Genome-Wide Mendelian Randomization Study Reveals Druggable Genes for Cerebral Small Vessel Disease.

BACKGROUND: Cerebral small vessel disease (CSVD) is a group of neurological disorders that affect the small blood vessels within the brain, for which no effective treatments are currently available. We conducted a Mendelian randomization (MR) study to identify candidate therapeutic genes for CSVD. METHODS: We retrieved genome-wide association study data from 6 recently conducted, extensive investigations focusing on CSVD magnetic resonance imaging markers and performed a 2-sample MR analysis to assess the potential causal effects of gene expression and protein level within druggable genes on CSVD in blood and brain tissues. Colocalization analyses and repeat studies were undertaken to verify the relationship. Additionally, mediation analysis was conducted to explore the potential mechanisms involving druggable genes and known risk factors for CSVD. Finally, phenome-wide MR analyses were applied to evaluate the potential adverse effects related to the identified druggable genes for CSVD treatment. RESULTS: Overall, 5 druggable genes consistently showed associations with CSVD in MR analyses across both the discovery and validation cohorts. Notably, the ALDH2 and KLHL24 genes were identified as associated with CSVD in both blood and brain tissues, whereas the genes ADRB1, BTN3A2, and EFEMP1 were exclusively detected in brain tissue. Moreover, mediation analysis elucidated the proportion of the total effects mediated by CSVD risk factors through candidate druggable genes, which ranged from 5.5% to 18.5%, and offered potential explanations for the observed results. A comprehensive phenome-wide MR analysis further emphasized both the therapeutic benefits and potential side effects of targeting these candidate druggable genes. CONCLUSIONS: This study provides genetic evidence supporting the potential therapeutic benefits of targeting druggable genes for treating CSVD, which will be useful for prioritizing CSVD drug development.

Improved Dementia Prediction in Cerebral Small Vessel Disease Using Deep Learning-Derived Diffusion Scalar Maps From T1.

BACKGROUND: Cerebral small vessel disease is the most common pathology underlying vascular dementia. In small vessel disease, diffusion tensor imaging is more sensitive to white matter damage and better predicts dementia risk than conventional magnetic resonance imaging sequences, such as T1 and fluid attenuation inversion recovery, but diffusion tensor imaging takes longer to acquire and is not routinely available in clinical practice. As diffusion tensor imaging-derived scalar maps-fractional anisotropy (FA) and mean diffusivity (MD)-are frequently used in clinical settings, one solution is to synthesize FA/MD from T1 images. METHODS: We developed a deep learning model to synthesize FA/MD from T1. The training data set consisted of 4998 participants with the highest white matter hyperintensity volumes in the UK Biobank. Four external validations data sets with small vessel disease were included: SCANS (St George's Cognition and Neuroimaging in Stroke; n=120), RUN DMC (Radboud University Nijmegen Diffusion Tensor and Magnetic Resonance Imaging Cohort; n=502), PRESERVE (Blood Pressure in Established Cerebral Small Vessel Disease; n=105), and NETWORKS (n=26), along with 1000 normal controls from the UK Biobank. RESULTS: The synthetic maps resembled ground-truth maps (structural similarity index >0.89 for MD maps and >0.80 for FA maps across all external validation data sets except for SCANS). The prediction accuracy of dementia using whole-brain median MD from the synthetic maps is comparable to the ground truth (SCANS ground-truth c-index, 0.822 and synthetic, 0.821; RUN DMC ground truth, 0.816 and synthetic, 0.812) and better than white matter hyperintensity volume (SCANS, 0.534; RUN DMC, 0.710). CONCLUSIONS: We have developed a fast and generalizable method to synthesize FA/MD maps from T1 to improve the prediction accuracy of dementia in small vessel disease when diffusion tensor imaging data have not been acquired.

Association and causal impact of TERT genetic variants on peripheral blood leukocyte telomere length and cerebral small vessel disease risk in a Chinese Han population: a mendelian randomization analysis.

BACKGROUND: Previous observational studies have highlighted potential relationships between the telomerase reverse transcriptase (TERT) gene, short leukocyte telomere length (LTL), and cerebrovascular disease. However, it remains to be established as to whether TERT gene variants are associated with an elevated risk of cerebral small vessel disease (CSVD), and whether there is a causal relationship between LTL and CSVD. METHODS: Five TERT single nucleotide polymorphisms (SNPs) were analyzed in 307 CSVD patients and 320 healthy controls in whom LTL values were quantified. Allele models and four genetic models were used to explore the relationship between these SNP genotypes and CSVD risk. A Mendelian randomization analysis of CSVD risk was then performed using LTL-related SNPs and the polygenic risk score (PRS) constructed from these SNPs as genetic instrumental variables to predict the causal relationship between LTL and CSVD risk. RESULTS: Model association analyses identified two SNPs that were significantly associated with CSVD risk. LTL was significantly correlated with age (P < 0.001), and the MR analysis revealed an association between short LTL and an elevated risk of CSVD. PRS-based genetic prediction of short LTLs was also significantly related to an elevated CSVD risk. CONCLUSION: Multiple genetic models and MR results indicate that TERT gene SNPs may be related to an elevated risk of CSVD, and that shorter LTL may be causally linked to such CSVD risk.

Augmentation of perivascular space visualization in basal ganglia and white matter hyperintensity lesion is a meaningful finding for subsequent cognitive decline.

BACKGROUND: Cerebral small vessel disease (CSVD) causes cognitive decline and perivascular space enlargement is one of the image markers for CSVD. PURPOSE: To search for clinical significance in the time-course augmentation of perivascular space in basal ganglia (BG-PVS) for cognitive decline. MATERIAL AND METHODS: This study population included 179 participants from a community-based cohort, aged 70 years at baseline. They had undergone magnetic resonance imaging (MRI) studies two or three times between 2000 and 2008. Based on the severity of BG-PVS or white matter hyperintensity lesions (WMHL) in 2000, the participants were divided into low-grade or high-grade groups, respectively. In addition, their time-course augmentation was evaluated, and we created a categorical BG-PVS WMHL change score based on their augmentation (1 = neither, 2 = BG-PVS augmentation only, 3 = WMHL augmentation only, 4 = both). Cognitive function was assessed based on the Mini-Mental State Examination (MMSE); the change was defined as the difference between scores in 2000 and 2008. We used simple or multiple regression analysis for MMSE score change according to MRI findings and clinical characteristics that were probably related to cognitive decline. RESULTS: In univariate analysis, MMSE score change was negatively associated with BG-PVS high grade at baseline and BG-PVS WMHL change score 4; this remained significant in multivariate analysis. In the final model based on the Akaike Information Criterion, BG-PVS WMHL change score 4 was associated with a 3.3-point decline in subsequent MMSE score. CONCLUSIONS: This study suggested that augmentation in both BG-PVS and WMHL was associated with subsequent cognitive decline.

Cerebrovascular Endothelial Dysfunction: Role of BACE1.

Dysfunctional endothelium is increasingly recognized as a mechanistic link between cardiovascular risk factors and dementia, including Alzheimer disease. BACE1 (ß-site amyloid-ß precursor protein-cleaving enzyme 1) is responsible for ß-processing of APP (amyloid-ß precursor protein), the first step in the production of Aß (amyloid-ß) peptides, major culprits in the pathogenesis of Alzheimer disease. Under pathological conditions, excessive activation of BACE1 exerts detrimental effects on endothelial function by Aß-dependent and Aß-independent mechanisms. High local concentration of Aß in the brain blood vessels is responsible for the loss of key vascular protective functions of endothelial cells. More recent studies recognized significant contribution of Aß-independent proteolytic activity of endothelial BACE1 to the pathogenesis of endothelial dysfunction. This review critically evaluates existing evidence supporting the concept that excessive activation of BACE1 expressed in the cerebrovascular endothelium impairs key homeostatic functions of the brain blood vessels. This concept has important therapeutic implications. Indeed, improved understanding of the mechanisms of endothelial dysfunction may help in efforts to develop new approaches to the protection and preservation of healthy cerebrovascular function.

Cerebrovascular Effects of Sildenafil in Small Vessel Disease: The OxHARP Trial.

BACKGROUND: Vascular cognitive impairment due to cerebral small vessel disease is associated with cerebral pulsatility, white matter hypoperfusion, and reduced cerebrovascular reactivity (CVR), and is potentially improved by endothelium-targeted drugs such as cilostazol. Whether sildenafil, a phosphodiesterase-5 inhibitor, improves cerebrovascular dysfunction is unknown. METHODS: OxHARP trial (Oxford Haemodynamic Adaptation to Reduce Pulsatility) was a double-blind, randomized, placebo-controlled, 3-way crossover trial after nonembolic cerebrovascular events with mild-moderate white matter hyperintensities (WMH), the most prevalent manifestation of cerebral small vessel disease. The primary outcome assessed the superiority of 3 weeks of sildenafil 50 mg thrice daily versus placebo (mixed-effect linear models) on middle cerebral artery pulsatility, derived from peak systolic and end-diastolic velocities (transcranial ultrasound), with noninferiority to cilostazol 100 mg twice daily. Secondary end points included the following: cerebrovascular reactivity during inhalation of air, 4% and 6% CO2 on transcranial ultrasound (transcranial ultrasound-CVR); blood oxygen-level dependent-magnetic resonance imaging within WMH (CVR-WMH) and normal-appearing white matter (CVR-normal-appearing white matter); cerebral perfusion by arterial spin labeling (magnetic resonance imaging pseudocontinuous arterial spin labeling); and resistance by cerebrovascular conductance. Adverse effects were compared by Cochran Q. RESULTS: In 65/75 (87%) patients (median, 70 years;79% male) with valid primary outcome data, cerebral pulsatility was unchanged on sildenafil versus placebo (0.02, -0.01 to 0.05; P=0.18), or versus cilostazol (-0.01, -0.04 to 0.02; P=0.36), despite increased blood flow (∆ peak systolic velocity, 6.3 cm/s, 3.5-9.07; P<0.001; ∆ end-diastolic velocity, 1.98, 0.66-3.29; P=0.004). Secondary outcomes improved on sildenafil versus placebo for CVR-transcranial ultrasound (0.83 cm/s per mm Hg, 0.23-1.42; P=0.007), CVR-WMH (0.07, 0-0.14; P=0.043), CVR-normal-appearing white matter (0.06, 0.00-0.12; P=0.048), perfusion (WMH: 1.82 mL/100 g per minute, 0.5-3.15; P=0.008; and normal-appearing white matter, 2.12, 0.66-3.6; P=0.006) and cerebrovascular resistance (sildenafil-placebo: 0.08, 0.05-0.10; P=4.9×10-8; cilostazol-placebo, 0.06, 0.03-0.09; P=5.1×10-5). Both drugs increased headaches (P=1.1×10-4), while cilostazol increased moderate-severe diarrhea (P=0.013). CONCLUSIONS: Sildenafil did not reduce pulsatility but increased cerebrovascular reactivity and perfusion. Sildenafil merits further study to determine whether it prevents the clinical sequelae of small vessel disease. REGISTRATION: URL: https://www.clinicaltrials.gov/study/NCT03855332; Unique identifier: NCT03855332.

The clinical characteristics of cerebral small vessel disease patients with motoric cognitive risk syndrome during single- and dual-task walking.

Objective: We aimed to (1) identify neuroimaging biomarkers of distinguishing motoric cognitive risk syndrome (MCRS) risk among older Chinese adults with cerebral small vessel disease (CSVD) and (2) detect differences in gait parameters and neuroimaging biomarkers between CSVD individual with and without MCRS, especially during dual-task walking (DTW). Methods: We enrolled 126 inpatients with CSVD who were divided into two groups according to MCRS status. Data on basic parameters, variability, asymmetry, and coordination were collected during single-task walking (STW) and DTW. Neuroimaging features (white matter hyperintensities, lacunes, and microbleeds) and total disease burden were calculated. Analysis of variance and logistic regression analyses were applied to assess the role of STW, DTW, and neuroimaging biomarkers in MCRS. Results: In total, 126 consecutive inpatients with CSVD were included (84 and 42 patients were classified as MCRS-negative and MCRS-positive, respectively). The MCRS-positive group showed poorer performance for nearly all gait parameters compared with the MCRS-negative group during cognitive DTW. Meanwhile, all gait parameters except asymmetry were assessed in participants with MCRS for significant deterioration during cognitive DTW compared with that during STW. However, only basic parameters differed between STW and cognitive DTW in participants without MCRS. A significant independent association between total CSVD scores and MCRS was also detected. Conclusions: For CSVD patients, with higher total CSVD burden rather than any single neuroimaging marker, was linked to a greater risk of MCRS. In addition, CSVD individuals with MCRS had higher variability and phase coordination index (PCI), especially in cognitive DTW. Thus, they should concentrate more on their gait variability or coordination and reduce secondary task loads while walking in daily life, especially in cognitive secondary tasks.

Hypertension control after intracerebral hemorrhage among varying small vessel disease etiologies.

INTRODUCTION: Intracerebral hemorrhage (ICH) is attributable to cerebral small vessel disease (cSVD), which includes cerebral amyloid angiopathy (CAA) and hypertensive-cSVD (HTN-cSVD). HTN-cSVD includes patients with strictly deep ICH/microbleeds and mixed location ICH/microbleeds, the latter representing a more severe form of HTN-cSVD. We test the hypothesis that more severe forms of HTN-cSVD are related to worse hypertension control in long-term follow-up after ICH. METHODS: From consecutive non-traumatic ICH patients admitted to a tertiary care center, we classified the ICH as CAA, strictly deep ICH/microbleeds, and mixed-location ICH/microbleeds. CSVD burden was quantified using a validated MRI-based score (range: 0-6 points). We created a multivariable (linear mixed effects) model adjusting for age, sex, race, year of inclusion, hypertension, and antihypertensive medication usage to investigate the association of average systolic blood pressure (SBP) during follow-up with cSVD etiology/severity. RESULTS: 796 ICH survivors were followed for a median of 48.8 months (IQR 41.5-60.4). CAA-related ICH survivors (n = 373) displayed a lower median SBP (138 mmHg, IQR 133-142 mmHg) compared to those of strictly deep ICH (n = 222, 141 mmHg, IQR 136-143 mmHg, p = 0.04), and mixed location ICH/microbleeds (n = 201, 142 mmHg, IQR 135-144 mmHg, p = 0.02). In the multivariable analysis, mixed location ICH/microbleeds (effect: + 3.8 mmHg, SE: 1.3 mmHg, p = 0.01) and increasing cSVD severity (+ 1.8 mmHg per score point, SE: 0.8 mmHg, p = 0.03) were associated with higher SBP in follow-up. CONCLUSION: CSVD severity and subtype predicts long-term hypertension control in ICH patients.

Association of Incident Stroke Risk With an IL-18-Centered Inflammatory Network Biomarker Composite.

BACKGROUND: A coordinated network of circulating inflammatory molecules centered on the pleotropic pro-atherogenic cytokine interleukin-18 (IL-18) is linked to cerebral small vessel disease. We sought to validate the association of this inflammatory biomarker network with incident stroke risk, cognitive impairment, and imaging metrics in a sample of the Framingham Offspring Cohort. METHODS: Using available baseline measurements of serum levels of IL-18, GDF (growth and differentiation factor)-15, soluble form of receptor for advanced glycation end products, myeloperoxidase, and MCP-1 (monocyte chemoattractant protein-1) from Exam 7 of the Framingham Offspring Cohort (1998-2001), we constructed a population-normalized, equally weighted log-transformed mean Z-score value representing the average level of each serum analyte to create an inflammatory composite score (ICS5). Multivariable regression models were used to determine the association of ICS5 with incident stroke, brain magnetic resonance imaging features, and cognitive testing performance. RESULTS: We found a significant association between ICS5 score and increased risk for incident all-cause stroke (hazard ratio, 1.48 [95% CI, 1.05-2.08]; P=0.024) and ischemic stroke (hazard ratio, 1.51 [95% CI, 1.03-2.21]; P=0.033) in the Exam 7 cohort of 2201 subjects (mean age 62±9 years; 54% female) aged 45+ years with an all-cause incident stroke rate of 6.1% (135/2201) and ischemic stroke rate of 4.9% (108/2201). ICS5 and its component serum markers are all associated with the Framingham Stroke Risk Profile score (ß±SE, 0.19±0.02; P<0.0001). In addition, we found a significant inverse association of ICS5 with a global cognitive score, derived from a principal components analysis of the neuropsychological battery used in the Framingham cohort (-0.08±0.03; P=0.019). No association of ICS5 with magnetic resonance imaging metrics of cerebral small vessel disease was observed. CONCLUSIONS: Circulating serum levels of inflammatory biomarkers centered on IL-18 are associated with an increased risk of stroke and cognitive impairment in the Framingham Offspring Cohort. Linking specific inflammatory pathways to cerebral small vessel disease may enhance individualized quantitative risk assessment for future stroke and vascular cognitive impairment.

Effect of the Blood Pressure and Antihypertensive Drugs on Cerebral Small Vessel Disease: A Mendelian Randomization Study.

BACKGROUND: Previous studies yielded conflicting results about the influence of blood pressure (BP) and antihypertensive treatment on cerebral small vessel disease. Here, we conducted a Mendelian randomization study to investigate the effect of BP and antihypertensive drugs on cerebral small vessel disease. METHODS: We extracted single-nucleotide polymorphisms for systolic BP and diastolic BP from a genome-wide association study (N=757 601) and screened single-nucleotide polymorphisms associated with calcium channel blockers, thiazides, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and ß-blockers from public resources as instrumental variables. Then, we chose the genome-wide association study of white matter hyperintensity (WMH; N=18 381), cerebral microbleed (3556 cases, 22 306 controls), white matter perivascular space (9317 cases, 29 281 controls), basal ganglia perivascular space (BGPVS; 8950 cases, 29 953 controls), hippocampal perivascular space (HIPPVS; 9163 cases, 29 708 controls), and lacunar stroke (6030 cases, 248 929 controls) as outcome data sets. Subsequently, we conducted a 2-sample Mendelian randomization analysis. RESULTS: We found that elevated systolic BP significantly increases the risk of BGPVS (odds ratio [OR], 1.05 [95% CI, 1.04-1.07]; P=1.72×10-12), HIPPVS (OR, 1.04 [95% CI, 1.02-1.05]; P=2.71×10-7), and lacunar stroke (OR, 1.41 [95% CI, 1.30-1.54]; P=4.97×10-15). There was suggestive evidence indicating that elevated systolic BP is associated with higher WMH volume (ß=0.061 [95% CI, 0.018-0.105]; P=5.58×10-3) and leads to an increased risk of cerebral microbleed (OR, 1.16 [95% CI, 1.04-1.29]; P=7.17×10-3). Elevated diastolic BP was significantly associated with higher WMH volume (ß=0.087 [95% CI, 0.049-0.124]; P=5.23×10-6) and significantly increased the risk of BGPVS (OR, 1.05 [95% CI, 1.04-1.06]; P=1.20×10-16), HIPPVS (OR, 1.03 [95% CI, 1.02-1.04]; P=2.96×10-6), and lacunar stroke (OR, 1.31 [95% CI, 1.21-1.41]; P=2.67×10-12). The use of calcium channel blocker to lower BP was significantly associated with lower WMH volume (ß=-0.287 [95% CI, -0.408 to -0.165]; P=4.05×10-6) and significantly reduced the risk of BGPVS (OR, 0.85 [95% CI, 0.81-0.89]; P=8.41×10-19) and HIPPVS (OR, 0.88 [95% CI, 0.85-0.92]; P=6.72×10-9). CONCLUSIONS: Our findings contribute to a better understanding of the pathogenesis of cerebral small vessel disease. Additionally, the utilization of calcium channel blockers to decrease BP can effectively reduce the likelihood of WMH, BGPVS, and HIPPVS. These findings offer valuable insights for the management and prevention of cerebral small vessel disease.

Relationship between Body Composition and Gait Characteristics in Patients with Cerebral Small Vessel Disease.

BACKGROUND: This study aims to explore the correlation between body composition, encompassing factors such as muscle mass and fat distribution, and gait performance during both single-task walking (STW) and dual-task walking (DTW) in patients diagnosed with cerebral small vessel disease (CSVD). METHODS: The data of hospitalized patients diagnosed with CSVD, including cadence, stride time, velocity and stride length, as well as information on variability, asymmetry and coordination during both STW and DTW, were assessed. The number of falls reported by each participant was also assessed. RESULTS: A total of 95 CSVD patients were assessed, and the results showed that individuals with low appendicular skeletal muscle mass (ASM), which includes both the low ASM group and the combination of low ASM and high body fat (BF) group, had reduced velocity or cadence, shortened stride length, and prolonged stride time across all walking modalities compared to the control group. Only the combination of the low ASM and high BF group exhibited a deterioration in the coefficient of variation (CV) for all basic parameters and the Phase Coordination Index (PCI) compared to the control group across all walking patterns. Conversely, patients in the high BF group displayed a decline in basic parameters, primarily during cognitive DTW. Concurrently, the high BF group showed a significant increase in the CV and the PCI compared to the control group only during cognitive DTW. Furthermore, regardless of gender, both ASM and BF independently correlated with the occurrence of falls. CONCLUSIONS: CSVD patients with varying body compositions could allocate different levels of attention to their daily walking routines.

Cardiovascular Management in Asymptomatic (Silent) Cerebral Microbleeds and Suspected Cerebral Amyloid Angiopathy.

Cerebral microbleeds (CMBs) detected on blood-sensitive magnetic resonance imaging sequences are usually a sign of an underlying cerebral small vessel disease such as sporadic cerebral amyloid angiopathy or sporadic nonamyloid small vessel pathology (eg, arteriolosclerosis). Much of the enduring interest in CMBs relates to their high prevalence (partly due to the widespread use of magnetic resonance imaging) in the context of stroke, cognitive impairment and in healthy individuals, and the clinical uncertainties created about the safety of antithrombotic medications due to their association with both future hemorrhagic and ischemic stroke. Historically, the research literature overwhelmingly emphasized the future hemorrhagic risk associated with CMBs, potentially leading to unnecessary withholding of treatments proven effective at preventing thrombosis, such as anticoagulants in patients with atrial fibrillation who happened to have some microbleeds. The lack of strong guidelines in this area contributes to wide variation in clinical practice. In this article, we critically review and discuss the implications of silent CMBs and cortical superficial siderosis (ie, without symptomatic intracerebral hemorrhage) in different clinical settings: the general population, patients with ischemic stroke, and the memory clinic. Emerging evidence, albeit not from randomized controlled trials, suggests that in most patients, CMBs alone should not prevent the use of antithrombotics or anticoagulants for stroke prevention, when they are otherwise indicated. Where possible, we provide specific suggestions for clinical care grounded in both the limited available literature and our personal clinical practice.

Strategic Lacunes Associated With Mild Cognitive Impairment in Rural Chinese Older Adults: A Population-Based Study.

BACKGROUND: Lacunes are associated with cognitive impairment. We sought to identify strategic lacune locations associated with mild cognitive impairment (MCI) and subtypes of MCI among older adults, and further to examine the role of white matter hyperintensities and perivascular spaces in the association. METHODS: This population-based cross-sectional study included 1230 dementia-free participants in the brain magnetic resonance imaging substudy (2018-2020) in MIND-China (Multimodal Interventions to Delay Dementia and Disability in Rural China). Lacunes were visually identified in frontal lobe, parieto-occipital lobe, temporal lobe, insula, basal ganglia, thalamus, cerebellum, and brainstem. MCI, amnestic MCI (aMCI), and nonamnestic MCI (naMCI) were defined following the Petersen's criteria. Data were analyzed using logistic regression models. RESULTS: Of the 1230 participants (age, ≥60 years; mean age, 69.40; SD, 4.30 years; 58.5% women), lacunes were detected in 357 people and MCI was defined in 286 individuals, including 243 with aMCI and 43 with naMCI. Lacunes in the supratentorial area, internal capsula, putamen/pallidum, and insula was significantly associated with increased odds ratio of MCI (multivariable-adjusted odds ratio ranged 1.40-3.21; P<0.05) and aMCI (multivariable-adjusted odds ratio ranged 1.46-3.36; P<0.05), whereas lacunes in the infratentorial area and brainstem were significantly associated with naMCI (multivariable-adjusted odds ratio ranged 2.68-3.46; P<0.01). Furthermore, the associations of lacunes in insula and internal capsula with MCI and aMCI, as well as the associations of lacunes in infratentorial area and brainstem with naMCI were present independent of white matter hyperintensities volume and perivascular spaces number. CONCLUSIONS: Lacunes in the internal capsula, putamen/pallidum, insula, and brainstem may represent the strategic lacunes that are independently associated with MCI, aMCI, or naMCI in Chinese older adults. REGISTRATION: URL: https://www.chictr.org.cn; Unique identifier: ChiCTR1800017758.

Does Thrombosis Play a Causal Role in Lacunar Stroke and Cerebral Small Vessel Disease?

BACKGROUND: The importance of thromboembolism in the pathogenesis of lacunar stroke (LS), resulting from cerebral small vessel disease (cSVD), is debated, and although antiplatelets are widely used in secondary prevention after LS, there is limited trial evidence from well-subtyped patients to support this approach. We sought to evaluate whether altered anticoagulation plays a causal role in LS and cSVD using 2-sample Mendelian randomization. METHODS: From a recent genome-wide association study (n=81 190), we used 119 genetic variants associated with venous thrombosis at genome-wide significance (P<5*10-8) and with a linkage disequilibrium r2<0.001 as instrumental variables. We also used genetic associations with stroke from the GIGASTROKE consortium (62 100 ischemic stroke cases: 10 804 cardioembolic stroke, 6399 large-artery stroke, and 6811 LS). In view of the lower specificity for LS with the CT-based phenotyping mainly used in GIGASTROKE, we also used data from patients with magnetic resonance imaging-confirmed LS (n=3199). We also investigated associations with more chronic magnetic resonance imaging features of cSVD, namely, white matter hyperintensities (n=37 355) and diffusion tensor imaging metrics (n=36 533). RESULTS: Mendelian randomization analyses showed that genetic predisposition to venous thrombosis was associated with an increased odds of any ischemic stroke (odds ratio [OR], 1.19 [95% CI, 1.13-1.26]), cardioembolic stroke (OR, 1.32 [95% CI, 1.21-1.45]), and large-artery stroke (OR, 1.41 [95% CI, 1.26-1.57]) but not with LS (OR, 1.07 [95% CI, 0.99-1.17]) in GIGASTROKE. Similar results were found for magnetic resonance imaging-confirmed LS (OR, 0.94 [95% CI, 0.81-1.09]). Genetically predicted risk of venous thrombosis was not associated with imaging markers of cSVD. CONCLUSIONS: These findings suggest that altered thrombosis plays a role in the risk of cardioembolic and large-artery stroke but is not a causal risk factor for LS or imaging markers of cSVD. This raises the possibility that antithrombotic medication may be less effective in cSVD and underscores the necessity for further trials in well-subtyped cohorts with LS to evaluate the efficacy of different antithrombotic regimens in LS.

Effect of Remote Ischemic Conditioning in Ischemic Stroke Subtypes: A Post Hoc Subgroup Analysis From the RESIST Trial.

BACKGROUND: Remote ischemic conditioning (RIC) is a simple and noninvasive procedure that has proved to be safe and feasible in numerous smaller clinical trials. Mixed results have been found in recent large randomized controlled trials. This is a post hoc subgroup analysis of the RESIST trial (Remote Ischemic Conditioning in Patients With Acute Stroke), investigating the effect of RIC in different acute ischemic stroke etiologies, and whether an effect was modified by treatment adherence. METHODS: Eligible patients were adults (aged ≥18 years), independent in activities of daily living, who had prehospital stroke symptoms with a duration of less than 4 hours. They were randomized to RIC or sham. The RIC treatment protocol consisted of 5 cycles with 5 minutes of cuff inflation alternating with 5 minutes with a deflated cuff. Acceptable treatment adherence was defined as when at least 80% of planned RIC cycles were received. The analysis was performed using the entire range (shift analysis) of the modified Rankin Scale (ordinal logistic regression). RESULTS: A total of 698 had acute ischemic stroke, 253 (36%) were women, and the median (interquartile range) age was 73 (63-80) years. Median (interquartile range) overall adherence to RIC/sham was 91% (68%-100%). In patients with a stroke due to cerebral small vessel disease, who were adherent to treatment, RIC was associated with improved functional outcome, and the odds ratio for a shift to a lower score on the modified Rankin Scale was 2.54 (1.03-6.25); P=0.042. The association remained significant after adjusting for potential confounders. No significant associations were found with other stroke etiologies, and the overall test for interaction was not statistically significant (χ2, 4.33, P=0.23). CONCLUSIONS: In patients with acute ischemic stroke due to cerebral small vessel disease, who maintained good treatment adherence, RIC was associated with improved functional outcomes at 90 days. These results should only serve as a hypothesis-generating for future trials. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03481777.

Prevention of Vascular Contributions to Cognitive Impairment and Dementia: The Role of Physical Activity and Exercise.

Vascular contributions to cognitive impairment and dementia, specifically cerebral small vessel disease (CSVD), are the second most common cause of dementia. Currently, there are no specific pharmacological treatments for CSVD, and the use of conventional antidementia drugs is not recommended. Exercise has the potential to prevent and mitigate CSVD-related brain damage and improve cognitive function. Mechanistic pathways underlying the neurocognitive benefits of exercise include the control of vascular risk factors, improving endothelial function, and upregulating exerkines. Notably, the therapeutic efficacy of exercise may vary by exercise type (ie, aerobic versus resistance training) and biological sex; thus, studies designed specifically to examine these moderating factors within a CSVD context are needed. Furthermore, future research should prioritize resistance training interventions, given their tremendous therapeutic potential. Addressing these knowledge gaps will help us refine exercise recommendations to maximize their therapeutic impact in the prevention and mitigation of CSVD.