Antithrombotic Treatment for Cervical Artery Dissection: A Systematic Review and Individual Patient Data Meta-Analysis.

Importance: Cervical artery dissection is the most common cause of stroke in younger adults. To date, there is no conclusive evidence on which antithrombotic therapy should be used to treat patients. Objective: To perform an individual patient data meta-analysis of randomized clinical trials comparing anticoagulants and antiplatelets in prevention of stroke after cervical artery dissection. Data Sources: PubMed.gov, Cochrane database, Embase, and ClinicalTrials.gov were searched from inception to August 1, 2023. Study Selection: Randomized clinical trials that investigated the effectiveness and safety of antithrombotic treatment (antiplatelets vs anticoagulation) in patients with cervical artery dissection were included in the meta-analysis. The primary end point was required to include a composite of (1) any stroke, (2) death, or (3) major bleeding (extracranial or intracranial) at 90 days of follow-up. Data Extraction/Synthesis: Two independent investigators performed a systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, and inconsistencies were resolved by a principal investigator. Main Outcomes and Measures: The primary outcome was a composite of (1) ischemic stroke, (2) death, or (3) major bleeding (extracranial or intracranial) at 90 days of follow-up. The components of the composite outcome were also secondary outcomes. Subgroup analyses based on baseline characteristics with a putative association with the outcome were performed. Logistic regression was performed using the maximum penalized likelihood method including interaction in the subgroup analyses. Results: Two randomized clinical trials, Cervical Artery Dissection in Stroke Study and Cervical Artery Dissection in Stroke Study and the Biomarkers and Antithrombotic Treatment in Cervical Artery Dissection, were identified, of which all participants were eligible. A total of 444 patients were included in the intention-to-treat population and 370 patients were included in the per-protocol population. Baseline characteristics were balanced. There were fewer primary end points in those randomized to anticoagulation vs antiplatelet therapy (3 of 218 [1.4%] vs 10 of 226 [4.4%]; odds ratio [OR], 0.33 [95% CI, 0.08-1.05]; P = .06), but the finding was not statistically significant. In comparison with aspirin, anticoagulation was associated with fewer strokes (1 of 218 [0.5%] vs 10 of 226 [4.0%]; OR, 0.14 [95% CI, 0.02-0.61]; P = .01) and more bleeding events (2 vs 0). Conclusions and Relevance: This individual patient data meta-analysis of 2 currently available randomized clinical trial data found no significant difference between anticoagulants and antiplatelets in preventing early recurrent events.

MINocyclinE to Reduce inflammation and blood-brain barrier leakage in small Vessel diseAse (MINERVA): A phase II, randomized, double-blind, placebo-controlled experimental medicine trial.

INTRODUCTION: Cerebral small vessel disease (SVD) is a common cause of stroke/vascular dementia with few effective treatments. Neuroinflammation and increased blood-brain barrier (BBB) permeability may influence pathogenesis. In rodent models, minocycline reduced inflammation/BBB permeability. We determined whether minocycline had a similar effect in patients with SVD. METHODS: MINERVA was a single-center, phase II, randomized, double-blind, placebo-controlled trial. Forty-four participants with moderate-to-severe SVD took minocycline or placebo for 3 months. Co-primary outcomes were microglial signal (determined using 11C-PK11195 positron emission tomography) and BBB permeability (using dynamic contrast-enhanced MRI). RESULTS: Forty-four participants were recruited between September 2019 and June 2022. Minocycline had no effect on 11C-PK11195 binding (relative risk [RR] 1.01, 95% confidence interval [CI] 0.98-1.04), or BBB permeability (RR 0.97, 95% CI 0.91-1.03). Serum inflammatory markers were not affected. DISCUSSION: 11C-PK11195 binding and increased BBB permeability are present in SVD; minocycline did not reduce either process. Whether these pathophysiological mechanisms are disease-causing remains unclear. INTERNATIONAL CLINICAL TRIALS REGISTRY PORTAL IDENTIFIER: ISRCTN15483452 HIGHLIGHTS: We found focal areas of increased microglial signal and increased blood-brain barrier permeability in patients with small vessel disease. Minocycline treatment was not associated with a change in these processes measured using advanced neuroimaging. Blood-brain barrier permeability was dynamic but MRI-derived measurements correlated well with CSF/serum albumin ratio. Advanced neuroimaging is a feasible outcome measure for mechanistic clinical trials.

Relationship of Perivascular Space Markers With Incident Dementia in Cerebral Small Vessel Disease.

BACKGROUND: Recent studies, using diffusion tensor image analysis along the perivascular space (DTI-ALPS), suggest impaired perivascular space (PVS) function in cerebral small vessel disease, but they were cross-sectional, making inferences on causality difficult. We determined associations between impaired PVS, measured using DTI-ALPS and PVS volume, and cognition and incident dementia. METHODS: In patients with lacunar stroke and confluent white matter hyperintensities, without dementia at baseline, recruited prospectively in a single center, magnetic resonance imaging was performed annually for 3 years, and cognitive assessments, including global, memory, executive function, and processing speed, were performed annually for 5 years. We determined associations between DTI-ALPS and PVS volume with cerebral small vessel disease imaging markers (white matter hyperintensity volume, lacunes, and microbleeds) at baseline and with changes in imaging markers. We determined whether DTI-ALPS and PVS volume at baseline and change over 3 years predicted incident dementia. Analyses were controlled for conventional diffusion tensor image metrics using 2 markers (median mean diffusivity [MD] and peak width of skeletonized MD) and adjusted for age, sex, and vascular risk factors. RESULTS: A total of 120 patients, mean age 70.0 years and 65.0% male, were included. DTI-ALPS declined over 3 years, while no change in PVS volume was found. Neither DTI-ALPS nor PVS volume was associated with cerebral small vessel disease imaging marker progression. Baseline DTI-ALPS was associated with changes in global cognition (ß=0.142, P=0.032), executive function (ß=0.287, P=0.027), and long-term memory (ß=0.228, P=0.027). Higher DTI-ALPS at baseline predicted a lower risk of dementia (hazard ratio, 0.328 [0.183-0.588]; P<0.001), and this remained significant after including median MD as a covariate (hazard ratio, 0.290 [0.139-0.602]; P<0.001). Change in DTI-ALPS predicted dementia conversion (hazard ratio, 0.630 [0.428-0.964]; P=0.048), but when peak width of skeletonized MD and median MD were entered as covariates, the association was not significant. There was no association between baseline PVS volume, or PVS change over 3 years, and conversion to dementia. CONCLUSIONS: DTI-ALPS predicts future dementia risk in patients with lacunar strokes and confluent white matter hyperintensities. However, the weakening of the association between change in DTI-ALPS and incident dementia after controlling for peak width of skeletonized MD and median MD suggests part of the signal may represent conventional diffusion tensor image metrics. PVS volume is not a predictor of future dementia risk.

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.

Are central and systemic inflammation associated with fatigue in cerebral small vessel disease?

BACKGROUND: Fatigue is a common symptom in cerebral small vessel disease (SVD), but its pathogenesis is poorly understood. It has been suggested that inflammation may play a role. We determined whether central (neuro) inflammation and peripheral inflammation were associated with fatigue in SVD. METHODS: Notably, 36 patients with moderate-to-severe SVD underwent neuropsychometric testing, combined positron emission tomography and magnetic resonance imaging (PET-MRI) scan, and blood draw for the analysis of inflammatory blood biomarkers. Microglial signal was taken as a proxy for neuroinflammation, assessed with radioligand 11C-PK11195. Of these, 30 subjects had full PET datasets for analysis. We assessed global 11C-PK11195 binding and hotspots of 11C-PK11195 binding in the normal-appearing white matter, lesioned tissue, and combined total white matter. Peripheral inflammation was assessed with serum C-reactive protein (CRP) and using the Olink cardiovascular III proteomic panel comprising 92 biomarkers of cardiovascular inflammation and endothelial activation. Fatigue was assessed using the fatigue severity scale (FSS), the visual analog fatigue scale, and a subscale of the Geriatric Depression Scale. RESULTS: Mean (SD) age was 68.7 (11.2) years, and 63.9% were male. Of these, 55.6% showed fatigue on the FSS. Fatigued participants had higher disability scores (p = 0.02), higher total GDS scores (p = 0.02), and more commonly reported a history of depression (p = 0.04). 11C-PK11195 ligand binding in the white matter was not associated with any measure of fatigue. Serum CRP was significantly associated with average fatigue score on FSS (ρ = 0.48, p = 0.004); this association persisted when controlling for age, sex, disability score, and depression (ß = 0.49, 95% CI (0.17, 2.26), p = 0.03). Blood biomarkers from the Olink panel showed no association with fatigue. CONCLUSION: In symptomatic SVD patients, neuroinflammation, assessed with microglial marker 11C-PK11195, was not associated with fatigue. We found some evidence for a role of systematic inflammation, evidenced by an association between fatigue severity and raised CRP, but further studies are required to understand this relationship and inform whether it could be therapeutically modified to reduce fatigue severity. DATA ACCESS STATEMENT: Data for this study are available from the corresponding author upon reasonable request.

Sleep Characteristics and Risk of Stroke and Dementia: An Observational and Mendelian Randomization Study.

BACKGROUND AND OBJECTIVES: Sleep disturbances are implicated as risk factors of both stroke and dementia. However, whether these associations are causal and whether treatment of sleep disorders could reduce stroke and dementia risk remain uncertain. We aimed to evaluate associations and ascertain causal relationships between sleep characteristics and stroke/dementia risk and MRI markers of small vessel disease (SVD). METHODS: We used data sets from a multicenter population-based study and summary statistics from genome-wide association studies (GWASs) of sleep characteristics and outcomes. We analyzed 502,383 UK Biobank participants with self-reported sleep measurements, including sleep duration, insomnia, chronotype, napping, daytime dozing, and snoring. In observational analyses, the primary outcomes were incident stroke, dementia, and their subtypes, alongside SVD markers. Hazard ratios (HRs) and odds ratios (ORs) were adjusted for age, sex, and ethnicity, and additional vascular risk factors. In Mendelian randomization (MR) analyses, ORs or risk ratios are reported for the association of each genetic score with clinical or MRI end points. RESULTS: Among 502,383 participants (mean [SD] age, 56.5 [8.1] years; 54.4% female), there were 7,668 cases of all-cause dementia and 10,334 strokes. In longitudinal analyses, after controlling for cardiovascular risk factors, participants with insomnia, daytime napping, and dozing were associated with increased risk of any stroke (HR 1.05, 95% CI 1.01-1.11, p = 8.53 × 10-3; HR 1.09, 95% CI 1.05-1.14, p = 3.20 × 10-5; HR 1.19, 95% CI 1.08-1.32, p = 4.89 × 10-4, respectively). Almost all sleep measures were associated with dementia risk (all p < 0.001, except insomnia). Cross-sectional analyses identified associations between napping, snoring, and MRI markers of SVD (all p < 0.001). MR analyses supported a causal link between genetically predicted insomnia and increased stroke risk (OR 1.31, 95% CI 1.13-1.51, p = 0.00072), but not with dementia or SVD markers. DISCUSSION: We found that multiple sleep measures predicted future risk of stroke and dementia, but these associations were attenuated after controlling for cardiovascular risk factors and were absent in MR analyses for Alzheimer disease. This suggests possible confounding or reverse causation, implying caution before proposing sleep disorder modifications for dementia treatment.

Prevalence, clinical characteristics, and risk factors of intracerebral haemorrhage in CADASIL: a case series and systematic review.

BACKGROUND: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is the most common monogenic form of stroke and is characterised by early onset stroke and dementia. Most strokes are lacunar ischaemic strokes, but intracerebral haemorrhage (ICH) has also been reported, although there are limited published data on its frequency and characteristics. METHODS: A retrospective review of a prospectively recruited CADASIL register from the British National Referral clinic was performed to identify acute ICH cases and their characteristics. In addition, a systematic review of ICH in CADASIL was performed. MEDLINE (Pubmed), Embase, and Web of Science were searched for articles published from inception until 31/05/2023. RESULTS: Ten cases of ICH were identified from the National clinic register of 516 symptomatic patients, giving an estimated point prevalence of 1.9%. An additional 119 cases were identified from the systematic review, comprising 129 cases and 142 ICH events in total. Including all identified cases, the mean age at onset of ICH was 56.6 ± 15.7 (SD) years, and 74 (57.4%) were male. ICH was the first manifestation of the disease in 32 patients (38.1%), and ICH recurrence occurred in 16 (12.4%). Most ICHs were subcortical, with the thalamus, 58 (40.8%), and basal ganglia, 34 (23.9%), being the commonest sites. Anticoagulation, but not antiplatelet agents, was associated with an increased risk of ICH (20.0% vs. 1.9%, p = 0.006). CONCLUSIONS: ICH is a relatively rare manifestation of CADASIL, occurring in about 2% of symptomatic cases. Most of the haemorrhages occurred in the subcortical regions.

Apathy After Stroke: Incidence, Symptom Trajectory, and Impact on Quality of Life and Disability

BACKGROUND AND OBJECTIVES: Apathy is one of the most common symptoms following stroke and is often associated with worse functional outcome and poor quality of life (QoL). The trajectory of apathy symptoms has been previously described, and different trajectories have been identified. We determined group and individual changes in apathy symptomatology from the acute phase until 1 year after stroke. We also examined the association of apathy and depression with disability and QoL 1 year after stroke. METHODS: We measured apathy in a cohort of ischemic stroke survivors at 4 time points from 0 to 12 months after stroke. The Apathy Evaluation Scale (AES) and Dimensional Apathy Scale (DAS) were administered at each time point. Where possible we obtained apathy measured from carers. Depression was assessed with the Geriatric Depression Scale (GDS). Disability and QoL were assessed with the modified Rankin Scale (mRS) and 36-Item Short Form Survey (SF-36). We examined the cross-sectional and individual trajectory of apathy symptoms in each dimension and looked at associations of apathy and depression soon after stroke with mRS and SF-36 at 1 year. RESULTS: Of 200 participants enrolled, 165 completed apathy measures at 12 months. Patient-rated apathy scores increased in both tests at the group level (AES: χ2(3) = 9.86, p = 0.019; DAS: χ2(3) = 8.49, p = 0.037) and individual level (AES: ß = 0.13, p = 0.002; DAS ß = 0.13, p = 0.005; DAS: executive ß = 0.08, p < 0.001). By contrast, carer-rated apathy did not significantly increase (AES: χ2(3) = 0.75, p = 0.862; DAS: χ2(3) = 2.45, p = 0.484). Apathy scores were associated with worse mRS and SF-36, although most associations were no longer significant when controlling for depression. GDS was associated with worse mRS and SF-36 after controlling for covariates and apathy (mRS: ß = 0.08, p = 0.006; SF-36 Mental Component Summary: ß = -1.53, p < 0.001; SF-36 Physical Component Summary: ß = -0.57, p = 0.016). DISCUSSION: Self-reported apathy progressively increases after stroke, especially in the executive dimension. Apathy is associated with worse QoL and greater disability, although some of these associations might be mediated by depression.

Cerebral Small Vessel Disease, Hypertension, and Vascular Contributions to Cognitive Impairment and Dementia.

Hypertension-associated cerebral small vessel disease is a common finding in older people. Strongly associated with age and hypertension, small vessel disease is found at autopsy in over 50% of people aged ≥65 years, with a spectrum of clinical manifestations. It is the main cause of lacunar stroke and a major source of vascular contributions to cognitive impairment and dementia. The brain areas affected are subcortical and periventricular white matter and deep gray nuclei. Neuropathological sequelae are diffuse white matter lesions (seen as white matter hyperintensities on T2-weighted magnetic resonance imaging), small ischemic foci (lacunes or microinfarcts), and less commonly, subcortical microhemorrhages. The most common form of cerebral small vessel disease is concentric, fibrotic thickening of small penetrating arteries (up to 300 microns outer diameter) termed arteriolosclerosis. Less common forms are small artery atheroma and lipohyalinosis (the lesions described by C. Miller Fisher adjacent to lacunes). Other microvascular lesions that are not reviewed here include cerebral amyloid angiopathy and venous collagenosis. Here, we review the epidemiology, neuropathology, clinical management, genetics, preclinical models, and pathogenesis of hypertensive small vessel disease. Knowledge gaps include initiating factors, molecular pathogenesis, relationships between arterial pathology and tissue damage, possible reversibility, pharmacological targets, and molecular biomarkers. Progress is anticipated from multicell transcriptomic and proteomic profiling, novel experimental models and further target-finding and interventional clinical studies.

A multi-disciplinary commentary on preclinical research to investigate vascular contributions to dementia.

Although dementia research has been dominated by Alzheimer's disease (AD), most dementia in older people is now recognised to be due to mixed pathologies, usually combining vascular and AD brain pathology. Vascular cognitive impairment (VCI), which encompasses vascular dementia (VaD) is the second most common type of dementia. Models of VCI have been delayed by limited understanding of the underlying aetiology and pathogenesis. This review by a multidisciplinary, diverse (in terms of sex, geography and career stage), cross-institute team provides a perspective on limitations to current VCI models and recommendations for improving translation and reproducibility. We discuss reproducibility, clinical features of VCI and corresponding assessments in models, human pathology, bioinformatics approaches, and data sharing. We offer recommendations for future research, particularly focusing on small vessel disease as a main underpinning disorder.

HDAC9 Inhibition as a Novel Treatment for Stroke.

The identification of a variant in the HDAC9 gene as a risk factor for large-artery atherosclerotic stroke, and subsequently coronary artery disease, has opened novel treatment pathways for stroke and more widely atherosclerotic disease. This article describes the pathway from gene discovery to novel therapeutic approaches that are now entering man. HDAC9 expression is elevated in human atherosclerotic plaque, while in animal and cellular models, reducing HDAC9 (histone deacetylase 9) protein is associated with reduced disease. Several mechanisms have been proposed to account for the association between HDAC9 and atherosclerosis including alterations in the inflammatory response and cholesterol efflux and endothelial-mesenchymal transition. The association raises the possibility that inhibiting HDAC9 may provide a novel treatment approach for atherosclerotic cardiovascular disease. This is supported by intervention studies demonstrating HDAC9 inhibition reduces atherosclerosis in animal and cellular models. Indirect data support such an approach in man. The antiseizure drug sodium valproate, which has nonspecific HDAC inhibitory properties, both inhibits atherosclerosis in animal models and is epidemiologically associated with reduced stroke and myocardial infarction risk in man. It is now being trailed in phase 2 studies in large-artery stroke, while more specific HDAC9 inhibitors are being developed.

A novel human iPSC model of COL4A1/A2 small vessel disease unveils a key pathogenic role of matrix metalloproteinases.

Cerebral small vessel disease (SVD) affects the small vessels in the brain and is a leading cause of stroke and dementia. Emerging evidence supports a role of the extracellular matrix (ECM), at the interface between blood and brain, in the progression of SVD pathology, but this remains poorly characterized. To address ECM role in SVD, we developed a co-culture model of mural and endothelial cells using human induced pluripotent stem cells from patients with COL4A1/A2 SVD-related mutations. This model revealed that these mutations induce apoptosis, migration defects, ECM remodeling, and transcriptome changes in mural cells. Importantly, these mural cell defects exert a detrimental effect on endothelial cell tight junctions through paracrine actions. COL4A1/A2 models also express high levels of matrix metalloproteinases (MMPs), and inhibiting MMP activity partially rescues the ECM abnormalities and mural cell phenotypic changes. These data provide a basis for targeting MMP as a therapeutic opportunity in SVD.

Genetic Insights on the Relation of Vascular Risk Factors and Cervical Artery Dissection.

BACKGROUND: The association between vascular risk factors and cervical artery dissections (CeADs), a leading cause of ischemic stroke (IS) in the young, remains controversial. OBJECTIVES: This study aimed to explore the causal relation of vascular risk factors with CeAD risk and recurrence and compare it to their relation with non-CeAD IS. METHODS: This study used 2-sample Mendelian randomization analyses to explore the association of blood pressure (BP), lipid levels, type 2 diabetes, waist-to-hip ratio, smoking, and body mass index with CeAD and non-CeAD IS. To simulate effects of the most frequently used BP-lowering drugs, this study constructed genetic proxies and tested their association with CeAD and non-CeAD IS. In analyses among patients with CeAD, the investigators studied the association between weighted genetic risk scores of vascular risk factors and the risk of multiple or early recurrent dissections. RESULTS: Genetically determined higher systolic BP (OR: 1.51; 95% CI: 1.32-1.72) and diastolic BP (OR: 2.40; 95% CI: 1.92-3.00) increased the risk of CeAD (P < 0.0001). Genetically determined higher body mass index was inconsistently associated with a lower risk of CeAD. Genetic proxies for ß-blocker effects were associated with a lower risk of CeAD (OR: 0.65; 95% CI: 0.50-0.85), whereas calcium-channel blockers were associated with a lower risk of non-CeAD IS (OR: 0.75; 95% CI: 0.63-0.90). Weighted genetic risk scores for systolic BP and diastolic BP were associated with an increased risk of multiple or early recurrent CeAD. CONCLUSIONS: These results are supportive of a causal association between higher BP and increased CeAD risk and recurrence and provide genetic evidence for lower CeAD risk under ß-blockers. This may inform secondary prevention strategies and trial design for CeAD.

Predicting incident dementia in cerebral small vessel disease: comparison of machine learning and traditional statistical models.

Background: Cerebral small vessel disease (SVD) contributes to 45% of dementia cases worldwide, yet we lack a reliable model for predicting dementia in SVD. Past attempts largely relied on traditional statistical approaches. Here, we investigated whether machine learning (ML) methods improved prediction of incident dementia in SVD from baseline SVD-related features over traditional statistical methods. Methods: We included three cohorts with varying SVD severity (RUN DMC, n = 503; SCANS, n = 121; HARMONISATION, n = 265). Baseline demographics, vascular risk factors, cognitive scores, and magnetic resonance imaging (MRI) features of SVD were used for prediction. We conducted both survival analysis and classification analysis predicting 3-year dementia risk. For each analysis, several ML methods were evaluated against standard Cox or logistic regression. Finally, we compared the feature importance ranked by different models. Results: We included 789 participants without missing data in the survival analysis, amongst whom 108 (13.7%) developed dementia during a median follow-up of 5.4 years. Excluding those censored before three years, we included 750 participants in the classification analysis, amongst whom 48 (6.4%) developed dementia by year 3. Comparing statistical and ML models, only regularised Cox/logistic regression outperformed their statistical counterparts overall, but not significantly so in survival analysis. Baseline cognition was highly predictive, and global cognition was the most important feature. Conclusions: When using baseline SVD-related features to predict dementia in SVD, the ML survival or classification models we evaluated brought little improvement over traditional statistical approaches. The benefits of ML should be evaluated with caution, especially given limited sample size and features.

Reproducibility of regional structural and functional MRI networks in cerebral small vessel disease compared to age matched and stroke-free controls.

Abnormalities in structural and functional MRI connectivity measures have been reported in cerebral small vessel disease (SVD). Previous research has shown that whole-brain structural connectivity was highly reproducible in SVD patients, while whole-brain functional connectivity showed low reproducibility. It remains unclear whether the lower reproducibility of functional networks reported in SVD is due to selective disruption of reproducibility in specific networks or is generalised in patients with SVD. In this case-control study 15 SVD and 10 age-matched control participants were imaged twice with diffusion tensor imaging and resting state fMRI. Structural and functional connectivity matrices were constructed from this data and the default mode, fronto-parietal, limbic, salience, somatomotor and visual networks were extracted and the average connectivity between connections calculated and used to determine their reproducibility. Regional structural networks were more reproducible than functional networks, all structural networks showed ICC values ≥0.64 (except the salience network in SVD). The functional networks showed greater reproducibility in the controls compared to SVD with ICC values >0.7 for control participants and <=0.5 for the SVD group. The default mode network showed the greatest reproducibility for both control and SVD groups. Reproducibility of functional networks was affected by disease status with lower reproducibility in SVD compared with controls.