Total MRI load of cerebral small vessel disease and cognitive ability in older people

Retinal microvasculature changes in amyloid-negative subcortical vascular cognitive impairment compared to amyloid-positive Alzheimer's disease

BACKGROUND AND PURPOSE

To investigate small vessel abnormalities in patients with cognitive impairment, we compared retinal microvascular alterations between patients with cognitive impairment related to Alzheimer's disease (ADCI) and those with subcortical vascular cognitive impairment (SVCI).

METHODS

We prospectively recruited 29 amyloid-positive ADCI patients, 28 amyloid-negative SVCI patients that were confirmed by ¹¹C-PiB-PET scan and 34 individuals with normal cognition (NC). The three groups were compared in terms of retinal vascular variables (retinal fractal dimension, vascular caliber, tortuosity and branching angle) by using a semi-automated, computer-assisted analysis of digital fundus photographs. We also investigated the relationship between retinal variables and white matter hyperintensities (WMH) on MRI.

RESULTS

Compared to NC individuals, the SVCI patients had smaller total and arteriolar fractal dimensions, whereas there was no significant difference of fractal dimension between ADCI and NC. Other retinal variables did not differ among the three groups. A significant correlation existed between fractal dimension and WMH volume.

CONCLUSIONS

Retinal microvascular alterations, especially retinal fractal dimension, may be useful markers that reflect cerebral microvascular changes in patients with SVCI as opposed to ADCI, who had no definite difference in retinal variables compared to the NC group.

[Cognitive disorders in the middle-aged population and cerebrovascular risk factors]

AIM

To study the frequency of subjective and objective cognitive disorders in the middle-aged population and their associations with main and additional cerebrovascular risk factors.

MATERIAL AND METHODS

The authors examined 169 men and 239 women aged 40-59 years. Medical history study, blood tests, electrocardiography, brachiocephalic and common femoral arteries scan, echocardiography, magnetic resonance imaging of the brain (MRI) were performed. Luria and Munsterberg tests were done to assess cognitive dysfunction. Affective disorders were assessed by the Hospital scale of anxiety and depression.

RESULTS AND CONCLUSION

Absence of subjective (SCI) and/or objective (OCI) cognitive impairments was found in 26,5%; 10% had purely SCI, more than 35,7% of complaints were accompanied by deviations in neuropsychological test results (OCI+), over 25% had only OCI-. The average age of patients with OCI+ was higher than in the control group. In women, the frequency of SCI was twice as high and OCI less frequent as in men. Absence of cognitive impairment and SCI were observed more frequently in individuals with higher education. The prevalence of multiple white matter lesions (WML) in MRI was 36%. Multiple WML and atherosclerosis of major arteries were more common in OCI+ group (47%). Mild affective disorders were more frequent in the studied groups. Anxiety disorders were more common than depressive ones. The amount of patients with affective disorders was highest in OCI+. Therefore, SCI is a common phenomenon among people aged 40-60 years. The use of simple neuropsychological tests in screening examination allows to identify individuals who are most appropriate for active search for vascular risk factors. Anxiety and depressive disorders cause a significant proportion of SCI among middle-aged people and are an important additional target for therapeutic measures.

Small vessel disease and biomarkers of endothelial dysfunction after ischaemic stroke

Introduction

Although pathogenesis of small vessel disease is poorly understood, increasing evidence suggests that endothelial dysfunction may have a relevant role in development and progression of small vessel disease. In this cross-sectional study, we investigated the associations between imaging signs of small vessel disease and blood biomarkers of endothelial dysfunction at two different time points in a population of ischaemic stroke patients.

Patients and methods

In stroke patients treated with intravenous thrombolysis, we analysed blood levels of von Willebrand factor, intercellular adhesion molecule-1, vascular cell adhesion molecule-1 and vascular endothelial growth factor. Three reviewers independently assessed small vessel disease features using computed tomography. At baseline and 90 days after the index stroke, we tested the associations between single and combined small vessel disease features and levels of blood biomarkers using linear regression analysis adjusting for age, sex, hypertension, diabetes, smoke.

Results

A total of 263 patients were available for the analysis. Mean age (±SD) was 69 (±13) years, 154 (59%) patients were male. We did not find any relation between small vessel disease and endothelial dysfunction at baseline. At 90 days, leukoaraiosis was independently associated with intercellular adhesion molecule-1 (β = 0.21; p = 0.016) and vascular cell adhesion molecule-1 (β = 0.22; p = 0.009), and lacunes were associated with vascular endothelial growth factor levels (β = 0.21; p = 0.009) whereas global small vessel disease burden was associated with vascular endothelial growth factor (β = 0.26; p = 0.006).

Discussion

Leukoaraiosis and lacunes were associated with endothelial dysfunction, which could play a key role in pathogenesis of small vessel disease.

Conclusions

Small vessel disease features and total burden were associated with endothelial dysfunction 90 days after the stroke, whereas there was no relation during the acute phase. Our results suggest that endothelial dysfunction, particularly vascular endothelial growth factor, is involved in pathological process of small vessel disease.

MRI Lesion Load of Cerebral Small Vessel Disease and Cognitive Impairment in Patients With CADASIL

Background and objective: Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the best known and the most common monogenic small vessel disease (SVD). Cognitive impairment is an inevitable feature of CADASIL. Total SVD score and global cortical atrophy (GCA) scale were found to be good predictors of poor cognitive performance in community-dwelling adults. We aimed to estimate the association between the total SVD score, GCA scale and the cognitive performance in patients with CADASIL. Methods: We enrolled 20 genetically confirmed CADASIL patients and 20 controls matched by age, gender, and years of education. All participants underwent cognitive assessments to rate the global cognition and individual domain of executive function, information processing speed, memory, language, and visuospatial function. The total SVD score and GCA scale were rated. Results: The CADASIL group performed worse than the controls on all cognition measures. Neither global cognition nor any separate domain of cognition was significantly different among patients grouped by total SVD score. Negative correlations between the GCA score and cognitive performance were observed. Approximately 40% of the variance was explained by the total GCA score in the domains of executive function, information processing speed, and language. The superficial atrophy score was associated with poor performance in most of the domains of cognition. Adding the superficial atrophy score decreased the prediction power of the deep atrophy score on cognitive impairment alone. Conclusions: The GCA score, not the total SVD score, was significantly associated with poor cognitive performance in patients with CADASIL. Adding the superficial atrophy score attenuated the prediction power of the deep atrophy score on cognitive impairment alone.

Cerebral small vessel disease burden and functional and radiographic outcomes in intracerebral hemorrhage

OBJECTIVE

To examine the effect of individual cerebral small vessel disease (CSVD) markers and cumulative CSVD burden on functional independence, ambulation and hematoma expansion in spontaneous intracerebral hemorrhage (ICH).

METHODS

Retrospective analysis of prospectively collected data from an observational study of consecutive patients with spontaneous ICH, brain MRI within 1 month from ictus, premorbid modified Rankin Scale (mRS) score ≤ 2, available imaging data and 90-day functional status in a tertiary academic center. Functional outcomes included 90-day functional independence (mRS ≤ 2) and independent ambulation; radiographic outcome was hematoma expansion (> 12.5 ml absolute or > 33% relative increase in ICH volume). We identified the presence and burden of individual CSVD markers (cerebral microbleeds (CMBs), enlarged perivascular spaces, lacunes, white matter hyperintensities) and composite CSVD burden score and explored their association with outcomes of interest in multivariable models adjusting for well-established confounders.

RESULTS

111 patients were included, 65% lobar ICH, with a median volume 20.8 ml. 43 (38.7%) achieved functional independence and 71 (64%) independent ambulation. In multivariable adjusted models, there was higher total CSVD burden (OR 0.61, 95% CI 0.37-0.96, p = 0.03) and CMBs presence (OR 0.32, 95% CI 0.1-0.88, p = 0.04) remained independently inversely associated with functional independence. Individual CSVD markers or total CSVD score had no significant relation with ambulation and ICH expansion. Larger ICH volume and deep ICH location were the major determinants of lack of independent ambulation.

CONCLUSIONS

Our findings suggest that in ICH patients without previous functional dependence, total CSVD burden and particularly presence of CMBs significantly affect functional recovery. The latter is a novel finding and merits further exploration.

Genetic overlap between vascular pathologies and Alzheimer's dementia and potential causal mechanisms

INTRODUCTION

We sought to examine the genetic overlap between vascular pathologies and Alzheimer's disease (AD) dementia, and the potential mediating role of vascular pathologies between AD-related genetic variants and late-life cognition.

METHODS

For 2907 stroke-free older individuals, we examined the association of polygenic risk scores for AD dementia (ADPRSs) with vascular pathologies and with cognition. Mediation analyses addressed whether association between ADPRSs and cognition was mediated by a vascular pathology.

RESULTS

ADPRSs were associated with lobar cerebral microbleeds, white matter lesion load, and coronary artery calcification, mostly explained by single nucleotide polymorphisms in the 19q13 region. The effect of ADPRSs on cognition was partially but significantly mediated by cerebral microbleeds, white matter lesions, and coronary artery calcification.

DISCUSSION

Our findings provide evidence for genetic overlap, mostly due to apolipoprotein E (APOE) gene, between vascular pathologies and AD dementia. The association between AD polygenic risk and late-life cognition is mediated in part via effects on vascular pathologies.

MRI load of cerebral microvascular lesions and neurodegeneration, cognitive decline, and dementia

Objective

To explore the differential associations of neurodegeneration and microvascular lesion load with cognitive decline and dementia in older people and the modifying effect of the APOE genotype on these associations.

Methods

A sample of 436 participants (age ≥ 60 years) was derived from the population-based Swedish National study on Aging and Care in Kungsholmen, Stockholm, and clinically examined at baseline (2001–2003) and 3 occasions during the 9-year follow-up. At baseline, we assessed microvascular lesion load using a summary score for MRI markers of lacunes, white matter hyperintensities (WMHs), and perivascular spaces and neurodegeneration load for markers of enlarged ventricles, smaller hippocampus, and smaller gray matter. We assessed cognitive function using the Mini-Mental State Examination (MMSE) test and diagnosed dementia following the Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. We analyzed data using linear mixed-effects, mediation, and random-effects Cox models.

Results

During the follow-up, 46 participants were diagnosed with dementia. Per 1-point increase in microvascular lesion and neurodegeneration score (range 0–3) was associated with multiple adjusted β-coefficients of −0.35 (95% confidence interval, −0.51 to −0.20) and −0.44 (−0.56 to −0.32), respectively, for the MMSE score and multiple adjusted hazard ratios of 1.68 (1.12–2.51) and 2.35 (1.58–3.52), respectively, for dementia; carrying APOE ε4 reinforced the associations with MMSE decline. WMH volume changes during the follow-up mediated 66.9% and 12.7% of the total association of MMSE decline with the baseline microvascular score and neurodegeneration score, respectively.

Conclusions

Both cerebral microvascular lesion and neurodegeneration loads are strongly associated with cognitive decline and dementia. The cognitive decline due to microvascular lesions is exacerbated by APOE ε4 and is largely attributed to progression and development of microvascular lesions.

Understanding the role of the perivascular space in cerebral small vessel disease

Small vessel diseases (SVDs) are a group of disorders that result from pathological alteration of the small blood vessels in the brain, including the small arteries, capillaries and veins. Of the 35-36 million people that are estimated to suffer from dementia worldwide, up to 65% have an SVD component. Furthermore, SVD causes 20-25% of strokes, worsens outcome after stroke and is a leading cause of disability, cognitive impairment and poor mobility. Yet the underlying cause(s) of SVD are not fully understood. Magnetic resonance imaging has confirmed enlarged perivascular spaces (PVS) as a hallmark feature of SVD. In healthy tissue, these spaces are proposed to form part of a complex brain fluid drainage system which supports interstitial fluid exchange and may also facilitate clearance of waste products from the brain. The pathophysiological signature of PVS and what this infers about their function and interaction with cerebral microcirculation, plus subsequent downstream effects on lesion development in the brain has not been established. Here we discuss the potential of enlarged PVS to be a unique biomarker for SVD and related brain disorders with a vascular component. We propose that widening of PVS suggests presence of peri-vascular cell debris and other waste products that form part of a vicious cycle involving impaired cerebrovascular reactivity, blood-brain barrier dysfunction, perivascular inflammation and ultimately impaired clearance of waste proteins from the interstitial fluid space, leading to accumulation of toxins, hypoxia, and tissue damage. Here, we outline current knowledge, questions and hypotheses regarding understanding the brain fluid dynamics underpinning dementia and stroke through the common denominator of SVD.

Neuroimaging and neuropathology indices of cerebrovascular disease burden

Objective

To systematically review the literature on the use of both neuroimaging and neuropathologic indices of cerebrovascular disease (CVD) burden, as estimation of this burden could have multiple benefits in the diagnosis and prognosis of cognitive impairment and dementia.

Methods

MEDLINE and EMBASE databases were searched (inception to June 2017) to obtain and then systematically review all pertinent neuroimaging and neuropathology studies, where an index of CVD was developed or tested.

Results

Twenty-five neuroimaging articles were obtained, which included 4 unique indices. These utilized a limited range of CVD markers from mainly structural MRI, most commonly white matter hyperintensities (WMH), cerebral microbleeds, and dilated perivascular spaces. Weighting of the constituent markers was often coarse. There were 7 unique neuropathology indices, which were heterogeneous in their regions sampled and lesions examined.

Conclusion

There is increasing interest in indices of total CVD burden that incorporate multiple lesions, as traditional individual markers of CVD such as WMH only provide limited information. Neuropathologic indices are needed to validate neuroimaging findings. The studies clearly demonstrated proof of concept that information from multiple imaging measures of CVD provide more information, including a stronger association with cognitive impairment and dementia, than that provided by a single measure. There has been limited exploration of the psychometric properties of published indices and no comparison between indices. Further development of indices is recommended, including the use of data from diffusion tensor and perfusion imaging.

The cumulative effect of small vessel disease lesions is reflected in structural brain networks of memory clinic patients

Background and purpose

Mechanisms underlying cognitive impairment in patients with small vessel disease (SVD) are still unknown. We hypothesized that cognition is affected by the cumulative effect of multiple SVD-related lesions on brain connectivity. We therefore assessed the relationship between the total SVD burden on MRI, global brain network efficiency, and cognition in memory clinic patients with vascular brain injury.

Methods

173 patients from the memory clinic of the University Medical Center Utrecht underwent a 3 T brain MRI scan (including diffusion MRI sequences) and neuropsychological testing. MRI markers for SVD were rated and compiled in a previously developed total SVD score. Structural brain networks were reconstructed using fiber tractography followed by graph theoretical analysis. The relationship between total SVD burden score, global network efficiency and cognition was assessed using multiple linear regression analyses.

Results

Each point increase on the SVD burden score was associated with 0.260 [−0.404 - -0.117] SD units decrease of global brain network efficiency (p < .001). Global network efficiency was associated with information processing speed (standardized B = −0.210, p = .004) and attention and executive functioning (B = 0.164, p = .042), and mediated the relationship between SVD burden and information processing speed (p = .027) but not with executive functioning (p = .12).

Conclusion

Global network efficiency is sensitive to the cumulative effect of multiple manifestations of SVD on brain connectivity. Global network efficiency may therefore serve as a useful marker for functionally relevant SVD-related brain injury in clinical trials.

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Increasing small vessel disease burden (SVD) related to decreasing network efficiency.

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Network efficiency mediates association between SVD burden and processing speed.

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Cumulative effect of SVD might partly affect cognition through disrupted connectivity.

Association of Renal Dysfunction With Remote Diffusion-Weighted Imaging Lesions and Total Burden of Cerebral Small Vessel Disease in Patients With Primary Intracerebral Hemorrhage

Objective: Remote diffusion-weighted imaging (DWI) lesions (R-DWIL) found in intracerebral hemorrhage (ICH) patients are considered as an additional marker of cerebral small vessel disease (cSVD). This study aimed to investigate the association of renal dysfunction and R-DWIL, as well as the total burden of cSVD on magnetic resonance imaging among patients with primary ICH. Methods: One hundred and twenty-six consecutive patients were prospectively enrolled. R-DWIL on DWI, as well as other imaging markers of cSVD, including lacunes, white matter lesions, cerebral microbleeds, and enlarged perivascular spaces were rated using validated scales. Renal dysfunction was evaluated either by reduced estimated glomerular filtration rate (eGFR) or the presence of proteinuria or increased cystatin C. Results: After adjustments for potential confounders by logistic regression, impaired eGFR [odds ratio (OR) 6.00, 95% confidence interval (CI) 1.73-20.78], proteinuria (OR 3.07, 95% CI 1.25-7.54) and increased cystatin C (OR 2.73, 95% CI 1.11-6.72) were correlated with presence of R-DWIL. A similar association was also found between cystatin C levels (OR 3.16, 95% CI 1.39-7.19), proteinuria (OR 2.79, 95% CI 1.34-5.83) and the comprehensive cSVD burden. Conclusions: Renal dysfunction are associated with the presence of R-DWIL, and total burden of cSVD in patients with primary ICH.

Cerebral small vessel disease and the risk of dementia: A systematic review and meta-analysis of population-based evidence

INTRODUCTION

Cerebral small vessel disease is increasingly linked to dementia.

METHODS

We systematically searched Medline, Embase, and Cochrane databases for prospective population-based studies addressing associations of white matter hyperintensities, covert brain infarcts (i.e., clinically silent infarcts), and cerebral microbleeds with risk of all-dementia or Alzheimer's disease and performed meta-analyses.

RESULTS

We identified 11 studies on white matter hyperintensities, covert brain infarcts, or cerebral microbleeds with risk of all-dementia or Alzheimer's disease. Pooled analyses showed an association of white matter hyperintensity volume and a borderline association of covert brain infarcts with risk of all-dementia (hazard ratio: 1.39 [95% confidence interval: 1.00; 1.94], N = 3913, and 1.47 [95% confidence interval: 0.97; 2.22], N = 8296). Microbleeds were not statistically significantly associated with an increased risk of all-dementia (hazard ratio: 1.25 [95% confidence interval: 0.66; 2.38], N = 8739).

DISCUSSION

White matter hyperintensities are associated with an increased risk of all-dementia and Alzheimer's disease in the general population. However, studies are warranted to further determine the role of markers of cerebral small vessel disease in dementia.

The effect of the total small vessel disease burden on the structural brain network

Different cerebral small vessel disease (SVD) lesion types have been shown to disrupt structural brain network individually. Considering that they often coexist, we investigated the relation between their collective effect using the recently proposed total SVD score and structural brain network on MRI in 95 patients with first transient ischemic attack (TIA) or ischemic stroke. Fifty-nine patients with and 36 without any SVD lesions were included. The total SVD score was recorded. Diffusion tensor imaging was performed to estimate structural brain connections for subsequent brain connectivity analysis. The global efficiency and characteristic path length of the structural brain network are respectively lower and higher due to SVD. Lower nodal efficiency is also found in the insular, precuneus, supplementary motor area, paracentral lobule, putamen and hippocampus. The total SVD score is correlated with global network measures, the local clustering coefficient and nodal efficiency of hippocampus, and the nodal efficiency of paracentral lobule. We have successfully demonstrated that the disruption of global and local structural brain networks are associated with the increase in the overall SVD severity or burden of patients with TIA or first-time stroke.

The brain health index: Towards a combined measure of neurovascular and neurodegenerative structural brain injury

Background

A structural magnetic resonance imaging measure of combined neurovascular and neurodegenerative burden may be useful as these features often coexist in older people, stroke and dementia.

Aim

We aimed to develop a new automated approach for quantifying visible brain injury from small vessel disease and brain atrophy in a single measure, the brain health index.

Materials and methods

We computed brain health index in N = 288 participants using voxel-based Gaussian mixture model cluster analysis of T1, T2, T2*, and FLAIR magnetic resonance imaging. We tested brain health index against a validated total small vessel disease visual score and white matter hyperintensity volumes in two patient groups (minor stroke, N = 157; lupus, N = 51) and against measures of brain atrophy in healthy participants (N = 80) using multiple regression. We evaluated associations with Addenbrooke’s Cognitive Exam Revised in patients and with reaction time in healthy participants.

Results

The brain health index (standard beta = 0.20–0.59, P < 0.05) was significantly and more strongly associated with Addenbrooke’s Cognitive Exam Revised, including at one year follow-up, than white matter hyperintensity volume (standard beta = 0.04–0.08, P > 0.05) and small vessel disease score (standard beta = 0.02–0.27, P > 0.05) alone in both patient groups. Further, the brain health index (standard beta = 0.57–0.59, P < 0.05) was more strongly associated with reaction time than measures of brain atrophy alone (standard beta = 0.04–0.13, P > 0.05) in healthy participants.

Conclusions

The brain health index is a new image analysis approach that may usefully capture combined visible brain damage in large-scale studies of ageing, neurovascular and neurodegenerative disease.

Total cerebral small vessel disease score and cognitive performance in community-dwelling older adults. Results from the Atahualpa Project

OBJECTIVE

Cerebral small vessel disease (SVD) is inversely associated with cognitive performance. However, whether the total SVD score is a better predictor of poor cognitive performance than individual signatures of SVD is inconclusive. We aimed to estimate the combined and independent predictive power of these MRI findings.

METHODS

Atahualpa residents aged ≥60 years underwent brain MRI. Cognitive performance was measured by the Montreal Cognitive Assessment (MoCA). The presence of moderate-to-severe white matter hyperintensities, deep cerebral microbleeds, lacunar infarcts, and >10 enlarged perivascular spaces was added for estimating the total SVD score ranging from 0 to 4 points. Montreal Cognitive Assessment predictive models were fitted to assess how well the total SVD score or each of its components predicts cognitive performance.

RESULTS

Of 351 eligible candidates, 331 (94%) were included. The total SVD score was 0 points in 202 individuals (61%), 1 point in 67 (20%), 2 points in 40 (12%), 3 points in 15 (5%), and 4 points in seven (2%). A generalized lineal model showed an inverse relationship between the total SVD score and the MoCA (p = 0.015). The proportion of variance in the MoCA score explained by the SVD score was 32.8% (R²  = 0.328). This predictive power was similar for white matter hyperintensities (R²  = 0.306), microbleeds (R²  = 0.313), lacunar infarcts (R²  = 0.323), and perivascular spaces (R²  = 0.313).

CONCLUSIONS

This study shows a significant association between the SVD score and worse cognitive performance. The SVD score is a predictor of poor cognitive performance. This predictive power is not better than that of isolated neuroimaging signatures of SVD. Copyright © 2017 John Wiley & Sons, Ltd.

Total Small Vessel Disease Score in Neurologically Healthy Japanese Adults in the Kashima Scan Study

Objective We explored the association between the total small vessel disease (SVD) score obtained with magnetic resonance imaging and risk factors and outcomes in the Japanese population. Methods The presence of SVD features, including lacunes, cerebral microbleeds, white matter changes, and basal ganglia perivascular spaces on MRI, was summed to obtain a "total SVD score" (range 0-4). Ordinal and multinomial logistic regression analyses were performed to investigate the association of higher total SVD scores with vascular risk factors, the Mini-Mental State Examination (MMSE) score, and cerebral atrophy. Results We included 1,451 neurologically healthy adults (mean age, 57.1 years; 47% male). A multivariate ordinal logistic regression analysis showed that the total SVD score was associated with aging, hypertension, blood pressure (BP), diabetes mellitus, MMSE score, and deep cerebral atrophy, but the equal slopes assumption between scores did not hold. A multivariate multinomial logistic regression analysis (total SVD score 0=reference) showed that aging, hypertension, and BP were positively associated with scores of 1, 2, or ≥3. These effects, presented as odds ratios (ORs), increased as the score increased and were strongest with a score of ≥3 [aging (per 10-year increment), OR 4.00, 95% confidence interval (CI) 2.47-6.46; hypertension, OR 5.68, 95% CI 2.52-12.80; systolic BP (per standard deviation increase), OR 1.96, 95% CI 1.41-2.74, respectively]. Diabetes mellitus and deep cerebral atrophy tended to be associated with the SVD scores. The MMSE score showed no consistent associations. Conclusion The total SVD score may be a promising tool for indexing SVD, even in the Japanese population.

Healthy cognitive ageing in the Lothian Birth Cohort studies: marginal gains not magic bullet

In the face of shifting demographics and an increase in human longevity, it is important to examine carefully what is known about cognitive ageing, and to identify and promote possibly malleable lifestyle and health-related factors that might mitigate age-associated cognitive decline. The Lothian Birth Cohorts of 1921 (LBC1921, n = 550) and 1936 (LBC1936, n = 1091) are longitudinal studies of cognitive and brain ageing based in Scotland. Childhood IQ data are available for these participants, who were recruited in later life and then followed up regularly. This overview summarises some of the main LBC findings to date, illustrating the possible genetic and environmental contributions to cognitive function (level and change) and brain imaging biomarkers in later life. Key associations include genetic variation, health and fitness, psychosocial and lifestyle factors, and aspects of the brain's structure. It addresses some key methodological issues such as confounding by early-life intelligence and social factors and emphasises areas requiring further investigation. Overall, the findings that have emerged from the LBC studies highlight that there are multiple correlates of cognitive ability level in later life, many of which have small effects, that there are as yet few reliable predictors of cognitive change, and that not all of the correlates have independent additive associations. The concept of marginal gains, whereby there might be a cumulative effect of small incremental improvements across a wide range of lifestyle and health-related factors, may offer a useful way to think about and promote a multivariate recipe for healthy cognitive and brain ageing.

Cognitive Impairment Before Intracerebral Hemorrhage Is Associated With Cerebral Amyloid Angiopathy

Supplemental Digital Content is available in the text.

Background and Purpose—

Although the association between cerebral amyloid angiopathy (CAA) and cognitive impairment is increasingly recognized, it is not clear whether this is because of the impact of recurrent intracerebral hemorrhage (ICH) events, disruptions caused by cerebral small vessel damage, or both. We investigated this by considering whether cognitive impairment before ICH was associated with neuroimaging features of CAA on magnetic resonance imaging.

Methods—

We studied 166 patients with neuroimaging-confirmed ICH recruited to a prospective multicentre observational study. Preexisting cognitive impairment was determined using the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE). Magnetic resonance imaging markers of cerebral small vessel disease, including CAA, were rated by trained observers according to consensus guidelines.

Results—

The prevalence of cognitive impairment before ICH was 24.7% (n=41) and, in adjusted analyses, was associated with fulfilling the modified Boston criteria for probable CAA at presentation (odds ratio, 4.01; 95% confidence interval, 1.53–10.51; P=0.005) and a higher composite CAA score (for each point increase, odds ratio, 1.42; 95% confidence interval, 1.03–1.97; P=0.033). We also found independent associations between pre-ICH cognitive decline and the presence of cortical superficial siderosis, strictly lobar microbleeds, and lobar ICH location, but not with other neuroimaging markers, or a composite small vessel disease score.

Conclusions—

CAA (defined using magnetic resonance imaging markers) is associated with cognitive decline before symptomatic ICH. This provides evidence that small vessel disruption in CAA makes an independent contribution to cognitive impairment, in addition to effects due to brain injury caused directly by ICH.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov. Unique identifier: NCT02513316.

Early life characteristics and late life burden of cerebral small vessel disease in the Lothian Birth Cohort 1936

It is unknown whether relations between early-life factors and overall health in later life apply to burden of cerebral small vessel disease (cSVD), a major cause of stroke and dementia. We explored relations between early-life factors and cSVD in the Lothian Birth Cohort, a healthy aging cohort. Participants were recruited at age 70 (N = 1091); most had completed a test of cognitive ability at age 11 as part of the Scottish Mental Survey of 1947. Of those, 700 participants had brain MRI that could be rated for cSVD conducted at age 73. Presence of lacunes, white matter hyperintensities, microbleeds, and perivascular spaces were summed in a score of 0-4 representing all MRI cSVD features. We tested associations with early-life factors using multivariate logistic regression. Greater SVD score was significantly associated with lower age-11 IQ (OR higher SVD score per SD age-11 IQ = .78, 95%CI 0.65-.95, p=.01). The associations between SVD score and own job class (OR higher job class, .64 95%CI .43-.95, p=.03), age-11 deprivation index (OR per point deprivation score, 1.08, 95%CI 1.00-1.17, p=.04), and education (OR some qualifying education, .60 95%CI .37-.98, p=.04) trended towards significance (p<.05 for all) but did not meet thresholds for multiple testing. No early-life factor was significantly associated with any one individual score component. Early-life factors may contribute to age-73 burden of cSVD. These relations, and the potential for early social interventions to improve brain health, deserve further study.

Blood-brain barrier leakage increases with small vessel disease in acute ischemic stroke

OBJECTIVE

In patients with acute ischemic stroke, we aimed to investigate the relation between preexisting small vessel disease (SVD) and the amount of blood-brain barrier (BBB) leakage in ischemic and nonischemic area before IV thrombolysis.

METHODS

We retrospectively accessed anonymous patient-level data from the Stroke Imaging Repository and the Virtual International Stroke Trials Archive resources and included patients treated with IV thrombolysis with pretreatment MRI. We rated SVD features using validated qualitative magnetic resonance (MR) scales. Leakage of BBB was assessed with postprocessing of perfusion-weighted images. We evaluated associations between SVD features (individually and summed in a global SVD score) and BBB leakage using linear regression analysis, adjusting for major clinical confounders.

RESULTS

A total of 212 patients, mean age (±SD) 69.5 years (±16.1), 102 (48%) male, had available MR before IV thrombolysis. Evidence of BBB leakage was present in 175 (80%) and 205 (94%) patients in the ischemic and nonischemic area, respectively. Lacunar infarcts (β = 0.17, p = 0.042) were associated with BBB leakage in the ischemic area, and brain atrophy was associated with BBB leakage in both ischemic (β = 0.20, p = 0.026) and nonischemic (β = 0.27, p = 0.001) areas. Increasing SVD grade was independently associated with BBB leakage in both ischemic (β = 0.26, p = 0.007) and nonischemic (β = 0.27, p = 0.003) area.

CONCLUSIONS

Global SVD burden is associated with increased BBB leakage in both acutely ischemic and nonischemic area. Our results support that SVD score has construct validity, and confirm a relation between SVD and BBB disruption also in patients with acute stroke.

Increased level of procalcitonin is associated with total MRI burden of cerebral small vessel disease in patients with ischemic stroke

BACKGROUND

Procalcitonin (PCT) has been found to be associated with subclinical cerebrovascular damage. The relationship between PCT levels and cerebral small vessel disease (cSVD), especially cSVD burden, has not been fully understood. This study aimed to investigate the association between PCT levels and cSVD in patients with first-ever acute ischemic stroke or transient ischemic attack (TIA).

METHODS

Two hundred and seventy-eight consecutive patients were prospectively recruited during Jan 2016 to Jun 2017. Serum PCT concentrations measurement was performed after admission. The presence and burden of cSVD was determined by magnetic resonance imaging (MRI). Multivariable logistic regression was used to assess whether serum PCT levels were associated with cSVD.

RESULTS

The median PCT level was 0.042μg/L (interquartile range, 0.025-0.065μg/L). Univariable logistic regression analysis indicated that patients with PCT level in the top quartile, compared with the lowest quartile, were more likely to have silent lacunar infarctions [odds ratio (OR), 2.266; 95% confidence interval (CI) 1.131-4.538, P=0.021], white matter lesions (OR, 1.793; 95% CI 1.029-3.574, P=0.047), high-grade enlarged perivascular spaces (OR, 8.061; 95% CI 3.599-14.055, P=0.001) and increased total MRI cSVD burden (OR, 3.743; 95% CI 1.998-7.008, P=0.002). These results persisted even after adjusting for potential confounders.

CONCLUSIONS

This study demonstrated that elevated PCT levels might be associated with total MRI cSVD burden in patients with ischemic stroke or TIA.

The relation between total cerebral small vessel disease burden and gait impairment in patients with minor stroke

Background and aims Individual MRI markers of cerebral small vessel disease are associated with gait impairment. The impact of total cerebral small vessel disease-related brain damage, expressed by a cerebral small vessel disease MRI burden score, on mobility after stroke, has not been considered, although this score gives a better representation of the overall effect of cerebral small vessel disease on the brain. We determined if the total cerebral small vessel disease burden is associated with gait impairment three years after minor stroke. Methods In total, 200 patients with minor lacunar or non-lacunar stroke (NIHSS ≤ 7) underwent a brain MRI at presentation. Presence of lacunes, white matter hyperintensities, cerebral microbleeds, and perivascular spaces were summed in a total cerebral small vessel disease MRI burden score (range 0-4). Gait disturbances, measured by timed-up-and-go test and self-reported stroke impact scale mobility domain were assessed three years after stroke. We tested associations adjusted for key variables by linear regression analysis. Results Total cerebral small vessel disease burden was not associated with gait impairment after minor stroke in all patients, nor in lacunar stroke patients ( n = 87). In non-lacunar stroke patients ( n = 113), total cerebral small vessel disease burden was associated with lower stroke impact scale mobility domain scores, independent of age, vascular risk factors, and stroke severity (unstandardized B -4.61; 95% CI -8.42; -0.79, p < 0.05). Conclusion Patients with non-lacunar stroke and a higher total cerebral small vessel disease burden have more subjective mobility impairment three years after stroke. The total cerebral small vessel disease MRI burden score is a possible marker to identify patients at risk for subjective gait impairment. These findings should be confirmed in larger studies.

Total small vessel disease burden and brain network efficiency in cerebral amyloid angiopathy

BACKGROUND

Cerebral amyloid angiopathy (CAA) is associated with hemorrhagic and nonhemorrhagic markers small vessel disease (SVD). A composite score to quantify the total burden of SVD on MRI specifically for CAA patients was recently developed. Brain network alterations related to individual MRI markers of SVD in CAA were demonstrated.

OBJECTIVES

Considering diffusion based network measures sensitive to detect different relevant SVD-related brain injury, we investigated if increased overall SVD injury on MRI corresponds to worse global brain connectivity in CAA.

METHODS

Seventy-three patients (79.5% male, mean age 70.58±8.22years) with a diagnosis CAA were considered. SVD markers in total MRI SVD score included: lobar cerebral microbleeds, cortical superficial siderosis (cSS), white matter hyperintensities (WMH) and centrum semiovale-enlarged perivascular spaces. Diffusion imaging based network reconstruction was made. The associations between total MRI SVD score and global network efficiency (GNE) were analyzed.

RESULTS

A modest significant inverse correlation between total MRI SVD score and GNE existed (p=0.013; R²=0.07). GNE was related with the presence of cSS and moderate-severe WMHs.

CONCLUSIONS

An increased burden of SVD neuroimaging markers corresponds to more reductions in global brain connectivity, implying a possible cumulative effect of overall SVD markers on disrupted physiology. GNE was related with some components of the score, specifically cSS and moderate-severe WMHs.

Small Vessel Disease and Dietary Salt Intake: Cross-Sectional Study and Systematic Review

BACKGROUND

Higher dietary salt intake increases the risk of stroke and may increase white matter hyperintensity (WMH) volume. We hypothesized that a long-term higher salt intake may be associated with other features of small vessel disease (SVD).

METHODS

We recruited consecutive patients with mild stroke presenting to the Lothian regional stroke service. We performed brain magnetic resonance imaging, obtained a basic dietary salt history, and measured the urinary sodium/creatinine ratio. We also carried out a systematic review to put the study in the context of other studies in the field.

RESULTS

We recruited 250 patients, 112 with lacunar stroke and 138 with cortical stroke, with a median age of 67.5 years. After adjustment for risk factors, including age and hypertension, patients who had not reduced their salt intake in the long term were more likely to have lacunar stroke (odds ratio [OR], 1.90; 95% confidence interval [CI], 1.10-3.29), lacune(s) (OR, 2.06; 95% CI, 1.09-3.99), microbleed(s) (OR, 3.4; 95% CI, 1.54, 8.21), severe WMHs (OR, 2.45; 95% CI 1.34-4.57), and worse SVD scores (OR, 2.17; 95% CI, 1.22-3.9). There was limited association between SVD and current salt intake or urinary sodium/creatinine ratio. Our systematic review found no previously published studies of dietary salt and SVD.

CONCLUSION

The association between dietary salt and background SVD is a promising indication of a potential neglected contributory factor for SVD. These results should be replicated in larger, long-term studies using the recognized gold-standard measures of dietary sodium.

Diffusion tensor image segmentation of the cerebrum provides a single measure of cerebral small vessel disease severity related to cognitive change

Cerebral small vessel disease (SVD) is the primary cause of vascular cognitive impairment and is associated with decline in executive function (EF) and information processing speed (IPS). Imaging biomarkers are needed that can monitor and identify individuals at risk of severe cognitive decline. Recently there has been interest in combining several magnetic resonance imaging (MRI) markers of SVD into a unitary score to describe disease severity. Here we apply a diffusion tensor image (DTI) segmentation technique (DSEG) to describe SVD related changes in a single unitary score across the whole cerebrum, to investigate its relationship with cognitive change over a three-year period. 98 patients (aged 43-89) with SVD underwent annual MRI scanning and cognitive testing for up to three years. DSEG provides a vector of 16 discrete segments describing brain microstructure of healthy and/or damaged tissue. By calculating the scalar product of each DSEG vector in reference to that of a healthy ageing control we generate an angular measure (DSEG θ) describing the patients' brain tissue microstructural similarity to a disease free model of a healthy ageing brain. Conventional MRI markers of SVD brain change were also assessed including white matter hyperintensities, cerebral atrophy, incident lacunes, cerebral-microbleeds, and white matter microstructural damage measured by DTI histogram parameters. The impact of brain change on cognition was explored using linear mixed-effects models. Post-hoc sample size analysis was used to assess the viability of DSEG θ as a tool for clinical trials. Changes in brain structure described by DSEG θ were related to change in EF and IPS (p < 0.001) and remained significant in multivariate models including other MRI markers of SVD as well as age, gender and premorbid IQ. Of the conventional markers, presence of new lacunes was the only marker to remain a significant predictor of change in EF and IPS in the multivariate models (p = 0.002). Change in DSEG θ was also related to change in all other MRI markers (p < 0.017), suggesting it may be used as a surrogate marker of SVD damage across the cerebrum. Sample size estimates indicated that fewer patients would be required to detect treatment effects using DSEG θ compared to conventional MRI and DTI markers of SVD severity. DSEG θ is a powerful tool for characterising subtle brain change in SVD that has a negative impact on cognition and remains a significant predictor of cognitive change when other MRI markers of brain change are accounted for. DSEG provides an automatic segmentation of the whole cerebrum that is sensitive to a range of SVD related structural changes and successfully predicts cognitive change. Power analysis shows DSEG θ has potential as a monitoring tool in clinical trials. As such it may provide a marker of SVD severity from a single imaging modality (i.e. DTIs).

Small vessel disease and clinical outcomes after IV rt-PA treatment

INTRODUCTION

Cerebral small vessel disease (SVD) contributes to dementia and disability in the elderly, and may negatively affect stroke outcomes. We aimed to evaluate to what extent single features and global burden of SVD detected with magnetic resonance (MR) are associated with worse outcomes in patients with ischaemic stroke treated with intravenous thrombolysis.

METHODS

We accessed anonymized data and MR images from the Stroke Imaging Repository (STIR) and the Virtual International Stroke Trials Archive (VISTA) Imaging. We described SVD features using validated scales and quantified the global burden of SVD with a combined score. Our mainoutcome was the modified Rankin Scale (mRS) at 90 days after stroke. We used logistic regression and ordinal regression models (adjusted for age, sex, stroke severity, onset to treatment time) to examine the associations between each SVD feature, SVD global burden and clinical outcomes.

RESULTS

A total of 259 patients had MR scans available at baseline (mean age±SD=68.7±15.5 years; 131 [49%] males). After adjustment for confounders, severe white matter changes were associated with disability (OR=5.14; 95%CI=2.30-11.48), functional dependency (OR=4.38; 95%CI=2.10-9.13) and worse outcomes in ordinal analysis (OR=2.71; 95%CI=1.25-5.85). SVD score was associated with disability (OR=1.66; 95%CI=1.03-2.66) and functional dependency (OR=1.47; 95%CI=1.00-2.45). Lacunes, enlarged perivascular spaces and brain atrophy showed no association with clinical outcomes.

CONCLUSION

Our results suggest that SVD negatively affects stroke outcomes after intravenous thrombolysis. Although white matter changes seem to be the major driver in relation to worse outcomes, global estimation of SVD is feasible and may provide helpful information.

Reliability of an automatic classifier for brain enlarged perivascular spaces burden and comparison with human performance

In the brain, enlarged perivascular spaces (PVS) relate to cerebral small vessel disease (SVD), poor cognition, inflammation and hypertension. We propose a fully automatic scheme that uses a support vector machine (SVM) to classify the burden of PVS in the basal ganglia (BG) region as low or high. We assess the performance of three different types of descriptors extracted from the BG region in T2-weighted MRI images: (i) statistics obtained from Wavelet transform's coefficients, (ii) local binary patterns and (iii) bag of visual words (BoW) based descriptors characterizing local keypoints obtained from a dense grid with the scale-invariant feature transform (SIFT) characteristics. When the latter were used, the SVM classifier achieved the best accuracy (81.16%). The output from the classifier using the BoW descriptors was compared with visual ratings done by an experienced neuroradiologist (Observer 1) and by a trained image analyst (Observer 2). The agreement and cross-correlation between the classifier and Observer 2 (κ = 0.67 (0.58-0.76)) were slightly higher than between the classifier and Observer 1 (κ = 0.62 (0.53-0.72)) and comparable between both the observers (κ = 0.68 (0.61-0.75)). Finally, three logistic regression models using clinical variables as independent variable and each of the PVS ratings as dependent variable were built to assess how clinically meaningful were the predictions of the classifier. The goodness-of-fit of the model for the classifier was good (area under the curve (AUC) values: 0.93 (model 1), 0.90 (model 2) and 0.92 (model 3)) and slightly better (i.e. AUC values: 0.02 units higher) than that of the model for Observer 2. These results suggest that, although it can be improved, an automatic classifier to assess PVS burden from brain MRI can provide clinically meaningful results close to those from a trained observer.

Advanced Neuroimaging of Cerebral Small Vessel Disease

Cerebral small vessel disease (SVD) is characterised by damage to deep grey and white matter structures of the brain and is responsible for a diverse range of clinical problems that include stroke and dementia. In this review, we describe advances in neuroimaging published since January 2015, mainly with magnetic resonance imaging (MRI), that, in general, are improving quantification, observation and investigation of SVD focussing on three areas: quantifying the total SVD burden, imaging brain microstructural integrity and imaging vascular malfunction. Methods to capture ‘whole brain SVD burden’ across the spectrum of SVD imaging changes will be useful for patient stratification in clinical trials, an approach that we are already testing. More sophisticated imaging measures of SVD microstructural damage are allowing the disease to be studied at earlier stages, will help identify specific factors that are important in development of overt SVD imaging features and in understanding why specific clinical consequences may occur. Imaging vascular function will help establish the precise blood vessel and blood flow alterations at early disease stages and, together with microstructural integrity measures, may provide important surrogate endpoints in clinical trials testing new interventions. Better knowledge of SVD pathophysiology will help identify new treatment targets, improve patient stratification and may in future increase efficiency of clinical trials through smaller sample sizes or shorter follow-up periods. However, most of these methods are not yet sufficiently mature to use with confidence in clinical trials, although rapid advances in the field suggest that reliable quantification of SVD lesion burden, tissue microstructural integrity and vascular dysfunction are imminent.

Total small vessel disease score and risk of recurrent stroke: Validation in 2 large cohorts

Objective:

In patients with TIA and ischemic stroke, we validated the total small vessel disease (SVD) score by determining its prognostic value for recurrent stroke.

Methods:

Two independent prospective studies were conducted, one comprising predominantly Caucasian patients with TIA/ischemic stroke (Oxford Vascular Study [OXVASC]) and one predominantly Chinese patients with ischemic stroke (University of Hong Kong [HKU]). Cerebral MRI was performed and assessed for lacunes, microbleeds, white matter hyperintensities (WMH), and perivascular spaces (PVS). Predictive value of total SVD score for risk of recurrent stroke was determined and potential refinements considered.

Results:

In 2,002 patients with TIA/ischemic stroke (OXVASC n = 1,028, HKU n = 974, 6,924 patient-years follow-up), a higher score was associated with an increased risk of recurrent ischemic stroke (adjusted hazard ratio [HR] per unit increase: 1.32, 1.16–1.51, p < 0.0001; c statistic 0.61, 0.56–0.65, p < 0.0001) and intracerebral hemorrhage (ICH) (HR 1.54, 1.11–2.13, p = 0.009; c statistic 0.65, 0.54–0.76, p = 0.006). A higher score predicted recurrent stroke in SVD and non-SVD TIA/ischemic stroke subtypes (c statistic 0.67, 0.59–0.74, p < 0.0001 and 0.60, 0.55–0.65, p < 0.0001). Including burden of microbleeds and WMH and adjusting the cutoff of basal ganglia PVS potentially improved predictive power for ICH (c statistic 0.71, 0.60–0.81, p_het = 0.45), but not for recurrent ischemic stroke (c statistic 0.60, 0.56–0.65, p_het = 0.76) on internal validation.

Conclusions:

The total SVD score has predictive value for recurrent stroke after TIA/ischemic stroke. Prediction of recurrence in patients with nonlacunar events highlights the potential role of SVD in wider stroke etiology.

Deep microbleeds and periventricular white matter disintegrity are independent predictors of attention/executive dysfunction in non-dementia patients with small vessel disease

BACKGROUND

Cerebral small vessel disease (SVD) is the common cause of cognitive decline in the old population. MRI can be used to clarify its mechanisms. However, the surrogate markers of MRI for early cognitive impairment in SVD remain uncertain to date. We investigated the cognitive impacts of cerebral microbleeds (CMBs), diffusion tensor imaging (DTI), and brain volumetric measurements in a cohort of post-stroke non-dementia SVD patients.

METHODS

Fifty five non-dementia SVD patients were consecutively recruited and categorized into two groups as no cognitive impairment (NCI) (n = 23) or vascular mild cognitive impairment (VaMCI) (n = 32). Detailed neuropsychological assessment and multimodal MRI were completed.

RESULTS

The two groups differed significantly on Z scores of all cognitive domains (all p < 0.01) except for the language. There were more patients with hypertension (p = 0.038) or depression (p = 0.019) in the VaMCI than those in the NCI group. Multiple regression analysis of cognition showed periventricular mean diffusivity (MD) (β = -0.457, p < 0.01) and deep CMBs numbers (β = -0.352, p < 0.01) as the predictors of attention/executive function, which explained 45.2% of the total variance. Periventricular MD was the independent predictor for either memory (β = -0.314, p < 0.05) or visuo-spatial function (β = -0.375, p < 0.01); however, only small proportion of variance could be accounted for (9.8% and 12.4%, respectively). Language was not found to be correlated with any of the MRI parameters. No correlation was found between brain atrophic indices and any of the cognitive measures.

CONCLUSION

Arteriosclerotic CMBs and periventricular white matter disintegrity seem to be independent MRI surrogated markers in the early stage of cognitive impairment in SVD.

The Disconnected Brain and Executive Function Decline in Aging

Higher order speeded cognitive abilities depend on efficient coordination of activity across the brain, rendering them vulnerable to age reductions in structural and functional brain connectivity. The concept of "disconnected aging" has been invoked, suggesting that degeneration of connections between distant brain regions cause cognitive reductions. However, it has not been shown that changes in cognitive functions over time can be explained by simultaneous changes in brain connectivity. We followed 119 young and middle-aged (23-52 years) and older (63-86 years) adults for 3.3 years with repeated assessments of structural and functional brain connectivity and executive functions. We found unique age-related longitudinal reductions in executive function over and above changes in more basic cognitive processes. Intriguingly, 82.5% of the age-related decline in executive function could be explained by changes in connectivity over time. While both structural and functional connectivity changes were related to longitudinal reductions in executive function, only structural connectivity change could explain the age-specific decline. This suggests that the major part of the age-related reductions in executive function can be attributed to micro- and macrostructural alterations in brain connectivity. Although correlational in nature, we believe the present results constitute evidence for a "disconnected brain" view on cognitive aging.

Age-related small vessel disease: a potential contributor to neurodegeneration in multiple sclerosis

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disorder of the central nervous system wherein, after an initial phase of transient neurological defects, slow neurological deterioration due to progressive neuronal loss ensues. Age is a major determinant of MS progression onset and disability. Over the past years, several mechanisms have been proposed to explain the key drivers of neurodegeneration and disability accumulation in MS. However, the effect of commonly encountered age-related cerebral vessel disease, namely small vessel disease (SVD), has been largely neglected and constitutes the aim of this review. SVD shares some features with MS, that is, white matter demyelination and brain atrophy, and has been shown to contribute to the neuronal damage seen in vascular cognitive impairment. Several lines of evidence suggest that an interaction between MS and SVD may influence MS-related neurodegeneration. SVD may contribute to hypoperfusion, reduced vascular reactivity and tissue hypoxia, features seen in MS. Venule and endothelium abnormalities have been documented in MS but the role of arterioles and of other neurovascular unit structures, such as the pericyte, has not been explored. Vascular risk factors (VRF) have recently been associated with faster progression in MS, though the mechanisms are unclear since very few studies have addressed the impact of VRF and SVD on MS imaging and pathology outcomes. Therapeutic agents targeting the microvasculature and the neurovascular unit may impact both SVD and MS and may benefit patients with dual pathology.

Valdés Hernández M, Royle NA, Corley J, Muñoz Maniega S, Pattie A, Dickie DA, Staals J, Gow AJ, Starr JM, Deary IJ, Enzinger C, Fazekas F, Wardlaw J. Impact of small vessel disease in the brain on gait and balance

Gait and balance impairment is highly prevalent in older people. We aimed to assess whether and how single markers of small vessel disease (SVD) or a combination thereof explain gait and balance function in the elderly. We analysed 678 community-dwelling healthy subjects from the Lothian Birth Cohort 1936 at the age of 71-74 years who had undergone comprehensive risk factor assessment, gait and balance assessment as well as brain MRI. We investigated the impact of individual SVD markers (white matter hyperintensity - WMH, microbleeds, lacunes, enlarged perivascular spaces, brain atrophy) as seen on structural brain MRI and of a global SVD score on the patients' performance. A regression model revealed that age, sex, and hypertension significantly explained gait speed. Among SVD markers white matter hyperintensity (WMH) score or volume were additional significant and independent predictors of gait speed in the regression model. A similar association was seen with the global SVD score. Our study confirms a negative impact of SVD-related morphologic brain changes on gait speed in addition to age, sex and hypertension independent from brain atrophy. The presence of WMH seems to be the major driving force for SVD on gait impairment in healthy elderly subjects.

What is the relationship between type 2 diabetes mellitus status and the neuroradiological correlates of cerebral small vessel disease in adults? Protocol for a systematic review

BACKGROUND

Cerebral small vessel disease (CSVD) is a common cause of stroke, dementia, and functional decline. In recent years, neuroradiologic correlates of CSVD have been identified. These imaging findings, best characterized on magnetic resonance imaging (MRI), include some combination of white matter hyperintensities, lacunes, cerebral microbleeds, enlarged perivascular spaces, and cerebral atrophy. Though some cohorts have reported that participants with type 2 diabetes mellitus (T2DM), an important risk factor for CSVD, may have a distinct neuroradiologic phenotype, this relationship is not well-characterized. Adults with diabetes mellitus have a two- to threefold higher incidence of ischemic stroke compared to controls and are an increasingly important population given global trends of increasing diabetes prevalence. This study aims to determine if adults with CSVD and T2DM have a distinct neuroradiologic phenotype.

METHODS

A systematic search of the literature will be conducted to find articles that report the MRI features of CSVD in a cohort of participants including those with and without type 2 diabetes mellitus (T2DM). A number of databases will be searched including MEDLINE, Embase, CINAHL, and Web of Science. Proceedings and abstracts from key conferences will also be reviewed and relevant journals hand searched for additional papers. The references from selected papers will be scanned. Screening of potential articles, data extraction, and quality appraisal will be performed in duplicate by independent reviewers. Odds ratios and 95% confidence intervals for the presence versus absence of each neuroradiologic correlate of interest from each included study will be calculated. If sufficient homogeneity exists among studies, a meta-analysis will be performed for each neuroradiologic correlate of CSVD. If heterogeneity of studies precludes data pooling, results will be presented in narrative form.

DISCUSSION

Determining whether a distinct neuroradiologic phenotype of CSVD exists in adults with T2DM will provide insight into the underlying mechanisms of CSVD and guide future research on therapeutic targets.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42016046669.

Total Cerebral Small Vessel Disease MRI Score Is Associated with Cognitive Decline in Executive Function in Patients with Hypertension

Objectives: Hypertension is a major risk factor for white matter hyperintensities (WMH), lacunes, cerebral microbleeds, and perivascular spaces, which are MRI markers of cerebral small vessel disease (SVD). Studies have shown associations between these individual MRI markers and cognitive functioning and decline. Recently, a “total SVD score” was proposed in which the different MRI markers were combined into one measure of SVD, to capture total SVD-related brain damage. We investigated if this SVD score was associated with cognitive decline over 4 years in patients with hypertension.

Methods: In this longitudinal cohort study, 130 hypertensive patients (91 patients with uncomplicated hypertension and 39 hypertensive patients with a lacunar stroke) were included. They underwent a neuropsychological assessment at baseline and after 4 years. The presence of WMH, lacunes, cerebral microbleeds, and perivascular spaces were rated on baseline MRI. Presence of each individual marker was added to calculate the total SVD score (range 0–4) in each patient.

Results: Uncorrected linear regression analyses showed associations between SVD score and decline in overall cognition (p = 0.017), executive functioning (p < 0.001) and information processing speed (p = 0.037), but not with memory (p = 0.911). The association between SVD score and decline in overall cognition and executive function remained significant after adjustment for age, sex, education, anxiety and depression score, potential vascular risk factors, patient group, and baseline cognitive performance.

Conclusion: Our study shows that a total SVD score can predict cognitive decline, specifically in executive function, over 4 years in hypertensive patients. This emphasizes the importance of considering total brain damage due to SVD.

"Cerebral Small Vessel Disease in subclinical and clinical stages, role of inflammation for risk prediction and potential treatment targets, and management strategies"

Stroke and dementia are the most common neurological disorders worldwide. Cerebrovascular disease, particularly cerebral small vessel disease (CSVD) is implicated in both, and the two main types of CSVD (hypertensive vasculopathy and cerebral amyloid angiopathy) account for the majority of cerebrovascular contributions to stroke and dementia. Current knowledge of CSVD may influence treatment decisions and preventive efforts. Although the causes of CSVD are not entirely elucidated, ongoing research of the pathophysiology of CSVD, such as the role of inflammation, is helping identify potential treatment targets, evaluate prediction models and develop preventive strategies. Given the detectability of CSVD in preclinical stages using brain MRI, a long window of opportunity is presented to implement existent preventive measures. This review considers CSVD including its subclinical manifestations detected using brain MRI, clinical manifestations, use of markers of CSVD as predictors of clinical outcomes such as dementia and stroke, and presents potential management strategies when seeing patients with cerebral small vessel disease to reduce its disease burden and clinical consequences. Clinical trials have evaluated some aspects of CSVD treatment and are beginning to recognize CSVD as endpoint in subclinical stages. Future studies will clarify if this approach is able to delay onset of dementia and prevent stroke occurrence, meanwhile implementation of existent recommendations for the prevention and treatment of stroke and dementia may reduce disability and clinical outcomes related to CSVD.

Blood‐brain barrier failure as a core mechanism in cerebral small vessel disease and dementia: evidence from a cohort study

Introduction

Methods

Results

Discussion

•

In 201 patients with non-disabling stroke and white matter hyperintensities (WMH), we measured blood-brain barrier (BBB) leakage with contrast-enhanced MRI.

•

BBB leakage was higher in WMH than in normal appearing white matter.

•

BBB leakage increased in both WMH and normal appearing white matter with the burden of small vessel disease, hypertension, and age.

•

BBB leakage predicted cognitive decline one year later.

•

The leakage pattern supported the hypothesis that BBB leak was pathogenic of diffuse brain damage in cerebral small vessel disease.

Total Magnetic Resonance Imaging Burden of Small Vessel Disease in Cerebral Amyloid Angiopathy: An Imaging-Pathologic Study of Concept Validation

IMPORTANCE

Cerebral amyloid angiopathy (CAA) is characteristically associated with magnetic resonance imaging (MRI) biomarkers of small vessel brain injury, including strictly lobar cerebral microbleeds, cortical superficial siderosis, centrum semiovale perivascular spaces, and white matter hyperintensities. Although these neuroimaging markers reflect distinct pathophysiologic aspects in CAA, no studies to date have combined these structural imaging features to gauge total brain small vessel disease burden in CAA.

OBJECTIVES

To investigate whether a composite score can be developed to capture the total brain MRI burden of small vessel disease in CAA and to explore whether this score contributes independent and complementary information about CAA severity, defined as intracerebral hemorrhage during life or bleeding-related neuropathologic changes.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective, cross-sectional study examined a single-center neuropathologic CAA cohort of eligible patients from the Massachusetts General Hospital from January 1, 1997, through December 31, 2012. Data analysis was performed from January 2, 2015, to January 9, 2016. Patients with pathologic evidence of CAA (ie, any presence of CAA from routinely collected brain biopsy specimen, biopsy specimen at hematoma evacuation, or autopsy) and available brain MRI sequences of adequate quality, including T2-weighted, T2*-weighted gradient-recalled echo, and/or susceptibility-weighted imaging and fluid-attenuated inversion recovery sequences, were considered for the study.

MAIN OUTCOMES AND MEASURES

Brain MRIs were rated for lobar cerebral microbleeds, cortical superficial siderosis, centrum semiovale perivascular spaces, and white matter hyperintensities. All 4 MRI lesions were incorporated into a prespecified ordinal total small vessel disease score, ranging from 0 to 6 points. Associations with severity of CAA-associated vasculopathic changes (fibrinoid necrosis and concentric splitting of the wall), clinical presentation, number of intracerebral hemorrhages, and other imaging markers not included in the score were explored using logistic and ordinal regression.

RESULTS

In total, 105 patients with pathologically defined CAA were included: 52 with autopsies, 22 with brain biopsy specimens, and 31 with pathologic samples from hematoma evacuations. The mean (range) age of the patients was 73 (71-74) years, and 55 (52.4%) were women. In multivariable ordinal regression analysis, severity of CAA-associated vasculopathic changes (odds ratio, 2.40; 95% CI, 1.06-5.45; P = .04) and CAA presentation with symptomatic intracerebral hemorrhage (odds ratio, 2.23; 95% CI, 1.07-4.64; P = .03) were independently associated with the total MRI small vessel disease score. The score was associated with small, acute, diffusion-weighted imaging lesions and posterior white matter hyperintensities in adjusted analyses.

CONCLUSIONS AND RELEVANCE

This study provides evidence of concept validity of a total MRI small vessel disease score in CAA. After further validation, this approach can be potentially used in prospective clinical studies.

Magnetic resonance imaging for assessment of cerebrovascular reactivity in cerebral small vessel disease: A systematic review

Cerebral small vessel disease (SVD) pathophysiology is poorly understood. Cerebrovascular reactivity (CVR) impairment may play a role, but evidence to date is mainly indirect. Magnetic resonance imaging (MRI) allows investigation of CVR directly in the tissues affected by SVD. We systematically reviewed the use of MRI to measure CVR in subjects with SVD. Five studies (total n = 155 SVD subjects, 84 controls) provided relevant data. The studies included different types of patients. Each study used blood oxygen level dependent (BOLD) MRI to assess CVR but a different vasoactive stimulus and method of calculating CVR. CVR decreased with increasing white matter hyperintensities in two studies (n = 17, 11%) and in the presence of microbleeds in another. Three studies (n = 138, 89%) found no association of CVR with white matter hyperintensities. No studies provided tissue-specific CVR values. CVR decreased with age in three studies, and with female gender and increasing diastolic blood pressure in one study. Safety and tolerability data were limited. Larger studies using CVR appear to be feasible and are needed, preferably with more standardized methods, to determine if specific clinical or radiological features of SVD are more or less associated with impaired CVR.

Development and initial evaluation of a semi-automatic approach to assess perivascular spaces on conventional magnetic resonance images

PURPOSE

Perivascular spaces (PVS) are associated with ageing, cerebral small vessel disease, inflammation and increased blood brain barrier permeability. Most studies to date use visual rating scales to assess PVS, but these are prone to observer variation.

METHODS

We developed a semi-automatic computational method that extracts PVS on bilateral ovoid basal ganglia (BG) regions on intensity-normalised T2-weighted magnetic resonance images. It uses Analyze™10.0 and was applied to 100 mild stroke patients' datasets. We used linear regression to test association between BGPVS count, volume and visual rating scores; and between BGPVS count & volume, white matter hyperintensity (WMH) rating scores (periventricular: PVH; deep: DWMH) & volume, atrophy rating scores and brain volume.

RESULTS

In the 100 patients WMH ranged from 0.4 to 119ml, and total brain tissue volume from 0.65 to 1.45l. BGPVS volume increased with BGPVS count (67.27, 95%CI [57.93 to 76.60], p<0.001). BGPVS count was positively associated with WMH visual rating (PVH: 2.20, 95%CI [1.22 to 3.18], p<0.001; DWMH: 1.92, 95%CI [0.99 to 2.85], p<0.001), WMH volume (0.065, 95%CI [0.034 to 0.096], p<0.001), and whole brain atrophy visual rating (1.01, 95%CI [0.49 to 1.53], p<0.001). BGPVS count increased as brain volume (as % of ICV) decreased (-0.33, 95%CI [-0.53 to -0.13], p=0.002).

COMPARISON WITH EXISTING METHOD

BGPVS count and volume increased with the overall increase of BGPVS visual scores (2.11, 95%CI [1.36 to 2.86] for count and 0.022, 95%CI [0.012 to 0.031] for volume, p<0.001). Distributions for PVS count and visual scores were also similar.

CONCLUSIONS

This semi-automatic method is applicable to clinical protocols and offers quantitative surrogates for PVS load. It shows good agreement with a visual rating scale and confirmed that BGPVS are associated with WMH and atrophy measurements.