Severe Cerebral Amyloid Angiopathy Research Articles

Histopathology of diffusion imaging abnormalities in cerebral amyloid angiopathy.

We sought to determine the underlying mechanism for altered white matter diffusion tensor imaging (DTI) measures at the histopathologic level in patients with cerebral amyloid angiopathy (CAA). Formalin-fixed intact hemispheres from 9 CAA cases and 2 elderly controls were scanned at 3-tesla MRI, including a diffusion-weighted sequence. DTI measures (i.e., fractional anisotropy [FA] and mean diffusivity [MD]) and histopathology measures were obtained from 2 tracts: the anterior thalamic radiation and inferior longitudinal fasciculus. FA was reduced in both tracts and MD was increased in cases with CAA compared to controls. Regional FA was significantly correlated with tissue rarefaction, myelin density, axonal density, and white matter microinfarcts. MD correlated significantly with tissue rarefaction, myelin density, and white matter microinfarcts, but not axonal density. FA and MD did not correlate with oligodendrocytes, astrocytes, or gliosis. Multivariate analysis revealed that tissue rarefaction (β = -0.32 ± 0.12, p = 0.009) and axonal density (β = 0.25 ± 0.12, p = 0.04) were both independently associated with FA, whereas myelin density was independently associated with MD (β = -0.32 ± 0.12, p = 0.013). Finally, we found an association between increased MD in the frontal white matter and CAA severity in the frontal cortex (p = 0.035). These results suggest that overall tissue loss, and in particular axonal and myelin loss, are major components underlying CAA-related alterations in DTI properties observed in living patients. The findings allow for a more mechanistic interpretation of DTI parameters in small vessel disease and for mechanism-based selection of candidate treatments to prevent vascular cognitive impairment.

The Impact of Cerebral Amyloid Angiopathy in Various Neurodegenerative Dementia Syndromes: A Neuropathological Study

Purpose The Boston criteria for cerebral amyloid angiopathy (CAA) have to be confirmed by postmortem examination. The present study investigates the incidence and the cerebrovascular impact of the severity of CAA in various neurodegenerative dementia diseases. Material and Methods 208 patients underwent an autopsy. They consisted of 92 brains with Alzheimer's disease (AD), 46 with frontotemporal lobar degeneration (FTLD), 24 with progressive supranuclear palsy (PSP), 21 with Lewy body dementia (LBD), 5 with corticobasal degeneration (CBD), and 20 controls. In addition to the macroscopic examination, a whole coronal section of a cerebral hemisphere, at the level of the mamillary body, was taken for semiquantitative microscopic evaluation of the small cerebrovascular lesions. Results CAA is present in 2/3% of the AD brains of which half of them have a severe form, grade 3. Only the latter displays more cerebrovascular lesions. CAA is present in 45% of the LBD brains. Cortical microinfarcts are only more frequent in the CAA grade 3 group. In LBD additional AD pathology is present in 41% of the CAA grade 0, 83% in grade 1-2, and 100% in grade 3. In PSP only 21% had CAA grade 1-2. In FTLD, CBD, and normal controls no CAA pathology is observed. Conclusions The present study shows that CAA is most frequently associated to AD but that only the severe form displays more cerebrovascular lesions. LBD is the second most frequent disease associated to CAA with a clear correlation between the incidence of the associated AD features and the increasing severity of the CAA. In PSP only 21% display mild CAA features. PSP, tau-FTLD, and CBD are part of the Pick complex diseases, who are known to have a favourable vascular profile which can explain their low incidence of cerebrovascular lesions, in contrast to AD and LBD brains.

Cerebral small vessel disease in patients with spontaneous cerebellar hemorrhage.

Spontaneous cerebellar-intracerebral hemorrhage (ICH) can be associated with both cerebral amyloid angiopathy (CAA) and hypertensive small vessel disease (HTN-SVD, i.e. arteriolosclerosis). To better understand the underlying microangiopathy of cerebellar-ICH, we aimed to evaluate the spatial distribution of supratentorial cerebral microbleeds (CMBs) and neuropathologic profiles in these patients. We enrolled consecutive cerebellar-ICH patients. Clinical variables and MRI markers specific for CAA and HTN-SVD were assessed. Patients were classified into categories according to the topography (strictly-lobar, strictly-deep, and mixed) of supratentorial CMBs and comparisons were performed. Available neuropathological material was reviewed to evaluate the presence and severity of arteriolosclerosis and CAA. Ninety-eight cerebellar-ICH patients were enrolled. Fifty patients (51%) had at least one supratentorial CMB. Twelve patients (12%) had strictly lobar-CMBs, 12 patients (12%) showed strictly deep-CMBs and mixed-CMBs (lobar and deep CMBs) were present in 26 cerebellar-ICH patients (27%). In multivariable analysis, cerebellar-ICH patients with mixed-CMBs were associated with higher prevalence of hypertension (OR 4.9, 95% confidence interval [CI] 1.2-20, p = 0.017) but with lower prevalence of severe centrum-semiovale enlarged perivascular spaces (OR 0.2, CI 0.05-0.8, p = 0.024) when compared to cerebellar-ICH patients with strictly lobar-CMBs. Vascular risk factors and neuroimaging characteristics were similar between strictly deep-CMBs and mixed-CMBs. Six patients had available neuropathological material for analyses and they all showed some degree of arteriolosclerosis. Cerebellar-ICH patients frequently show supratentorial CMBs. The mixed-CMBs pattern appears to be the most common. Our radiological and pathological results suggest that the majority of cerebellar-ICH patients harbor HTN-SVD as dominant microangiopathy.

Amyloid precursor protein-fragments-containing inclusions in cardiomyocytes with basophilic degeneration and its association with cerebral amyloid angiopathy and myocardial fibrosis

Cardiomyopathies with intracellular inclusions are a distinct subset of cardiomyopathies whereas basophilic degeneration (BD) of the heart describes inclusions in cardiomyocytes of the aging heart, which have not yet been related to a specific disease condition or to a distinct type of protein inclusion. To address the question whether BD represents a specific pathological feature and whether it is linked to a distinct disease condition we studied 62 autopsy cases. BD inclusions exhibited an immunohistochemical staining pattern related to glycosylated, δ- or η-secretase-derived N-terminal cleavage products of the amyloid precursor protein (sAPPδ/η) or shorter fragments of sAPPη. BD aggregates were found in the myocardium of both ventricles and atria with highest amounts in the atria and lowest in the interventricular septum. The frequency of BD-lesions correlated with age, degree of myocardial fibrosis in individuals with arterial hypertension, and the severity of cerebral amyloid angiopathy (CAA). The intracytoplasmic deposition of N-terminal sAPPδ/η fragments in BD indicates a specific inclusion body pathology related to APP metabolism. The correlation with the severity of CAA, which is related to the APP-derived amyloid β-protein, supports this point of view and suggests a possible link between myocardial and cerebrovascular APP-related lesions.

Pathological Correlates of Cognitive Impairment in The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age.

The neuropathological changes responsible for cognitive impairment and dementia remain incompletely understood. Longitudinal studies with a brain donation end point allow the opportunity to examine relationships between cognitive status and neuropathology. We report on the first 97 participants coming to autopsy with sufficient clinical information from The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age. This study began in 1983 and recruited 6,542 healthy individuals between 1983 and 1994, 312 of whom consented to brain donation. Alzheimer-type pathology was common throughout the cohort and generally correlated well with cognitive status. However, there was some overlap between cognitive status and measures of Alzheimer pathology with 26% of cognitively intact participants reaching either CERAD B or C, 11% reaching Thal phase 4 or 5, and 29% reaching Braak stage III- VI. Cerebral amyloid angiopathy(CAA), α-synuclein, and TDP-43 pathology was less common, but when present correlated well with cognitive status. Possession of APOEɛ4 allele(s) was associated with more severe Alzheimer-type and CAA pathology and earlier death, whereas possession of APOEɛ2 allele(s) had no effect on pathology but was more common in cognitively intact individuals. The University of Manchester Longitudinal Study of Cognition in Normal Healthy Old Age cohort is pathologically representative when compared with similar studies. Cognitive impairment in life correlates strongly with all pathologies examined and the APOE status of an individual can affect pathology severity and longevity.

On the role of sidechain size and charge in the aggregation of Aβ42 with familial mutations

The aggregation of the amyloid-β (Aβ) peptide is linked to the pathogenesis of Alzheimer's disease (AD). In particular, some point mutations within Aβ are associated with early-onset familial Alzheimer's disease. Here we set out to explore how the physical properties of the altered side chains, including their sizes and charges, affect the molecular mechanisms of aggregation. We focus on Aβ42 with familial mutations-A21G (Flemish), E22K (Italian), E22G (Arctic), E22Q (Dutch), and D23N (Iowa)-which lead to similar or identical pathology with sporadic AD or severe cerebral amyloid angiopathy. Through global kinetic analysis, we find that for the E22K, E22G, E22Q, and D23N mutations, the acceleration of the overall aggregation originates primarily from the modulation of the nucleation processes, in particular secondary nucleation on the surface of existing fibrils, whereas the elongation process is not significantly affected. Remarkably, the D23 position appears to be responsible for most of the charge effects during nucleation, while the size of the side chain at the E22 position plays a more significant role than its charge. Thus, we have developed a kinetic approach to determine the nature and the magnitude of the contribution of specific residues to the rate of individual steps of the aggregation reaction, through targeted mutations and variations in ionic strength. This strategy can help rationalize the effect of some disease-related mutations as well as yield insights into the mechanism of aggregation and the transition states of the wild-type protein.

Drusen in the Peripheral Retina of the Alzheimer's Eye.

Recent work on Alzheimer's disease (AD) diagnosis focuses on neuroimaging modalities; however, these methods are expensive, invasive, and not available to all patients. Ocular imaging of biomarkers, such as drusen in the peripheral retina, could provide an alternative method to diagnose AD. This study compares macular and peripheral drusen load in control and AD eyes. Postmortem eye tissues were obtained from donors with a neuropathological diagnosis of AD. Retina from normal donors were processed and categorized into younger (<55 years) and older (>55 years) groups. After fixation and dissection, 3-6 mm punches of RPE/choroid were taken in macular and peripheral (temporal, superior, and inferior) retinal regions. Oil red O positive drusen were counted and grouped into two size categories: small (<63 μm) and intermediate (63-125 μm). There was a significant increase in the total number of macular and peripheral hard drusen in older, compared to younger, normal eyes (p<0.05). Intermediate hard drusen were more commonly found in the temporal region of AD eyes compared to older normal eyes, even after controlling for age (p<0.05). Among the brain and eye tissues from AD donors, there was a significant relationship between cerebral amyloid angiopathy (CAA) severity and number of temporal intermediate hard drusen (r=0.78, p<0.05). Imaging temporal drusen in the eye may have benefit for diagnosing and monitoring progression of AD. Our results on CAA severity and temporal intermediate drusen in the AD eye are novel. Future studies are needed to further understand the interactions among CAA and drusen formation.

Patterns and severity of vascular amyloid in Alzheimer\u2019s disease associated with duplications and missense mutations in APP gene, Down syndrome and sporadic Alzheimer\u2019s disease

In this study, we have compared the severity of amyloid plaque formation and cerebral amyloid angiopathy (CAA), and the subtype pattern of CAA pathology itself, between APP genetic causes of AD (APPdup, APP mutations), older individuals with Down syndrome (DS) showing the pathology of Alzheimer’s disease (AD) and individuals with sporadic (early and late onset) AD (sEOAD and sLOAD, respectively). The aim of this was to elucidate important group differences and to provide mechanistic insights related to clinical and neuropathological phenotypes. Since lipid and cholesterol metabolism is implicated in AD as well as vascular disease, we additionally aimed to explore the role of APOE genotype in CAA severity and subtypes. Plaque formation was greater in DS and missense APP mutations than in APPdup, sEOAD and sLOAD cases. Conversely, CAA was more severe in APPdup and missense APP mutations, and in DS, compared to sEOAD and sLOAD. When stratified by CAA subtype from 1 to 4, there were no differences in plaque scores between the groups, though in patients with APPdup, APP mutations and sEOAD, types 2 and 3 CAA were more common than type 1. Conversely, in DS, sLOAD and controls, type 1 CAA was more common than types 2 and 3. APOE ε4 allele frequency was greater in sEOAD and sLOAD compared to APPdup, missense APP mutations, DS and controls, and varied between each of the CAA phenotypes with APOE ε4 homozygosity being more commonly associated with type 3 CAA than types 1 and 2 CAA in sLOAD and sEOAD. The differing patterns in CAA within individuals of each group could be a reflection of variations in the efficiency of perivascular drainage, this being less effective in types 2 and 3 CAA leading to a greater burden of CAA in parenchymal arteries and capillaries. Alternatively, as suggested by immunostaining using carboxy-terminal specific antibodies, it may relate to the relative tissue burdens of the two major forms of Aβ, with higher levels of Aβ40 promoting a more ‘aggressive’ form of CAA, and higher levels of Aβ42(3) favouring a greater plaque burden. Possession of APOE ε4 allele, especially ε4 homozygosity, favours development of CAA generally, and as type 3 particularly, in sEOAD and sLOAD.

Rapidly Progressive Alzheimer's Disease: Contributions to Clinical-Pathological Definition and Diagnosis.

Rapidly progressive Alzheimer's disease (rpAD) has recently been recognized as a clinical disease subtype characterized by rapidly progressive cognitive decline and/or short disease duration, and the possible occurrence of early focal neurological signs. Consistently, rpAD represents a relatively frequent alternative diagnosis among cases referred as possible or probable Creutzfeldt-Jakob disease (CJD) to surveillance centers for prion disease worldwide. Indeed, the early clinical differential diagnosis between the two disorders can be challenging given the partial overlap in clinical features and cerebrospinal fluid (CSF) levels of the protein surrogate markers 14-3-3 and total-tau. Although typical AD and rpAD seem to share the neuropathological core features, recent evidence suggests that a distinctive molecular signature involving the structure of amyloid-β aggregates and the proteomic landscape of amyloid plaques may distinguish rpAD from typical AD. Here we review clinical, neuropathological, and molecular features and diagnostic findings, including CSF biomarker data, reported to date in rpAD. Furthermore, we summarize the main clinical, pathological and laboratory features of 27 autopsy confirmed cases of rpAD referred to our center. The results of this retrospective analysis, while largely confirming previously published genetic, clinical, and neuropathological data, suggest a higher prevalence of moderate to severe cerebral amyloid angiopathy in rpAD compared to typical AD, a finding to explore further and validate in a larger patient group.

Cerebral Amyloid Angiopathy: Similarity in African-Americans and Caucasians with Alzheimer's Disease.

Cerebral amyloid angiopathy (CAA) of the Aβ type is variably present in the brains of patients with Alzheimer's disease (AD). CAA contributes to cognitive decline and increases the risk of lobar hemorrhage; because both AD-typical dementia and lobar hemorrhage are more common in African-Americans than in Caucasians, we postulated that African-Americans with AD might be particularly susceptible to CAA. To test this hypothesis, we analyzed CAA histopathologically in the large vessels and capillaries of autopsy-derived frontal, temporal, parietal, and occipital cortical samples from African-Americans (n = 18) and Caucasians (n = 19) with end-stage AD. In the combined cohort of 37 subjects, 22% of the subjects had severe CAA in large vessels, and 11% had severe CAA in capillaries. However, the prevalence and histopathologic characteristics of CAA were similar in the African-Americans and Caucasians. This conclusion was substantiated in an independent sample from the National Alzheimer's Coordinating Center database, in which the degree of CAA was comparable in 1,554 Caucasians and 68 African-Americans with end-stage AD. These findings support a growing consensus that the fundamental histopathologic features of AD are largely impartial to the race of the afflicted.

Capillary cerebral amyloid angiopathy in Alzheimer's disease: association with allocortical/hippocampal microinfarcts and cognitive decline.

Cerebral amyloid angiopathy (CAA) is caused by the deposition of the amyloid β-protein (Aβ) in the wall of cerebral and leptomeningeal blood vessels and is related to Alzheimer's disease (AD). Capillary Aβ deposition is observed in a subset of CAA cases and represents a distinct type of CAA named capillary CAA or CAA type 1. This type of CAA is strongly associated with the presence of the apolipoprotein E ε4 allele. CAA type 1-associated AD cases often exhibit a more severe Aβ plaque pathology but less widespread neurofibrillary tangle (NFT) pathology. The objective of this study was to analyze whether capillary CAA and its effects on cerebral blood flow have an impact on dementia. To address this objective, we performed neuropathological evaluation of 284 autopsy cases of demented and non-demented individuals. We assessed the presence of CAA and its subtypes as well as for that of hemorrhages and infarcts. Capillary CAA and CAA severity were associated with allocortical microinfarcts, comprising the CA1 region of the hippocampus. Allocortical microinfarcts, capillary CAA and CAA severity were, thereby, associated with cognitive decline. In conclusion, allocortical microinfarcts, CAA severity, and the capillary type of CAA were associated with one another and with the development of cognitive decline. Thus, AD cases with CAA type 1 (capillary CAA) appear to develop dementia symptoms not only due to AD-related Aβ plaque and NFT pathology but also due to hippocampal microinfarcts that are associated with CAA type 1 and CAA severity, and that damage a brain region important for memory function.

Intraventricular infusion of clusterin ameliorated cognition and pathology in Tg6799 model of Alzheimer\u2019s disease

BackgroundAlzheimer’s disease (AD) is characterized by the deposition of amyloid-β (Aβ) in brain parenchyma and cerebral blood vessels as cerebral amyloid angiopathy (CAA). Clusterin, a chaperon protein associated with Aβ aggregation, toxicity and transport through blood–brain barrier, may play a key role in the development of AD. Recently, clusterin peptide D-[113–122] was shown to mimic clusterin’s function and exerted therapeutic effect in atherosclerosis. In this study, we investigated whether this clusterin peptide also affected (Aβ) deposition in AD transgenic mouse.ResultsUsing a micropump, synthetic peptide 113–122 of clusterin protein (20 μg/200 μl) was infused into the lateral ventricle of 8-month 5 × FAD transgenic mouse model (Tg6799), for 2 weeks. Water-maze testing showed an improved cognitive function of the Tg6799 mice treated with clusterin. Immunocytochemistry and quantitative analysis revealed that intraventricular (icv) administration of clusterin peptide in Tg6799 mouse reduced Aβ plaques as well the severity of cerebral amyloid angiopathy. Enzyme-linked immunosorbent assay demonstrated a decreased in the soluble levels of Aβ (Aβ40 and Aβ42) in the brain. Western-blot revealed an increased level of LRP-2 after clusterin peptide treatment.ConclusionThese results suggest that icv infusion of clusterin peptide D-[113–122] offers a promising therapeutic approach to reduce Aβ deposition as well as CAA. The LRP2-mediated clearance system might be involved in the mechanism of these effects.

The Edinburgh CT and genetic diagnostic criteria for lobar intracerebral haemorrhage associated with cerebral amyloid angiopathy: model development and diagnostic test accuracy study

SummaryBackgroundIdentification of lobar spontaneous intracerebral haemorrhage associated with cerebral amyloid angiopathy (CAA) is important because it is associated with a higher risk of recurrent intracerebral haemorrhage than arteriolosclerosis-associated intracerebral haemorrhage. We aimed to develop a prediction model for the identification of CAA-associated lobar intracerebral haemorrhage using CT features and genotype.MethodsWe identified adults with first-ever intracerebral haemorrhage diagnosed by CT, who died and underwent research autopsy as part of the Lothian IntraCerebral Haemorrhage, Pathology, Imaging and Neurological Outcome (LINCHPIN) study, a prospective, population-based, inception cohort. We determined APOE genotype and radiologists rated CT imaging appearances. Radiologists were not aware of clinical, genetic, and histopathological features. A neuropathologist rated brain tissue for small vessel diseases, including CAA, and was masked to clinical, radiographic, and genetic features. We used CT and APOE genotype data in a logistic regression model, which we internally validated using bootstrapping, to predict the risk of CAA-associated lobar intracerebral haemorrhage, derive diagnostic criteria, and estimate diagnostic accuracy.FindingsAmong 110 adults (median age 83 years [IQR 76–87], 49 [45%] men) included in the LINCHPIN study between June 1, 2010 and Feb 10, 2016, intracerebral haemorrhage was lobar in 62 (56%) participants, deep in 41 (37%), and infratentorial in seven (6%). Of the 62 participants with lobar intracerebral haemorrhage, 36 (58%) were associated with moderate or severe CAA compared with 26 (42%) that were associated with absent or mild CAA, and were independently associated with subarachnoid haemorrhage (32 [89%] of 36 vs 11 [42%] of 26; p=0·014), intracerebral haemorrhage with finger-like projections (14 [39%] of 36 vs 0; p=0·043), and APOE ɛ4 possession (18 [50%] of 36 vs 2 [8%] of 26; p=0·0020). A prediction model for CAA-associated lobar intracerebral haemorrhage using these three variables had excellent discrimination (c statistic 0·92, 95% CI 0·86–0·98), confirmed by internal validation. For the rule-out criteria, neither subarachnoid haemorrhage nor APOE ɛ4 possession had 100% sensitivity (95% CI 88–100). For the rule-in criteria, subarachnoid haemorrhage and either APOE ɛ4 possession or finger-like projections had 96% specificity (95% CI 78–100).InterpretationThe CT and APOE genotype prediction model for CAA-associated lobar intracerebral haemorrhage shows excellent discrimination in this cohort, but requires external validation. The Edinburgh rule-in and rule-out diagnostic criteria might inform prognostic and therapeutic decisions that depend on identification of CAA-associated lobar intracerebral haemorrhage.FundingUK Medical Research Council, The Stroke Association, and The Wellcome Trust.

CT scanning to diagnose CAA: back to the future?

CT scanning to diagnose CAA: back to the future?

Aging and cerebrovascular lesions in pure and in mixed neurodegenerative and vascular dementia brains: aneuropathological study.

The prevalence of dementia is increasing in our aging population. Because of the complexity of disease pathology, dementia classifications remain controversial. The present post-mortem study investigates whether there are age differences between dementia brains with asingle pure neurodegenerative or cerebrovascular disease and those with mixed pathological features. Also, the impact of these vascular lesions is compared. Atotal of 132 dementia brains with apure neurodegenerative or cerebrovascular disease and 84 with mixed features were examined. Main age and gender distribution were compared between the overall group of pure and of mixed dementia. Also, the most common subgroups were compared separately. In addition to the detection of macroscopic visible lesions, awhole coronal section of acerebral hemisphere, at the level of the mamillary body, was taken for semi-quantitative microscopic evaluation of white matter changes (WMCs), cortical micro-bleeds (CoMBs), and cortical micro-infarcts (CoMIs). Overall, patients with mixed dementia were at death significantly older than those with pure dementia. According to the main diagnosis, the pure forms of Alzheimer's disease (AD) and frontotemporal lobar degeneration (FTLD) were more common in the younger age groups while in the older ones the mixed form of Lewy body disease (LBD) predominated. Neuropathological examination revealed an increased severity of cerebral amyloid angiopathy (CAA), territorial infarcts, lobar haematomas, and CoMIs in the mixed AD group. In FTLD only CoMIs were increased in the mixed group, while in LBD no differences in severity of all cerebrovascular lesions were observed. Lacunar infarcts were more frequent in pure vascular dementia, while CAA predominated in the mixed one. Mixed dementia during the aging process is mainly due to the severity of AD and LBD pathologies combined with CAA-related cerebrovascular lesions.

Cortical superficial siderosis multifocality in cerebral amyloid angiopathy: A prospective study.

In order to explore the mechanisms of cortical superficial siderosis (cSS) multifocality and its clinical implications for recurrent intracerebral hemorrhage (ICH) risk in patients with cerebral amyloid angiopathy (CAA), we used a new rating method that we developed specifically to evaluate cSS extent at spatially separated foci. Consecutive patients with CAA-related ICH according to Boston criteria from a single-center prospective cohort were analyzed. The new score that assesses cSS multifocality (total range 0-4) showed excellent interrater reliability (k = 0.87). The association of cSS with markers of CAA and acute ICH was investigated. Patients were followed prospectively for recurrent symptomatic ICH. The cohort included 313 patients with CAA. Multifocal cSS prevalence was 21.1%. APOE ε2 allele prevalence was higher in patients with multifocal cSS. In probable/definite CAA, cSS multifocality was independently associated with neuroimaging markers of CAA severity, including lobar microbleeds, but not with acute ICH features, which conversely, were determinants of cSS in possible CAA. During a median follow-up of 2.6 years (interquartile range 0.9-5.1 years), the annual ICH recurrence rates per cSS scores (0-4) were 5%, 6.5%, 13.5%, 16.2%, and 26.9%, respectively. cSS multifocality (presence and spread) was the only independent predictor of increased symptomatic ICH risk (hazard ratio 3.19; 95% confidence interval 1.77-5.75; p < 0.0001). The multifocality of cSS correlates with disease severity in probable CAA; therefore cSS is likely to be caused by discrete hemorrhagic foci. The new cSS scoring system might be valuable for clinicians in determining annual risk of ICH recurrence.

Acute convexity subarachnoid haemorrhage and cortical superficial siderosis in probable cerebral amyloid angiopathy without lobar haemorrhage

IntroductionAcute non-traumatic convexity subarachnoid haemorrhage (cSAH) is increasingly recognised in cerebral amyloid angiopathy (CAA). We investigated: (a) the overlap between acute cSAH and cortical superficial siderosis—a new CAA haemorrhagic imaging...

Aged chimpanzees exhibit pathologic hallmarks of Alzheimer's disease

Alzheimer's disease (AD) is a uniquely human brain disorder characterized by the accumulation of amyloid-beta protein (Aβ) into extracellular plaques, neurofibrillary tangles (NFT) made from intracellular, abnormally phosphorylated tau, and selective neuronal loss. We analyzed a large group of aged chimpanzees (n = 20, age 37–62 years) for evidence of Aβ and tau lesions in brain regions affected by AD in humans. Aβ was observed in plaques and blood vessels, and tau lesions were found in the form of pretangles, NFT, and tau-immunoreactive neuritic clusters. Aβ deposition was higher in vessels than in plaques and correlated with increases in tau lesions, suggesting that amyloid build-up in the brain's microvasculature precedes plaque formation in chimpanzees. Age was correlated to greater volumes of Aβ plaques and vessels. Tangle pathology was observed in individuals that exhibited plaques and moderate or severe cerebral amyloid angiopathy, a condition in which amyloid accumulates in the brain's vasculature. Amyloid and tau pathology in aged chimpanzees suggests these AD lesions are not specific to the human brain.

UNC5C variants are associated with cerebral amyloid angiopathy.

Objective:To determine whether common genetic variants in UNC5C, a recently identified late-onset Alzheimer disease (LOAD) dementia susceptibility gene, are associated with AD susceptibility or AD-related clinical/pathologic phenotypes.Methods:We used data from deceased individuals of European descent who participated in the Religious Orders Study or the Rush Memory and Aging Project (n = 1,288). We examined whether there were associations between single nucleotide polymorphisms (SNPs) within ±100 kb of the UNC5C gene and a diagnosis of AD dementia, global cognitive decline, a pathologic diagnosis of AD, β-amyloid load, neuritic plaque count, diffuse plaque count, paired helical filament tau density, neurofibrillary tangle count, and cerebral amyloid angiopathy (CAA) score. We also evaluated the relation of the CAA-associated variant and dorsolateral prefrontal cortex (DLPFC) UNC5C RNA expression. Secondary analyses were performed to examine the interaction of the CAA-associated SNP and known genetic risk factors of CAA as well as the association of the SNP with other cerebrovascular pathologies.Results:A set of UNC5C SNPs tagged by rs28660566T was associated with a higher CAA score (p = 2.3 × 10−6): each additional rs28660566T allele was associated with a 0.60 point higher CAA score, which is equivalent to approximately 75% of the higher CAA score associated with each allele of APOE ε4. rs28660566T was weakly associated with lower UNC5C expression in the human DLPFC (p = 0.036). Moreover, rs28660566T had a synergistic interaction with APOE ε4 on their association with higher CAA severity (p = 0.027) and was associated with more severe arteriolosclerosis (p = 0.0065).Conclusions:Targeted analysis of the UNC5C region uncovered a set of SNPs associated with CAA.

MRI-HISTOPATHOLOGY ASSOCIATIONS OF MICROBLEEDS AND MICROINFARCTS IN INTACT EX VIVO HEMISPHERES OF PATIENTS WITH CEREBRAL AMYLOID ANGIOPATHY

Microbleeds and microinfarcts are widespread lesions in cerebral amyloid angiopathy (CAA), at least partially detectable during life. We studied the prevalence and topographical distribution of microbleeds and microinfarcts on ex vivo MRI in CAA cases. Moreover, we determined number of microbleeds and microinfarcts on microscopy of standard samples to compare to the numbers detected by MRI. We specifically sought to compare MRI's methodologic advantage of providing full brain coverage to microscopy's advantage of greater sensitivity for detection of these two lesion types. We included four patients with a diagnosis of CAA during life who donated their brains to CAA research (mean age at death 73.4±6.7 years). One control case was included from our neuropathology database, a 90-year old individual without cognitive impairment. At autopsy, the brains were removed and formalin-fixed. The hemisphere without macrohemorrhage was packed in a bag with periodate-lysine-paraformaldehyde and scanned overnight at 3T MRI. The protocol included a flash (resolution 500x500x500μm3) and a T2-weighted sequence (resolution 500x500x500μm3). On the acquired scans, cortical microbleeds and microinfarcts were assessed. In parallel, the hemisphere was cut in 10mm-thick coronal slabs. Subsequently, four pre-defined standard areas were sampled, blinded to MRI (one area from the frontal, parietal, temporal, and occipital cortex), embedded in paraffin, and cut in 6μm-thick sections. One section was stained with H&E, and screened microscopically for microbleeds and microinfarcts. The adjacent section underwent Aβ immunohistochemistry to determine CAA severity. On ex vivo MRI 426 microbleeds [range 39–261] and 313 microinfarcts [range 21–144] were identified in the four CAA cases. Microbleeds and microinfarcts did not spatially overlap on MRI, but showed distinct topographical patterns. Microscopy revealed 3 microbleeds [range 0–2 per case] and 25 microinfarcts [range 0–15 per case] in the 16 examined sections. All cases showed CAA, ranging from mild-to-severe. The control case had 3 microinfarcts and 0 microbleeds on MRI, and microscopy revealed no lesions of either type and absence of CAA. In CAA, superior brain coverage provided by MRI resulted in more sensitive microbleed detection. In contrast, MRI appears to substantially undercount microinfarcts, which are often better detectable by the more sensitive method of histopathology.