Blood pressure and sodium: Association with MRI markers in cerebral small vessel disease

Effect of high-fat diet on cerebral pathological changes of cerebral small vessel disease in SHR/SP rats

Cerebral small vessel diseases (CSVD) are neurological disorders associated with microvessels, manifested pathologically as white matter (WM) changes and cortical microbleeds, with hypertension as a risk factor. Additionally, a high-fat diet (HFD) can affect peripheral vessel health. Our study explored how HFD affects cerebral small vessels in normotensive WKY, hypertensive SHR, and SHR/SP rats. The MRI results revealed that HFD specifically increased WM hyperintensity in SHR/SP rats. Pathologically, it increased WM pallor and vacuolation in SHR and SHR/SP rats. Levels of blood-brain barrier (BBB) protein claudin 5 were decreased in SHR and SHR/SP compared to WKY, with HFD having minimal impact on these levels. Conversely, collagen IV levels remained consistent among the rat strains, which were increased by HFD. Consequently, HFD caused vessel leakage in all rat strains, particularly within the corpus callosum of SHR/SP rats. To understand the underlying mechanisms, we assessed the levels of hypoxia-inducible factor-1α (HIF-1α), Gp91-phox, and neuroinflammatory markers astrocytes, and microglia were increased in SHR and SHR/SP compared to WKY and were further elevated by HFD in all rat strains. Gp91-phox was also increased in SHR and SHR/SP compared to WKY, with HFD causing an increase in WKY but little effect in SHR and SHR/SP. In conclusion, our study demonstrates that HFD, in combined with hypertension, intensifies cerebral pathological alterations in CSVD rats. This exacerbation involves increased oxidative stress and HIF-1α in cerebral vessels, triggering neuroinflammation, vascular basement membrane remodeling, IgG leakage, and ultimately WM damage.

Association between blood-brain barrier permeability and changes in pulse wave velocity following a recent small subcortical infarct

Cerebral small vessel disease (cSVD) is associated with increased blood-brain barrier (BBB) permeability. We sought to evaluate whether arterial stiffness might be associated with BBB permeability in patients with cSVD. We assessed BBB permeability using Dynamic Contrast-Enhanced MRI (DCE-MRI) in 29 patients that had suffered a recent small subcortical infarct (RSSI). BBB permeability in the whole brain (WB), gray matter (GM) and white matter (WM) was assessed with the parameter Ktrans. We used ambulatory blood pressure monitoring to measure 24-h systolic blood pressure (24-h SBP), diastolic blood pressure (24-h DBP), and pulse wave velocity (24-h PWV) both after stroke and following a 2-year follow-up. The differences between both measurements were calculated as Δ24-h SBP, Δ24-h DBP and Δ24-h PWV. DCE-MRI was acquired at a median (IQR) of 24 (19-27) months after stroke. Median age was 66.7 (9.7) years, and 24 (83%) patients were men. Median (IQR) Δ24-h PWV was 0.3 (-0.1, 0.5) m/s. WB-Ktrans, GM-Ktrans, and WM-Ktrans were associated with Δ24-h PWV (Spearman's, r [95% CI], WB 0.651 [0.363-0.839]; GM 0.657 [0.373-0.845], WM 0.530[0.197-0.777]) but not with Δ24-h SBP or Δ24-h DBP. These associations remained significant after adjustment with linear regression models, controlling for age, sex, body mass index, and Δ24-h SBP (b[95% CI], WB 0.725[0.384-1.127], GM 0.629 [0.316-1.369], WM 0.865 [0.455-0.892]) or Δ24-h DBP (b[95% CI], WM 0.707 [0.370-1.103], GM 0.643 [0.352-1.371], WM 0.772 [0.367-0.834]). Our results suggest that an increment on arterial stiffness in the months following a RSSI might increase BBB permeability.

European stroke organisation (ESO) guideline on cerebral small vessel disease, part 2, lacunar ischaemic stroke

A quarter of ischaemic strokes are lacunar subtype, typically neurologically mild, usually resulting from intrinsic cerebral small vessel pathology, with risk factor profiles and outcome rates differing from other stroke subtypes. This European Stroke Organisation (ESO) guideline provides evidence-based recommendations to assist with clinical decisions about management of lacunar ischaemic stroke to prevent adverse clinical outcomes. The guideline was developed according to ESO standard operating procedures and Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. We addressed acute treatment (including progressive lacunar stroke) and secondary prevention in lacunar ischaemic stroke, and prioritised the interventions of thrombolysis, antiplatelet drugs, blood pressure lowering, lipid lowering, lifestyle, and other interventions and their potential effects on the clinical outcomes recurrent stroke, dependency, major adverse cardiovascular events, death, cognitive decline, mobility, gait, or mood disorders. We systematically reviewed the literature, assessed the evidence and where feasible formulated evidence-based recommendations, and expert concensus statements. We found little direct evidence, mostly of low quality. We recommend that patients with suspected acute lacunar ischaemic stroke receive intravenous alteplase, antiplatelet drugs and avoid blood pressure lowering according to current acute ischaemic stroke guidelines. For secondary prevention, we recommend single antiplatelet treatment long-term, blood pressure control, and lipid lowering according to current guidelines. We recommend smoking cessation, regular exercise, other healthy lifestyle modifications, and avoid obesity for general health benefits. We cannot make any recommendation concerning progressive stroke or other drugs. Large randomised controlled trials with clinically important endpoints, including cognitive endpoints, are a priority for lacunar ischaemic stroke.

Cerebral Small Vessel Disease: a Review of the Pathophysiological Mechanisms

Cerebral small vessel disease (cSVD) refers to the age-dependent pathological processes involving the brain small vessels and leading to vascular cognitive impairment, intracerebral hemorrhage, and acute lacunar ischemic stroke. Despite the significant public health burden of cSVD, disease-specific therapeutics remain unavailable due to the incomplete understanding of the underlying pathophysiological mechanisms. Recent advances in neuroimaging acquisition and processing capabilities as well as findings from cSVD animal models have revealed critical roles of several age-dependent processes in cSVD pathogenesis including arterial stiffness, vascular oxidative stress, low-grade systemic inflammation, gut dysbiosis, and increased salt intake. These factors interact to cause a state of endothelial cell dysfunction impairing cerebral blood flow regulation and breaking the blood brain barrier. Neuroinflammation follows resulting in neuronal injury and cSVD clinical manifestations. Impairment of the cerebral waste clearance through the glymphatic system is another potential process that has been recently highlighted contributing to the cognitive decline. This review details these mechanisms and attempts to explain their complex interactions. In addition, the relevant knowledge gaps in cSVD mechanistic understanding are identified and a systematic approach to future translational and early phase clinical research is proposed in order to reveal new cSVD mechanisms and develop disease-specific therapeutics.

Dietary sodium/potassium intake and cognitive impairment in older patients with hypertension: Data from NHANES 2011-2014

This study aimed to assess the relationship between dietary sodium/potassium intake and cognition in elderly individuals with hypertension. We designed a cross-sectional study based on the 2011-2014 National Health and Nutrition Examination Survey (NHANES) 2011-2014. A multivariable-logistic regression analysis was performed to analyze the relationship between sodium/potassium intake and cognitive impairment. Restricted cubic spline (RCS) based on regression analysis to assess the nonlinear dose-response relationship between dietary sodium intake and cognitive performance. Out of the 2276 participants included in this study, 1670 patients had hypertension. Compared with the lowest quartile of dietary sodium intake, the lowest weighted odds ratio of cognitive impairment in DSST was observed in Q4 (OR = 0.45, 0.29-0.70), and a similar trend was observed in AFT (OR = 0.34, 0.18-0.65). After adjusting the covariates, the lowest weighted multivariable-adjusted OR of cognitive impairment in DSST were also observed in Q4 (OR = 0.47, 0.26-0.84) compared with the lowest quartile of dietary sodium intake. The RCS results showed that dietary sodium intake was U-shaped and associated with the risk of cognitive impairment in the DSST (P_{non-linearity}  = 0.0067). In addition, no significant association was observed between dietary potassium intake and different dimensions of cognitive performance. In conclusion, excessively high and low low dietary sodium were associated with impairment of specific processing speed, sustained attention, and working memory for elderly patients with hypertension in the United States. However, no association was observed between dietary potassium intake and cognition.

Excessive salt intake accelerates the progression of cerebral small vessel disease in older adults

BACKGROUND

It is unclear whether excessive salt intake accelerates the progression of cerebral small vessel disease (CSVD). The major objective of this study was to investigate the harmful effect of excessive salt intake on the progression of CSVD in older individuals.

METHODS

Between May 2007 and November 2010, 423 community-dwelling individuals aged 60 years and older were recruited from the Shandong area, China. Salt intake was estimated using 24-hour urine collection for 7 consecutive days at baseline. Participants were classified into low, mild, moderate and high groups according to the salt intake estimation. CSVD including white matter hyperintensities (WMHs), lacunes, microbleeds and an enlarged perivascular space (EPVS) were determined using brain magnetic resonance imaging.

RESULTS

During an average of five years of follow-up, the WMH volume and WMH-to-intracranial ratio were increased in the four groups. However, the increasing trends in the WMH volume and WMH-to-intracranial ratio were significantly faster in the higher salt intake groups compared with the lower salt intake groups (P_adjusted < 0.001). The cumulative hazard ratios of new-incident WMHs (defined as those with Fazekas scale scores ≥ 2), new-incident lacunes, microbleeds or an EPVS, as well as composites of CSVD, were respectively 2.47, 2.50, 3.33, 2.70 and 2.89 for the mild group; 3.72, 3.74, 4.66, 4.01 and 4.49 for the moderate group; and 7.39, 5.82, 7.00, 6.40 and 6.61 for the high group, compared with the low group after adjustment for confounders (P_adjusted < 0.001). The risk of new-incident WMHs, lacunes, microbleeds or an EPVS, and composites of CSVD was significantly increased with each 1-standard-deviation increment in salt intake (P_adjusted < 0.001).

CONCLUSION

Our data indicates that excessive salt intake is an important and independent contributor to the progression of CVSD in older adults.

Diffusion tensor imaging pipeline measures of cerebral white matter integrity: An overview of recent advances and prospects

Cerebral small vessel disease (CSVD) is a leading cause of age-related microvascular cognitive decline, resulting in significant morbidity and decreased quality of life. Despite a progress on its key pathophysiological bases and general acceptance of key terms from neuroimaging findings as observed on the magnetic resonance imaging (MRI), key questions on CSVD remain elusive. Enhanced relationships and reliable lesion studies, such as white matter tractography using diffusion-based MRI (dMRI) are necessary in order to improve the assessment of white matter architecture and connectivity in CSVD. Diffusion tensor imaging (DTI) and tractography is an application of dMRI that provides data that can be used to non-invasively appraise the brain white matter connections via fiber tracking and enable visualization of individual patient-specific white matter fiber tracts to reflect the extent of CSVD-associated white matter damage. However, due to a lack of standardization on various sets of software or image pipeline processing utilized in this technique that driven mostly from research setting, interpreting the findings remain contentious, especially to inform an improved diagnosis and/or prognosis of CSVD for routine clinical use. In this minireview, we highlight the advances in DTI pipeline processing and the prospect of this DTI metrics as potential imaging biomarker for CSVD, even for subclinical CSVD in at-risk individuals.

The effect of dietary patterns on mild cognitive impairment and dementia incidence among community-dwelling older adults

Multiple studies have shown that dietary patterns have beneficial health effects on cognitive function. However, information on this relationship is presently limited, particularly among older adults. Thus, this study aimed to determine the effects of dietary patterns on mild cognitive impairment (MCI) and dementia incidence among Malaysian community-dwelling older adults. In this prospective cohort study, a total of 280 participants aged 60 years and above were included in the 5-year follow-up analysis. Participants' sociodemographic, medical history, anthropometry, blood pressure, body composition, biochemical indices, cognitive assessments, psychosocial functions, functional status, and dietary intake were obtained. MCI was classified based on Petersen criteria, whereas dementia status was assessed using clinical dementia rating (CDR). Univariate analysis was performed for all variables, followed by multinomial regression analysis to identify the ability of dietary patterns in predicting the incidence of MCI and dementia. After controlling for confounding factors, the findings indicated that "local snacks-fish and seafood-high salt foods" dietary pattern was associated with an increased risk of MCI incidence, where the T3 [adjusted OR = 3.943 (95% CI: 1.212-12.832), p = 0.032] had the highest OR compared to T2 [adjusted OR = 3.252 (95% CI: 1.108-9.546), p = 0.023]. Meanwhile, a negative association across the tertiles of tropical fruits-oats dietary pattern and dementia incidence was observed [T2: adjusted OR = 0.152 (95% CI: 0.026-0.871), p = 0.034; T3: Adjusted OR = 0.101 (95% CI: 0.011-0.967), p = 0.047]. In conclusion, specific dietary patterns, particularly "local snacks-fish and seafoods-high salt foods," were shown to increase the risk of MCI, while increasing intakes of "tropical fruits-oats" dietary patterns would protect against the dementia incidence among Malaysian older adults.

Contrast agent-free state-of-the-art magnetic resonance imaging on cerebral small vessel disease - Part 2: Diffusion tensor imaging and functional magnetic resonance imaging

Cerebral small vessel disease (cSVD) has been widely studied using conventional magnetic resonance imaging (MRI) methods, although the association between MRI findings and clinical features of cSVD is not always concordant. We assessed the additional contribution of contrast agent-free, state-of-the-art MRI techniques, particularly diffusion tensor imaging (DTI) and functional magnetic resonance imaging (fMRI), to understand brain damage and structural and functional connectivity impairment related to cSVD. We performed a review following the PICOS worksheet and Search Strategy, including 152 original papers in English, published from 2000 to 2022. For each MRI method, we extracted information about their contributions regarding the origins, pathology, markers, and clinical outcomes in cSVD. In general, DTI studies have shown that changes in mean, radial, and axial diffusivity measures are related to the presence of cSVD. In addition to the classical deficit in executive functions and processing speed, fMRI studies indicate connectivity dysfunctions in other domains, such as sensorimotor, memory, and attention. Neuroimaging metrics have been correlated with the diagnosis, prognosis, and rehabilitation of patients with cSVD. In short, the application of contrast agent-free, state-of-the-art MRI techniques has provided a complete picture of cSVD markers and tools to explore questions that have not yet been clarified about this clinical condition. Longitudinal studies are desirable to look for causal relationships between image biomarkers and clinical outcomes.

Endothelial Cells and the Cerebral Circulation

Endothelial cells form the innermost layer of all blood vessels and are the only vascular component that remains throughout all vascular segments. The cerebral vasculature has several unique properties not found in the peripheral circulation; this requires that the cerebral endothelium be considered as a unique entity. Cerebral endothelial cells perform several functions vital for brain health. The cerebral vasculature is responsible for protecting the brain from external threats carried in the blood. The endothelial cells are central to this requirement as they form the basis of the blood-brain barrier. The endothelium also regulates fibrinolysis, thrombosis, platelet activation, vascular permeability, metabolism, catabolism, inflammation, and white cell trafficking. Endothelial cells regulate the changes in vascular structure caused by angiogenesis and artery remodeling. Further, the endothelium contributes to vascular tone, allowing proper perfusion of the brain which has high energy demands and no energy stores. In this article, we discuss the basic anatomy and physiology of the cerebral endothelium. Where appropriate, we discuss the detrimental effects of high blood pressure on the cerebral endothelium and the contribution of cerebrovascular disease endothelial dysfunction and dementia. © 2022 American Physiological Society. Compr Physiol 12:3449-3508, 2022.

High-Salt Diet in the Pre- and Postweaning Periods Leads to Amygdala Oxidative Stress and Changes in Locomotion and Anxiety-Like Behaviors of Male Wistar Rats

High-salt (HS) diets have recently been linked to oxidative stress in the brain, a fact that may be a precursor to behavioral changes, such as those involving anxiety-like behavior. However, to the best of our knowledge, no study has evaluated the amygdala redox status after consuming a HS diet in the pre- or postweaning periods. This study aimed to evaluate the amygdala redox status and anxiety-like behaviors in adulthood, after inclusion of HS diet in two periods: preconception, gestation, and lactation (preweaning); and only after weaning (postweaning). Initially, 18 females and 9 male Wistar rats received a standard (n = 9 females and 4 males) or a HS diet (n = 9 females and 5 males) for 120 days. After mating, females continued to receive the aforementioned diets during gestation and lactation. Weaning occurred at 21-day-old Wistar rats and the male offspring were subdivided: control-control (C-C)—offspring of standard diet fed dams who received a standard diet after weaning (n = 9–11), control-HS (C-HS)—offspring of standard diet fed dams who received a HS diet after weaning (n = 9–11), HS-C—offspring of HS diet fed dams who received a standard diet after weaning (n = 9–11), and HS-HS—offspring of HS diet fed dams who received a HS diet after weaning (n = 9–11). At adulthood, the male offspring performed the elevated plus maze and open field tests. At 152-day-old Wistar rats, the offspring were euthanized and the amygdala was removed for redox state analysis. The HS-HS group showed higher locomotion and rearing frequency in the open field test. These results indicate that this group developed hyperactivity. The C-HS group had a higher ratio of entries and time spent in the open arms of the elevated plus maze test in addition to a higher head-dipping frequency. These results suggest less anxiety-like behaviors. In the analysis of the redox state, less activity of antioxidant enzymes and higher levels of the thiobarbituric acid reactive substances (TBARS) in the amygdala were shown in the amygdala of animals that received a high-salt diet regardless of the period (pre- or postweaning). In conclusion, the high-salt diet promoted hyperactivity when administered in the pre- and postweaning periods. In animals that received only in the postweaning period, the addition of salt induced a reduction in anxiety-like behaviors. Also, regardless of the period, salt provided amygdala oxidative stress, which may be linked to the observed behaviors.

Dietary Salt Disrupts Tricarboxylic Acid Cycle and Induces Tau Hyperphosphorylation and Synapse Dysfunction during Aging

Dietary salt causes synaptic deficits and tau hyperphosphorylation, which are detrimental to cognitive function. However, the specific effects of a high-salt diet on synapse and tau protein remain poorly understood. In this study, aged (15-month-old) C57BL/6 mice received a normal (0.5% NaCl) or high-salt (8% NaCl) diet for 3 months, and N2a cells were treated with normal culture medium or a NaCl medium (40 mM). Spatial learning and memory abilities were tested using the Morris water maze. The levels of metabolites and related enzymes in the tricarboxylic acid (TCA) cycle were confirmed using liquid chromatography-tandem mass spectrometry, western blotting, and immunofluorescence. We also investigated synapse morphology and the phosphorylation of tau protein. Under the high-salt diet, mice displayed impaired learning and memory compared to mice fed the normal diet. Furthermore, excessive salt intake disturbed the TCA cycle in both animals and cells compared to the respective normal controls. High dietary salt reduced postsynaptic density protein 95 (PSD95) and brain-derived neurotrophic factor (BDNF) expression, impaired neurons, and caused synaptic loss in the mice. We also detected tau hyperphosphorylation at different sites (Thr205, Thr231, and Thr181) without increasing total tau levels in response to high salt treatment, both in vivo and in vitro. We concluded that elevated salt intake impairs the TCA cycle and induces tau hyperphosphorylation and synapse dysfunction during aging, which ultimately results in cognitive impairment.

Effects of Nutrition on Cognitive Function in Adults with or without Cognitive Impairment: A Systematic Review of Randomized Controlled Clinical Trials

New dietary approaches for the prevention of cognitive impairment are being investigated. However, evidence from dietary interventions is mainly from food and nutrient supplement interventions, with inconsistent results and high heterogeneity between trials. We conducted a comprehensive systematic search of randomized controlled trials (RCTs) published in MEDLINE-PubMed, from January 2018 to July 2021, investigating the impact of dietary counseling, as well as food-based and dietary supplement interventions on cognitive function in adults with or without cognitive impairment. Based on the search strategy, 197 eligible publications were used for data abstraction. Finally, 61 articles were included in the analysis. There was reasonable evidence that dietary patterns, as well as food and dietary supplements improved cognitive domains or measures of brain integrity. The Mediterranean diet showed promising results, whereas the role of the DASH diet was not clear. Healthy food consumption improved cognitive function, although the quality of these studies was relatively low. The role of dietary supplements was mixed, with strong evidence of the benefits of polyphenols and combinations of nutrients, but with low evidence for PUFAs, vitamin D, specific protein, amino acids, and other types of supplements. Further well-designed RCTs are needed to guide the development of dietary approaches for the prevention of cognitive impairment.

Vascular contributions to cognitive impairment and dementia: the emerging role of 20-HETE

The accumulation of extracellular amyloid-β (Aβ) and intracellular hyperphosphorylated τ proteins in the brain are the hallmarks of Alzheimer's disease (AD). Much of the research into the pathogenesis of AD has focused on the amyloid or τ hypothesis. These hypotheses propose that Aβ or τ aggregation is the inciting event in AD that leads to downstream neurodegeneration, inflammation, brain atrophy and cognitive impairment. Multiple drugs have been developed and are effective in preventing the accumulation and/or clearing of Aβ or τ proteins. However, clinical trials examining these therapeutic agents have failed to show efficacy in preventing or slowing the progression of the disease. Thus, there is a need for fresh perspectives and the evaluation of alternative therapeutic targets in this field. Epidemiology studies have revealed significant overlap between cardiovascular and cerebrovascular risk factors such as hypertension, diabetes, atherosclerosis and stroke to the development of cognitive impairment. This strong correlation has given birth to a renewed focus on vascular contributions to AD and related dementias. However, few genes and mechanisms have been identified. 20-Hydroxyeicosatetraenoic acid (20-HETE) is a potent vasoconstrictor that plays a complex role in hypertension, autoregulation of cerebral blood flow and blood-brain barrier (BBB) integrity. Multiple human genome-wide association studies have linked mutations in the cytochrome P450 (CYP) 4A (CYP4A) genes that produce 20-HETE to hypertension and stroke. Most recently, genetic variants in the enzymes that produce 20-HETE have also been linked to AD in human population studies. This review examines the emerging role of 20-HETE in AD and related dementias.

Urinary sodium and potassium excretion and cerebrovascular health: a multimodal imaging study

PURPOSE

Dietary sodium and potassium intake are associated with stroke, but the potential mechanisms are unclear. We aimed to study the association between sodium and potassium intake and subclinical cerebrovascular health in hypertensive older males using multimodal magnetic resonance imaging.

METHODS

A total of 189 hypertensive male subjects without previous cardiovascular or cerebrovascular disease were included. Daily urinary sodium and potassium excretion were estimated from a fasting spot urine sample using a formula approach. A dedicated cerebrovascular health imaging protocol including vessel wall imaging, angiography, arterial spin labeling imaging and T2-weighted fluid-attenuated inversion recovery imaging was performed to study intracranial atherosclerosis, vascular rarefaction (defined as fewer discernible vessels on angiography), brain perfusion and small vessel disease, respectively.

RESULTS

The mean age was 64.9 (± 7.2) years. The average daily urinary and potassium excretion was 4.7 (± 1.4) g/L and 2.1 (± 0.5) g/L, respectively. Increased urinary sodium excretion was associated with decreased cerebral blood flow and elevated urinary potassium excretion was associated with reduced prevalence of intracranial plaque. The associations remained significant after adjusting for covariates, even including blood pressure control. Quadratic regression analysis indicated a marginally significant U-shaped association between urinary sodium intake and white matter hyperintensity, which lost significance in fully adjusted models. No significant association of urinary sodium and potassium excretion with other cerebrovascular health measures was noted.

CONCLUSION

We concluded that in hypertensive older males without overt cardiovascular disease, increased sodium intake and reduced potassium intake are associated with impaired subclinical cerebrovascular health.

Cerebrovascular disease in patients with cognitive impairment: A white paper from the ESO dementia committee - A practical point of view with suggestions for the management of cerebrovascular diseases in memory clinics

PURPOSE

Practical suggestions on clinical decisions about vascular disease management in patients with cognitive impairment are proposed.

METHODS

The document was produced by the Dementia Committee of the European Stroke Organisation (ESO) based on the evidence from the literature where available and on the clinical experience of the Committee members. This paper was endorsed by the ESO.

FINDINGS

Vascular risk factors and cerebrovascular disease are frequent in patients with cognitive impairment. While acute stroke treatment has evolved substantially in last decades, evidence of management of cerebrovascular pathology beyond stroke in patients with cognitive impairment and dementia is quite limited. Additionally, trials to test some daily-life clinical decisions are likely to be complex, difficult to undertake and take many years to provide sufficient evidence to produce recommendations. This document was conceived to provide some suggestions until data from field trials are available. It was conceived for the use of clinicians from memory clinics or involved specifically in cognitive disorders, addressing practical aspects on diagnostic tools, vascular risk management and suggestions on some therapeutic options.

DISCUSSION AND CONCLUSIONS

The authors did not aim to do an exhaustive or systematic review or to cover all current evidence. The document approach in a very practical way frequent issues concerning cerebrovascular disease in patients with known cognitive impairment.

[Salt sensitivity and osmotic fragility are newly specified risk factors for age-related cerebral microangiopathy]

AIM/

To assess individual values of salt sensitivity and osmotic fragility on the patient's erythrocytes and evaluate predictive ability of these parameters in the development of cerebral small vessel disease (CSVD).

MATERIAL AND METHODS

The study included 73 patients with CSVD (48 women, mean age 60.1±6.5 years) and 19 volunteers (14 women, mean age 56.9±5.4 years). Their erythrocytes were used for the measurement of salt-sensitivity by a modified salt blood test and of osmotic fragility by the classical osmotic fragility test. Binary logistic regression was used to assess the ability of salt-sensitivity and osmotic fragility to predict CSVD development. ROC analysis was used to find out the optimal threshold values of these predictors, their sensitivity and specificity.

RESULTS

An increase in salt sensitivity (cut-off: 8.5 mm/h; sensitivity 64%, specificity 74%) and osmotic fragility (cut-off: 0.62 u.a.; sensitivity 52%, specificity 90%) or their simultaneous use (p of the model <0.000001, cut-off 0.62; sensitivity 88%, specificity 68%) are the independent predictors of CSVD. An increase in salt sensitivity and osmotic fragility is also independently associated with the acceleration of severity of white matter hyperintensities according to Fazekas stages (p=0.019 and 0.004, respectively).

CONCLUSION

The possibility of prediction of CSVD according to an increase in salt sensitivity and osmotic fragility allows us to consider them as the risk factors of CSVD. The standardization of these tests for use in clinical practice is necessary to identify the risk group for CSVD and its individual prevention.

Lacunar Stroke Lesion Extent and Location and White Matter Hyperintensities Evolution 1 Year Post-lacunar Stroke

Lacunar strokes are a common type of ischemic stroke. They are associated with long-term disability, but the factors affecting the dynamic of the infarcted lesion and the brain imaging features associated with them, reflective of small vessel disease (SVD) severity, are still largely unknown. We investigated whether the distribution, volume and 1-year evolution of white matter hyperintensities (WMH), one of these SVD features, relate to the extent and location of these infarcts, accounting for vascular risk factors. We used imaging and clinical data from all patients [n = 118, mean age 64.9 (SD 11.75) years old] who presented to a regional hospital with a lacunar stroke syndrome within the years 2010 and 2013 and consented to participate in a study of stroke mechanisms. All patients had a brain MRI scan at presentation, and 88 had another scan 12 months after. Acute lesions (i.e., recent small subcortical infarcts, RSSI) were identified in 79 patients and lacunes in 77. Number of lacunes was associated with baseline WMH volume (B = 0.370, SE = 0.0939, P = 0.000174). RSSI volume was not associated with baseline WMH volume (B = 3.250, SE = 2.117, P = 0.129), but predicted WMH volume change (B = 2.944, SE = 0.913, P = 0.00184). RSSI location was associated with the spatial distribution of WMH and the pattern of 1-year WMH evolution. Patients with the RSSI in the centrum semiovale (n = 33) had significantly higher baseline volumes of WMH, recent and old infarcts, than patients with the RSSI located elsewhere [median 33.69, IQR (14.37 50.87) ml, 0.001 ≤ P ≤ 0.044]. But patients with the RSSI in the internal/external capsule/lentiform nucleus experienced higher increase of WMH volume after a year [n = 21, median (IQR) from 18 (11.70 31.54) ml to 27.41 (15.84 40.45) ml]. Voxel-wise analyses of WMH distribution in patients grouped per RSSI location revealed group differences increased in the presence of vascular risk factors, especially hypertension and recent or current smoking habit. In our sample of patients presenting to the clinic with lacunar strokes, lacunar strokes extent influenced WMH volume fate; and RSSI location and WMH spatial distribution and dynamics were intertwined, with differential patterns emerging in the presence of vascular risk factors. These results, if confirmed in wider samples, open potential avenues in stroke rehabilitation to be explored further.

Post-stroke Cognition at 1 and 3 Years Is Influenced by the Location of White Matter Hyperintensities in Patients With Lacunar Stroke

Lacunar strokes are a common type of ischemic stroke. They are known to have long-term cognitive deficits, but the influencing factors are still largely unknown. We investigated if the location of the index lacunar stroke or regional WMH and their change at 1 year could predict the cognitive performance at 1 and 3 years post-stroke in lacunar stroke patients. We used lacunar lesion location and WMH-segmented data from 118 patients, mean age 64.9 who had a brain MRI scan soon after presenting with symptoms, of which 88 had a repeated scan 12 months later. Premorbid intelligence (National Adult Reading Test) and current intelligence [Addenbrooke's Cognitive Exam-Revised (ACE-R)] were measured at 1, 12, and 36 months after the stroke. ANCOVA analyses adjusting for baseline cognition/premorbid intelligence, vascular risk factors, age, sex and total baseline WMH volume found that the recent small subcortical infarcts (RSSI) in the internal/external capsule/lentiform nucleus and centrum semiovale did not predict cognitive scores at 12 and 36 months. However, RSSI location moderated voxel-based associations of WMH change from baseline to 1 year with cognitive scores at 1 and 3 years. WMH increase in the external capsule, intersection between the anterior limb of the internal and external capsules, and optical radiation, was associated with worsening of ACE-R scores 1 and 3 years post-stroke after accounting for the location of the index infarct, age and baseline cognition.

Diets and Cellular-Derived Microparticles: Weighing a Plausible Link With Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a spectrum of pathological processes of various etiologies affecting the brain microcirculation that can trigger neuroinflammation and the subsequent neurodegenerative cascade. Prevalent with aging, CSVD is a recognized risk factor for stroke, vascular dementia, Alzheimer disease, and Parkinson disease. Despite being the most common neurodegenerative condition with cerebrocardiovascular axis, understanding about it remains poor. Interestingly, modifiable risk factors such as unhealthy diet including high intake of processed food, high-fat foods, and animal by-products are known to influence the non-neural peripheral events, such as in the gastrointestinal tract and cardiovascular stress through cellular inflammation and oxidation. One key outcome from such events, among others, includes the cellular activations that lead to elevated levels of endogenous cellular-derived circulating microparticles (MPs). MPs can be produced from various cellular origins including leukocytes, platelets, endothelial cells, microbiota, and microglia. MPs could act as microthrombogenic procoagulant that served as a plausible culprit for the vulnerable end-artery microcirculation in the brain as the end-organ leading to CSVD manifestations. However, little attention has been paid on the potential role of MPs in the onset and progression of CSVD spectrum. Corroboratively, the formation of MPs is known to be influenced by diet-induced cellular stress. Thus, this review aims to appraise the body of evidence on the dietary-related impacts on circulating MPs from non-neural peripheral origins that could serve as a plausible microthrombosis in CSVD manifestation as a precursor of neurodegeneration. Here, we elaborate on the pathomechanical features of MPs in health and disease states; relevance of dietary patterns on MP release; preclinical studies pertaining to diet-based MPs contribution to disease; MP level as putative surrogates for early disease biomarkers; and lastly, the potential of MPs manipulation with diet-based approach as a novel preventive measure for CSVD in an aging society worldwide.

Clinical management of cerebral small vessel disease: a call for a holistic approach

ABSTRACT

Cerebral small vessel disease (SVD) is a common global brain disease that causes cognitive impairment, ischemic or hemorrhagic stroke, problems with mobility, and neuropsychiatric symptoms. The brain damage, seen as focal white and deep grey matter lesions on brain magnetic resonance imaging (MRI) or computed tomography (CT), typically accumulates "covertly" and may reach an advanced state before being detected incidentally on brain scanning or causing symptoms. Patients have typically presented to different clinical services or been recruited into research focused on one clinical manifestation, perhaps explaining a lack of awareness, until recently, of the full range and complexity of SVD.In this review, we discuss the varied clinical presentations, established and emerging risk factors, relationship to SVD features on MRI or CT, and the current state of knowledge on the effectiveness of a wide range of pharmacological and lifestyle interventions. The core message is that effective assessment and clinical management of patients with SVD, as well as future advances in diagnosis, care, and treatment, will require a more "joined-up"' approach. This approach should integrate clinical expertise in stroke neurology, cognitive, and physical dysfunctions. It requires more clinical trials in order to improve pharmacological interventions, lifestyle and dietary modifications. A deeper understanding of the pathophysiology of SVD is required to steer the identification of novel interventions. An essential prerequisite to accelerating clinical trials is to improve the consistency, and standardization of clinical, cognitive and neuroimaging endpoints.

Cerebral Microbleeds Are Associated with Loss of White Matter Integrity

BACKGROUND AND PURPOSE

Previous studies have shown that diffusion tensor imaging suggests a diffuse loss of white matter integrity in people with white matter hyperintensities or lacunes. The purpose of this study was to investigate whether the presence of cerebral microbleeds and their distribution are related to the integrity of white matter microstructures.

MATERIALS AND METHODS

The study comprised 982 participants who underwent brain MR imaging to determine microbleed status. The cross-sectional relation between microbleeds and the microstructural integrity of the white matter was assessed by 2 statistical methods: a multilinear regression model based on the average DTI parameters of normal-appearing white matter and Tract-Based Spatial Statistics analysis, a tract-based voxelwise analysis. Fiber tractography was used to spatially describe the microstructural abnormalities along WM tracts containing a cerebral microbleed.

RESULTS

The presence of cerebral microbleeds was associated with lower mean fractional anisotropy and higher mean diffusivity, axial diffusivity, and radial diffusivity, and the association remained when cardiovascular risk factors and cerebral small-vessel disease markers were further adjusted. Tract-Based Spatial Statistics analysis indicated strictly lobar cerebral microbleeds associated with lower fractional anisotropy, higher mean diffusivity, and higher radial diffusivity in the internal capsule and corpus callosum after adjusting other cerebral small-vessel disease markers, while only a few voxels remained associated with deep cerebral microbleeds. Diffusion abnormalities gradients along WM tracts containing a cerebral microbleed were not found in fiber tractography analysis.

CONCLUSIONS

Cerebral microbleeds are associated with widely distributed changes in white matter, despite their focal appearance on SWI.

Proportion of intracerebral haemorrhage due to cerebral amyloid angiopathy in the East and West: Comparison between single hospital centres in Japan and the United Kingdom

PURPOSE

We investigated whether the proportion of intracerebral haemorrhage (ICH) due to cerebral amyloid angiopathy (CAA) differs between patients admitted to hospitals in the East and the West.

METHODS

This international cross-sectional study included consecutive spontaneous ICH patients admitted to one stroke centre in the United Kingdom (Western centre origin) and one in Japan (Eastern centre origin) during the same period. We classified spontaneous ICH into "CAA-related" or "other" using the Edinburgh CT-based diagnostic criteria. We used multivariable logistic regression analyses to assess the relationship between CAA-related ICH and geographical location or ethnicity (White vs. East Asian or other ethnicities). Sensitivity analyses were performed using the modified Boston MRI-based diagnostic criteria for CAA-related ICH.

RESULTS

Of 433 patients (median age, 72 years; Western centre origin, 55%), 15% were classified as CAA-related ICH. In the multivariable logistic regression model, Eastern centre and ethnicity had a lower proportion of CAA-related ICH (odds ratio [OR] vs Western centre origin 0.55, 95%CI 0.31-0.98; OR [vs. White] 0.47, 95%CI 0.25-0.87); these findings remained robust in sensitivity analyses. The estimated incidence of "other" (non-CAA) ICH (attributed to hypertensive arteriopathy) was 2.5-fold higher in East Asian populations.

CONCLUSIONS

The proportion CAA-related ICH is lower in an Eastern compared to a Western hospital ICH population; this might be explained by a higher incidence of ICH related to hypertensive arteriopathy in East Asian populations, suggesting that optimal ICH prevention strategies might differ between the East and West.

The Predictive Value of Salt Sensitivity and Osmotic Fragility in the Development of Cerebral Small Vessel Disease

Increased salt intake in food probably affects the progression of cerebral small vessel disease (CSVD), which justifies the study of disturbances in sodium homeostasis associated with the development of CSVD. We aimed to clarify the role of salt sensitivity and osmotic fragility in the development of CSVD. Erythrocyte salt sensitivity was measured using the modified salt blood test, and osmotic fragility was measured using the classic osmotic fragility test in 73 patients with CSVD (48 women; 60.1 ± 6.5 years) and 19 healthy volunteers (14 women; 56.9 ± 6.4 years). Salt sensitivity and osmotic fragility exhibited a predictive value in relation to CSVD. These parameters were associated with an increase in white matter hyperintensities (P = 0.019 and 0.004, respectively). Their simultaneous use increased their predictive ability for CSVD (P < 0.000001; AUC (95% CI), 0.824 (0.724-0.923)). The possibility of predicting CSVD using erythrocyte salt sensitivity and osmotic fragility indicates the value of the individual glycocalyx buffer capacity in relation to sodium and the activity of sodium channels in the development of CSVD. Increased salt sensitivity and osmotic fragility seem to be risk factors for CSVD.

Excess salt intake promotes M1 microglia polarization via a p38/MAPK/AR-dependent pathway after cerebral ischemia in mice

A high salt diet (HSD) is among the most important risk factors for many diseases. One mechanism by which HSD aggravates cerebral ischemic injury is independent of blood pressure changes. The direct role of HSD in inflammation after cerebral ischemia is unclear. In this research, after twenty-one days of being fed a high salt diet, permanent focal ischemia was induced in mice via operation. At 12 h and 1, 3 and 5 days postischemia, the effects of HSD on the lesion volume, microglia polarization, aldose reductase (AR) expression, and inflammatory processes were analyzed. We report that in mice, surplus dietary salt promotes inflammation and increases the activation of classical lipopolysaccharide (LPS)-induced microglia/macrophages (M1). This effect depends on the expression of the AR protein in activated microglia after permanent middle cerebral artery ligation (pMCAL) in HSD mice. The administration of either the AR inhibitor Epalrestat or a p38-neutralizing antibody blocked the polarization of microglia and alleviated stroke injury. In conclusion, HSD promotes polarization in pro-inflammatory M1 microglia by upregulating the expression of the AR protein via p38/MAPK, thereby exacerbating the development of ischemia stroke.

Predictors of Lesion Cavitation After Recent Small Subcortical Stroke

Morphologic evolution of recent small subcortical infarcts (RSSI) ranges from lesion disappearance to lacune formation and the reasons for this variability are still poorly understood. We hypothesized that diffusion tensor imaging (DTI) and blood-brain-barrier (BBB) abnormalities early on can predict tissue damage 1 year after an RSSI. We studied prospectively recruited patients with a symptomatic MRI-defined RSSI who underwent baseline and two pre-specified MRI examinations at 1-3-month and 1-year post-stroke. We defined the extent of long-term tissue destruction, termed cavitation index, as the ratio of the 1-year T1-weighted cavity volume to the baseline RSSI volume on FLAIR. We calculated fractional anisotropy and mean diffusivity (MD) of the RSSI and normal-appearing white matter, and BBB leakage in different tissues on dynamic contrast-enhanced MRI. Amongst 60 patients, at 1-year post-stroke, 44 patients showed some degree of RSSI cavitation on FLAIR, increasing to 50 on T2- and 56 on T1-weighted high-resolution scans, with a median cavitation index of 7% (range, 1-36%). Demographic, clinical, and cerebral small vessel disease features were not associated with the cavitation index. While lower baseline MD of the RSSI (r_s = - 0.371; p = 0.004) and more contrast leakage into CSF (r_s = 0.347; p = 0.007) were associated with the cavitation index in univariable analysis, only BBB leakage in CSF remained independently associated with cavitation (beta = 0.315, p = 0.046). Increased BBB leakage into CSF may indicate worse endothelial dysfunction and increased risk of tissue destruction post RSSI. Although cavitation was common, it only affected a small proportion of the original RSSI.

Cerebral Small Vessel Disease (CSVD) - Lessons From the Animal Models

Cerebral small vessel disease (CSVD) refers to a spectrum of clinical and imaging findings resulting from pathological processes of various etiologies affecting cerebral arterioles, perforating arteries, capillaries, and venules. Unlike large vessels, it is a challenge to visualize small vessels in vivo, hence the difficulty to directly monitor the natural progression of the disease. CSVD might progress for many years during the early stage of the disease as it remains asymptomatic. Prevalent among elderly individuals, CSVD has been alarmingly reported as an important precursor of full-blown stroke and vascular dementia. Growing evidence has also shown a significant association between CSVD's radiological manifestation with dementia and Alzheimer's disease (AD) pathology. Although it remains contentious as to whether CSVD is a cause or sequelae of AD, it is not far-fetched to posit that effective therapeutic measures of CSVD would mitigate the overall burden of dementia. Nevertheless, the unifying theory on the pathomechanism of the disease remains elusive, hence the lack of effective therapeutic approaches. Thus, this chapter consolidates the contemporary insights from numerous experimental animal models of CSVD, to date: from the available experimental animal models of CSVD and its translational research value; the pathomechanical aspects of the disease; relevant aspects on systems biology; opportunities for early disease biomarkers; and finally, converging approaches for future therapeutic directions of CSVD.

Dietary salt promotes cognitive impairment through tau phosphorylation

Dietary habits and vascular risk factors promote both Alzheimer's disease and cognitive impairment caused by vascular factors^1-3. Furthermore, accumulation of hyperphosphorylated tau, a microtubule-associated protein and a hallmark of Alzheimer's pathology⁴, is also linked to vascular cognitive impairment^5,6. In mice, a salt-rich diet leads to cognitive dysfunction associated with a nitric oxide deficit in cerebral endothelial cells and cerebral hypoperfusion⁷. Here we report that dietary salt induces hyperphosphorylation of tau followed by cognitive dysfunction in mice, and that these effects are prevented by restoring endothelial nitric oxide production. The nitric oxide deficiency reduces neuronal calpain nitrosylation and results in enzyme activation, which, in turn, leads to tau phosphorylation by activating cyclin-dependent kinase 5. Salt-induced cognitive impairment is not observed in tau-null mice or in mice treated with anti-tau antibodies, despite persistent cerebral hypoperfusion and neurovascular dysfunction. These findings identify a causal link between dietary salt, endothelial dysfunction and tau pathology, independent of haemodynamic insufficiency. Avoidance of excessive salt intake and maintenance of vascular health may help to stave off the vascular and neurodegenerative pathologies that underlie dementia in the elderly.

Effects of dietary intake and nutritional status on cerebral oxygenation in patients with chronic kidney disease not undergoing dialysis: A cross-sectional study

BACKGROUND

Dietary management is highly important for the maintenance of renal function in patients with chronic kidney disease (CKD). Cerebral oxygen saturation (rSO2) was reportedly associated with the estimated glomerular filtration rate (eGFR) and cognitive function. However, data concerning the association between cerebral rSO2 and dietary intake of CKD patients is limited.

METHODS

This was a single-center observational study. We recruited 67 CKD patients not undergoing dialysis. Cerebral rSO2 was monitored using the INVOS 5100c oxygen saturation monitor. Energy intake was evaluated by dietitians based on 3-day meal records. Daily protein and salt intakes were calculated from 24-h urine collection.

RESULTS

Multivariable regression analysis showed that cerebral rSO2 was independently associated with energy intake (standardized coefficient: 0.370) and serum albumin concentration (standardized coefficient: 0.236) in Model 1 using parameters with p < 0.10 in simple linear regression analysis (body mass index, Hb level, serum albumin concentration, salt and energy intake) and confounding factors (eGFR, serum sodium concentration, protein intake), and the energy/salt index (standardized coefficient: 0.343) and Hb level (standardized coefficient: 0.284) in Model 2 using energy/protein index as indicated by energy intake/protein intake and energy/salt index by energy intake/salt intake in place of salt, protein and energy intake.

CONCLUSIONS

Cerebral rSO2 is affected by energy intake, energy/salt index, serum albumin concentration and Hb level. Sufficient energy intake and adequate salt restriction is important to prevent deterioration of cerebral oxygenation, which might contribute to the maintenance of cognitive function in addition to the prevention of renal dysfunction in CKD patients.

Association between Striatal Brain Iron Deposition, Microbleeds and Cognition 1 Year After a Minor Ischaemic Stroke

Brain iron deposits (IDs) are inversely associated with cognitive function in community-dwelling older people, but their association with cognition after ischemic stroke, and whether that differs from microbleeds, is unknown. We quantified basal ganglia IDs (BGID) and microbleeds (BMBs) semi-automatically on brain magnetic resonance images from patients with minor stroke (NIHSS < 7), at presentation and 12 months after stroke. We administered the National Adult Reading Test (NART, estimates premorbid or peak adult cognition) and the Revised Addenbrooke's Cognitive Examination (ACE-R; current cognition) at 1 and 12 months after stroke. We adjusted analyses for baseline cognition, age, gender, white matter hyperintensity (WMH) volume and vascular risk factors. In 200 patients, mean age 65 years, striatal IDs and BMBs volumes did not change over the 12 months. Baseline BGID volumes correlated positively with NART scores at both times (ρ = 0.19, p < 0.01). Baseline and follow-up BGID volumes correlated positively with age (ρ = 0.248, p < 0.001 and ρ = 0.271, p < 0.001 respectively), but only baseline (and not follow-up) BMB volume correlated with age (ρ = 0.129, p < 0.05). Both smoking and baseline WMH burden predicted verbal fluency and visuospatial abilities scores (B = -1.13, p < 0.02 and B = -0.22, p = 0.001 respectively) at 12 months after stroke. BGIDs and BMBs are associated differently with cognition post-stroke; studies of imaging and post-stroke cognition should adjust for premorbid cognition. The positive correlation of BGID with NART may reflect the lower premorbid cognition in patients with stroke at younger vs older ages.

Lifestyle and neurocognition in older adults with cognitive impairments: A randomized trial

OBJECTIVE

To determine the independent and additive effects of aerobic exercise (AE) and the Dietary Approaches to Stop Hypertension (DASH) diet on executive functioning in adults with cognitive impairments with no dementia (CIND) and risk factors for cardiovascular disease (CVD).

METHODS

A 2-by-2 factorial (exercise/no exercise and DASH diet/no DASH diet) randomized clinical trial was conducted in 160 sedentary men and women (age >55 years) with CIND and CVD risk factors. Participants were randomly assigned to 6 months of AE, DASH diet nutritional counseling, a combination of both AE and DASH, or health education (HE). The primary endpoint was a prespecified composite measure of executive function; secondary outcomes included measures of language/verbal fluency, memory, and ratings on the modified Clinical Dementia Rating Scale.

RESULTS

Participants who engaged in AE (d = 0.32, p = 0.046) but not those who consumed the DASH diet (d = 0.30, p = 0.059) demonstrated significant improvements in the executive function domain. The largest improvements were observed for participants randomized to the combined AE and DASH diet group (d = 0.40, p = 0.012) compared to those receiving HE. Greater aerobic fitness (b = 2.3, p = 0.049), reduced CVD risk (b = 2.6, p = 0.042), and reduced sodium intake (b = 0.18, p = 0.024) were associated with improvements in executive function. There were no significant improvements in the memory or language/verbal fluency domains.

CONCLUSIONS

These preliminary findings show that AE promotes improved executive functioning in adults at risk for cognitive decline.

CLINICALTRIALSGOV IDENTIFIER

NCT01573546.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that for adults with CIND, AE but not the DASH diet significantly improves executive functioning.

Hypertension Is Associated with White Matter Disruption in Apparently Healthy Middle-Aged Individuals

BACKGROUND AND PURPOSE

Traditional cardiovascular risk factors have been associated with white matter disease. Because hypertension results in vascular stiffness and impaired cerebral perfusion, we hypothesized that it would be the most relevant risk factor for microstructural white matter disruption in apparently healthy middle-aged individuals with a family history of early-onset coronary artery disease.

MATERIALS AND METHODS

This was a cross-sectional analysis of participants in the Genetic Study of Atherosclerosis Risk with DTI. Regional fractional anisotropy of 181 segmented brain regions was measured using Eve WM Atlas. Risk factors were examined using univariate analysis for 48 regions representing deep WM structures. Minimal multivariable linear regression models adjusting for age, sex, and race and maximal linear regression models adjusting for cardiovascular risk factors were performed for regions meeting the Bonferroni threshold in the initial analysis.

RESULTS

Included were 116 subjects (mean age, 49 ± 11 years; 57% men) with a moderate load of cardiovascular risk factors. Subjects with hypertension had significantly lower regional fractional anisotropy in the right cingulum and left stria terminalis in the minimal and maximal regression models. Additionally, there was lower regional fractional anisotropy in the left fornix in the maximal model and right sagittal stratum in the minimal model. Systolic blood pressure values were significantly associated with regional fractional anisotropy in the left superior longitudinal fasciculus in the maximal model. There were no significant differences among regional fractional anisotropy values for other cardiovascular risk factors.

CONCLUSIONS

In middle-aged apparently healthy individuals with susceptibility to vascular disease, among all known cardiovascular risk factors, hypertension was associated with microstructural WM disruption.

Hypertension, dietary salt and cognitive impairment

Dementia is growing at an alarming rate worldwide. Although Alzheimer disease is the leading cause, over 50% of individuals diagnosed with Alzheimer disease have vascular lesions at autopsy. There has been an increasing appreciation of the pathogenic role of vascular risk factors in cognitive impairment caused by neurodegeneration. Midlife hypertension is a leading risk factor for late-life dementia. Hypertension alters cerebrovascular structure, impairs the major factors regulating the cerebral microcirculation, and promotes Alzheimer pathology. Experimental studies have identified brain perivascular macrophages as the major free radical source mediating neurovascular dysfunction of hypertension. Recent evidence indicates that high dietary salt may also induce cognitive impairment. Contrary to previous belief, the effect is not necessarily associated with hypertension and is mediated by a deficit in endothelial nitric oxide. Collectively, the evidence suggests a remarkable cellular diversity of the impact of vascular risk factors on the cerebral vasculature and cognition. Whereas long-term longitudinal epidemiological studies are needed to resolve the temporal relationships between vascular risk factors and cognitive dysfunction, single-cell molecular studies of the vasculature in animal models will provide a fuller mechanistic understanding. This knowledge is critical for developing new preventive, diagnostic, and therapeutic approaches for these devastating diseases of the mind.

Plasma brain natriuretic peptide is a biomarker for screening ischemic cerebral small vessel disease in patients with hypertension

Plasma brain natriuretic peptide (BNP), a diagnostic marker of cardiovascular diseases, has been previously linked to cerebrovascular diseases. Our goal was to determine whether plasma BNP level is helpful for identifying high-risk individuals who are likely to present with the 3 main subtypes of cerebral small vessel diseases (CSVDs), namely, white matter lesions, lacunar infarcts, and cerebral microbleeds, on magnetic resonance imaging (MRI) in patients with hypertension.Three hundred forty-six consecutive hypertensive patients presenting at our cardiology or neurology clinic were investigated. Plasma BNP level was measured by chemiluminescent microparticle immunoassay. The presence of CSVD was assessed by 1.5-T brain MRI. Multivariate linear regression was used to determine whether individual or combined MRI-defined CSVD subtypes were associated with BNP level, after adjustment for several covariates.The mean age of patients was 69.1 ± 9.8 years, and 44.2% were female. The highest quartile BNP group was positively associated with advanced age, female sex, clinically manifesting cardiac diseases, and ischemic CSVD (white matter lesions and lacunar infarcts) and no association with cerebral microbleeds. According to multivariate linear regression, white matter lesions [β = 0.722; 95% confidence interval (95% CI), 0.624-0.819] and lacunar infarcts (β = 0.635; 95% CI, 0.508-0.762) were independently associated with BNP level, even after controlling for vascular risk factors and clinically manifesting cardiac diseases. Combined white matter lesions and lacunar infarcts were more strongly associated with BNP level than each subtype alone. With the cutoff value of 106.4 pg/mL, BNP level had a sensitivity, a specificity, and an area under the curve of 95.2%, 64.9%, and 0.799, respectively, for white matter lesions, whereas the values were 143.0 pg/mL, 81.6%, 73.5%, and 0.848, respectively, for lacunar infarcts.Plasma BNP level, which is independently correlated with individual or combined white matter lesions and lacunar infarcts, is a useful molecular marker for identifying ischemic CSVD in patients with hypertension.

Effects of dietary salt on gene and protein expression in brain tissue of a model of sporadic small vessel disease

BACKGROUND

The effect of salt on cerebral small vessel disease (SVD) is poorly understood. We assessed the effect of dietary salt on cerebral tissue of the stroke-prone spontaneously hypertensive rat (SHRSP) - a relevant model of sporadic SVD - at both the gene and protein level. Methods: Brains from 21-week-old SHRSP and Wistar-Kyoto rats, half additionally salt-loaded (via a 3-week regime of 1% NaCl in drinking water), were split into two hemispheres and sectioned coronally - one hemisphere for mRNA microarray and qRT-PCR, the other for immunohistochemistry using a panel of antibodies targeting components of the neurovascular unit. Results: We observed differences in gene and protein expression affecting the acute phase pathway and oxidative stress (ALB, AMBP, APOH, AHSG and LOC100129193, up-regulated in salt-loaded WKY versus WKY, >2-fold), active microglia (increased Iba-1 protein expression in salt-loaded SHRSP versus salt-loaded WKY, p<0.05), vascular structure (ACTB and CTNNB, up-regulated in salt-loaded SHRSP versus SHRSP, >3-fold; CLDN-11, VEGF and VGF down-regulated >2-fold in salt-loaded SHRSP versus SHRSP) and myelin integrity (MBP down-regulated in salt loaded WKY rats versus WKY, >2.5-fold). Changes of salt-loading were more pronounced in SHRSP and occurred without an increase in blood pressure in WKY rats.

CONCLUSION

Salt exposure induced changes in gene and protein expression in an experimental model of SVD and its parent rat strain in multiple pathways involving components of the glio-vascular unit. Further studies in pertinent experimental models at different ages would help clarify the short- and long-term effect of dietary salt in SVD.

Dietary salt promotes neurovascular and cognitive dysfunction through a gut-initiated TH17 response

A diet rich in salt is linked to an increased risk of cerebrovascular diseases and dementia, but it remains unclear how dietary salt harms the brain. We report that, in mice, excess dietary salt suppresses resting cerebral blood flow and endothelial function, leading to cognitive impairment. The effect depends on expansion of TH17 cells in the small intestine, resulting in a marked increase in plasma interleukin-17 (IL-17). Circulating IL-17, in turn, promotes endothelial dysfunction and cognitive impairment by the Rho kinase-dependent inhibitory phosphorylation of endothelial nitric oxide synthase and reduced nitric oxide production in cerebral endothelial cells. The findings reveal a new gut-brain axis linking dietary habits to cognitive impairment through a gut-initiated adaptive immune response compromising brain function via circulating IL-17. Thus, the TH17 cell-IL-17 pathway is a putative target to counter the deleterious brain effects induced by dietary salt and other diseases associated with TH17 polarization.

Neuroimaging in cerebral small vessel disease: Update and new concepts

In recent years, small vessel disease (SVD) has been recognized for its major impact on cognitive impairment in elderly people, where it is often difficult to separate its effects from those of neurodegenerative diseases individually. SVD is a systemic disease, probably related to diffuse endothelial dysfunction, which affects the perforating arterioles, capillaries and venules in the brain. Although often asymptomatic, it is responsible for almost half of all dementia cases and a significant proportion of stroke cases. Imaging features found on magnetic resonance include recent small subcortical infarctions, lacunes of presumed vascular origin, white matter hyperintensity of presumed vascular origin, prominent perivascular spaces and cerebral microbleeds. The recognition of these imaging findings as a spectrum of the same disease caused by endothelial dysfunction of small cerebral vessels can allow an overall analysis of the disease and thus the development of more effective preventive and therapeutic strategies.

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.

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.

Application of Texture Analysis to Study Small Vessel Disease and Blood-Brain Barrier Integrity

Objectives

We evaluate the alternative use of texture analysis for evaluating the role of blood–brain barrier (BBB) in small vessel disease (SVD).

Methods

We used brain magnetic resonance imaging from 204 stroke patients, acquired before and 20 min after intravenous gadolinium administration. We segmented tissues, white matter hyperintensities (WMH) and applied validated visual scores. We measured textural features in all tissues pre- and post-contrast and used ANCOVA to evaluate the effect of SVD indicators on the pre-/post-contrast change, Kruskal–Wallis for significance between patient groups and linear mixed models for pre-/post-contrast variations in cerebrospinal fluid (CSF) with Fazekas scores.

Results

Textural “homogeneity” increase in normal tissues with higher presence of SVD indicators was consistently more overt than in abnormal tissues. Textural “homogeneity” increased with age, basal ganglia perivascular spaces scores (p < 0.01) and SVD scores (p < 0.05) and was significantly higher in hypertensive patients (p < 0.002) and lacunar stroke (p = 0.04). Hypertension (74% patients), WMH load (median = 1.5 ± 1.6% of intracranial volume), and age (mean = 65.6 years, SD = 11.3) predicted the pre/post-contrast change in normal white matter, WMH, and index stroke lesion. CSF signal increased with increasing SVD post-contrast.

Conclusion

A consistent general pattern of increasing textural “homogeneity” with increasing SVD and post-contrast change in CSF with increasing WMH suggest that texture analysis may be useful for the study of BBB integrity.

STROKOG (stroke and cognition consortium): An international consortium to examine the epidemiology, diagnosis, and treatment of neurocognitive disorders in relation to cerebrovascular disease

INTRODUCTION

The Stroke and Cognition consortium (STROKOG) aims to facilitate a better understanding of the determinants of vascular contributions to cognitive disorders and help improve the diagnosis and treatment of vascular cognitive disorders (VCD).

METHODS

Longitudinal studies with ≥75 participants who had suffered or were at risk of stroke or TIA and which evaluated cognitive function were invited to join STROKOG. The consortium will facilitate projects investigating rates and patterns of cognitive decline, risk factors for VCD, and biomarkers of vascular dementia.

RESULTS

Currently, STROKOG includes 25 (21 published) studies, with 12,092 participants from five continents. The duration of follow-up ranges from 3 months to 21 years.

DISCUSSION

Although data harmonization will be a key challenge, STROKOG is in a unique position to reuse and combine international cohort data and fully explore patient level characteristics and outcomes. STROKOG could potentially transform our understanding of VCD and have a worldwide impact on promoting better vascular cognitive outcomes.

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.

Reproducibility and variability of quantitative magnetic resonance imaging markers in cerebral small vessel disease

Brain imaging is essential for the diagnosis and characterization of cerebral small vessel disease. Several magnetic resonance imaging markers have therefore emerged, providing new information on the diagnosis, progression, and mechanisms of small vessel disease. Yet, the reproducibility of these small vessel disease markers has received little attention despite being widely used in cross-sectional and longitudinal studies. This review focuses on the main small vessel disease-related markers on magnetic resonance imaging including: white matter hyperintensities, lacunes, dilated perivascular spaces, microbleeds, and brain volume. The aim is to summarize, for each marker, what is currently known about: (1) its reproducibility in studies with a scan-rescan procedure either in single or multicenter settings; (2) the acquisition-related sources of variability; and, (3) the techniques used to minimize this variability. Based on the results, we discuss technical and other challenges that need to be overcome in order for these markers to be reliably used as outcome measures in future clinical trials. We also highlight the key points that need to be considered when designing multicenter magnetic resonance imaging studies of small vessel disease.

Brain structural connectivity in late-life major depressive disorder

Disrupted brain connectivity might explain both the pathogenesis and consequences of late-life major depressive disorder (LLD). However, it remains difficult to ascertain whether and how specific circuits are affected. We reviewed literature regarding brain connectivity in LLD, and we specifically focused on the role of structural pathology. LLD is associated with greater levels of cerebrovascular disease, and greater levels of cerebrovascular disease are associated with both depression development and treatment responsiveness. Cerebrovascular disease is most often measured as white matter hyperintensity (WMH) burden, and histopathology studies suggest WMH reflect myelin damage and fluid accumulation (among other underlying pathology). WMHs appear as confluent caps around the ventricles (periventricular), as well as isolated lesions in the deep white matter. The underlying tissue damage and implications for brain connectivity may differ by WMH location or severity. WMHs are associated with lower white matter microstructural integrity (measured with diffusion tensor imaging) and altered brain function (measured with functional MRI). LLD is also associated with lower white matter microstructural integrity and grey matter loss which may also alter the network properties and function of the brain. Damage to brain structure reflected by WMH, reduced white matter microstructural integrity, and atrophy may affect brain function, and are therefore likely pathophysiological mechanisms of LLD. Additional research is needed to fully characterize the developmental course and pathology underlying these imaging markers, and to understand how structural damage explains LLD's various clinical manifestations.

Rationale, design and methodology of the image analysis protocol for studies of patients with cerebral small vessel disease and mild stroke

RATIONALE

Cerebral small vessel disease (SVD) is common in ageing and patients with dementia and stroke. Its manifestations on magnetic resonance imaging (MRI) include white matter hyperintensities, lacunes, microbleeds, perivascular spaces, small subcortical infarcts, and brain atrophy. Many studies focus only on one of these manifestations. A protocol for the differential assessment of all these features is, therefore, needed.

AIMS

To identify ways of quantifying imaging markers in research of patients with SVD and operationalize the recommendations from the STandards for ReportIng Vascular changes on nEuroimaging guidelines. Here, we report the rationale, design, and methodology of a brain image analysis protocol based on our experience from observational longitudinal studies of patients with nondisabling stroke.

DESIGN

The MRI analysis protocol is designed to provide quantitative and qualitative measures of disease evolution including: acute and old stroke lesions, lacunes, tissue loss due to stroke, perivascular spaces, microbleeds, macrohemorrhages, iron deposition in basal ganglia, substantia nigra and brain stem, brain atrophy, and white matter hyperintensities, with the latter separated into intense and less intense. Quantitative measures of tissue integrity such as diffusion fractional anisotropy, mean diffusivity, and the longitudinal relaxation time are assessed in regions of interest manually placed in anatomically and functionally relevant locations, and in others derived from feature extraction pipelines and tissue segmentation methods. Morphological changes that relate to cognitive deficits after stroke, analyzed through shape models of subcortical structures, complete the multiparametric image analysis protocol.

OUTCOMES

Final outcomes include guidance for identifying ways to minimize bias and confounds in the assessment of SVD and stroke imaging biomarkers. It is intended that this information will inform the design of studies to examine the underlying pathophysiology of SVD and stroke, and to provide reliable, quantitative outcomes in trials of new therapies and preventative strategies.