis of WMH of presumed vascular origin.

METHOD

We registered the systematic review protocol with the International Prospective Register of Systematic Reviews (PROSPERO), registration number - CRD42019132200. We conducted the search for fully automatic methods developed from 2015 to July 2020 on Medline, Science direct, IEE Explore, and Web of Science. We assessed risk of bias and applicability of the studies using QUADAS 2.

RESULTS

The search yielded 2327 papers after removing 104 duplicates. After screening titles, abstracts and full text, 37 were selected for detailed analysis. Of these, 16 proposed a supervised segmentation method, 10 proposed an unsupervised segmentation method, and 11 proposed a deep learning segmentation method. Average DSC values ranged from 0.538 to 0.91, being the highest value obtained from an unsupervised segmentation method. Only four studies validated their method in longitudinal samples, and eight performed an additional validation using clinical parameters. Only 8/37 studies made available their methods in public repositories.

CONCLUSIONS

We found no evidence that favours deep learning methods over the more established k-NN, linear regression and unsupervised methods in this task. Data and code availability, bias in study design and ground truth generation influence the wider validation and applicability of these methods in clinical research.

Recovery of balance and gait after stroke is deteriorated by confluent white matter hyperintensities: Cohort study

BACKGROUND

White matter hyperintensities (WMHs) are well known to affect post-stroke disability, mainly by cognitive impairment. Their impact on post-stroke balance and gait disorders is unclear.

OBJECTIVES

We aimed to test the hypothesis that WMHs would independently deteriorate post-stroke balance and gait recovery.

METHODS

This study was performed in 210 individuals of the cohort Determinants of Balance Recovery After Stroke (DOBRAS), consecutively enrolled after a first-ever hemisphere stroke. Clinical data were systematically collected on day 30±3 (D30) post-stroke and at discharge from the rehabilitation ward. WMHs were searched on MRI, graded with the Fazekas scale, and dichotomized as no/mild (absence/sparse) or moderate/severe (confluent). The primary endpoint was the recovery of the single limb stance, assessed with the Postural Assessment Scale for Stroke (PASS). The secondary endpoint was the recovery of independent gait, assessed with the modified Fugl-Meyer Gait Assessment (mFMA). The adjusted hazard ratios (aHRs) of achievements of these endpoints by level of WMHs were estimated by using Cox models, accounting for other relevant clinical and imaging factors.

RESULTS

Individuals with moderate/severe WMHs (n=86, 41%) had greater balance and gait disorders and were more often fallers than others (n=124, 59%). Overall, they had worse and slower recovery of single limb stance and independent gait (p<0.001). Moderate/severe WMHs was the most detrimental factor for recovery of balance (aHR 0.46, 95% confidence interval [CI] 0.32-0.68, p<0.001) and gait (0.51, 0.35-0.74, p<0.001), along with age, stroke severity, lesion volume and disrupted corticospinal tract. With cerebral infarct, endovascular treatments had an independent positive effect, both on the recovery of balance (aHR 1.65, 95% CI 1.13-2.4, p=0.009) and gait (1.78, 1.24-2.55, p=0.002).

CONCLUSIONS

WMHs magnify balance and gait disorders after stroke and worsen their recovery. They should be better accounted for in post-stroke rehabilitation, especially to help establish a prognosis of mobility. ClinicalTrials.gov registration: NCT03203109.

Association of Bone Mineral Density to Cerebral Small Vessel Disease Burden

OBJECTIVE

To test the hypothesis that bone mineral loss is mechanistically related to cerebral small vessel disease (SVD), we investigated the relationship between bone mineral density and the prevalence and intensity of SVD among patients with stroke.

METHODS

We analyzed data of 1,190 consecutive patients with stroke who were >50 years of age and underwent both brain MRI and dual-energy x-ray absorptiometry from the stroke registry of Chung-Ang University Hospital in Seoul, Korea. The patients were categorized into 3 groups according to their bone mineral density (normal, osteopenia, and osteoporosis). White matter hyperintensities, silent lacunes, cerebral microbleeds, and extensive perivascular space were assessed from brain MRI. Multinomial logistic regression model was used to examine the association between osteoporosis and total SVD score. We also recruited 70 patients with stroke to study serum bone turnover markers and microRNAs related to both cerebral atherosclerosis and bone metabolism to understand bone and brain interaction.

RESULTS

Osteoporosis was determined among 284 patients (23.9%), and 450 patients (37.8%) had osteopenia. As bone mineral density decreased, total SVD score and the incidence of every SVD phenotype increased except strictly lobar cerebral microbleeds. Multinomial logistic regression analysis showed that osteoporosis was independently associated with severe SVD burden. The levels of microRNA-378f were significantly increased among the patients with osteoporosis and maximal total SVD score and positively correlated with parathyroid hormone and osteocalcin.

CONCLUSIONS

These findings suggest a pathophysiologic link between bone mineral loss and hypertensive cerebral arteriolar degeneration, possibly mediated by circulating microRNA.

Periventricular White Matter Hyperintensity in Males is Associated with Post-Stroke Depression Onset at 3 Months

OBJECTIVE

This study aimed to explore the correlation between white matter hyperintensity (WMH) and post-stroke depression (PSD) at 3 months, and to further investigate sex differences in the pathogenesis of PSD.

METHODS

A total of 238 consecutive patients with acute cerebral infarction were recruited. PSD was assessed at 2 weeks and at 3 months after stroke onset. All stroke cases were divided into four subgroups according to the diagnosis of depression at two time nodes: continuous depression; depression remission; late-onset PSD; and continuous non-depression. The Fazekas and Scheltens visual rating scales were adopted to assess WMH.

RESULTS

Logistic regression revealed that the presence of periventricular white matter hyperintensity (PVWMH) at baseline in male patients was an independent risk factor for PSD at 3 months. Further subgroup analysis revealed that PVWMH was associated with late-onset PSD in males, but not with continuous depression 3 months after stroke. Male acute stroke patients with PVWMH at baseline were more likely to develop PSD at 3 months, especially late-onset PSD.

CONCLUSION

Our data suggest that sex differences may influence the pathogenesis of PSD.

Processing moving visual scenes during upright stance in elderly patients with mild cognitive impairment

Background

The ability to maintain balance in an upright stance gradually worsens with age and is even more difficult for patients with cognitive disorders. Cognitive impairment plays a probable role in the worsening of stability. The purpose of this study was to expose subjects with mild cognitive impairment (MCI) and healthy, age-matched controls to moving visual scenes in order to examine their postural adaptation abilities.

Methods

We observed postural responses to moving visual stimulation while subjects stood on a force platform. The visual disturbance was created by interposing a moving picture in four directions (forward, backward, right, and left). The pre-stimulus (a static scene for 10 s), stimulus (a dynamic visual scene for 20 seconds) and post-stimulus (a static scene for 20 seconds) periods were evaluated. We separately analyzed the total path (TP) of the center of pressure (COP) and the root mean square (RMS) of the COP displacement in all four directions.

Results

We found differences in the TP of the COP during the post-stimulus period for all stimulus directions except in motion towards the subject (left p = 0.006, right p = 0.004, and away from the subject p = 0.009). Significant RMS differences between groups were also observed during the post-stimulus period in all directions except when directed towards the subject (left p = 0.002, right p = 0.007, and away from the subject p = 0.014).

Conclusion

Exposing subjects to a moving visual scene induced greater destabilization in MCI subjects compared to healthy elderly controls. Surprisingly, the moving visual scene also induced significant aftereffects in the MCI group. Our findings indicate that the MCI group had diminished adaptation to the dynamic visual scene and recovery. These results suggest that even mild cognitive deficits can impair sensory information integration and alter the sensory re-weighing process.

Overactive Bladder in Frail Older Adults

Overactive bladder (OAB) and frailty are multidimensional syndromes, and the prevalence of both increases with age. Little evidence exists for a direct association between OAB and frailty, but urinary urgency may well be a precursor of frailty in older people. Frail older adults are no less deserving of treatment than fit older adults, and lifestyle, behavioral, and pharmacological interventions remain the primary options for treatment, with some evidence for efficacy. Data on onabotulinumtoxinA therapy or percutaneous tibial nerve stimulation in frail older adults are sparse. Frail older adults are often excluded from drug trials, but evidence is accumulating that antimuscarinics and, to a lesser extent, beta-adrenergic agonists are safe, well-tolerated, and effective in older adults. Cognitive impairment associated with frailty should not be used as justification for avoiding the use of antimuscarinics. More studies are required to better understand the association between OAB and frailty, as both are associated with poor outcomes and may be amenable to intervention. Drug trials for OAB treatments should be encouraged to include frail older adults, as this population is highly affected yet often excluded.

Is impaired dopaminergic function associated with mobility capacity in older adults?

The capacity to move is essential for independence and declines with age. Slow movement speed, in particular, is strongly associated with negative health outcomes. Prior research on mobility (herein defined as movement slowness) and aging has largely focused on musculoskeletal mechanisms and processes. More recent work has provided growing evidence for a significant role of the nervous system in contributing to reduced mobility in older adults. In this article, we report four pieces of complementary evidence from behavioral, genetic, and neuroimaging experiments that, we believe, provide theoretical support for the assertion that the basal ganglia and its dopaminergic function are responsible, in part, for age-related reductions in mobility. We report four a posteriori findings from an existing dataset: (1) slower central activation of ballistic force development is associated with worse mobility among older adults; (2) older adults with the Val/Met intermediate catecholamine-O-methyl-transferase (COMT) genotype involved in dopamine degradation exhibit greater mobility than their homozygous counterparts; (3) there are moderate relationships between performance times from a series of lower and upper extremity tasks supporting the notion that movement speed in older adults is a trait-like attribute; and (4) there is a relationship of functional connectivity within the medial orbofrontal (mOFC) cortico-striatal network and measures of mobility, suggesting that a potential neural mechanism for impaired mobility with aging is the deterioration of the integrity of key regions within the mOFC cortico-striatal network. These findings align with recent basic and clinical science work suggesting that the basal ganglia and its dopaminergic function are mechanistically linked to age-related reductions in mobility capacity.

Forced forelimb use following stroke enhances oligodendrogenesis and functional recovery in the rat

Forced limb use, which forces the use of the impaired arm following stroke, improves functional recovery. The study was designed to investigate the mechanisms of recovery underlying forced impaired limbuse. Furthermore, forced unimpaired arm use was also performed in order to explore its effect on functional behavior. We hypothesized that forced forelimb use could improve functional recovery in rats that have had an experimentally induced ischemic stroke, through promoting the recruitment and differentiation of the oligodendrocyte progenitor cells (OPCs). Indeed the proliferation of Olig2 and NG2 positive cells, as well as the expression of myelin basic protein (MBP)were increased in the perilesional striatum, whereas quantitative changes of Olig2+ and NG2+ oligodendrocyte progenitor cells was not observed in the subventricular zone. Through comparing rats forced to rely on affected or unaffected forelimb, the results demonstrated that forced impaired limb use boosted functional recovery. At the same time forced unimpaired limb use deteriorated limb movement of injured side. In addition, the expression of NogoA is reduced, when the injured limb was used more, suggesting that it played a role in the repair of white matter.

Cerebral Amyloid-β Deposition Is Associated with Impaired Gait Speed and Lower Extremity Function

BACKGROUND

Impaired physical function (i.e., slowing of gait, muscle weakness, and poor mobility) is common in older adults with cognitive impairment and dementia. Evidence suggests that cerebral small vessel disease, specifically white matter lesions (WMLs), is associated with impaired physical function, but little research has been conducted to understand the specific role of Alzheimer's disease pathology in physical outcomes.

OBJECTIVE

The objective of this study was to examine the association between cerebral amyloid-β (Aβ) deposition and physical function in people with cognitive impairment.

METHODS

Thirty participants completed an 11C Pittsburgh compound B (PIB) position emission tomography (PET) scan to quantify global Aβ deposition using standardized uptake value ratio (SUVR). We assessed usual gait speed, muscle strength of the lower extremities, balance, and functional mobility using the Short Physical Performance Battery (SPPB) and the Timed Up and Go Test (TUGT). Multiple linear regression analyses examined the association between Aβ and each measure of physical function, adjusting for age, body mass index, and WML load.

RESULTS

Global PIB SUVR was significantly associated with usual gait speed (β= -0.52, p = 0.01) and SPPB performance (β= -0.47, p = 0.02), such that increased Aβ deposition was associated with reduced performance on both measures. Global PIB SUVR was not significantly associated with TUGT performance (β= 0.32, p = 0.08).

CONCLUSIONS

Cerebral Aβ deposition is associated with reduced gait speed, muscle strength, and balance in older adults with cognitive impairment independent of WML load. However, Aβ deposition was not associated with functional mobility.

Mortality Risk Among Older People Who Did Versus Did Not Sustain a Fracture: Baseline Prefracture Strength and Gait Speed as Predictors in a 15-Year Follow-Up

BACKGROUND

Physiological reserve, as indicated by muscle strength and gait speed, may be especially determinant of survival in people who are exposed to a health stressor. We studied whether the association between strength/speed and mortality risk would be stronger in the time period after a fracture compared to other time periods.

METHODS

Participants were population-based sample of 157 men and 325 women aged 75 and 80 years at baseline. Maximal 10-m gait speed and maximal isometric grip and knee extension strength were tested at the baseline before the fracture. Subsequent fracture incidence and mortality were followed up for 15 years. Cox regression analysis was used to estimate fracture time-stratified effects of gait speed and muscle strength on mortality risk in three states: (i) nonfracture state, (ii) the first postfracture year, and (iii) after the first postfracture year until death/end of follow-up.

RESULTS

During the follow-up, 20% of the men and 44% of the women sustained a fracture. In both sexes, lower gait speed and in women lower knee extension strength was associated with increased mortality risk in the nonfracture state. During the first postfracture year, the mortality risk associated with slower gait and lower strength was increased and higher than in the nonfracture state. After the first postfracture year, mortality risk associated with lower gait speed and muscle strength attenuated.

CONCLUSIONS

Lower gait speed and muscle strength were more strongly associated with mortality risk after fracture than during nonfracture time, which may indicate decreased likelihood of recovery.

Association Between Arterial Stiffness, Frailty and Fall-Related Injuries in Older Adults

Purpose

This study was conducted to investigate the relationships between arterial stiffness, frailty and fall-related injuries among community-dwelling older adults.

Materials and Methods

A cross-sectional study of a random sample of older adults aged 60 years and older was conducted. Main study parameters: arterial stiffness was measured by the determining the cardio-ankle vascular index (CAVI); Frailty status was defined using a 7-item frailty screening scale, developed in Russia. This questionnaire included question about falls and fall-related injuries. Orthostatic test and anthropometric tests were done. Medical history (comorbidity, medications), the Osteoporosis Self-assessment Tool (OST), nutritional, physical, cognitive and functional status were evaluated.

Results

The study population included 163 people aged 60–89 years. The average predicted value of CAVI in women aged 60–69 was 9.13 ± 0.13, in men, 9.49 ± 0.05; in women aged 70–79, it was 9.49 ± 0.16, in men, 9.73 ±0.11; in women aged 80 and older it was 10.04 ±0.18, in men, 10.24 ±0.10 units. The CAVI above the predicted value was associated with fall-related injuries even after adjustment for age, sex, use of β-blockers (BBs), history of stroke, and region of residence with the odds ratio 3.52 (95% CI: 1.03 −12.04).

Conclusion

Our study revealed an independent association between arterial stiffness and fall-related injuries in older adults over 60 years. The findings suggest that clinicians, especially geriatricians, should pay attention to arterial stiffness of patients with fall-related injuries. Similarly, the patients with CAVI above age-predicted value should be evaluated for risk of falls for prevention of fall-related injuries.

Point your SmartPhone at the code above. If you have a QR code reader the video abstract will appear. Or use:

https://youtu.be/4G5FYK8dZWY

Clinical and Diffusion Tensor Imaging to Evaluate Falls, Balance and Gait Dysfunction in Leukoaraiosis: an Observational, Prospective Cohort Study

OBJECTIVE

To assess the correlation between leukoaraiosis (LA) and falls, to determine the risk factors for falls in patients with LA, and to detect specific white matter tracts are associated with the falls by using the diffusion tensor magnetic resonance imaging (DTI) screen.

METHODS

For the elderly patients with LA, we collected demographic information and scores for the Tinetti Balance and Gait Scale, Berg Balance Scale, Timed up-and-go test, and Cognitive, Emotional, Sleep-related Scale. All the patients underwent DTI scanning and were followed up for 1 year.

RESULTS

Ninety-four individuals were prospectively enrolled. After multivariable analyses, age, history of falls in the past year, antidepressants usage, and LA-Fazekas grade were reported to be risk factors for falls. In patients with severe LA, the fall incidence was higher than in those with mild LA. Tract-Based Spatial Statistics showed that fractional anisotropy values of the corpus callosum, cingulate gyrus, anterior limb of internal capsule, cerebral peduncle, anterior corona, and fronto-occipital fasciculus were significantly reduced in the patients who fell. The body of the corpus callosum and anterior corona radiate were significantly related to balance and gait function.

CONCLUSIONS

Our findings indicated that age, history of falls in the past year, antidepressants usage, and LA-Fazekas grade were risk factors for falls in elderly patients with LA. Leukoaraiosis was relevant for falls, but LA severity had a threshold effect with falls. The loss of integrity of some white matter tracts might influence balance and gait function. The DTI had preeminent clinical application prospects for identifying fall risk in patients with LA.

Association of Antidepressants With Recurrent, Injurious and Unexplained Falls is Not Explained by Reduced Gait Speed

OBJECTIVE

To examine if antidepressants at baseline are associated with falls and syncope over 4 years follow-up and if any observed associations are explained by baseline gait speed.

DESIGN

Longitudinal study (three waves).

SETTING

The Irish Longitudinal Study on Ageing (TILDA), a nationally representative cohort study.

PARTICIPANTS

Two thousand ninety-three community-dwelling adults aged ≥60 years.

MEASUREMENTS

Antidepressants (ATC code "N06A") were identified. Recurrent falls (≥2 falls), injurious falls (requiring medical attention), unexplained falls, and syncope were reported at either Wave 2 or 3. Usual gait speed was the mean of two walks on a 4.88 m GAITRite walkway. Poisson regression analysis was used to examine associations between baseline antidepressant use and future falls adjusting for sociodemographics, physical, cognitive and mental health, and finally, gait speed.

RESULTS

Compared to non-antidepressant users, those on antidepressants at baseline were more likely to report all types of falls (24.8-40.7% versus 9.8-18%) at follow-up. Antidepressants at baseline were independently associated with injurious falls (incidence risk ratio: 1.58, 95% confidence interval: 1.21, 2.06, z = 3.38, p = 0.001, df = 32) and unexplained falls (incidence risk ratio: 1.49, 95% confidence interval: 1.04, 2.15, z = 2.17, p = 0.030, df = 32) independent of all covariates including gait speed.

CONCLUSION

There was little evidence to support the hypothesis that gait would (partly) explain any observed associations between baseline use of antidepressants and future falls. The underlying mechanisms of the observed relationships may be related to depression, vascular pathology, or direct effects of antidepressants. Clinicians should identify the best treatment option for an individual based on existing risk factors for outcomes such as falls.

Prospective Associations Between Diffusion Tensor Imaging Parameters and Frailty in Older Adults

BACKGROUND

Cross-sectional associations have been found between frail individuals and worse white matter (WM) integrity. However, the prospective association between WM integrity and frailty is still unclear. Our objectives were to measure associations between WM integrity using diffusion tensor imaging (DTI) and the 5-year worsening of frailty in community-dwelling older adults.

DESIGN

Secondary analysis of the randomized controlled Multidomain Alzheimer Preventive Trial (MAPT).

SETTING

Thirteen memory centers in France and Monaco between 2008 and 2011.

PARTICIPANTS

Participants (mean age = 74.7 ± 3.9 years) with no dementia at baseline who had functional magnetic resonance imaging performed as part of the MAPT study (n = 227).

MEASUREMENTS

Fractional anisotropy and mean diffusivity (MD), axial diffusivity (AxD), and radial diffusivity (RD) were acquired for 10 different brain regions. Frailty was assessed by the Fried frailty phenotype (score from 0 to 5, higher is worse) at up to seven time points for 5 years. Mixed effect ordinal logistic regression model was used to assess the prospective association between DTI parameters (independent variables) and frailty (dependent variable). All the analyses were adjusted for age, sex, baseline total intracranial volume, and the presence of one of the following cardiovascular risk factors (hypertension, diabetes, and/or hypercholesterolemia).

RESULTS

A statistically significant association was found between the RD, AxD, and MD for different brain regions (anterior limb of internal capsule, external capsule, posterior corona radiata, posterior thalamic radiation, superior corona radiata, superior frontal occipital fasciculus, and superior longitudinal fasciculus) and worsening of frailty over 5 years after adjusting for multiple comparisons.

CONCLUSIONS

This is the first study to show that WM integrity is associated with frailty in older adults. The mechanisms related to these results require further investigation. J Am Geriatr Soc 68:1050-1055, 2020.

Gray Matter Regions Associated With Functional Mobility in Community-Dwelling Older Adults

BACKGROUND/OBJECTIVES

Neuroimaging indicators of reduced brain health in the form of lower gray matter volume (GMV), lower fractional anisotropy (FA), and higher white matter hyperintensity volume (WMHV) have been related to global mobility measures, such as gait speed, in older adults. The purpose was to identify associations between brain regions and specific mobility functions to provide a greater understanding of the contribution of the central nervous system to independent living.

DESIGN

Cross-sectional study.

SETTING

Research laboratory.

PARTICIPANTS

Seventy community-ambulating healthy older adults (mean age = 76 ± 5 years).

MEASUREMENTS

Participants performed the following tests: gait speed, Five Times Sit to Stand, Four Square Step Test (FSST), and Dynamic Gait Index (DGI). Structural magnetic resonance imaging of each participant's brain was collected. Measures of regional GMV, tract-specific WMHV, and FA were extracted. Correlational analyses between the mobility measures and neuroimaging measures were conducted using whole brain and regional and tract-specific measures. This was followed by linear regression models relating the mobility measures to regions or tracts identified in the correlation analysis, and adjusting for age, sex, and body mass index.

RESULTS

Significant associations were found between higher GMV in multiple regions, primarily the parietal and temporal lobes, and better performance in gait speed, DGI, and FSST. After adjusting for personal factors, greater parahippocampus GMV was independently associated with greater gait speed. Greater inferior parietal lobe, supramarginal gyrus, and superior temporal gyrus GMVs were associated with gait function. Greater postcentral gyrus, parahippocampus, and superior temporal gyrus GMVs were associated with faster FSST performance. The WMHV and FA were not significantly correlated with the mobility measures.

CONCLUSIONS

Gray matter regions associated with higher performance in mobility measures serving gait function and multidirectional stepping were those structures related to vestibular sensation, spatial navigation, and somatosensation. J Am Geriatr Soc 68:1023-1028, 2020.

Occurrence of Impaired Physical Performance in Memory Clinic Patients With Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) occurs often in memory clinic patients. Apart from cognitive deficits, these patients can express physical decline, which predicts adverse health outcomes. In this study, we investigated the cooccurrence of clinically relevant impairments in physical performance and CSVD in memory clinic patients. We included 131 patients with vascular brain injury, mild cognitive impairment or Alzheimer disease with available 3T MRI and physical performance scores. CSVD was visually rated according to 3 subtypes and as a total burden score, composed of the presence of white matter hyperintensities (WMH), lacunar infarcts (LI), and cerebral microbleeds (MB). Physical performance was assessed with the Short Physical Performance Battery (SPPB), covering gait speed, balance, and chair stand performance. CSVD markers and impaired physical performance both occurred often. High total CSVD burdens cooccurred with impaired chair stand performances [odds ratio (OR) 2.67; 95% confidence interval (CI) (1.12-6.34)]. WMH cooccurred with impaired SPPB scores (OR, 3.76; 95% CI, 1.68-8.44), impaired gait speeds (OR, 4.11; 95% CI, 1.81-9.31) and impaired chair stand performances (OR, 5.62; 95% CI, 2.29-13.80). In memory clinic patients, high burdens of CSVD, particularly WMH, often cooccur with impairments in physical performance. The presence of WMH should alert clinicians to the presence of these, clinically relevant, physical impairments.

Control of human gait stability through foot placement

During human walking, the centre of mass (CoM) is outside the base of support for most of the time, which poses a challenge to stabilizing the gait pattern. Nevertheless, most of us are able to walk without substantial problems. In this review, we aim to provide an integrative overview of how humans cope with an underactuated gait pattern. A central idea that emerges from the literature is that foot placement is crucial in maintaining a stable gait pattern. In this review, we explore this idea; we first describe mechanical models and concepts that have been used to predict how foot placement can be used to control gait stability. These concepts, such as for instance the extrapolated CoM concept, the foot placement estimator concept and the capture point concept, provide explicit predictions on where to place the foot relative to the body at each step, such that gait is stabilized. Next, we describe empirical findings on foot placement during human gait in unperturbed and perturbed conditions. We conclude that humans show behaviour that is largely in accordance with the aforementioned concepts, with foot placement being actively coordinated to body CoM kinematics during the preceding step. In this section, we also address the requirements for such control in terms of the sensory information and the motor strategies that can implement such control, as well as the parts of the central nervous system that may be involved. We show that visual, vestibular and proprioceptive information contribute to estimation of the state of the CoM. Foot placement is adjusted to variations in CoM state mainly by modulation of hip abductor muscle activity during the swing phase of gait, and this process appears to be under spinal and supraspinal, including cortical, control. We conclude with a description of how control of foot placement can be impaired in humans, using ageing as a primary example and with some reference to pathology, and we address alternative strategies available to stabilize gait, which include modulation of ankle moments in the stance leg and changes in body angular momentum, such as rapid trunk tilts. Finally, for future research, we believe that especially the integration of consideration of environmental constraints on foot placement with balance control deserves attention.