Xanthine oxidase inhibition for the improvement of long-term outcomes following ischaemic stroke and transient ischaemic attack (XILO-FIST) - Protocol for a randomised double blind placebo-controlled clinical trial

Cognitive impairment in cerebral small vessel disease induced by hypertension

ABSTRACT

Hypertension is a primary risk factor for the progression of cognitive impairment caused by cerebral small vessel disease, the most common cerebrovascular disease. However, the causal relationship between hypertension and cerebral small vessel disease remains unclear. Hypertension has substantial negative impacts on brain health and is recognized as a risk factor for cerebrovascular disease. Chronic hypertension and lifestyle factors are associated with risks for stroke and dementia, and cerebral small vessel disease can cause dementia and stroke. Hypertension is the main driver of cerebral small vessel disease, which changes the structure and function of cerebral vessels via various mechanisms and leads to lacunar infarction, leukoaraiosis, white matter lesions, and intracerebral hemorrhage, ultimately resulting in cognitive decline and demonstrating that the brain is the target organ of hypertension. This review updates our understanding of the pathogenesis of hypertension-induced cerebral small vessel disease and the resulting changes in brain structure and function and declines in cognitive ability. We also discuss drugs to treat cerebral small vessel disease and cognitive impairment.

Allopurinol and blood pressure variability following ischemic stroke and transient ischemic attack: a secondary analysis of XILO-FIST

Blood Pressure Variability (BPV) is associated with cardiovascular risk and serum uric acid level. We investigated whether BPV was lowered by allopurinol and whether it was related to neuroimaging markers of cerebral small vessel disease (CSVD) and cognition. We used data from a randomised, double-blind, placebo-controlled trial of two years allopurinol treatment after recent ischemic stroke or transient ischemic attack. Visit-to-visit BPV was assessed using brachial blood pressure (BP) recordings. Short-term BPV was assessed using ambulatory BP monitoring (ABPM) performed at 4 weeks and 2 years. Brain MRI was performed at baseline and 2 years. BPV measures were compared between the allopurinol and placebo groups, and with CSVD and cognition. 409 participants (205 allopurinol; 204 placebo) were included in the visit-to-visit BPV analyses. There were no significant differences found between placebo and allopurinol groups for any measure of visit-to-visit BPV. 196 participants were included in analyses of short-term BPV at week 4. Two measures were reduced by allopurinol: the standard deviation (SD) of systolic BP (by 1.30 mmHg (95% confidence interval (CI) 0.18-2.42, p = 0.023)); and the average real variability (ARV) of systolic BP (by 1.31 mmHg (95% CI 0.31-2.32, p = 0.011)). There were no differences in other measures at week 4 or in any measure at 2 years, and BPV was not associated with CSVD or cognition. Allopurinol treatment did not affect visit-to-visit BPV in people with recent ischemic stroke or TIA. Two BPV measures were reduced at week 4 by allopurinol but not at 2 years.

Vagus Nerve Stimulation Paired With Mobility Training in Chronic Ischemic Stroke: A Case Report

OBJECTIVE

The purpose of this case report is to describe pairing vagus nerve stimulation (VNS) with mobility training in an individual after stroke.

METHODS

A 53-year-old man with left hemiparesis 14.2 months after an ischemic stroke participated in a pilot study investigating the safety and feasibility of VNS paired with upper limb rehabilitation. In addition to upper limb impairment, the participant had impaired gait and wanted to improve his mobility. A single-subject design investigation of VNS paired with self-directed mobility training was conducted. Following the conclusion of the pilot study, the participant was instructed to complete daily sessions of self-activated VNS paired with walking or stationary biking. The 10-Meter Walk Test and timed distance (6-Minute Walk Test) were assessed at 4 baseline points and at 3 to 41 months after mobility training.

RESULTS

The participant had stable baseline values and was classified as a household ambulator with a quad cane. After VNS-paired mobility training, statistically significant improvements were observed in all measures, with the greatest improvements at 9 months exceeding the minimal detectable change: self-selected gait speed from 0.34 (standard deviation [SD] = 0.01) to 0.60 meters/second, fast gait speed from 0.37 (SD = 0.03) to 0.79 meters/second, and 6-Minute Walk Test distance from 106.91 (SD = 6.38) to 179.83 meters. The participant reported increased confidence and balance when walking. No falls or adverse events were reported.

CONCLUSION

The participant demonstrated improved gait speed and timed distance after VNS-paired mobility training. Randomized, blinded trials are needed to determine treatment efficacy.

IMPACT

This is the first documented case of VNS-paired mobility training in an individual with chronic poststroke gait impairments. VNS paired with mobility training may improve poststroke gait impairments.

Xanthine oxidase inhibition and white matter hyperintensity progression following ischaemic stroke and transient ischaemic attack (XILO-FIST): a multicentre, double-blinded, randomised, placebo-controlled trial

BACKGROUND

People who experience an ischaemic stroke are at risk of recurrent vascular events, progression of cerebrovascular disease, and cognitive decline. We assessed whether allopurinol, a xanthine oxidase inhibitor, reduced white matter hyperintensity (WMH) progression and blood pressure (BP) following ischaemic stroke or transient ischaemic attack (TIA).

METHODS

In this multicentre, prospective, randomised, double-blinded, placebo-controlled trial conducted in 22 stroke units in the United Kingdom, we randomly assigned participants within 30-days of ischaemic stroke or TIA to receive oral allopurinol 300 mg twice daily or placebo for 104 weeks. All participants had brain MRI performed at baseline and week 104 and ambulatory blood pressure monitoring at baseline, week 4 and week 104. The primary outcome was the WMH Rotterdam Progression Score (RPS) at week 104. Analyses were by intention to treat. Participants who received at least one dose of allopurinol or placebo were included in the safety analysis. This trial is registered with ClinicalTrials.gov, NCT02122718.

FINDINGS

Between 25th May 2015 and the 29th November 2018, 464 participants were enrolled (232 per group). A total of 372 (189 with placebo and 183 with allopurinol) attended for week 104 MRI and were included in analysis of the primary outcome. The RPS at week 104 was 1.3 (SD 1.8) with allopurinol and 1.5 (SD 1.9) with placebo (between group difference -0.17, 95% CI -0.52 to 0.17, p = 0.33). Serious adverse events were reported in 73 (32%) participants with allopurinol and in 64 (28%) with placebo. There was one potentially treatment related death in the allopurinol group.

INTERPRETATION

Allopurinol use did not reduce WMH progression in people with recent ischaemic stroke or TIA and is unlikely to reduce the risk of stroke in unselected people.

FUNDING

The British Heart Foundation and the UK Stroke Association.

Considerations for Choosing First-Line Urate-Lowering Treatment in Older Patients with Comorbid Conditions

Gout is the most common inflammatory arthritis in adults. The prevalence of gout increases with age. Urate-lowering treatment (ULT) among older patients is often challenging in that patients frequently suffer insufficient effectiveness or adverse events due to comorbidities, concurrent medications, and altered pharmacokinetics. The large-scale randomized controlled trials (RCTs) directly investigating gout patients regarding cardiovascular (CV) safety have only recently been introduced; CARES and FAST compared the CV safety of the two xanthine oxidase inhibitors (XOis), febuxostat versus allopurinol, in patients with gout. Based on the CARES trial that showed CV concerns with febuxostat, the current international guidelines recommend allopurinol as first-line ULT in gout, while preserving other agents as a second-line treatment, despite a higher potency of febuxostat. XOis would be more suitable than uricosurics to treat older patients with gout due to the high prevalence of chronic kidney disease (CKD) in older patients. However, allopurinol alone might not achieve the target serum uric acid levels below 6 mg/dL and CKD might confer an increased risk of allopurinol induced cutaneous adverse reactions in older patients. Furthermore, as well as the later analysis of CARES participants who were lost to follow-up, data from the FAST trial and real-world studies suggest non-inferior CV safety for febuxostat compared to allopurinol even in the presence of CV diseases. Thus, febuxostat use in older patients with renal impairment may be more positively considered. The combination therapy of a novel uricosuric, verinurad, plus febuxostat reduced albuminuria in hyperuricemic patients with type 2 diabetes and CKD in a phase 2a trial, and further RCTs are awaited. Finally, the sodium-glucose cotransporter-2 inhibitor class of oral hypoglycemic agents, known to exert beneficial CV and renal effects independent of glycemic control, have shown a uricosuric effect and could be used as adjunctive therapy in older patients with cardiorenal comorbidities.

Demographic, clinical and neuroimaging markers of post-stroke emotionalism: A preliminary investigation

INTRODUCTION

Post stroke emotionalism (PSE) is a common but poorly understood condition. The value of altered brain structure as a putative risk factor for PSE alongside routinely available demographic and clinical variables has yet to be elucidated.

METHODS

85 patients were recruited from acute inpatient settings within 2 weeks of stroke. PSE was diagnosed using a validated semi-structured interview and standardised measures of stroke severity, functional ability, cognition, mood and quality of life were obtained. Neuroimaging variables (intracranial volume and volumes of cortical grey matter, subcortical grey matter, normal appearing white matter, cerebrum, cerebrospinal fluid and stroke; white matter hyperintensities; and mean cortical thickness) were derived using standardised methods from Magnetic Resonance Imaging (MRI) studies. The relationships between PSE diagnosis, brain structure, demographic and clinical variables were investigated using machine learning algorithms to determine how well different sets of predictors could classify PSE.

RESULTS

The model with the best performance was derived from neuroradiological variables alone (sensitivity = 0.75; specificity = 0.8235), successfully classifying 9/12 individuals with PSE and 28/34 non-PSE cases.

CONCLUSIONS

Neuroimaging measures appear to be important in PSE. Future work is needed to determine which specific variables are key. Imaging may complement standard behavioural measures and aid clinicians and researchers.

Salivary Xanthine Oxidase as a Potential Biomarker in Stroke Diagnostics

Stroke is one of the most common cerebrovascular diseases. Despite significant progress in understanding stroke pathogenesis, cases are still increasing. Thus, laboratory biomarkers of stroke are sought to allow rapid and non-invasive diagnostics. Ischemia-reperfusion injury is an inflammatory process with characteristic cellular changes leading to microvascular disruption. Several studies have shown that hyperactivation of xanthine oxidase (XO) is a major pathogenic factor contributing to brain dysfunction. Given the critical role of XO in stroke complications, this study aimed to evaluate the activity of the enzyme and its metabolic products in the saliva of stroke subjects. Thirty patients in the subacute phase of stroke were included in the study: 15 with hemorrhagic stroke and 15 with ischemic stroke. The control group consisted of 30 healthy subjects similar to the cerebral stroke patients regarding age, gender, and status of the periodontium, dentition, and oral hygiene. The number of individuals was determined a priori based on our previous experiment (power of the test = 0.8; α = 0.05). The study material was mixed non‐stimulated whole saliva (NWS) and stimulated saliva (SWS). We showed that activity, specific activity, and XO output were significantly higher in NWS of ischemic stroke patients than in hemorrhagic stroke and healthy controls. Hydrogen peroxide and uric acid levels were also considerably higher in NWS of ischemic stroke patients. Using receiver operating curve (ROC) analysis, we demonstrated that XO-specific activity in NWS distinguishes ischemic stroke from hemorrhagic stroke (AUC: 0.764) and controls (AUC: 0.973) with very high sensitivity and specificity. Saliva collection is stress-free, requires no specialized medical personnel, and allows continuous monitoring of the patient’s condition through non-invasive sampling multiple times per day. Salivary XO also differentiates with high accuracy (100%) and specificity (93.75%) between stroke patients with mild to moderate cognitive decline (AUC = 0.988). Thus, salivary XO assessment may be a potential screening tool for a comprehensive neuropsychological evaluation. To summarize, our study demonstrates the potential utility of salivary XO in the differential diagnosis of stroke.

New Insights Into Cerebrovascular Pathophysiology and Hypertension

Despite advances in acute management and prevention of cerebrovascular disease, stroke and vascular cognitive impairment together remain the world's leading cause of death and neurological disability. Hypertension and its consequences are associated with over 50% of ischemic and 70% of hemorrhagic strokes but despite good control of blood pressure (BP), there remains a 10% risk of recurrent cerebrovascular events, and there is no proven strategy to prevent vascular cognitive impairment. Hypertension evolves over the lifespan, from predominant sympathetically driven hypertension with elevated mean BP in early and mid-life to a late-life phenotype of increasing systolic and falling diastolic pressures, associated with increased arterial stiffness and aortic pulsatility. This pattern may partially explain both the increasing incidence of stroke in younger adults as well as late-onset, chronic cerebrovascular injury associated with concurrent systolic hypertension and historic mid-life diastolic hypertension. With increasing arterial stiffness and autonomic dysfunction, BP variability increases, independently predicting the risk of ischemic and intracerebral hemorrhage, and is potentially modifiable beyond control of mean BP. However, the interaction between hypertension and control of cerebral blood flow remains poorly understood. Cerebral small vessel disease is associated with increased pulsatility in large cerebral vessels and reduced reactivity to carbon dioxide, both of which are being targeted in early phase clinical trials. Cerebral arterial pulsatility is mainly dependent upon increased transmission of aortic pulsatility via stiff vessels to the brain, while cerebrovascular reactivity reflects endothelial dysfunction. In contrast, although cerebral autoregulation is critical to adapt cerebral tone to BP fluctuations to maintain cerebral blood flow, its role as a modifiable risk factor for cerebrovascular disease is uncertain. New insights into hypertension-associated cerebrovascular pathophysiology may provide key targets to prevent chronic cerebrovascular disease, acute events, and vascular cognitive impairment.

The Need to Pair Molecular Monitoring Devices with Molecular Imaging to Personalize Health

By enabling the non-invasive monitoring and quantification of biomolecular processes, molecular imaging has dramatically improved our understanding of disease. In recent years, non-invasive access to the molecular drivers of health versus disease has emboldened the goal of precision health, which draws on concepts borrowed from process monitoring in engineering, wherein hundreds of sensors can be employed to develop a model which can be used to preventatively detect and diagnose problems. In translating this monitoring regime from inanimate machines to human beings, precision health posits that continual and on-the-spot monitoring are the next frontiers in molecular medicine. Early biomarker detection and clinical intervention improves individual outcomes and reduces the societal cost of treating chronic and late-stage diseases. However, in current clinical settings, methods of disease diagnoses and monitoring are typically intermittent, based on imprecise risk factors, or self-administered, making optimization of individual patient outcomes an ongoing challenge. Low-cost molecular monitoring devices capable of on-the-spot biomarker analysis at high frequencies, and even continuously, could alter this paradigm of therapy and disease prevention. When these devices are coupled with molecular imaging, they could work together to enable a complete picture of pathogenesis. To meet this need, an active area of research is the development of sensors capable of point-of-care diagnostic monitoring with an emphasis on clinical utility. However, a myriad of challenges must be met, foremost, an integration of the highly specialized molecular tools developed to understand and monitor the molecular causes of disease with clinically accessible techniques. Functioning on the principle of probe-analyte interactions yielding a transducible signal, probes enabling sensing and imaging significantly overlap in design considerations and targeting moieties, however differing in signal interpretation and readout. Integrating molecular sensors with molecular imaging can provide improved data on the personal biomarkers governing disease progression, furthering our understanding of pathogenesis, and providing a positive feedback loop toward identifying additional biomarkers and therapeutics. Coupling molecular imaging with molecular monitoring devices into the clinical paradigm is a key step toward achieving precision health.

Chronic kidney disease and neurological disorders: are uraemic toxins the missing piece of the puzzle?

Chronic kidney disease (CKD) perturbs the crosstalk with others organs, with the interaction between the kidneys and the heart having been studied most intensively. However, a growing body of data indicates that there is an association between kidney dysfunction and disorders of the central nervous system. In epidemiological studies, CKD is associated with a high prevalence of neurological complications, such as cerebrovascular disorders, movement disorders, cognitive impairment and depression. Along with traditional cardiovascular risk factors (such as diabetes, inflammation, hypertension and dyslipidaemia), non-traditional risk factors related to kidney damage (such as uraemic toxins) may predispose patients with CKD to neurological disorders. There is increasing evidence to show that uraemic toxins, for example indoxyl sulphate, have a neurotoxic effect. A better understanding of factors responsible for the elevated prevalence of neurological disorders among patients with CKD might facilitate the development of novel treatments. Here, we review (i) the potential clinical impact of CKD on cerebrovascular and neurological complications, (ii) the mechanisms underlying the uraemic toxins' putative action (based on pre-clinical and clinical research) and (iii) the potential impact of these findings on patient care.

Protective effect of grape seed extract and orlistat co-treatment against stroke: Effect on oxidative stress and energy failure

Ischemic stroke is a major health concern and a leading cause of mortality worldwide. Oxidative stress is an early event in the course of stroke inducing neuro-inflammation and cell death. Grape seed extract (GSE) is a natural phytochemical mixture exhibiting antioxidant, anti-inflammatory and neuroprotective properties. Orlistat (ORL) is an anti-obesity agent and a gastro-intestinal lipase inhibitor which showed recently beneficial effects on brain lipotoxicity. Recent studies reported the increase of lipase activity upon stroke which led us to investigate the neuroprotective effect of ORL on rat brain I/R injury as well as the putative synergism with GSE. I/R insult infarcted the brain parenchyma as assessed by TTC staining, induced an oxidative stress as revealed by increased lipoperoxidation along with alteration of antioxidant enzymes activities which was corrected using the cotreatment of ORL + GSE. I/R also disturbed the main metabolic pathways involved in brain fueling as glycolysis, neoglucogenesis, glycogenolysis, TCA cycle and electron transfer chain (ETC) complexes. These disturbances were also corrected with the cotreatment ORL + GSE which maintained energetic activities near to the control level. I/R also disrupted transition metals distribution, along with associated enzymes as tyrosinase, LDH or glutamine synthetase activities and induced hippocampal inflammation as revealed by glycogen depletion from dentate gyrus area along with depressed anti-inflammatory IL1β cytokine and increased pro-inflammatory CD68 antigen. Interestingly almost all I/R-induced disturbances were corrected either partially upon ORL and GSE on their own and the best neuroprotection was obtained in the presence of both drugs (ORL + GSE) enabling robust neuroprotection of the sub granular zone within hippocampal dentate gyrus area.

Serum Uric Acid Levels, but Not rs7442295 Polymorphism of SCL2A9 Gene, Predict Mortality in Clinically Stable Coronary Artery Disease

Serum uric acid (SUA) has been associated with cardiovascular disease, but up to now whether SUA is an independent cardiovascular risk factor or merely a disease-related epiphenomenon remains still controversial. within the framework of the Verona Heart Study, we prospectively followed 703 subjects with angiographically demonstrated and clinically stable coronary artery disease between May 1996 and March 2007. At baseline, SUA levels were measured in all the patients. Genotype data of SCL2A9 rs7442295 polymorphism, which has been associated with SUA by genome-wide association studies, were available for 686 subjects (97.6%). After a median follow-up of 57 months, 116 patients (16.5%) had died, 83 (11.8%) because of cardiovascular causes. Patients with hyperuricemia, defined by SUA levels above the 75th percentile (≥0.41 mmol/L), had an increased total and cardiovascular mortality rate than those with SUA below this threshold level (23.3% vs 14.1%, P = 0.048 and 19.4% vs 9.2%, P = 0.001, respectively, by Kaplan-Meier with Log-Rank test). These associations were confirmed by Cox regression after adjustment for sex, age, other predictors of mortality, coronary revascularization, and drug therapies at discharge (hazard ratio for total mortality 1.87 [1.05-3.34], P = 0.033; hazard ratio for cardiovascular mortality 2.09 [1.03-4.25], P = 0.041). Although associated with SUA levels, rs7442295 polymorphism did not predict total or cardiovascular mortality. our data support that SUA may be a prognostic cardiovascular biomarker, predicting total and cardiovascular mortality in the setting of secondary prevention of coronary artery disease. On the other hand, SCL2A9 gene polymorphism, notwithstanding a clear influence on SUA levels, was not associated with mortality.

Brain imaging factors associated with progression of subcortical hyperintensities in CADASIL over 2-year follow-up

BACKGROUND AND PURPOSE

Mutations in the NOTCH3 gene cause cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a cerebral small vessel disease manifesting with stroke, migraine and dementia in adults. The disease displays significant phenotypic variability that is incompletely explained. Early abnormalities in vascular function have been shown in animal models. We postulated that studying changes in vascular function may offer insights into disease progression.

METHODS

Twenty-two subjects with CADASIL [50% female, 50 (±11) years] from 19 pedigrees were included in a longitudinal multimodality study using brain magnetic resonance imaging (MRI), clinical measures, neuropsychology and measures of peripheral vascular function. MRI studies included measurement of structural brain changes, cerebral blood flow (CBF) and cerebrovascular reactivity by arterial spin labelling and a CO₂ respiratory challenge.

RESULTS

Over 2 years, new stroke or transient ischaemic attack (TIA) occurred in five (23%) subjects and new significant disability in one (5%). There were significant increases in number of lacunes, subcortical hyperintensity volume and microbleeds, and a decrease in brain volume. CBF declined by 3.2 (±4.5) ml/100 g/min over 2 years. CBF and carotid-femoral pulse wave velocity at baseline predicted change in subcortical hyperintensity volume at follow-up. Carotid intima-media thickness and age predicted brain atrophy. Baseline CBF was lower in subjects who showed a decline in attention and working memory.

CONCLUSIONS

Cerebral blood flow predicts radiological progression of hyperintensities and thus is a potential biomarker of disease progression in CADASIL. Over 2 years, there were changes in several relevant imaging biomarkers (CBF, brain volume, lacunes, microbleeds and hyperintensity volume). Future studies in CADASIL should consider assessment of CBF as prognostic factor.

The Whole Picture: From Isolated to Global MRI Measures of Neurovascular and Neurodegenerative Disease

Structural magnetic resonance imaging (MRI) has been used to characterise the appearance of the brain in cerebral small vessel disease (SVD), ischaemic stroke, cognitive impairment, and dementia. SVD is a major cause of stroke and dementia; features of SVD include white matter hyperintensities (WMH) of presumed vascular origin, lacunes of presumed vascular origin, microbleeds, and perivascular spaces. Cognitive impairment and dementia have traditionally been stratified into subtypes of varying origin, e.g., vascular dementia versus dementia of the Alzheimer's type (Alzheimer's disease; AD). Vascular dementia is caused by reduced blood flow in the brain, often as a result of SVD, and AD is thought to have its genesis in the accumulation of tau and amyloid-beta leading to brain atrophy. But after early seminal studies in the 1990s found neurovascular disease features in around 30% of AD patients, it is becoming recognised that so-called "mixed pathologies" (of vascular and neurodegenerative origin) exist in many more patients diagnosed with stroke, only one type of dementia, or cognitive impairment. On the back of these discoveries, attempts have recently been made to quantify the full extent of degenerative and vascular disease in the brain in vivo on MRI. The hope being that these "global" methods may one day lead to better diagnoses of disease and provide more sensitive measurements to detect treatment effects in clinical trials. Indeed, the "Total MRI burden of cerebral small vessel disease", the "Brain Health Index" (BHI), and "MRI measure of degenerative and cerebrovascular pathology in Alzheimer disease" have all been shown to have stronger associations with clinical and cognitive phenotypes than individual brain MRI features. This chapter will review individual structural brain MRI features commonly seen in SVD, stroke, and dementia. The relationship between these features and differing clinical and cognitive phenotypes will be discussed along with developments in their measurement and quantification. The chapter will go on to review emerging methods for quantifying the collective burden of structural brain MRI findings and how these "whole picture" methods may lead to better diagnoses of neurovascular and neurodegenerative disorders.

Combining Neurovascular and Neurodegenerative Magnetic Resonance Imaging Measures in Stroke

Background and Purpose- Individual markers of cerebral small vessel disease and cerebral atrophy explain a small proportion of variance in vascular risk factors and cognitive function. Combining these markers into a single measure of neurovascular and neurodegenerative disease may be more powerful. We assessed this using data contained in the Virtual International Stroke Trials Archive - Prevention sub-archive. Methods- We extracted white matter hyperintensities (WMH) and cerebrospinal fluid (CSF) volumes from 317 people with ischemic stroke or transient ischemic attack who had baseline magnetic resonance imaging. We assessed progression of volumes in 208 people who had 2-year follow-up magnetic resonance imaging. WMH and CSF volumes were segmented from fluid attenuated inversion recovery and T1 images. The combined neurovascular and neurodegenerative measure was the sum of WMH and CSF volume normalized by intracranial volume. We assessed (1) the relationship between baseline vascular risk factors and imaging markers; and (2) the relationship between baseline imaging markers and Mini-Mental State Examination score at follow-up using multiple linear regression. We also assessed implications for sample size calculations using n=208 participants with follow-up magnetic resonance imaging. Results- Vascular risk factors accounted for 7%, 11%, and 12% of the variance in WMH, CSF, and combined volume, respectively (all P<0.001). The association between baseline combined volume and 6-month follow-up Mini-Mental State Examination (β=-0.442; SE, 0.07; P<0.0001) was 32% greater than WMH (β=-0.302; SE, 0.06; P<0.0001) and 12% greater than CSF (β=-0.391; SE, 0.07; P<0.0001) alone. The combined volume required between 207 and 3305 (20%) fewer patients per arm than WMH alone to detect reductions of 10% to 40% in volume progression over 2 years. Conclusions- A combined neurovascular and neurodegenerative magnetic resonance imaging measure including WMH and CSF volume was more closely related to vascular risk factors and cognitive function than either WMH or CSF volume alone. The combined volume may be a more sensitive measurement for clinical trials.

An Exploratory Study of Predictors of Response to Vagus Nerve Stimulation Paired with Upper-Limb Rehabilitation After Ischemic Stroke

We have previously shown the safety and feasibility of vagus nerve stimulation (VNS) paired with upper-limb rehabilitation after ischemic stroke. In this exploratory study, we assessed whether clinical and brain MRI variables predict response to treatment. We used data from two completed randomised and blinded clinical trials (N = 35). All participants had moderate to severe upper-limb weakness and were randomised to 6-weeks intensive physiotherapy with or without VNS. Participants had 3 T brain MRI at baseline. The primary outcome was change in Fugl-Meyer Assessment, upper-extremity score (FMA-UE) from baseline to the first day after therapy completion. We used general linear regression to identify clinical and brain MRI predictors of change in FMA-UE. VNS-treated participants had greater improvement in FMA-UE at day-1 post therapy than controls (8.63 ± 5.02 versus 3.79 ± 5.04 points, t = 2.83, Cohen’s d = 0.96, P = 0.008). Higher cerebrospinal fluid volume was associated with less improvement in FMA-UE in the control but not VNS group. This was also true for white matter hyperintensity volume but not after removal of an outlying participant from the control group. Responders in the VNS group had more severe arm impairment at baseline than responders to control. A phase III trial is now underway to formally determine whether VNS improves outcomes and will explore whether these differ in people with more severe baseline upper-limb disability and cerebrovascular disease.

Genetically Determined Uric Acid and the Risk of Cardiovascular and Neurovascular Diseases: A Mendelian Randomization Study of Outcomes Investigated in Randomized Trials

Background Higher serum uric acid levels are associated with cardiovascular and neurovascular disease, but whether these relationships are causal is not known. We applied Mendelian randomization approaches to assess the association between genetically determined uric acid levels and outcomes under study in large clinical trials. Methods and Results We used 28 genetic variants related to serum uric acid as instruments to perform a range of 2-sample Mendelian randomization methods. Our analysis had statistical power to detect clinically relevant effects of genetically determined serum uric acid levels on the considered clinical outcomes; cognitive function, Alzheimer disease, coronary heart disease, myocardial infarction, systolic blood pressure, and stroke. There was some suggestive evidence for an association between higher genetically determined serum uric acid and cognitive function. There was also some suggestive evidence of a relationship between coronary heart disease, systolic blood pressure, and the serum uric acid genetic instruments, but likely related to genetic pleiotropy. Overall, there was no consistent evidence of a clinically relevant effect of genetically determined serum uric acid on any of the considered outcomes. Conclusions This Mendelian randomization study does not support a clinically relevant causal effect of genetically determined serum urate on a range of cardiovascular and neurovascular outcomes. The weak association of genetically determined serum urate with coronary heart disease and systolic blood pressure may be because of pleiotropic effects. If urate lowering drugs such as allopurinol are found to affect these outcomes in clinical trials, then the effects may be mediated through urate independent mechanisms.

Cortical thickness, white matter hyperintensities, and cognition after stroke

BACKGROUND

A thinner cerebral cortex is associated with higher white matter hyperintensity burden and cognitive impairment in community-dwelling and dementia cohorts. It is important to assess these associations in people with ischemic stroke because their cerebrovascular disease profiles are different to these cohorts.

AIMS

We aimed to determine whether cortical thickness was related to white matter hyperintensity burden and cognition after ischemic stroke.

METHODS

We measured cortical thickness using advanced normalization tools' "KellyKapowski" function in 244 patients with ischemic stroke or transient ischemic attack from the Virtual International Stroke Trials Archive. We measured white matter hyperintensity burden via quantitative volumes and Fazekas score. We extracted data on vascular risk factors at baseline and Mini Mental State Examination scores at one year. We assessed associations between imaging and clinical data using correlation and multiple linear regression.

RESULTS

Pairwise correlation showed that higher white matter hyperintensity Fazekas score was associated with a thinner cortex (rho = -0.284, P < 0.0001). White matter hyperintensities were generally distributed adjacent to and above the lateral ventricles. Voxel-wise analyses showed statistically significant negative associations between cortical thickness and white matter hyperintensities across fronto-temporal and inferior parietal cortical regions. Mean cortical thickness was positively related to Mini Mental State Examination in pair-wise correlation (r = 0.167, P = 0.0088) but there was no independent association after adjustment for age and white matter hyperintensities (beta = 0.016, P = 0.7874).

CONCLUSIONS

Cortical thickness was not an independent predictor of cognition after ischemic stroke. Further work is required to understand how white matter hyperintensities are associated with a thinner cortex in temporal regions but less so in more superior regions where white matter hyperintensities are generally found in people with stroke.

Hyperuricemia and prognosis of acute ischemic stroke in diabetic patients

OBJECTIVES

The relationship between hyperuricemia (HUA) and prognosis of acute ischemic stroke (AIS) is unclear. This prospective cohort study aims to evaluate potential value of HUA as a prognostic factor for AIS independent of diabetic status.

METHODS

A total of 1041 consecutive patients aged from 25 to 96 with AIS were included. 340 (32.7%) had diabetes and 246 (23.6%) had HUA. Diabetic patients were stratified by gender or age. Multivariate logistic regression was used to analyse the association between HUA and prognosis of AIS.

RESULTS

HUA independently predicted poor discharge outcome of AIS in diabetic patients [OR (95% CI): 2.061 (1.042-4.077), p < 0.05]. Among diabetics, HUA selectively predicted a poor functional outcome of AIS at discharge in patients aged ≤75 years [OR (95% CI): 2.381 (1.115-5.085), p < 0.05]. Furthermore, in patients aged ≤75 years, HUA independently predicted poor discharge outcome of AIS in male diabetics [OR (95% CI): 2.684 (1.001-7.200), p < 0.05]. No association between HUA and prognosis of AIS was observed at 3-month, 6-month and 12-month follow-up, either in diabetics or nondiabetics.

CONCLUSIONS

HUA independently predicted poor in-hospital outcome of AIS in diabetic patients, especially in patients aged ≤ 75 years.