Determinants of Perivascular Spaces in the General Population: A Pooled Cohort Analysis of Individual Participant Data

Avenues in the Analysis of Enlarged Perivascular Spaces Quantified from Brain Magnetic Resonance Images Acquired at 1.5T and 3T Magnetic Field Strengths

MR imaging-visible perivascular spaces (PVS) have been associated with disease phenotypes, risk factors, sleep measures, and overall brain health. We review avenues in the analysis of PVS quantified from brain MR imaging across dissimilar acquisition protocols, imaging modalities, scanner manufacturers and magnetic field strengths. We conduct a pilot analysis to evaluate different avenues to harmonise PVS assessments from using different parameters using brain MR imaging from 100 adult volunteers, acquired at two different magnetic field strengths with different sequence parameters. The 2024 MICCAI Enlarged Perivascular Spaces Segmentation Challenge provides a representative MRI dataset on which to test other harmonization methods.

Associations Between GFAP, Aβ42/40 Ratio, and Perivascular Spaces and Cognitive Domains in Vascular Cognitive Impairment

Perivascular spaces (PVS) support metabolic clearance in the brain and are increasingly recognized as key contributors to dementia pathogenesis. Plasma-based biomarkers, such as glial fibrillary acidic protein (GFAP) and the amyloid β42/40 (Aβ42/40) ratio, show promise in dementia diagnosis but remain understudied in vascular cognitive impairment (VCI). VCI, a major global cause of cognitive decline, may be more prevalent in Southeast Asia. Despite its impact, it is underdiagnosed compared to Alzheimer's, highlighting the need for early, reliable markers. This study aims to examine how these biomarkers relate to PVS burden and domain-specific cognitive outcomes in VCI. VCI was defined as global cognition as assessed by a Montreal Cognitive Assessment Score <26, along with the presence of confluent white matter hyperintensities (deep white matter hyperintensities score >2 or periventricular hyperintensities >3), and >1 lacuna. A total of 108 participants (mean age of 67.3 years, 51.9% female) were included. Multivariate ordinal regression assessed biomarker associations with PVS grade, adjusting for age and diastolic blood pressure. A Aβ42/40 ratio <0.05 and GFAP >54.1 pg/mL were used as biomarker thresholds to subgroup the participants, and the relationship between these thresholds and cognitive performance was analyzed. Elevated GFAP (p = 0.0438) and a reduced Aβ42/40 ratio (p < 0.01) were correlated with a higher PVS grade. In the subgroup with a low Aβ42/40 ratio, a greater PVS burden was associated with poorer executive function (p = 0.045, β = 0.612), while in those with high GFAP levels, it was linked to more pronounced impairments in learning and memory (p = 0.006, β = 0.375). A lower Aβ42/40 ratio and higher GFAP levels track greater PVS burden in VCI. PVS severity may be associated with domain-specific cognitive decline, highlighting the potential utility of these biomarkers in refining clinical assessments and monitoring disease progression.

Diffusion along Perivascular Spaces as a Marker for Glymphatic System Impairment in Huntington's Disease

BACKGROUND

The aim was to investigate if glymphatic function is impaired in patients with Huntington's disease (HD) and its clinical relevance.

METHODS

Forty-nine subjects carrying mutant Huntingtin (mHTT), comprising 35 manifest (mHD) and 14 pre-manifest (PreHD), and 35 healthy controls (HC) were recruited in this study. The diffusion along perivascular spaces (ALPS) index and the percentage of perivascular space in the basal ganglia (pPVS_BG) were obtained in different groups. The discrimination effects of ALPS index were detected using receiver operating characteristic (ROC) analysis, and the correlations of ALPS index with clinical features of HD were further analyzed.

RESULTS

ALPS index was decreased in mHTT carriers compared to HCs, and it was lower in mHD compared to PreHD patients. ROC analysis showed that the ALPS index could discriminate mHTT from HC (AUC [area under the curve] = 0.903), mHD from PreHD (AUC = 0.886), and PreHD from controls (AUC = 0.755). Lower ALPS index correlated with greater disease burden, severity of the disease, lager pPVS_BG, and lower brain volume and thickness of cortices. Regression analysis showed that ALPS index could predict the performance of motor and cognitive functions. Mediation analysis revealed that ALPS partially mediated the effects of CAG repeat and age on the cognitive decline in HD.

CONCLUSIONS

This study demonstrated that the impairment of the glymphatic system, especially in the paraventricular white matter and BG, was correlated with the clinical manifestations, disease burden, and brain structural changes in mHTT carriers. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Imaging brain fluid dynamics and waste clearance involving perivascular spaces in cerebral small vessel disease

Cerebral small vessel disease (SVD) is recognized as a major vascular contributor to cognitive decline, ultimately leading to dementia and stroke. While the pathogenesis of SVD remains unclear, emerging evidence suggests that waste clearance involving perivascular space (PVS) - also known as the glymphatic system - dysfunction may play a role. Among SVD radiological markers, the increased presence of dilated PVS is recognized as a marker of waste clearance disruption. Recently developed neuroimaging methods have been proposed as indirect measures of brain fluid dynamics, but they currently lack formal validation. Here, we provide a comprehensive overview of the latest neuroimaging advancements for assessing brain fluid dynamics, including waste clearance involving PVS function in SVD. We review the mechanisms by which clearance dysfunction might contribute to SVD. Finally, we argue that robust, multimodal, and longitudinal studies are essential for understanding the waste clearance (involving PVS) function and for establishing a diagnostic gold standard. HIGHLIGHTS: The majority of PVS are not visible on MRI, making it crucial to understand how and why they become dilated. The origin of waste clearance involving PVS disruption in SVD may be multifactorial. The BBB and waste clearance (involving PVS) dysfunction likely affect each other, forming a vicious cycle, promoting further amyloid beta accumulation. Yet their direct association in humans over time remains to be studied. Comparative studies can aid in the standardization of methods for assessing waste clearance involving PVS function.

Cerebral Small Vessel Disease Outperforms Brain Atrophy as an Imaging Biomarker in Diabetic Retinopathy

AIM

This study aimed to examine microvascular lesions and neurodegenerative changes in diabetic retinopathy (DR) compared to type 2 diabetes mellitus (T2DM) without DR (NDR) using structural MRI and to explore their associations with DR.

METHODS

243 patients with NDR and 122 patients with DR were included. Participants underwent conventional brain MRI scans, clinical measurements, and fundus examinations. Cerebral small vessel disease (CSVD) imaging parameters were obtained using AI-based software, manually verified, and corrected for accuracy. Volumes of major cortical and subcortical regions representing neurodegeneration were assessed using automated brain segmentation and quantitative techniques. Statistical analysis included T-test, chi-square test, Mann-Whitney U test, multivariate analysis of variance (MANCOVA), multivariate logistic regression, area under the receiver operating characteristic curve (AUC), and Delong test.

RESULTS

DR group exhibited significant differences in 11 CSVD features. Meanwhile, DR showed an atrophy trend in the frontal cortex, occipital cortex, and subcortical gray matter (GM) compared to NDR. After adjustment, DR patients exhibited greater perivascular spaces (PVS) numbers in the parietal lobe (OR = 1.394) and deep brain regions (OR = 1.066), greater dilated perivascular spaces (DPVS) numbers in the left basal ganglia (OR = 2.006), greater small subcortical infarcts (SSI) numbers in the right hemisphere (OR = 3.104), and decreased left frontal PVS (OR = 0.824), total left DPVS (OR = 0.714), and frontal cortex volume (OR = 0.959) compared to NDR. Further, the CSVD model showed a larger AUC (0.823, 95% CI: 0.781-0.866) than the brain atrophy model (AUC = 0.757, 95% CI: 0.706-0.808).

CONCLUSION

Microvascular and neurodegeneration are significantly associated with DR. CSVD is a better imaging biomarker for DR than brain atrophy.

Rewiring of the glymphatic landscape in metabolic disorders

The incorporation of the glymphatic clearance system in the study of brain physiology aids in the advancement of innovative diagnostic and treatment strategies for neurological disorders. Exploring the glymphatic system across (from) neurological and (to) metabolic diseases may provide a better link between obesity and neurological disorders. Recent studies indicate the role of metabolic dysfunction as a risk factor for cognitive decline and neurological disorders through the disruption of the glymphatic system. Further investigation into how metabolic dysfunction disrupts glymphatic homeostasis and the domino effects on the neurovascular landscape, including neurovascular uncoupling, cerebral blood flow disruptions, blood-brain barrier leakage, and demyelination, can provide mechanistic insights into the link between obesity and neurological disorders.

Clinical Relevance of Different Loads of Perivascular Spaces According to Their Localization in Patients with a Recent Small Subcortical Infarct

Background and Purpose: Perivascular spaces (PVS) are usually enlarged in small vessel disease (SVD). However, the significance of PVS patterns in different locations is uncertain. Hence, we analyzed the distribution of PVS in patients with a recent small subcortical infarct (RSSI) and their correlation with clinical and imaging factors. Materials and Methods: In a cohort of 71 patients with an RSSI with complete clinical data, including the Pittsburgh Sleep Quality Index (PSQI), we segmented PVS in white matter (WM-PVS), basal ganglia (BG-PVS), and brainstems (BS-PVS) on 3T-MRI T2-weighted sequences, obtaining fractional volumes (%), and calculated the WM/BG-PVS ratio. We analyzed the Pearson's correlation coefficients between PVS regional loads. We used normalized PVS measures to assess the associations with clinical and MRI-SVD features (white matter hyperintensities (WMHs), number of lacunes, and microbleeds) in univariable and multivariable linear regressions adjusted for age, sex, and hypertension. Results: In our cohort (mean age 70 years; 27% female), the Pearson's correlation coefficients between WM-PVS/BG-PVS, WM-PVS/BS-PVS, and BG-PVS/BS-PVS were 0.67, 0.61, and 0.59 (all p < 0.001). In the adjusted models, BG-PVS were associated with lacunes (p = 0.034), WMHs (p = 0.006), and microbleeds (p = 0.017); WM-PVS with lacunes (p = 0.003); while BS-PVS showed no associations. The WM/BG-PVS ratio was associated with lacunes (p = 0.018) and the PSQI (p = 0.046). Conclusions: PVS burdens in different regions are highly correlated in patients with RSSI but with different SVD patterns. Sleep quality impairment might affect waste removal mechanisms differently in the WM and BG regions.

Perivascular space enlargement accelerates in ageing and Alzheimer's disease pathology: evidence from a three-year longitudinal multicentre study

BACKGROUND

Perivascular space (PVS) enlargement in ageing and Alzheimer's disease (AD) and the drivers of such a structural change in humans require longitudinal investigation. Elucidating the effects of demographic factors, hypertension, cerebrovascular dysfunction, and AD pathology on PVS dynamics could inform the role of PVS in brain health function as well as the complex pathophysiology of AD.

METHODS

We studied PVS in centrum semiovale (CSO) and basal ganglia (BG) computationally over three to four annual visits in 503 participants (255 females; meanage = 70.78 ± 5.78) of the ongoing observational multicentre "DZNE Longitudinal Cognitive Impairment and Dementia Study" (DELCODE) cohort. We analysed data from subjects who were cognitively unimpaired (n = 401), had amnestic mild cognitive impairment (n = 71), or had AD (n = 31). We used linear mixed-effects modelling to test for changes of PVS volumes in relation to cross-sectional and longitudinal age, as well as sex, years of education, hypertension, white matter hyperintensities, AD diagnosis, and cerebrospinal-fluid-derived amyloid (A) and tau (T) status (available for 46.71%; A-T-/A + T-/A + T + n = 143/48/39).

RESULTS

PVS volumes increased significantly over follow-ups (CSO: B = 0.03 [0.02, 0.05], p < 0.001; BG: B = 0.05 [0.03, 0.07], p < 0.001). PVS enlargement rates varied substantially across subjects and depended on the participant's age, white matter hyperintensities volumes, and amyloid and tau status. PVS volumes were higher across elderly participants, regardless of region of interest (CSO: B = 0.12 [0.02, 0.21], p = 0.017; BG: B = 0.19 [0.09, 0.28], p < 0.001). Faster BG-PVS enlargement related to lower baseline white matter hyperintensities volumes (ρspearman = -0.17, pFDR = 0.001) and was more pronounced in individuals who presented with combined amyloid and tau positivity versus negativity (A + T +  > A-T-, pFDR = 0.004) or who were amyloid positive but tau negative (A + T +  > A + T-, pFDR = 0.07). CSO-PVS volumes increased at a faster rate with amyloid positivity as compared to amyloid negativity (A + T-/A + T +  > A-T-, pFDR = 0.021).

CONCLUSION

Our longitudinal evidence supports the relevance of PVS enlargement in presumably healthy ageing as well as in AD pathology. We further discuss the region-specific involvement of white matter hyperintensities and neurotoxic waste accumulation in PVS enlargement and the possibility of additional factors contributing to PVS progression. A comprehensive understanding of PVS dynamics could facilitate the understanding of pathological cascades and might inform targeted treatment strategies.

TRIAL REGISTRATION

German Clinical Trials Register DRKS00007966. Registered 04.05.2015 - retrospectively registered, https://drks.de/search/en/trial/DRKS00007966 .

Dose-Dependent Effect of Current Smoking on Enlarged Perivascular Space Identified on Brain Magnetic Resonance Imaging

INTRODUCTION

Cerebral small-vessel disease (CSVD) is a common cause of cognitive decline and stroke. Several studies have shown that smoking is a risk factor for CSVD progression. However, the extent to which smoking exacerbates CSVD lesions remains unclear. In this study, we aimed to clarify the association between total smoking exposure and the severity of CSVD in healthy participants.

METHODS

We analyzed the data of participants aged ≥50 years who underwent brain screening. The participants' age, sex, body mass index, alcohol consumption history, and medical history (hypertension, diabetes mellitus, and dyslipidemia) were investigated. Smoking status was assessed in pack-years, and smokers were classified as current or past smokers. CSVD findings on magnetic resonance imaging were used to evaluate the severity of periventricular hyperintensity (PVH), deep subcortical white matter hyperintensity (DSWMH), and enlarged perivascular spaces (EPVSs). The EPVSs were measured in the basal ganglia and centrum semiovale regions. Multivariable ordinal logistic regression analyses were performed to evaluate the effect of smoking, adjusted for the participants' baseline characteristics.

RESULTS

A total of 2,137 participants were included in this study. The mean age of the participants was 58.7 years. The mean pack-years were 20.5 for past smokers and 26.8 for current smokers. Among current smokers, increased pack-years were significantly associated with a high EPVS burden in the basal ganglia (odds ratio: 1.14, 95% confidence interval: 1.00-1.28), whereas no such significant association was found for past smokers. No statistically significant association was found between pack-years and the risks of PVH, DSWMH, or EPVS in the centrum semiovale.

CONCLUSION

Current smoking was associated with a dose-dependent risk of EPVS in the basal ganglia in healthy participants.

Development and validation of a perivascular space segmentation method in multi-center datasets

BACKGROUND

Perivascular spaces (PVS) visible on magnetic resonance imaging (MRI) are significant markers associated with various neurological diseases. Although quantitative analysis of PVS may enhance sensitivity and improve consistency across studies, the field lacks a universally validated method for analyzing images from multi-center studies.

METHODS

We annotated PVS on multi-center 3D T1-weighted (T1w) images acquired using scanners from three major vendors (Siemens, General Electric, and Philips). A neural network, mcPVS-Net (multi-center PVS segmentation network), was trained using data from 40 subjects and then tested in a separate cohort of 15 subjects. We assessed segmentation accuracy against ground truth masks tailored for each scanner vendor. Additionally, we evaluated the agreement between segmented PVS volumes and visual scores for each scanner. We also explored correlations between PVS volumes and various clinical factors such as age, hypertension, and white matter hyperintensities (WMH) in a larger sample of 1020 subjects. Furthermore, mcPVS-Net was applied to a new dataset comprising both T1w and T2-weighted (T2w) images from a United Imaging scanner to investigate if PVS volumes could discriminate between subjects with differing visual scores. We also compared the mcPVS-Net with a previously published method that segments PVS from T1 images.

RESULTS

In the test dataset, mcPVS-Net achieved a mean DICE coefficient of 0.80, with an average Precision of 0.81 and Recall of 0.79, indicating good specificity and sensitivity. The segmented PVS volumes were significantly associated with visual scores in both the basal ganglia (r = 0.541, p < 0.001) and white matter regions (r = 0.706, p < 0.001), and PVS volumes were significantly different among subjects with varying visual scores. Segmentation performance was consistent across different scanner vendors. PVS volumes exhibited significant associations with age, hypertension, and WMH. In the United Imaging scanner dataset, PVS volumes showed good associations with PVS visual scores evaluated on either T1w or T2w images. Compared to a previously published method, mcPVS-Net showed a higher accuracy and improved PVS segmentation in the basal ganglia region.

CONCLUSION

The mcPVS-Net demonstrated good accuracy for segmenting PVS from 3D T1w images. It may serve as a useful tool for future PVS research.

Biological sex and BMI influence the longitudinal evolution of adolescent and young adult MRI-visible perivascular spaces

Background and Purpose

An association recently emerged between magnetic resonance imaging (MRI)-visible perivascular spaces (MV-PVS) with intracerebral solute clearance and neuroinflammation, in adults. However, it is unknown how MV-PVS change throughout adolescence and what factors influence MV-PVS volume and morphology. This study assesses the temporal evolution of MV-PVS volume in adolescents and young adults, and secondarily evaluates the relationship between MV-PVS, age, sex, and body mass index (BMI).

Materials and Methods

This analysis included a 783 participant cohort from the longitudinal multicenter National Consortium on Alcohol and Neurodevelopment in Adolescence study that involved up to 6 imaging visits spanning 5 years. Healthy adolescents aged 12-21 years at study entry with at least two MRI scans were included. The primary outcome was mean MV-PVS volume (mm 3 /white matter cm 3 ).

Results

On average, males had greater MV-PVS volume at all ages compared to females. A linear mixed-effect model for MV-PVS volume was performed. Mean BMI and increases in a person's BMI were associated with increases in MV-PVS volume over time. In females only, changes in BMI correlated with MV-PVS volume. One unit increase in BMI above a person's average BMI was associated with a 0.021 mm 3 /cm 3 increase in MV-PVS volume (p<0.001).

Conclusion

This longitudinal study showed sex differences in MV-PVS features during adolescence and young adulthood. Importantly, we report that increases in BMI from a person's mean BMI are associated with increases in MV-PVS volume in females only. These findings suggest a potential link between MV-PVS, sex, and BMI that warrants future study.

A "glympse" into neurodegeneration: Diffusion MRI and cerebrospinal fluid aquaporin-4 for the assessment of glymphatic system in Alzheimer's disease and other dementias

The glymphatic system (GS) is a whole-brain perivascular network, consisting of three compartments: the periarterial and perivenous spaces and the interposed brain parenchyma. GS dysfunction has been implicated in neurodegenerative diseases, particularly Alzheimer's disease (AD). So far, comprehensive research on GS in humans has been limited by the absence of easily accessible biomarkers. Recently, promising non-invasive methods based on magnetic resonance imaging (MRI) along with aquaporin-4 (AQP4) quantification in the cerebrospinal fluid (CSF) were introduced for an indirect assessment of each of the three GS compartments. We recruited 111 consecutive subjects presenting with symptoms suggestive of degenerative cognitive decline, who underwent 3 T MRI scanning including multi-shell diffusion-weighted images. Forty nine out of 111 also underwent CSF examination with quantification of CSF-AQP4. CSF-AQP4 levels and MRI measures-including perivascular spaces (PVS) counts and volume fraction (PVSVF), white matter free water fraction (FW-WM) and mean kurtosis (MK-WM), diffusion tensor imaging analysis along the perivascular spaces (DTI-ALPS) (mean, left and right)-were compared among patients with AD (n = 47) and other neurodegenerative diseases (nAD = 24), patients with stable mild cognitive impairment (MCI = 17) and cognitively unimpaired (CU = 23) elderly people. Two runs of analysis were conducted, the first including all patients; the second after dividing both nAD and AD patients into two subgroups based on gray matter atrophy as a proxy of disease stage. Age, sex, years of education, and scanning time were included as confounding factors in the analyses. Considering the whole cohort, patients with AD showed significantly higher levels of CSF-AQP4 (exp(b) = 2.05, p = .005) and FW-WM FW-WM (exp(b) = 1.06, p = .043) than CU. AQP4 levels were also significantly higher in nAD in respect to CU (exp(b) = 2.98, p < .001). CSF-AQP4 and FW-WM were significantly higher in both less atrophic AD (exp(b) = 2.20, p = .006; exp(b) = 1.08, p = .019, respectively) and nAD patients (exp(b) = 2.66, p = .002; exp(b) = 1.10, p = .019, respectively) compared to CU subjects. Higher total (exp(b) = 1.59, p = .013) and centrum semiovale PVS counts (exp(b) = 1.89, p = .016), total (exp(b) = 1.50, p = .036) and WM PVSVF (exp(b) = 1.89, p = .005) together with lower MK-WM (exp(b) = 0.94, p = .006), mean and left ALPS (exp(b) = 0.91, p = .043; exp(b) = 0.88, p = .010 respectively) were observed in more atrophic AD patients in respect to CU. In addition, more atrophic nAD patients exhibited higher levels of AQP4 (exp(b) = 3.39, p = .002) than CU. Our results indicate significant changes in putative MRI biomarkers of GS and CSF-AQP4 levels in AD and in other neurodegenerative dementias, suggesting a close interaction between glymphatic dysfunction and neurodegeneration, particularly in the case of AD. However, the usefulness of some of these biomarkers as indirect and standalone indices of glymphatic activity may be hindered by their dependence on disease stage and structural brain damage.

Systematic review and meta-analysis of automated methods for quantifying enlarged perivascular spaces in the brain

Research into magnetic resonance imaging (MRI)-visible perivascular spaces (PVS) has recently increased, as results from studies in different diseases and populations are cementing their association with sleep, disease phenotypes, and overall health indicators. With the establishment of worldwide consortia and the availability of large databases, computational methods that allow to automatically process all this wealth of information are becoming increasingly relevant. Several computational approaches have been proposed to assess PVS from MRI, and efforts have been made to summarise and appraise the most widely applied ones. We systematically reviewed and meta-analysed all publications available up to September 2023 describing the development, improvement, or application of computational PVS quantification methods from MRI. We analysed 67 approaches and 60 applications of their implementation, from 112 publications. The two most widely applied were the use of a morphological filter to enhance PVS-like structures, with Frangi being the choice preferred by most, and the use of a U-Net configuration with or without residual connections. Older adults or population studies comprising adults from 18 years old onwards were, overall, more frequent than studies using clinical samples. PVS were mainly assessed from T2-weighted MRI acquired in 1.5T and/or 3T scanners, although combinations using it with T1-weighted and FLAIR images were also abundant. Common associations researched included age, sex, hypertension, diabetes, white matter hyperintensities, sleep and cognition, with occupation-related, ethnicity, and genetic/hereditable traits being also explored. Despite promising improvements to overcome barriers such as noise and differentiation from other confounds, a need for joined efforts for a wider testing and increasing availability of the most promising methods is now paramount.

Estimated Pulse-Wave Velocity and Magnetic Resonance Imaging Markers of Cerebral Small-Vessel Disease in the NOMAS

BACKGROUND

Pulse-wave velocity is a measure of arterial stiffness and a risk factor for cardiovascular disease. Recently, an estimated pulse-wave velocity (ePWV) was introduced that was predictive of increased risk of cardiovascular disease. Our objective was to determine whether ePWV was associated with cerebral small-vessel disease on magnetic resonance imaging.

METHODS AND RESULTS

We included 1257 participants from the NOMAS (Northern Manhattan Study). The ePWV values were calculated using a nonlinear function of age and mean arterial blood pressure. The association between ePWV and white matter hyperintensity volume was assessed. Modification by race and ethnicity was evaluated. Associations between ePWV and other cerebral small-vessel disease markers, covert brain infarcts, cerebral microbleeds, and enlarged perivascular spaces, were explored as secondary outcomes. Mean±SD age of the cohort was 64±8 years; 61% were women; 18% self-identified as non-Hispanic Black, 67% as Hispanic, and 15% as non-Hispanic White individuals. Mean±SD ePWV was 11±2 m/s in the total NOMAS population and was similar across race and ethnic groups. The ePWV was significantly associated with white matter hyperintensity volume (β=0.23 [95% CI, 0.20-0.26]) after adjustment. Race and ethnicity modified the association between ePWV and white matter hyperintensity volume, with stronger associations in Hispanic and non-Hispanic Black individuals. Significant associations were found between ePWV and covert brain infarcts, cerebral microbleeds, and perivascular spaces after adjustment.

CONCLUSIONS

The ePWV function may provide a vascular mechanism for deleterious cerebrovascular outcomes in individuals with cerebral small-vessel disease and is particularly apparent in the racial and ethnic minorities represented in the NOMAS cohort.

Genetic Determinants of Vascular Dementia

Vascular dementia (VaD) is a prevalent form of cognitive impairment with underlying vascular etiology. In this review, we examine recent genetic advancements in our understanding of VaD, encompassing a range of methodologies including genome-wide association studies, polygenic risk scores, heritability estimates, and family studies for monogenic disorders revealing the complex and heterogeneous nature of the disease. We report well known genetic associations and highlight potential pathways and mechanisms implicated in VaD and its pathological risk factors, including stroke, cerebral small vessel disease, and cerebral amyloid angiopathy. Moreover, we discuss important modifiable risk factors such as hypertension, diabetes, and dyslipidemia, emphasizing the importance of a multifactorial approach in prevention, treatment, and understanding the genetic basis of VaD. Last, we outline several areas of scientific advancements to improve clinical care, highlighting that large-scale collaborative efforts, together with an integromics approach can enhance the robustness of genetic discoveries. Indeed, understanding the genetics of VaD and its pathophysiological risk factors hold the potential to redefine VaD on the basis of molecular mechanisms and to generate novel diagnostic, prognostic, and therapeutic tools.

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 β-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 (β=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 (β=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 (β=-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.

Non-hemorrhagic imaging markers of cerebral amyloid angiopathy in memory clinic patients

INTRODUCTION

The Boston criteria v2.0 for cerebral amyloid angiopathy (CAA) incorporated non-hemorrhagic imaging markers. Their prevalence and significance in patients with cognitive impairment remain uncertain.

METHODS

We studied 622 memory clinic patients with available magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) biomarkers. Two raters assessed non-hemorrhagic markers, and we explored their association with clinical characteristics through multivariate analyses.

RESULTS

Most patients had mild cognitive impairment; median age was 71 years and 50% were female. Using the v2.0 criteria, possible or probable CAA increased from 75 to 383 patients. Sixty-eight percent of the sample had non-hemorrhagic CAA markers, which were independently associated with age (odds ratio [OR] = 1.04, 95% confidence interval [CI] = 1.01-1.07), female sex (OR = 1.68, 95% CI = 1.11-2.54), and hemorrhagic CAA markers (OR = 2.11, 95% CI = 1.02-4.35).

DISCUSSION

Two-thirds of patients from a memory clinic cohort had non-hemorrhagic CAA markers, increasing the number of patients meeting the v2.0 CAA criteria. Longitudinal approaches should explore the implications of these markers, particularly the hemorrhagic risk in this population.

HIGHLIGHTS

The updated Boston criteria for cerebral amyloid angiopathy (CAA) now include non-hemorrhagic markers. The prevalence of non-hemorrhagic CAA markers in memory clinic patients is unknown. Two-thirds of patients in our memory clinic presented non-hemorrhagic CAA markers. The presence of these markers was associated with age, female sex, and hemorrhagic CAA markers. The hemorrhagic risk of patients presenting these type of markers remains unclear.

Association of enlarged perivascular spaces with cognitive function in dementia-free older adults: A population-based study

Introduction

We sought to characterize cognitive profiles associated with enlarged perivascular spaces (EPVS) among Chinese older adults.

Methods

This population-based study included 1191 dementia-free participants (age ≥60 years) in the MIND-China MRI Substudy (2018-2020). We visually evaluated EPVS in basal ganglia (BG) and centrum semiovale (CSO), white matter hyperintensities (WMHs), lacunes, cerebral microbleeds (CMBs), and cortical superficial siderosis. We used a neuropsychological test battery to assess cognitive function. Data were analyzed using general linear models.

Results

Greater BG-EPVS load was associated with lower z-scores in memory, verbal fluency, and global cognition (p < 0.05); these associations became non-significant when controlling for other cerebral small vessel disease (CSVD) markers (e.g., WMHs, lacunes, and mixed CMBs). Overall, CSO-EPVS load was not associated with cognitive z-scores (p > 0.05); among apolipoprotein E (APOE) -ε4 carriers, greater CSO-EPVS load was associated with lower verbal fluency z-score, even when controlling for other CSVD markers (p < 0.05).

Discussion

The associations of BG-EPVS with poor cognitive function in older adults are largely attributable to other CSVD markers.

HIGHLIGHTS

The association of enlarged perivascular spaces (EPVS) with cognitive function in older people is poorly defined.The association of basal ganglia (BG)-EPVS with poor cognition is attributed to other cerebral small vessel disease (CSVD) markers.In apolipoprotein E (APOE) ε4 carriers, a higher centrum semiovale (CSO)-EPVS load is associated with poorer verbal fluency.

Enlarged perivascular spaces and their association with motor, cognition, MRI markers and cerebrovascular risk factors in male fragile X premutation carriers

FMR1 premutation carriers (55-200 CGG repeats) are at risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder associated with motor and cognitive impairment. Bilateral hyperintensities of the middle cerebellar peduncles (MCP sign) are the major radiological hallmarks of FXTAS. In the general population, enlarged perivascular spaces (PVS) are biomarkers of small vessel disease and glymphatic dysfunction and are associated with cognitive decline. Our aim was to determine if premutation carriers show higher ratings of PVS than controls and whether enlarged PVS are associated with motor and cognitive impairment, MRI features of neurodegeneration, cerebrovascular risk factors and CGG repeat length. We evaluated 655 MRIs (1-10 visits/participant) from 229 carriers (164 with FXTAS and 65 without FXTAS) and 133 controls. PVS in the basal ganglia (BG-EPVS), centrum semiovale, and midbrain were evaluated with a semiquantitative scale. Mixed-effects models were used for statistical analysis adjusting for age. In carriers with FXTAS, we revealed that (1) BG-PVS ratings were higher than those of controls and carriers without FXTAS; (2) BG-PVS severity was associated with brain atrophy, white matter hyperintensities, enlarged ventricles, FXTAS stage and abnormal gait; (3) age-related increase in BG-PVS was associated with cognitive dysfunction; and (4) PVS ratings of all three regions showed robust associations with CGG repeat length and were higher in carriers with the MCP sign than carriers without the sign. This study demonstrates clinical relevance of PVS in FXTAS especially in the basal ganglia region and suggests microangiopathy and dysfunctional cerebrospinal fluid circulation in FXTAS physiopathology.

Perivascular Spaces, Diffusivity Along Perivascular Spaces, and Free Water in Cerebral Small Vessel Disease

BACKGROUND AND OBJECTIVES

Previous studies have linked the MRI measures of perivascular spaces (PVSs), diffusivity along the perivascular spaces (DTI-ALPS), and free water (FW) to cerebral small vessel disease (SVD) and SVD-related cognitive impairments. However, studies on the longitudinal associations between the three MRI measures, SVD progression, and cognitive decline are lacking. This study aimed to explore how PVS, DTI-ALPS, and FW contribute to SVD progression and cognitive decline.

METHODS

This is a cohort study that included participants with SVD who underwent neuroimaging and cognitive assessment, specifically measuring Mini-Mental State Examination (MMSE), cognitive index, and processing speed, at 2 time points. Three MRI measures were quantified: PVS in basal ganglia (BG-PVS) volumes, FW fraction, and DTI-ALPS. We performed a latent change score model to test inter-relations between the 3 MRI measures and linear regression mixed models to test their longitudinal associations with the changes of other SVD MRI markers and cognitive performances.

RESULTS

In baseline assessment, we included 289 participants with SVD, characterized by a median age of 67.0 years and 42.9% women. Of which, 220 participants underwent the follow-up assessment, with a median follow-up time of 3.4 years. Baseline DTI-ALPS was associated with changes in BG-PVS volumes (β = -0.09, p = 0.030), but not vice versa (β = -0.08, p = 0.110). Baseline BG-PVS volumes were associated with changes in white matter hyperintensity (WMH) volumes (β = 0.33, p-corrected < 0.001) and lacune numbers (β = 0.28, p-corrected < 0.001); FW fraction was associated with changes in WMH volumes (β = 0.30, p-corrected < 0.001), lacune numbers (β = 0.28, p-corrected < 0.001), and brain volumes (β = -0.45, p-corrected < 0.001); DTI-ALPS was associated with changes in WMH volumes (β = -0.20, p-corrected = 0.002) and brain volumes (β = 0.23, p-corrected < 0.001). Furthermore, baseline FW fraction was associated with decline in MMSE score (β = -0.17, p-corrected = 0.006); baseline FW fraction and DTI-ALPS were associated with changes in cognitive index (FW fraction: β = -0.25, p-corrected < 0.001; DTI-ALPS: β = 0.20, p-corrected = 0.001) and processing speed over time (FW fraction: β = -0.29, p-corrected < 0.001; DTI-ALPS: β = 0.21, p-corrected < 0.001).

DISCUSSION

Our results showed that increased BG-PVS volumes, increased FW fraction, and decreased DTI-ALPS are related to progression of MRI markers of SVD, along with SVD-related cognitive decline over time. These findings may suggest that the glymphatic dysfunction is related to SVD progression, but further studies are needed.

The relationship between amyloid pathology, cerebral small vessel disease, glymphatic dysfunction, and cognition: a study based on Alzheimer's disease continuum participants

BACKGROUND

Glymphatic dysfunction is a crucial pathway for dementia. Alzheimer's disease (AD) pathologies co-existing with cerebral small vessel disease (CSVD) is the most common pathogenesis for dementia. We hypothesize that AD pathologies and CSVD could be associated with glymphatic dysfunction, contributing to cognitive impairment.

METHOD

Participants completed with amyloid PET, diffusion tensor imaging (DTI), and T2 fluid-attenuated inversion-recovery (FLAIR) sequences were included from the Alzheimer's Disease Neuroimaging Initiative (ADNI). White matter hyperintensities (WMH), the most common CSVD marker, was evaluated from T2FLAIR images and represented the burden of CSVD. Amyloid PET was used to assess Aβ aggregation in the brain. We used diffusion tensor image analysis along the perivascular space (DTI-ALPS) index, the burden of enlarged perivascular spaces (PVS), and choroid plexus volume to reflect glymphatic function. The relationships between WMH burden/Aβ aggregation and these glymphatic markers as well as the correlations between glymphatic markers and cognitive function were investigated. Furthermore, we conducted mediation analyses to explore the potential mediating effects of glymphatic markers in the relationship between WMH burden/Aβ aggregation and cognition.

RESULTS

One hundred and thirty-three participants along the AD continuum were included, consisting of 40 CN - , 48 CN + , 26 MCI + , and 19 AD + participants. Our findings revealed that there were negative associations between whole-brain Aβ aggregation (r =  - 0.249, p = 0.022) and WMH burden (r =  - 0.458, p < 0.001) with DTI-ALPS. Additionally, Aβ aggregation (r = 0.223, p = 0.041) and WMH burden (r = 0.294, p = 0.006) were both positively associated with choroid plexus volume. However, we did not observe significant correlations with PVS enlargement severity. DTI-ALPS was positively associated with memory (r = 0.470, FDR-p < 0.001), executive function (r = 0.358, FDR-p = 0.001), visual-spatial (r = 0.223, FDR-p < 0.040), and language (r = 0.419, FDR-p < 0.001). Conversely, choroid plexus volume showed negative correlations with memory (r =  - 0.315, FDR-p = 0.007), executive function (r =  - 0.321, FDR-p = 0.007), visual-spatial (r =  - 0.233, FDR-p = 0.031), and language (r =  - 0.261, FDR-p = 0.021). There were no significant correlations between PVS enlargement severity and cognitive performance. In the mediation analysis, we found that DTI-ALPS acted as a mediator in the relationship between WMH burden/Aβ accumulation and memory and language performances.

CONCLUSION

Our study provided evidence that both AD pathology (Aβ) and CSVD were associated with glymphatic dysfunction, which is further related to cognitive impairment. These results may provide a theoretical basis for new targets for treating AD.

The Rotterdam Study. Design update and major findings between 2020 and 2024

The Rotterdam Study is a population-based cohort study, started in 1990 in the district of Ommoord in the city of Rotterdam, the Netherlands, with the aim to describe the prevalence and incidence, unravel the etiology, and identify targets for prediction, prevention or intervention of multifactorial diseases in mid-life and elderly. The study currently includes 17,931 participants (overall response rate 65%), aged 40 years and over, who are examined in-person every 3 to 5 years in a dedicated research facility, and who are followed-up continuously through automated linkage with health care providers, both regionally and nationally. Research within the Rotterdam Study is carried out along two axes. First, research lines are oriented around diseases and clinical conditions, which are reflective of medical specializations. Second, cross-cutting research lines transverse these clinical demarcations allowing for inter- and multidisciplinary research. These research lines generally reflect subdomains within epidemiology. This paper describes recent methodological updates and main findings from each of these research lines. Also, future perspective for coming years highlighted.

Sleep disorders and Alzheimer's disease pathophysiology: The role of the Glymphatic System. A scoping review

BACKGROUND

Alzheimer's disease (AD) is highly intertwined with sleep disturbances throughout its whole natural history. Sleep consists of a major compound of the functionality of the glymphatic system, as the synchronized slow-wave activity during NREM facilitates cerebrospinal and interstitial long-distance mixing.

OBJECTIVE

The present study undertakes a scoping review of research on the involvement of the glymphatic system in AD-related sleep disturbances.

DESIGN

we searched Medline, Embase, PsychInfo and HEAL-link databases, without limitations on date and language, along with reference lists of relevant reviews and all included studies. We included in vivo, in vitro and post-mortem studies examining glymphatic implications of sleep disturbances in human populations with AD spectrum pathology. A thematic synthesis of evidence based on the extracted content was applied and presented in a narrative way.

RESULTS

In total, 70 original research articles were included and were grouped as following: a) Protein aggregation and toxicity, after sleep deprivation, along with its effects on sleep architecture, b) Glymphatic Sequalae in SDB, yielding potential glymphatic markers c) Circadian Dysregulation, d) Possible Interventions.

CONCLUSIONS

this review sought to provide insight into the role of sleep disturbances in AD pathogenesis, in the context of the glymphatic disruption.

Cerebral Small Vessel Disease Burden in Patients with Transient Global Amnesia and its Relationship with Recurrence

OBJECTIVE

Cerebral Small Vessel Disease (CSVD) has not been systematically studied in patients with Transient Global Amnesia (TGA). We aimed to investigate the CSVD burden in patients with TGA and its relationship with TGA recurrence.

METHODS

We retrospectively examined 69 patients diagnosed with TGA in a single center between January 2015 and November 2023. The overall CSVD burden and single CSVD imaging markers, including enlarged perivascular spaces in the hippocampus (H-EPVS), were measured in each patient and compared with those in 69 age- and sex-matched healthy controls. Multivariate logistic regression was performed to determine independent predictors of recurrence.

RESULTS

Of the 69 included patients, 40 (58%) were female, and the median age was 67 years (range 42-83 years). Twenty-one patients (30.4%) showed dot-like hippocampal hyperintensities on diffusion-weighted imaging (DWI). The mean follow-up was 51 months. Sixteen patients (23.2%) experienced TGA recurrence. The burden of overall CSVD, lacunes, WMH, EPVS, and extensive H-EPVS was higher in TGA patients than in controls. TGA patients who experienced recurrence had a heavier overall CSVD burden, lower frequency of hippocampal DWI hyperintensities, and longer follow-up duration than those who had with single episode. In the multivariate analysis, only follow-up duration was an independent predictor of TGA recurrence.

CONCLUSION

The overall CSVD burden and extensive H-EPVS burden were higher in patients with TGA than healthy controls. Follow-up duration but not overall CSVD burden may predict TGA recurrence.

Association between enlarged perivascular spaces and cerebrospinal fluid aquaporin-4 and tau levels: report from a memory clinic

Background

Perivascular spaces (PVS) are fluid-filled compartments that dilate in response to many different conditions. A high burden of enlarged PVS (EPVS) in the centrum semiovale (CSO) has been linked to neurodegeneration. Moreover, an increase in cerebrospinal fluid (CSF) levels of aquaporin-4 (AQP4), a water channel expressed on PVS-bounding astrocytes, has been described in patients with neurodegenerative dementia. Our aim was to investigate the relationship between neurodegenerative diseases and two putative glymphatic system biomarkers: AQP4 and EPVS.

Methods

We included 70 individuals, 54 patients with neurodegenerative diseases and 16 subjects with non-degenerative conditions. EPVS were visually quantified on MRI-scans applying Paradise's scale. All subjects underwent lumbar puncture for the measurement of AQP4 levels in the cerebrospinal fluid (CSF). CSF levels of amyloid-β-1-42, phosphorylated and total tau (tTau) were also measured. Linear regression analyses were adjusted for age, sex, education and disease duration, after excluding outliers.

Results

Cerebrospinal fluid (CSF)-AQP4 levels were independent predictors of total (β = 0.28, standard error [SE] = 0.08, p = 0.001), basal ganglia (β = 0.20, SE = 0.08, p = 0.009) and centrum semiovale EPVS (β = 0.37, SE = 0.12, p = 0.003). tTau levels predicted CSO-EPVS (β = 0.30, SE = 0.15, p = 0.046). Moreover, increased levels of AQP4 were strongly associated with higher levels of tTau in the CSF (β = 0.35, SE = 0.13, p = 0.008).

Conclusion

We provide evidence that CSO-EPVS and CSF-AQP4 might be clinically meaningful biomarkers of glymphatic dysfunction and associated neurodegeneration.

Imaging of congenital and developmental cystic lesions of the brain: a narrative review

INTRODUCTION

Congenital and developmental intracranial cysts represent a large heterogenous group with varied presentations and etiologies. They can range from normal variants to pathologic lesions often associated with known congenital syndromes or acquired insults. While some are incidentally found, others are symptomatic or may become symptomatic over time. The preferred type of neuroimaging for timely diagnosis helps determine appropriate management and treatment, if indicated.

AREAS COVERED

In this narrative review article, authors present a comprehensive description of developmental cystic lesions. Imaging descriptions are provided for each type of cystic lesion as well as several representative images.

EXPERT OPINION

As advanced neuroimaging techniques become more ubiquitous in clinical use, more light may be shed on the natural history of certain intracranial cystic lesions throughout the lifespan. This includes prenatal imaging for early identification and prognostication to surveillance imaging into advanced age to ascertain associations of certain cystic lesions with age-related cognitive dysfunction.

MRI Visible Perivascular Spaces and the Risk of Incident Mild Cognitive Impairment in a Community Sample

BACKGROUND

Magnetic resonance imaging (MRI) visible perivascular spaces (PVS) are associated with the risk of incident dementia but their association with the early stages of cognitive impairment remains equivocal.

OBJECTIVE

We examined the association between MRI visible PVS and the risk of incident mild cognitive impairment (MCI) in the community-based Framingham Heart Study (FHS).

METHODS

FHS participants aged at least 50 years free of stroke, cognitive impairment, and dementia at the time of MRI were included. PVS were rated according to severity in the basal ganglia and centrum semiovale (CSO) using established criteria. Cox regression analyses were used to relate PVS to incident MCI adjusted for demographic and cardiovascular variables.

RESULTS

The mean age of the sample (1,314 participants) at MRI was 68 years (SD, 9; 54% women). There were 263 cases of incident MCI over a median 7.4 years follow-up (max, 19.8 years). MCI risk increased with higher PVS severity in the CSO. Relative to persons with the lowest severity rating, persons with the highest severity rating in the CSO had a higher risk of incident MCI (hazard ratio [HR] = 2.55; 95% confidence interval [CI], 1.48-4.37; p = 0.0007). In secondary analysis, this association seemed stronger in women. Risk of incident MCI was nominally higher for participants with the highest severity grade of PVS in the basal ganglia, though not statistically significant relative to the lowest grade (HR = 2.19; 95% CI, 0.78-6.14; p = 0.14).

CONCLUSIONS

PVS burden in the CSO may be a risk marker for early cognitive impairment.

Cerebral small vessel disease: Recent advances and future directions

Cerebral small vessel disease (SVD) causes lacunar stroke and intracerebral hemorrhage, and is the most common pathology underlying vascular cognitive impairment. Increasingly, the importance of other clinical features of SVD is being recognized including motor impairment, (vascular) parkinsonism, impaired balance, falls, and behavioral symptoms, such as depression, apathy, and personality change. Epidemiological data show a high prevalence of the characteristic magnetic resonance imaging (MRI) features of white matter hyperintensities and lacunar infarcts in community studies, and recent data suggest that it is also a major health burden in low- and middle-income countries. In this review, we cover advances in diagnosis, imaging, clinical presentations, pathogenesis, and treatment.The two most common pathologies underlying SVD are arteriolosclerosis caused by aging, hypertension, and other conventional vascular risk factors, and cerebral amyloid angiopathy (CAA) caused by vascular deposition of β-amyloid. We discuss the revised Boston criteria of CAA based on MRI features, which have been recently validated. Imaging is providing important insights into pathogenesis, including improved detection of tissue damage using diffusion tensor imaging (DTI) leading to its use to monitor progression and surrogate endpoints in clinical trials. Advanced MRI techniques can demonstrate functional or dynamic abnormalities of the blood vessels, while the high spatial resolution provided by ultrahigh field MRI at 7 T allows imaging of individual perforating arteries for the first time, and the measurement of flow velocity and pulsatility within these arteries. DTI and structural network analysis have highlighted the importance of network disruption in mediating the effect of different SVD pathologies in causing a number of symptoms, including cognitive impairment, apathy, and gait disturbance.Despite the public health importance of SVD, there are few proven treatments. We review the evidence for primary prevention, and recent data showing how intensive blood pressure lowering reduces white matter hyperintensities (WMH) progression and delays the onset of cognitive impairment. There are few treatments for secondary prevention, but a number of trials are currently evaluating novel treatment approaches. Recent advances have implicated molecular processes related to endothelial dysfunction, nitric oxide synthesis, blood-brain barrier integrity, maintenance and repair of the extracellular matrix, and inflammation. Novel treatment approaches are being developed to a number of these targets. Finally, we highlight the importance of large International collaborative initiatives in SVD to address important research questions and cover a number which have recently been established.