Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts And Leukoencephalopathy Subjects Research Articles

ER stress induced immunopathology involving complement in CADASIL: implications for therapeutics

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by NOTCH3 mutations. Typical CADASIL is characterised by subcortical ischemic strokes due to severe arteriopathy and fibrotic thickening of small arteries. Arteriolar vascular smooth muscle cells (VSMCs) are the key target in CADASIL, but the potential mechanisms involved in their degeneration are still unclear. Focusing on cerebral microvessels in the frontal and anterior temporal lobes and the basal ganglia, we used advanced proteomic and immunohistochemical methods to explore the extent of inflammatory and immune responses in CADASIL subjects compared to similar age normal and other disease controls. There was variable loss of VSMC in medial layers of arteries in white matter as well as the cortex, that could not be distinguished whether NOTCH3 mutations were in the epidermal growth factor (EGFr) domains 1–6 or EGFr7-34. Proteomics of isolated cerebral microvessels showed alterations in several proteins, many associated with endoplasmic reticulum (ER) stress including heat shock proteins. Cerebral vessels with sparsely populated VSMCs also attracted robust accrual of perivascular microglia/macrophages in order CD45+ > CD163+ > CD68+cells, with > 60% of vessel walls exhibiting intercellular adhesion molecule-1 (ICAM-1) immunoreactivity. Functional VSMC cultures bearing the NOTCH3 Arg133Cys mutation showed increased gene expression of the pro-inflammatory cytokine interleukin 6 and ICAM-1 by 16- and 50-fold, respectively. We further found evidence for activation of the alternative pathway of complement. Immunolocalisation of complement Factor B, C3d and C5-9 terminal complex but not C1q was apparent in ~ 70% of cerebral vessels. Increased complement expression was corroborated in > 70% of cultured VSMCs bearing the Arg133Cys mutation independent of N3ECD immunoreactivity. Our observations suggest that ER stress and other cellular features associated with arteriolar VSMC damage instigate robust localized inflammatory and immune responses in CADASIL. Our study has important implications for immunomodulation approaches to counter the characteristic arteriopathy of CADASIL.

Neuropathology of microbleeds in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).

Cerebral microbleeds (CMBs) detected on magnetic resonance imaging are common in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). The neuropathologic correlates of CMBs are unclear. In this study, we characterized findings relevant to CMBs in autopsy brain tissue of 8 patients with genetically confirmed CADASIL and 10 controls within the age range of the CADASIL patients by assessing the distribution and extent of hemosiderin/iron deposits including perivascular hemosiderin leakage (PVH), capillary hemosiderin deposits, and parenchymal iron deposits (PID) in the frontal cortex and white matter, basal ganglia and cerebellum. We also characterized infarcts, vessel wall thickening, and severity of vascular smooth muscle cell degeneration. CADASIL subjects had a significant increase in hemosiderin/iron deposits compared with controls. This increase was principally seen with PID. Hemosiderin/iron deposits were seen in the majority of CADASIL subjects in all brain areas. PVH was most pronounced in the frontal white matter and basal ganglia around small to medium sized arterioles, with no predilection for the vicinity of vessels with severe vascular changes or infarcts. CADASIL subjects have increased brain hemosiderin/iron deposits but these do not occur in a periarteriolar distribution. Pathogenesis of these lesions remains uncertain.

Evidence of beta amyloid independent small vessel disease in familial Alzheimer's disease.

We studied small vessel disease (SVD) pathology in Familial Alzheimer's disease (FAD) subjects carrying the presenilin 1 (PSEN1) p.Glu280Ala mutation in comparison to those with sporadic Alzheimer's disease (SAD) as a positive control for Alzheimer's pathology and Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) bearing different NOTCH3 mutations, as positive controls for SVD pathology. Upon magnetic resonance imaging (MRI) in life, some FAD showed mild white matter hyperintensities and no further radiologic evidence of SVD. In post-mortem studies, total SVD pathology in cortical areas and basal ganglia was similar in PSEN1 FAD and CADASIL subjects, except for the feature of arteriosclerosis which was higher in CADASIL subjects than in PSEN1 FAD subjects. Further only a few SAD subjects showed a similar degree of SVD pathology as observed in CADASIL. Furthermore, we found significantly enlarged perivascular spaces in vessels devoid of cerebral amyloid angiopathy in FAD compared with SAD and CADASIL subjects. As expected, there was greater fibrinogen-positive perivascular reactivity in CADASIL but similar reactivity in PSEN1 FAD and SAD groups. Fibrinogen immunoreactivity correlated with onset age in the PSEN1 FAD cases, suggesting increased vascular permeability may contribute to cognitive decline. Additionally, we found reduced perivascular expression of PDGFRβ AQP4 in microvessels with enlarged PVS in PSEN1 FAD cases. We demonstrate that there is Aβ-independent SVD pathology in PSEN1 FAD, that was marginally lower than that in CADASIL subjects although not evident by MRI. These observations suggest presence of covert SVD even in PSEN1, contributing to disease progression. As is the case in SAD, these consequences may be preventable by early recognition and actively controlling vascular disease risk, even in familial forms of dementia.

Abstract P332: Cerebral Small Vessel Disease Score in CADASIL: Relationships to Cognitive Dysfunctions

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary cerebral small vessel disease (cSVD) linked to NOTCH3 mutations and leading to the early onset of stroke and vascular cognitive impairment. Neuroimaging features of CADASIL include extensive white matter hyperintensity, lacunes, cerebral microbleeds and enlarged perivascular spaces. Researchers from the Rotterdam study recently proposed a MRI-based cSVD Score reflecting the overall burden of cerebrovascular injury (Yilmaz et al., 2018). Here, we explored the relevance of this cSVD Score in distinguishing CADASIL subjects from non-carriers and its relationships to cognition. We evaluated 26 NOTCH3 mutation carriers and 25 non-carriers from large Colombian families. Of the CADASIL subjects, 4 had previous strokes (symptomatic) and 22 had no history of strokes (asymptomatic). All subjects underwent a 3T MRI and a neuropsychological evaluation. Structural MRI markers of cSVD, as well as the cSVD Score, were quantified in each subject following established protocols. Demographic, cognitive and neuroimaging features across groups are presented in Table 1. The cSVD Score significantly differed between groups, after adjusting for age (Figure 1-A). In CADASIL subjects, the cSVD Score was negatively related to performance in Memory, Processing Speed, Executive Function, after accounting for age and education (Figure 1-B). These results suggest that the cSVD Score could be a useful marker of disease severity in CADASIL. Longitudinal studies are now needed to determine if this score allows predicting clinical outcomes in CADASIL, such as stroke or dementia.

Intracerebral hemorrhage in CADASIL.

Intracerebral hemorrhage (ICH) has been reported in few cases of Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), mostly in hypertensive patients. We aimed to assess the clinical and radiological characteristics of patients with CADASIL who presented with ICH. A retrospective analysis of all neuroimaging exams of CADASIL patients hospitalized in our academic neurology department for acute cerebrovascular events was performed to find ICH. A systematic review of the literature was performed on this topic. Including our five patients, a total number of 52 subjects with CADASIL and ICH (mean age: 56 years, SD 11, 36-69%- male) were reported. Intracerebral hemorrhages were mainly deep (34 subjects), followed by lobar (8 subjects), infratentorial (6 subjects) and mixed locations (4 subjects). Three ICHs were asymptomatic. Fourteen patients were taking antithrombotic medication, 18 had no regular antiplatelet or anticoagulant treatment while in 20 patients medical treatment was not detailed. Arterial hypertension was present in 37 out of 51 patients with available information. Neuroimaging showed extensive FLAIR hyperintensities in all CADASIL subjects with ICH, cerebral microbleeds in all but three patients, and lacunar infarction in 19 out of 25 subjects with available information. Intracerebral hemorrhage represents a possible yet uncommon manifestation of CADASIL and should be considered as a possibility in patients with ICH associated with leukoencephalopathy and microbleeds, even in the absence of other clinical symptoms.

Insulin-Independent and Dependent Glucose Transporters in Brain Mural Cells in CADASIL

Typical cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is caused by mutations in the human NOTCH3 gene. Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy is characterized by subcortical ischemic strokes due to severe arteriopathy and fibrotic thickening of small vessels. Blood regulating vascular smooth muscle cells (VSMCs) appear as the key target in CADASIL but the pathogenic mechanisms remain unclear. With the hypothesis that brain glucose metabolism is disrupted in VSMCs in CADASIL, we investigated post-mortem tissues and VSMCs derived from CADASIL patients to explore gene expression and protein immunoreactivity of glucose transporters (GLUTs), particularly GLUT4 and GLUT2 using quantitative RT-PCR and immunohistochemical techniques. In vitro cell model analysis indicated that both GLUT4 and -2 gene expression levels were down-regulated in VSMCs derived from CADASIL patients, compared to controls. In vitro studies further indicated that the down regulation of GLUT4 coincided with impaired glucose uptake in VSMCs, which could be partially rescued by insulin treatment. Our observations on reduction in GLUTs in VSMCs are consistent with previous findings of decreased cerebral blood flow and glucose uptake in CADASIL patients. That impaired ability of glucose uptake is rescued by insulin is also consistent with previously reported lower proliferation rates of VSMCs derived from CADASIL subjects. Overall, these observations are consistent with the development of severe cerebral arteriopathy in CADASIL, in which VSMCs are replaced by widespread fibrosis.

The INECO Frontal Screening for the Evaluation of Executive Dysfunction in Cerebral Small Vessel Disease: Evidence from Quantitative MRI in a CADASIL Cohort from Colombia.

Executive dysfunction is a predominant cognitive symptom in cerebral small vessel disease (SVD). The Institute of Cognitive Neurology Frontal Screening (IFS) is a well-validated screening tool allowing the rapid assessment of multiple components of executive function in Spanish-speaking individuals. In this study, we examined performance on the IFS in subjects with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), an inherited condition leading to the early onset of SVD. We further explored associations between performance on the IFS and magnetic resonance imaging (MRI) markers of SVD. We recruited 24 asymptomatic CADASIL subjects and 23 noncarriers from Colombia. All subjects underwent a research MRI and a neuropsychological evaluation, including the IFS. Structural MRI markers of SVD were quantified in each subject, together with an SVD Sum Score representing the overall burden of cerebrovascular alterations. General linear model, correlation, and receiver operating characteristic curve analyses were used to explore group differences on the IFS and relationships with MRI markers of SVD. CADASIL subjects had a significantly reduced performance on the IFS Total Score. Performance on the IFS correlated with all quantified markers of SVD, except for brain atrophy and perivascular spaces enlargement. Finally, while the IFS Total Score was not able to accurately discriminate between carriers and noncarriers, it showed adequate sensitivity and specificity in detecting the presence of multiple MRI markers of SVD. These results suggest that the IFS may be a useful screening tool to assess executive function and disease severity in the context of SVD.

Abstract TP169: Migraine Phenotypic Spectrum in a CADASIL Cohort: Mayo Clinic Florida

Objective: To characterize migraine in patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). Background: CADASIL serves as a key model of a monoallelic stroke disease. A portion of patients have coexistent migraine with aura, yet the relationship between migraine and the pathophysiology of CADASIL is poorly understood. Design/Methods: We performed a prospective study of adults with a confirmed genetic diagnosis of CADASIL, age-matched controls with migraine with aura (MA), and headache-free controls. The Migraine Disability Assessment Questionnaire (MIDAS) and Headache Impact Test (HIT-6) were used to quantify migraine-related disability. Subjects were followed for one year after enrollment. Results: We enrolled 88 subjects, which included 33 subjects with CADASIL, 32 subjects without CADASIL but with MA, and 23 control subjects without CADASIL or MA. Mean age was 53.6 (range, 22-86), 64.8% (57/88) were females, and 83% (73/88) were white. Of the CADASIL subjects, 61% (20/33) suffered from MA (CAD/+MA). Aura semiology amongst the CAD/+MA and MA patients were as follows: visual (80% vs 81%), sensory (75% vs 81%), speech (75% vs 50%), motor (30% vs 50%), brain stem (60% vs 81%) and retinal (30% vs 25%). Mean MIDAS scores at enrollment were comparable between the CAD/+MA and MA populations (32.3 vs 33.5), as were mean HIT-6 scores (56.3 vs 56.9). Discussion: These preliminary results do not show a significant difference in migraine disability between CADASIL migraineurs and chronic migraineurs. Minor differences were observed in aura distribution between the two groups, although further investigations are needed to better understand the underlying pathology of CADASIL and migraine.

Severe white matter astrocytopathy in CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is characterized by strategic white matter (WM) hyperintensities on MRI. Pathological features include WM degeneration, arteriolosclerosis, lacunar infarcts, and the deposition of granular osmiophilic material. Based on the hypothesis that the gliovascular unit is compromised, we assessed the nature of astrocyte damage in the deep WM of CADASIL subjects. We evaluated post-mortem brains from CADASIL, cerebral small vessel disease, similar age cognitively normal and older control subjects. Standard immunohistochemical, immunofluorescent, and unbiased stereological methods were used to evaluate the distribution of astrocytes, microvessels, and autophagy markers in five different brain regions. Compared to the controls, the deep WM of CADASIL subjects overall showed increased numbers of glial fibrillary acidic protein (GFAP)-positive clasmatodendritic astrocytes (P=0.037) and a decrease in the percentage of normal appearing astrocytes (P=0.025). In accord with confluent WM hyperintensities, the anterior temporal pole contained abundant clasmatodendritic astrocytes with displaced aquaporin 4 immunoreactivity. Remarkably, we also found strong evidence for the immunolocalization of autophagy markers including microtubule-associated protein 1, light chain 3 (LC3), and sequestosome 1/p62 and Caspase-3 in GFAP-positive clasmatodendritic cells, particularly within perivascular regions of the deep WM. LC3 was co-localized in more than 90% of the GFAP-positive clasmatodendrocytes. Our novel findings show astrocytes undergo autophagy-like cell death in CADASIL, with the anterior temporal pole being highly vulnerable. We propose astrocytes transform from normal appearing type A to hypertrophic type B and eventually to clasmatodendritic type C cells. These observations also suggest the gliovascular unit of the deep WM is severely impaired in CADASIL.

In vivo high-resolution 7 Tesla MRI shows early and diffuse cortical alterations in CADASIL.

Background and PurposeRecent data suggest that early symptoms may be related to cortex alterations in CADASIL (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), a monogenic model of cerebral small vessel disease (SVD). The aim of this study was to investigate cortical alterations using both high-resolution T2* acquisitions obtained with 7 Tesla MRI and structural T1 images with 3 Tesla MRI in CADASIL patients with no or only mild symptomatology (modified Rankin’s scale ≤1 and Mini Mental State Examination (MMSE) ≥24).MethodsComplete reconstructions of the cortex using 7 Tesla T2* acquisitions with 0.7 mm isotropic resolution were obtained in 11 patients (52.1±13.2 years, 36% male) and 24 controls (54.8±11.0 years, 42% male). Seven Tesla T2* within the cortex and cortical thickness and morphology obtained from 3 Tesla images were compared between CADASIL and control subjects using general linear models.ResultsMMSE, brain volume, cortical thickness and global sulcal morphology did not differ between groups. By contrast, T2* measured by 7 Tesla MRI was significantly increased in frontal, parietal, occipital and cingulate cortices in patients after correction for multiple testing. These changes were not related to white matter lesions, lacunes or microhemorrhages in patients having no brain atrophy compared to controls.ConclusionsSeven Tesla MRI, by contrast to state of the art post-processing of 3 Tesla acquisitions, shows diffuse T2* alterations within the cortical mantle in CADASIL whose origin remains to be determined.

White matter pathology and disconnection in the frontal lobe in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL)

BackgroundMagnetic resonance imaging indicates diffuse white matter (WM) changes are associated with cognitive impairment in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). We examined whether the distribution of axonal abnormalities is related to microvascular pathology in the underlying WM.MethodsWe used post-mortem brains from CADASIL subjects and similar age cognitively normal controls to examine WM axonal changes, microvascular pathology, and glial reaction in up to 16 different regions extending rostro-caudally through the cerebrum. Using unbiased stereological methods, we estimated length densities of affected axons immunostained with neurofilament antibody SMI32. Standard immunohistochemistry was used to assess amyloid precursor protein immunoreactivity per WM area. To relate WM changes to microvascular pathology, we also determined the sclerotic index (SI) in WM arterioles.ResultsThe degree of WM pathology consistently scored higher across all brain regions in CADASIL subjects (P < 0.01) with the WM underlying the primary motor cortex exhibiting the most severe change. SMI32 immunoreactive axons in CADASIL were invariably increased compared with controls (P < 0.01), with most prominent axonal abnormalities observed in the frontal WM (P < 0.05). The SIs of arterioles in CADASIL were increased by 25–45% throughout the regions assessed, with the highest change in the mid-frontal region (P = 0.000).ConclusionsOur results suggest disruption of either cortico-cortical or subcortical-cortical networks in the WM of the frontal lobe that may explain motor deficits and executive dysfunction in CADASIL. Widespread WM axonal changes arise from differential stenosis and sclerosis of arterioles in the WM of CADASIL subjects, possibly affecting some axons of projection neurones connecting to targets in the subcortical structures.

Genome-Wide Genotyping Demonstrates a Polygenic Risk Score Associated With White Matter Hyperintensity Volume in CADASIL

White matter hyperintensities (WMH) on MRI are a quantitative marker for sporadic cerebral small vessel disease and are highly heritable. To date, large-scale genetic studies have identified only a single locus influencing WMH burden. This might in part relate to biological heterogeneity of sporadic WMH. The current study searched for genetic modifiers of WMH volume in cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), a monogenic small vessel disease. We performed a genome-wide association study to identify quantitative trait loci for WMH volume by combining data from 517 CADASIL patients collected through 7 centers across Europe. WMH volumes were centrally analyzed and quantified on fluid attenuated inversion recovery images. Genotyping was performed using the Affymetrix 6.0 platform. Individuals were assigned to 2 distinct genetic clusters (cluster 1 and cluster 2) based on their genetic background. Four hundred sixty-six patients entered the final genome-wide association study analysis. The phenotypic variance of WMH burden in CADASIL explained by all single nucleotide polymorphisms in cluster 1 was 0.85 (SE=0.21), suggesting a substantial genetic contribution. Using cluster 1 as derivation and cluster 2 as a validation sample, a polygenic score was significantly associated with WMH burden (P=0.001) after correction for age, sex, and vascular risk factors. No single nucleotide polymorphism reached genome-wide significance. We found a polygenic score to be associated with WMH volume in CADASIL subjects. Our findings suggest that multiple variants with small effects influence WMH burden in CADASIL. The identification of these variants and the biological pathways involved will provide insights into the pathophysiology of white matter disease in CADASIL and possibly small vessel disease in general.

Is the Oxidant/Antioxidant Status Altered in CADASIL Patients?

The altered aggregation of proteins in non-native conformation is associated with endoplasmic reticulum derangements, mitochondrial dysfunction and excessive production of reactive oxygen species. Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary systemic vasculopathy, caused by NOTCH3 mutations within the receptor extracellular domain, that lead to abnormal accumulation of the mutated protein in the vascular wall. NOTCH3 misfolding could cause free radicals increase also in CADASIL. Aim of the study was to verify whether CADASIL patients have increased oxidative stress compared to unrelated healthy controls. We enrolled 15 CADASIL patients and 16 gender- and age-matched healthy controls with comparable cardiovascular risk factor. Blood and plasma reduced and total aminothiols (homocysteine, cysteine, glutathione, cysteinylglycine) were measured by HPLC and plasma 3-nitrotyrosine by ELISA. Only plasma reduced cysteine (Pr-Cys) and blood reduced glutathione (Br-GSH) concentrations differed between groups: in CADASIL patients Br-GSH levels were higher (p = 0.019) and Pr-Cys lower (p = 0.010) than in controls. No correlation was found between Br-GSH and Pr-Cys either in CADASIL patients (rho 0.25, P=0.36) or in controls (rho -0.15, P=0.44). Conversely, 3-nitrotyrosine values were similar in CADASIL and healthy subjects (p = 0.82). The high levels of antioxidant molecules and low levels of oxidant mediators found in our CADASIL population might either be expression of an effective protective action against free radical formation at an early stage of clinical symptoms or they could suggest that oxidative stress is not directly involved in the pathogenesis of CADASIL.

Lenticulostriate Arterial Lumina Are Normal in Cerebral Autosomal-Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary small vessel disease. Although postmortem studies have demonstrated mural thickening in leptomeningeal arteries and lenticulostriate perforating arteries, it is unclear whether this also leads to luminal narrowing. High-field MRI scanners enable in vivo imaging of the lumen of the lenticulostriate arteries. The aim of this study is to examine the luminal diameters of lenticulostriate arteries in living patients with CADASIL and to investigate whether luminal narrowing is correlated with the number of lacunar infarcts in the basal ganglia. Twenty-two NOTCH3 mutation carriers and 11 healthy control subjects were examined using high-resolution 3-dimensional time-of-flight MR angiography imaging on a 7-T MRI scanner. Scans were analyzed for the presence of focal stenotic segments. The total number, length, and total cross-sectional area of lenticulostriate arteries were measured and compared between mutation carriers and control subjects. These measurements were correlated with age, disease duration, and number of lacunar infarcts in the basal ganglia. No stenotic segments were observed. No differences between mutation carriers and control subjects were found in total number of end branches (mutation carriers: mean, 14.6; control subjects: mean, 12.8), length of the lenticulostriate system, or total cross-sectional area of lenticulostriate artery lumina. Measurements of lenticulostriate artery lumina were not associated with lacunar infarct load in the basal ganglia area or with basal ganglia hyperintensities. Three-dimensional time-of-flight MR angiographic on 7 T showed no differences in luminal diameters of lenticulostriate arteries between patients with CADASIL and control subjects.

Neuropathological Correlates of Temporal Pole White Matter Hyperintensities in CADASIL

White matter (WM) hyperintensities on MRI or leukoaraiosis is characteristic of stroke syndromes. Increased MRI signals in the anterior temporal pole are suggested to be diagnostic for cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), with 90% sensitivity and 100% specificity. The structural correlates of these specific WM hyperintensities seen on T2-weighted and FLAIR sequences in the temporal pole of CADASIL are unclear. We assessed pathological changes in postmortem tissue from the temporal pole to reveal the cause of CADASIL-specific WM hyperintensities. A combination of tinctorial and immunostaining approaches and in vitro imaging methods were used to quantify the extent of perivascular space (PVS), arteriosclerosis determined as the sclerotic index, WM myelination as the myelin index, and damage within the WM as accumulated degraded myelin basic protein in samples of the anterior temporal pole from 9 CADASIL and 8 sporadic subcortical ischemic vascular dementia cases, and 5 similarly aged (young) and 5 older controls. Luxol fast blue-stained serial sections from a CADASIL case were also used to reconstruct the temporal pole, which was then compared to the MR images. Luxol fast blue sections used to reconstruct the temporal pole revealed an abundance of enlarged PVS in the WM that topographically appeared as indistinct opaque regions. The mean and total areas of the PVS per WM area (%PVS) were significantly greater in CADASIL compared to the controls. The myelin index was severely reduced in CADASIL in relation to the subcortical ischemic vascular dementia and control sample that was consistent with increased immunoreactivity of degraded myelin basic protein, indicating myelin degeneration. Cerebral microvessels associated with the PVS exhibited a 4.5-fold greater number of basophilic (hyalinized) vessels and a 57% increase in the sclerotic index values in CADASIL subjects compared to young controls. A significant correlation between the quantity of hyalinized vessels and sclerotic index values was also apparent (P<0.05). Our findings suggest that MRI hyperintensities in the temporal pole of CADASIL patients are explained by enlarged PVS and degeneration of myelin accompanied by lack of drainage of the interstitial fluid rather than lacunar infarcts. Consistent with the lack of MR hypersignals in the temporal pole of older subcortical ischemic vascular dementia subjects, our observations imply greater progression of pathological changes in CADASIL patients.

Plasma Levels of Asymmetric Dimethylarginine in Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarct and Leukoencephalopathy

Background: Asymmetric dimethylarginine (ADMA) is a marker of endothelial dysfunction and a new independent risk factor for adverse cerebrovascular events in small vessel disease. Conversely, L-arginine (LARG) may have a protective role. Methods: To assess ADMA, LARG levels and LARG/ADMA ratio in 16 patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and normal controls, and to look for possible correlations with white matter changes. Plasma levels of ADMA and LARG were assayed by high-performance liquid chromatography in all subjects. The overall T₁ and T₂ lesion load was obtained from brain MRI of patients with CADASIL. Results: ADMA plasma concentrations (1.5 ± 2.0 µM) were significantly higher (p < 0.05) in CADASIL patients than in controls (0.35 ± 0.075 µM). Analyzing only CADASIL subjects, an inverse borderline-significant correlation was found between LARG/ADMA (190 ± 20) and T₂-weighted lesion volumes (57.9 ± 46.5; r = –0.578, p = 0.024). Conclusion: Our results may indicate the possible coexistence of endothelial dysfunction in CADASIL patients, broadening the range of potentially pathogenetic mechanisms in this disease and providing insights for future therapeutic strategies.

Cardiac Autonomic Nervous System and Risk of Arrhythmias in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy (CADASIL)

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited systemic microangiopathy with prevalently cerebral manifestations. Among the causes of death, sudden unexpected death seems to occur in a significant number of CADASIL patients. Because potential causes of sudden unexpected death may include cardiac arrhythmias and myocardial infarction, we evaluated risk factors for life-threatening arrhythmias, such as reduced heart rate variability, sympathetic overactivity and QT interval (QTc) prolongation, in 23 CADASIL patients. The relationship of these changes with brain MRI pattern was also investigated. Frequency domain measures of heart rate variability (10 minutes recordings) and QTc interval were recorded in 23 CADASIL patients (17 males, 6 females) and 22 healthy age- and sex-matched control subjects. The following heart rate variability spectral parameters were considered at rest during spontaneous and controlled breathing (Cb): total power, very-low-frequency component, low-frequency component, high-frequency component, low-frequency/high-frequency ratio, and Cb-total power, Cb-very-low-frequency component, Cb-low-frequency component, Cb-high-frequency component, Cb-low-frequency/high-frequency ratio. R-to-R wave and QTc interval were also analyzed. All data were statistically compared between CADASIL and control subjects. Conventional brain MRI was performed in patients with CADASIL and T1-weighted and T2-weighted lesion volumes, and were compared with each spectral component of the tachogram. During spontaneous and controlled breathing, total power spectrum and all spectral components (very low frequency component, high-frequency component, low-frequency component) of heart rate variability were significantly reduced in CADASIL patients with respect to controls (P<0.05). The low-frequency/high-frequency component ratio was significantly higher in CADASIL patients than in controls. No significant correlation between heart rate variability spectral parameters and other variables including total brain T2-weighted and T1-weighted lesion volumes were observed in CADASIL subjects. We found a statistically significant reduction in all frequency domain parameters of heart rate variability associated with a higher low frequency/high frequency ratio for CADASIL patients with respect to normal subjects. These data are consistent with autonomic derangement and suggests that CADASIL patients may be at risk for life-threatening arrhythmias. This could at least in part explain their higher recurrence of sudden unexpected death and should be taken into account in planning therapy.

Cholinergic Neuronal Deficits in CADASIL

Previous evidence from MRI and acetylcholinesterase histochemistry suggests cholinergic fibers are affected in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL). As a measure of cholinergic function, we assessed choline acetyltransferase (ChAT) activities in the frontal and temporal neocortices and the immunocytochemical distribution of ChAT and p75 neurotrophin receptor (P75(NTR)) by in vitro imaging in the nucleus basalis of Meynert of CADASIL subjects. ChAT activities were significantly reduced by 60% to 70% in frontal and temporal cortices of CADASIL cases, as were ChAT and P75(NTR) immunoreactivities in the nucleus basalis. Our findings suggest cholinergic neuronal impairment in CADASIL and implicate cholinomimetic therapy for subcortical vascular dementias.

Brain volume changes in CADASIL

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an inherited small vessel disease causing stroke and subcortical vascular dementia. Recent studies in sporadic subcortical ischemic vascular disease have drawn attention to brain atrophy as a clinically important marker of disease progression. However, little is known about the role of brain atrophy and its clinical correlates in CADASIL. The authors determined the normalized brain volume (NBV) and percent brain volume change (PBVC) over 2 years in 76 CADASIL subjects (45.1 +/- 9.7 years) using the SIENA (structural image evaluation using normalization of atrophy) software and its adaptation for cross-sectional measurements (SIENAX). Baseline assessments included systolic blood pressure (SBP), homocysteine levels, BMI, and APOE genotyping. T2-lesion volumes and clinical scales were assessed at both time points. The NBV significantly correlated with all clinical scores (Rankin, NIH Stroke Scale, Barthel, structured interview for the diagnosis of Alzheimer dementia and multi-infarct dementia, Mattis dementia rating scale) at both time points independently of age and sex. PBVC correlated with changes of all clinical scores (all p < 0.01) except for the Mattis dementia rating scale (p = 0.10). In a linear regression model, age (p < 0.001), male sex (p < 0.01), and SBP (p = 0.07) were the main risk factors for a lower NBV at baseline. Age (p < 0.001) and SBP (p = 0.01) were risk factors for brain volume loss during follow-up. Sample size estimates showed that the number of individuals needed to demonstrate a treatment effect in a trial can be reduced when PBVC is used as an endpoint. This study identifies brain atrophy as an important aspect of the disease process in CADASIL and establishes significant correlations with multiple clinical aspects including cognition. Age and systolic blood pressure are risk factors for brain volume loss during follow-up. Percent brain volume change seems promising as an adjunct outcome measure in future interventional trials.

The cognitive profiles of CADASIL and sporadic small vessel disease

Interpretation of treatment trials in vascular dementia is confounded by the presence of coexistent Alzheimer disease (AD) pathology. The younger onset genetic disease cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) offers a model of pure vascular dementia, in which such confounding is unlikely. To validate CADASIL's use as a model it is important to show it results in a similar cognitive impairment. The same neuropsychological assessment was administered to patients with CADASIL (n = 34, 14 of whom had had stroke), sporadic small vessel disease (SVD) presenting with lacunar stroke and having confluent leukoaraiosis (n = 54), and healthy controls (n = 25). A similar pattern of neuropsychological impairment was seen in the two diseases, with prominent early executive dysfunction. Patients with CADASIL and SVD performed worse than controls on Trails switching test (CADASIL p = 0.006; SVD p < 0.001), and on verbal fluency test (CADASIL p = 0.015; SVD p = 0.004). The SVD group also performed worse on immediate (p = 0.050) and delayed (p = 0.049) memory. When only patients with CADASIL with stroke were included in analysis with SVD subjects, all of whom had had stroke, a very similar cognitive profile was seen. The only difference was on verbal fluency, where CADASIL subjects performed worse (p = 0.044). Patients with cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and small vessel disease show a similar pattern of cognitive deficits. This suggests that CADASIL provides a model of pure vascular dementia relevant for sporadic small vessel disease vascular dementia.