Cerebral amyloid angiopathy in the aged

Superficial small cerebellar infarcts in cerebral amyloid angiopathy on 3 T MRI: A preliminary study

BACKGROUND

Strictly superficial cerebellar microbleeds and cerebellar superficial siderosis have been considered markers of advanced cerebral amyloid angiopathy (CAA), but there are few studies on cerebellar ischemic lesions in CAA. We investigated the presence of superficial small cerebellar infarct (SCI) ≤15 mm and its relation to magnetic resonance imaging (MRI) markers in patients with probable CAA.

METHODS

Eighty patients with probable CAA were retrospectively evaluated. The presence of superficial SCIs was examined, along with cerebellar microbleeds and cerebellar superficial siderosis, using 3-T MRI. Lobar cerebral microbleeds, cortical superficial siderosis (cSS), enlargement of the perivascular space in the centrum semiovale, and white matter hyperintensity were assessed and the total CAA-small vessel disease (SVD) score was calculated.

RESULTS

Nine of the 80 patients (11.3%) had a total of 16 superficial SCIs. By tentatively defining SCI <4 mm as cerebellar microinfarcts, 8 out of 16 (50%) superficial SCIs corresponded to cerebellar microinfarcts. The total CAA-SVD score was significantly higher in patients with superficial SCIs (p = 0.01). The prevalence of cSS (p = 0.018), cortical cerebral microinfarct (p = 0.034), and superficial cerebellar microbleeds (p = 0.006) was significantly higher in patients with superficial SCIs. The number of superficial cerebellar microbleeds was also significantly higher in patients with superficial SCIs (p = 0.001).

CONCLUSIONS

Our results suggest that in patients with CAA, superficial SCIs (including microinfarcts) on MRI may indicate more severe, advanced-stage CAA. These preliminary findings should be verified by larger prospective studies in the future.

Amyloid accumulation in cases of suspected comorbid cerebral amyloid angiopathy and isolated cortical venous thrombosis

BACKGROUND AND AIM

The differentiation of isolated cortical venous thrombosis (ICVT) from cerebral amyloid angiopathy (CAA) can be difficult because both diseases share similar neurological symptoms and imaging findings. N-methyl-11C-2-(4'-methylaminophenyl)-6-hydroxybenzo-thiazole (11C-PiB) positron emission tomography (PET) functions as a diagnostic modality for CAA by detecting amyloid deposition. The present prospective study evaluated amyloid deposition using 11C-PiB-PET in consecutive patients with suspected ICVT.

METHOD

This study was a prospective observational study. Patients who attended or were hospitalized between May 2019 and March 2020 were included in the analysis. Consecutive patients who met the criteria for suspicion of ICVT were enrolled in the study, and the clinical course, symptoms, imaging findings (including magnetic resonance imaging), and the 11C-PiB-PET findings of each case were analyzed.

RESULTS

The study cohort included four patients (64-82 years of age, all women). In one younger patient, 11C-PiB-PET afforded no findings suggestive of CAA, whereas the remaining three patients exhibited 11C-PiB-PET findings suggestive of CAA.

CONCLUSION

Although 11C-PiB-PET would be a reasonable modality for distinguishing ICVT from CAA, especially in younger patients, it might be difficult to differentiate ICVT from CAA in elderly patients because of the potential deposition of amyloid.

CLINICAL TRIAL REGISTRATION

URL: https://www.umin.ac.jp/ctr/ Unique identifier: UMIN 000037101.

Approaches for Increasing Cerebral Efflux of Amyloid-β in Experimental Systems

Amyloid protein-β (Aβ) concentrations are increased in the brain in both early onset and late onset Alzheimer's disease (AD). In early onset AD, cerebral Aβ production is increased and its clearance is decreased, while increased Aβ burden in late onset AD is due to impaired clearance. Aβ has been the focus of AD therapeutics since development of the amyloid hypothesis, but efforts to slow AD progression by lowering brain Aβ failed until phase 3 trials with the monoclonal antibodies lecanemab and donanemab. In addition to promoting phagocytic clearance of Aβ, antibodies lower cerebral Aβ by efflux of Aβ-antibody complexes across the capillary endothelia, dissolving Aβ aggregates, and a "peripheral sink" mechanism. Although the blood-brain barrier is the main route by which soluble Aβ leaves the brain (facilitated by low-density lipoprotein receptor-related protein-1 and ATP-binding cassette sub-family B member 1), Aβ can also be removed via the blood-cerebrospinal fluid barrier, glymphatic drainage, and intramural periarterial drainage. This review discusses experimental approaches to increase cerebral Aβ efflux via these mechanisms, clinical applications of these approaches, and findings in clinical trials with these approaches in patients with AD or mild cognitive impairment. Based on negative findings in clinical trials with previous approaches targeting monomeric Aβ, increasing the cerebral efflux of soluble Aβ is unlikely to slow AD progression if used as monotherapy. But if used as an adjunct to treatment with lecanemab or donanemab, this approach might allow greater slowing of AD progression than treatment with either antibody alone.

Etiology of Primary Cerebellar Intracerebral Hemorrhage Based on Topographic Localization

BACKGROUND

Cerebellar intracerebral hemorrhage (cICH) is often attributed to hypertension or cerebral amyloid angiopathy (CAA). However, deciphering the exact etiology can be challenging. A recent study reported a topographical etiologic relationship with superficial cICH secondary to CAA. We aimed to reexamine this relationship between topography and etiology in a separate cohort of patients and using the most recent Boston criteria version 2.0.

METHODS

We performed a retrospective analysis of consecutive patients with primary cICH admitted to a tertiary academic center between 2000 and 2022. cICH location on brain computed tomography/magnetic resonance imaging scan(s) was divided into strictly superficial (cortex, surrounding white matter, vermis) versus deep (cerebellar nuclei, deep white matter, peduncular region) or mixed (both regions). Magnetic resonance imaging was rated for markers of cerebral small vessel disease. We assigned possible/probable versus absent CAA using Boston criteria 2.0.

RESULTS

We included 197 patients; 106 (53.8%) were females, median age was 74 (63-82) years. Fifty-six (28%) patients had superficial cICH and 141 (72%) deep/mixed cICH. Magnetic resonance imaging was available for 112 (57%) patients (30 [26.8%] with superficial and 82 [73.2%] with deep/mixed cICH). Patients with superficial cICH were more likely to have possible/probable CAA (48.3% versus 8.6%; odds ratio [OR], 11.43 [95% CI, 3.26-40.05]; P<0.001), strictly lobar cerebral microbleeds (51.7% versus 6.2%; OR, 14.18 [95% CI, 3.98-50.50]; P<0.001), and cortical superficial siderosis (13.8% versus 1.2%; OR, 7.70 [95% CI, 0.73-80.49]; P=0.08). Patients with deep/mixed cICH were more likely to have deep/mixed cerebral microbleeds (59.2% versus 3.4%; OR, 41.39 [95% CI, 5.01-341.68]; P=0.001), lacunes (54.9% versus 17.2%; OR, 6.14 [95% CI, 1.89-19.91]; P=0.002), severe basal ganglia enlarged perivascular spaces (36.6% versus 7.1%; OR, 7.63 [95% CI, 1.58-36.73]; P=0.01), hypertension (84.4% versus 62.5%; OR, 3.43 [95% CI, 1.61 to -7.30]; P=0.001), and higher admission systolic blood pressure (172 [146-200] versus 146 [124-158] mm Hg, P<0.001).

CONCLUSIONS

Our results suggest that superficial cICH is strongly associated with CAA whereas deep/mixed cICH is strongly associated with hypertensive arteriopathy.

Cerebral Amyloid Angiopathy-Related Inflammation (CAA-ri): Presentation at an Unusual Age

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a less common but aggressive manifestation of CAA caused by an autoimmune reaction to the amyloid-beta (Ab) deposits in affected vessels. Here, we report the case of a 96-year-old patient, with a history of Alzheimer's disease, who presented to our hospital due to a sudden onset of high-intensity holocranial headache followed by dysarthria, left hemiplegia, and gaze deviation to the right. MRI of the brain was performed, which revealed a heterogeneous hypointense signal on the right frontal T2 and fluid-attenuated inversion recovery (FLAIR) sequences, with an asymmetric hyperintensity surrounding the lesion compatible with perilesional vasogenic edema. Given the clinical radiographic findings, a diagnosis of CAA-ri was established and immediate treatment with intravenous corticosteroids was started, with a rapid clinical response and remarkable improvement in follow-up neuroimaging.

Elevated late-life blood pressure may maintain brain oxygenation and slow amyloid-β accumulation at the expense of cerebral vascular damage

Hypertension in midlife contributes to cognitive decline and is a modifiable risk factor for dementia. The relationship between late-life hypertension and dementia is less clear. We have investigated the relationship of blood pressure and hypertensive status during late life (after 65 years) to post-mortem markers of Alzheimer's disease (amyloid-β and tau loads); arteriolosclerosis and cerebral amyloid angiopathy; and to biochemical measures of ante-mortem cerebral oxygenation (the myelin-associated glycoprotein:proteolipid protein-1 ratio, which is reduced in chronically hypoperfused brain tissue, and the level of vascular endothelial growth factor-A, which is upregulated by tissue hypoxia); blood-brain barrier damage (indicated by an increase in parenchymal fibrinogen); and pericyte content (platelet-derived growth factor receptor β, which declines with pericyte loss), in Alzheimer's disease (n = 75), vascular (n = 20) and mixed dementia (n = 31) cohorts. Systolic and diastolic blood pressure measurements were obtained retrospectively from clinical records. Non-amyloid small vessel disease and cerebral amyloid angiopathy were scored semiquantitatively. Amyloid-β and tau loads were assessed by field fraction measurement in immunolabelled sections of frontal and parietal lobes. Homogenates of frozen tissue from the contralateral frontal and parietal lobes (cortex and white matter) were used to measure markers of vascular function by enzyme-linked immunosorbent assay. Diastolic (but not systolic) blood pressure was associated with the preservation of cerebral oxygenation, correlating positively with the ratio of myelin-associated glycoprotein to proteolipid protein-1 and negatively with vascular endothelial growth factor-A in both the frontal and parietal cortices. Diastolic blood pressure correlated negatively with parenchymal amyloid-β in the parietal cortex. In dementia cases, elevated late-life diastolic blood pressure was associated with more severe arteriolosclerosis and cerebral amyloid angiopathy, and diastolic blood pressure correlated positively with parenchymal fibrinogen, indicating blood-brain barrier breakdown in both regions of the cortex. Systolic blood pressure was related to lower platelet-derived growth factor receptor β in controls in the frontal cortex and in dementia cases in the superficial white matter. We found no association between blood pressure and tau. Our findings demonstrate a complex relationship between late-life blood pressure, disease pathology and vascular function in dementia. We suggest that hypertension helps to reduce cerebral ischaemia (and may slow amyloid-β accumulation) in the face of increasing cerebral vascular resistance, but exacerbates vascular pathology.

Fatal thrombolysis-related intracerebral haemorrhage associated with amyloid-β-related angiitis in a middle-aged patient - case report and literature review

BACKGROUND

Amyloid-β-related angiitis (ABRA) is a rare complication of cerebral amyloid angiopathy, characterized by amyloid-β deposition in the leptomeningeal and cortical vessels with associated angiodestructive granulomatous inflammation. The clinical presentation is variable, including subacute cognitive decline, behavioural changes, headaches, seizures and focal neurological deficits, which may mimic other conditions. Here, we present a case with fatal thrombolysis-related haemorrhage associated with ABRA in a middle-aged patient.

CASE PRESENTATION

A 55-year-old man was admitted to hospital with sudden onset left-sided cheek, arm and hand sensory loss, blurred vision, and worsening headache, with a National Institutes of Health Stroke Scale (NIHSS) score of 3. An acute CT head scan showed no contraindications, and therefore the decision was made to give intravenous thrombolysis. Post-thrombolysis, he showed rapid deterioration with visual disturbances, headache and confusion, and a repeat CT head scan confirmed several areas of intracerebral haemorrhage. No benefit from surgical intervention was expected, and the patient died four days after the first presentation. Neuropathological examination found acute ischemic infarcts of three to five days duration in the basal ganglia, insular cortex and occipital lobe, correlating with the initial clinical symptoms. There were also extensive recent intracerebral haemorrhages most likely secondary to thrombolysis. Furthermore, the histological examination revealed severe cerebral amyloid angiopathy associated with granulomatous inflammatory reaction, consistent with ABRA.

CONCLUSIONS

Presentation of ABRA in a middle-aged patient highlighted the difficulties in recognition and management of this rare condition. There is emerging evidence that patients with CAA may have increased risk of fatal intracerebral haemorrhages following thrombolysis. This may be further increased by a coexisting CAA-related inflammatory vasculopathy which is potentially treatable with steroid therapy if early diagnosis is made.

PET imaging for the evaluation of cerebral amyloid angiopathy: a systematic review

Purpose

In the last years, the role of PET imaging in the assessment of cerebral amyloid angiopathy (CAA) is emerging. In this setting, some tracers have proven their utility for the evaluation of the disease (mainly 11C-Pittsburgh compound B [11C-PIB]), however, the value of other radiotracers has to be clarified. The aim of this systematic review is, therefore, to assess the role of PET imaging in the evaluation of CAA.

Methods

A wide literature search of the PubMed/MEDLINE, Scopus, Embase, Web of Science and Cochrane library databases was made to find relevant published articles about the diagnostic performance of PET imaging for the evaluation of CAA. Quality assessment including the risk of bias and applicability concerns was carried out using QUADAS-2 evaluation.

Results

The comprehensive computer literature search revealed 651 articles. On reviewing the titles and abstracts, 622 articles were excluded because the reported data were not within the field of interest. Twenty-nine studies were included in the review. In general, PET imaging with amyloid tracers revealed its value for the assessment of CAA, for its differential diagnosis and a correlation with some clinico-pathological features. With less evidence, a role for 18F-fluorodeoxiglucose (18F-FDG) and tau tracers is starting to emerge.

Conclusion

PET imaging demonstrated its utility for the assessment of CAA. In particular, amiloid tracers revealed higher retention in CAA patients, correlation with cerebral bleed, the ability to differentiate between CAA and other related conditions (such as Alzheimer's disease) and a correlation with some cerebrospinal fluid biomarkers.

Aging, prevalence and risk factors of MRI-visible enlarged perivascular spaces

BACKGROUND AND PURPOSE

Cerebral small vessel disease (CSVD) increases with age and is associated with stroke and cognitive decline. Enlarged Perivascular Spaces (ePVS) is an emerging marker of CSVD, but its prevalence over the life span remain unclear. We characterized the age and sex-specific prevalence of ePVS and relation to age-specific risk factors, in a large community-based sample.

METHODS

We included 3,710 Framingham Heart Study participants with available brain MRI (average age 61.4±14.6, 46% men). ePVS burden was rated in the centrum semiovale (CSO) and basal ganglia (BG) regions. Individual vascular risk factors were related to ePVS burden in the CSO, BG, and mixed CSO-BG regions using multivariable adjusted ordinal logistic regression analysis.

RESULTS

Severe ePVS prevalence increased with age in men and women, and paralleled increase in vascular risk factors, and prevention treatment use. Older age, hypertension (and resulting higher treatment use), higher systolic and diastolic blood pressure, and smoking were associated with higher burden of ePVS in the CSO, BG and mixed regions.

CONCLUSIONS

Our observations reinforce the hypothesis that ePVS may be a marker of aging-driven brain vascular pathologies, and its association with vascular risk factors support their role as CSVD imaging biomarker.

Cerebellar and Cerebral Amyloid Visualized by [18F]flutemetamol PET in Long-Term Hereditary V30M (p.V50M) Transthyretin Amyloidosis Survivors

Introduction

Hereditary transthyretin (ATTRv) amyloidosis caused by the V30M (p. V50M) mutation is a fatal, neuropathic systemic amyloidosis. Liver transplantation has prolonged the survival of patients and central nervous system (CNS) complications, attributed to amyloid angiopathy caused by CNS synthesis of variant transthyretin, have emerged. The study aimed to ascertain amyloid deposition within the brain in long-term ATTRv amyloidosis survivors with neurological symptoms from the CNS.

Methods

A total of 20 patients with ATTR V30M having symptoms from the CNS and a median disease duration of 16 years (8–25 years) were included in this study. The cognitive and peripheral nervous functions were determined for 18 patients cross-sectionally at the time of the investigation. Amyloid brain deposits were examined by [¹⁸F]flutemetamol PET/CT. Five patients with Alzheimer's disease (AD) served as positive controls.

Result

60% of the patients with ATTRv had a pathological Z-score in the cerebellum, compared to only 20% in the patients with AD. 75% of the patients with transient focal neurological episodes (TFNEs) displayed a pathological uptake only in the cerebellum. Increased cerebellar uptake was related to an early age of onset of the ATTRv disease. 55% of the patients with ATTRv had a pathological Z-score in the global cerebral region compared to 100% of the patients with AD.

Conclusion

Amyloid deposition within the brain after long-standing ATTRv amyloidosis is common, especially in the cerebellum. A cerebellar amyloid uptake profile seems to be related to TFNE symptoms.

The α-dystrobrevins play a key role in maintaining the structure and function of the extracellular matrix-significance for protein elimination failure arteriopathies

The extracellular matrix (ECM) of the cerebral vasculature provides a pathway for the flow of interstitial fluid (ISF) and solutes out of the brain by intramural periarterial drainage (IPAD). Failure of IPAD leads to protein elimination failure arteriopathies such as cerebral amyloid angiopathy (CAA). The ECM consists of a complex network of glycoproteins and proteoglycans that form distinct basement membranes (BM) around different vascular cell types. Astrocyte endfeet that are localised against the walls of blood vessels are tethered to these BMs by dystrophin associated protein complex (DPC). Alpha-dystrobrevin (α-DB) is a key dystrophin associated protein within perivascular astrocyte endfeet; its deficiency leads to a reduction in other dystrophin associated proteins, loss of AQP4 and altered ECM. In human dementia cohorts there is a positive correlation between dystrobrevin gene expression and CAA. In the present study, we test the hypotheses that (a) the positive correlation between dystrobrevin gene expression and CAA is associated with elevated expression of α-DB at glial-vascular endfeet and (b) a deficiency in α-DB results in changes to the ECM and failure of IPAD. We used human post-mortem brain tissue with different severities of CAA and transgenic α-DB deficient mice. In human post-mortem tissue we observed a significant increase in vascular α-DB with CAA (CAA vrs. Old p < 0.005, CAA vrs. Young p < 0.005). In the mouse model of α-DB deficiency, there was early modifications to vascular ECM (collagen IV and BM thickening) that translated into reduced IPAD efficiency. Our findings highlight the important role of α-DB in maintaining structure and function of ECM, particularly as a pathway for the flow of ISF and solutes out of the brain by IPAD.

Exogenous Aβ seeds induce Aβ depositions in the blood vessels rather than the brain parenchyma, independently of Aβ strain-specific information

Little is known about the effects of parenchymal or vascular amyloid β peptide (Aβ) deposition in the brain. We hypothesized that Aβ strain-specific information defines whether Aβ deposits on the brain parenchyma or blood vessels. We investigated 12 autopsied patients with different severities of Aβ plaques and cerebral amyloid angiopathy (CAA), and performed a seeding study using an Alzheimer’s disease (AD) mouse model in which brain homogenates derived from the autopsied patients were injected intracerebrally. Based on the predominant pathological features, we classified the autopsied patients into four groups: AD, CAA, AD + CAA, and less Aβ. One year after the injection, the pathological and biochemical features of Aβ in the autopsied human brains were not preserved in the human brain extract-injected mice. The CAA counts in the mice injected with all four types of human brain extracts were significantly higher than those in mice injected with PBS. Interestingly, parenchymal and vascular Aβ depositions were observed in the mice that were injected with the human brain homogenate from the less Aβ group. The Aβ and CAA seeding activities, which had significant positive correlations with the Aβ oligomer ratio in the human brain extracts, were significantly higher in the human brain homogenate from the less Aβ group than in the other three groups. These results indicate that exogenous Aβ seeds from different Aβ pathologies induced Aβ deposition in the blood vessels rather than the brain parenchyma without being influenced by Aβ strain-specific information, which might be why CAA is a predominant feature of Aβ pathology in iatrogenic transmission cases. Furthermore, our results suggest that iatrogenic transmission of Aβ pathology might occur due to contamination of brain tissues from patients with little Aβ pathology, and the development of inactivation methods for Aβ seeding activity to prevent iatrogenic transmission is urgently required.

Cerebrospinal fluid cytokines and metalloproteinases in cerebral amyloid angiopathy-related inflammation

OBJECTIVES

To clarify pathomechanisms of cerebral amyloid angiopathy-related inflammation/vasculitis (CAA-ri).

METHODS

We collected cerebrospinal fluid (CSF) samples of nine patients with CAA-ri of before (acute CAA-ri group) and after treatment (post-treatment CAA-ri group) and nine patients with CAA (CAA without inflammation group). We examined anti-amyloid β protein (Aβ) antibody titer by ELISA, and measured 27 Cytokines, nine matrix metalloproteinases (MMPs), and four tissue inhibitors of MMPs (TIMPs) by multiplexed fluorescent bead-based immunoassay.

RESULTS

We demonstrated TIMP-2 (median) in CSF of the acute CAA-ri group (30,994.49 pg/ml, p = 0.007) and the post-treatment CAA-ri group (36,430.97 pg/ml, p = 0.001) was significantly elevated compared to that of the CAA without inflammation group (22,013.58 pg/ml). TIMP-1 was also higher in the post-treatment CAA-ri group than that in the CAA without inflammation group (58,167.75 pg/ml vs. 45,770.03 pg/ml, p = 0.005). There was a significant positive correlation between TIMP-1 and anti-Aβ antibodies in CAA-ri (r_s  = 0.900, p = 0.037). Median MMP-2 tended to be higher in the acute and post-treatment CAA-ri groups (10,619.82 pg/ml and 8396.98 pg/ml, respectively) than in the CAA without inflammation group (4436.34 pg/ml). Platelet-derived growth factor (PDGF)-BB levels before treatment were higher than those after treatment (median, 12.66 pg/ml vs. 6.39 pg/ml; p = 0.011) and correlated with the titer of anti-Aβ antibodies (r_s  =0.900, p = 0.037).

CONCLUSIONS

Elevated levels of MMP-2, TIMP-1, and TIMP-2 might be related to the development of CAA-ri. Elevation of PDGF-BB could be a useful marker for clinical diagnosis of CAA-ri.

Inflammation, Nitro-Oxidative Stress, Impaired Autophagy, and Insulin Resistance as a Mechanistic Convergence Between Arterial Stiffness and Alzheimer's Disease

The average age of the world's elderly population is steadily increasing. This unprecedented rise in the aged world population will increase the prevalence of age-related disorders such as cardiovascular disease (CVD) and neurodegeneration. In recent years, there has been an increased interest in the potential interplay between CVDs and neurodegenerative syndromes, as several vascular risk factors have been associated with Alzheimer's disease (AD). Along these lines, arterial stiffness is an independent risk factor for both CVD and AD. In this review, we discuss several inflammaging-related disease mechanisms including acute tissue-specific inflammation, nitro-oxidative stress, impaired autophagy, and insulin resistance which may contribute to the proposed synergism between arterial stiffness and AD.

Cerebral blood flow and cerebrovascular reactivity are preserved in a mouse model of cerebral microvascular amyloidosis

Impaired cerebrovascular function is an early biomarker for cerebral amyloid angiopathy (CAA), a neurovascular disease characterized by amyloid-β accumulation in the cerebral vasculature, leading to stroke and dementia. The transgenic Swedish Dutch Iowa (Tg-SwDI) mouse model develops cerebral microvascular amyloid-β deposits, but whether this leads to similar functional impairments is incompletely understood. We assessed cerebrovascular function longitudinally in Tg-SwDI mice with arterial spin labeling (ASL)-magnetic resonance imaging (MRI) and laser Doppler flowmetry (LDF) over the course of amyloid-β deposition. Unexpectedly, Tg-SwDI mice showed similar baseline perfusion and cerebrovascular reactivity estimates as age-matched wild-type control mice, irrespective of modality (ASL or LDF) or anesthesia (isoflurane or urethane and α-chloralose). Hemodynamic changes were, however, observed as an effect of age and anesthesia. Our findings contradict earlier results obtained in the same model and question to what extent microvascular amyloidosis as seen in Tg-SwDI mice is representative of cerebrovascular dysfunction observed in CAA patients.

A Pictorial Review of Intracranial Haemorrhage Revisited

BACKGROUND

The many causes of Intracerebral Haemorrhage (IH) can be difficult to differentiate. However, there are imaging features that can provide useful clues. This paper aims to provide a pictorial review of the common causes of IH, to identify some distinguishing diagnostic features and to provide guidance on subsequent imaging and follow up. It is hoped that this review would benefit radiology and non-radiology consultants, multi-professional workers and trainees who are commonly exposed to unenhanced CT head studies but are not neuroradiology specialists.

DISCUSSION

In the absence of trauma, Spontaneous Intracerebral Haemorrhage (SIH) can be classified as idiopathic or secondary. Secondary causes of IH include hypertension and amyloid angiopathy (75-80%) and less common pathologies such as vascular malformations (arteriovenous malformations, aneurysms and cavernomas), malignancy , venous sinus thrombosis and infection. SIH causes between 10 to 15% of all strokes and has a higher mortality than ischaemic stroke. Trauma is another cause of IH with significant mortality and some of the radiological features will be reviewed.

CONCLUSION

Unenhanced CT is a mainstay of acute phase imaging due to its availability and, sensitivity and specificity for detecting acute haemorrhage. Several imaging features can be identified on CT and, along with clinical information, can provide some certainty in diagnosis. For those suitable and where diagnostic uncertainty remains CT angiogram, time-resolved CT angiography and catheter angiography can help identify underlying AVMs, aneurysms, cavernomas and vasculitides. MRI is more sensitive for the detection of subacute and chronic haemorrhage and identification of underlying mass lesions.

Amyloid Beta Immunoreactivity in the Retinal Ganglion Cell Layer of the Alzheimer's Eye

Alzheimer’s disease (AD) is the most prevalent form of dementia, accounting for 60–70% of all dementias. AD is often under-diagnosed and recognized only at a later, more advanced stage, and this delay in diagnosis has been suggested as a contributing factor in the numerous unsuccessful AD treatment trials. Although there is no known cure for AD, early diagnosis is important for disease management and care. A hallmark of AD is the deposition of amyloid-β (Aβ)-containing senile neuritic plaques and neurofibrillary tangles composed of hyperphosporylated tau in the brain. However, current in vivo methods to quantify Aβ in the brain are invasive, requiring radioactive tracers and positron emission tomography. Toward development of alternative methods to assess AD progression, we focus on the retinal manifestation of AD pathology. The retina is an extension of the central nervous system uniquely accessible to light-based, non-invasive ophthalmic imaging. However, earlier studies in human retina indicate that the literature is divided on the presence of Aβ in the AD retina. To help resolve this disparity, this study assessed retinal tissues from neuropathologically confirmed AD cases to determine the regional distribution of Aβ in retinal wholemounts and to inform on future retinal image studies targeting Aβ. Concurrent post-mortem brain tissues were also collected. Neuropathological cortical assessments including neuritic plaque (NP) scores and cerebral amyloid angiopathy (CAA) were correlated with retinal Aβ using immunohistochemistry, confocal microscopy, and quantitative image analysis. Aβ load was compared between AD and control (non-AD) eyes. Our results indicate that levels of intracellular and extracellular Aβ retinal deposits were significantly higher in AD than controls. Mid-peripheral Aβ levels were greater than central retina in both AD and control eyes. In AD retina, higher intracellular Aβ was associated with lower NP score, while higher extracellular Aβ was associated with higher CAA score. Our data support the feasibility of using the retinal tissue to assess ocular Aβ as a surrogate measure of Aβ in the brain of individuals with AD. Specifically, mid-peripheral retina possesses more Aβ deposition than central retina, and thus may be the optimal location for future in vivo ocular imaging.

Disturbed balance in the expression of MMP9 and TIMP3 in cerebral amyloid angiopathy-related intracerebral haemorrhage

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of the amyloid β (Aβ) protein in the cerebral vasculature and poses a major risk factor for the development of intracerebral haemorrhages (ICH). However, only a minority of patients with CAA develops ICH (CAA-ICH), and to date it is unclear which mechanisms determine why some patients with CAA are more susceptible to haemorrhage than others. We hypothesized that an imbalance between matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) contributes to vessel wall weakening. MMP9 plays a role in the degradation of various components of the extracellular matrix as well as of Aβ and increased MMP9 expression has been previously associated with CAA. TIMP3 is an inhibitor of MMP9 and increased TIMP3 expression in cerebral vessels has also been associated with CAA. In this study, we investigated the expression of MMP9 and TIMP3 in occipital brain tissue of CAA-ICH cases (n = 11) by immunohistochemistry and compared this to the expression in brain tissue of CAA cases without ICH (CAA-non-haemorrhagic, CAA-NH, n = 18). We showed that MMP9 expression is increased in CAA-ICH cases compared to CAA-NH cases. Furthermore, we showed that TIMP3 expression is increased in CAA cases compared to controls without CAA, and that TIMP3 expression is reduced in a subset of CAA-ICH cases compared to CAA-NH cases. In conclusion, in patients with CAA, a disbalance in cerebrovascular MMP9 and TIMP3 expression is associated with CAA-related ICH.

Nationwide survey on cerebral amyloid angiopathy in Japan

BACKGROUND AND PURPOSE

A nationwide survey was conducted to understand the epidemiology of cerebral amyloid angiopathy-related intracerebral hemorrhage (CAA-related ICH) and cerebral amyloid angiopathy-related inflammation/vasculitis (CAA-ri) in Japan.

METHODS

To estimate the total number and clinical features of patients with CAA-related ICH and CAA-ri between January 2012 and December 2014 and to analyze their clinical features, questionnaires were sent to randomly selected hospitals in Japan.

RESULTS

In the first survey, 2348 of 4657 departments responded to the questionnaire (response rate 50.4%). The total numbers of reported patients with CAA-related ICH and CAA-ri were 1338 and 61, respectively, and their total numbers in Japan were estimated to be 5900 [95% confidence interval (CI) 4800-7100] and 170 (95% CI 110-220), respectively. The crude prevalence rates were 4.64 and 0.13 per 100 000 population, respectively. The clinical information of 474 patients with CAA-related ICH obtained in the second survey was as follows: (i) the average age of onset was 78.4 years; (ii) the prevalence increased with age; (iii) the disease was common in women; and (iv) hematoma most frequently occurred in the frontal lobe. Sixteen patients with CAA-ri for whom data were collected in the second survey had the following characteristics: (i) median age of onset was 75 years; (ii) cognitive impairment and headache were the most frequent initial manifestations; and (iii) focal neurological signs, such as motor paresis and visual disturbance, were frequently observed during the clinical course.

CONCLUSIONS

The numbers of patients with CAA-related ICH and CAA-ri in Japan were estimated.

Intracerebral hemorrhage: an update on diagnosis and treatment

Introduction: Spontaneous non-traumatic intracerebral hemorrhage (ICH) is most often caused by small vessel diseases: deep perforator arteriopathy (hypertensive arteriopathy) or cerebral amyloid angiopathy (CAA). Although ICH accounts for only 10-15% of all strokes it causes a high proportion of stroke mortality and morbidity, with few proven effective acute or preventive treatments. Areas covered: We conducted a literature search on etiology, diagnosis, treatment, management and current clinical trials in ICH. In this review, We describe the causes, diagnosis (including new brain imaging biomarkers), classification, pathophysiological understanding, treatment (medical and surgical), and secondary prevention of ICH. Expert opinion: In recent years, significant advances have been made in deciphering causes, understanding pathophysiology, and improving acute treatment and prevention of ICH. However, the clinical outcome remains poor and many challenges remain. Acute interventions delivered rapidly (including medical therapies - targeting hematoma expansion, hemoglobin toxicity, inflammation, edema, anticoagulant reversal - and minimally invasive surgery) are likely to improve acute outcomes. Improved classification of the underlying arteriopathies (from neuroimaging and genetic studies) and prognosis should allow tailored prevention strategies (including sustained blood pressure control and optimized antithrombotic therapy) to further improve longer-term outcome in this devastating disease.

Cerebellar Microbleed Distribution Patterns and Cerebral Amyloid Angiopathy

Background and Purpose- Hematoma location within the cerebellum may help identify the dominant small vessel disease type (cerebral amyloid angiopathy [CAA] versus nonamyloid small vessel disease). However, it is unknown whether this holds true for cerebral microbleeds (CMBs) within the cerebellum. We tested the hypothesis that cerebellar CMBs restricted to the cortex and vermis (defined as superficial regions) are associated with clinically diagnosed and pathology-verified CAA. Methods- Three hundred and seven consecutive spontaneous intracerebral hemorrhage (ICH) patients with a baseline magnetic resonance imaging that included susceptibility-weighted imaging or angiography were enrolled. Using a topographical template, cerebellar CMB patterns were defined as strictly superficial versus deep (cerebellar gray nuclei and white matter) or mixed (both regions involved). Thirty-six ICH patients with cerebellar CMBs and neuropathology data available were evaluated for the presence of CAA. Results- One hundred and thirty-five (44%) ICH patients had CMBs in the cerebellum. In the patient group with cerebellar CMBs, 85 (63%) showed a superficial pattern, and 50 (37%) had a deep/mixed pattern. Strictly superficial cerebellar CMBs were independently associated with a supratentorial pattern of probable CAA-ICH according to the Boston criteria (odds ratio, 1.6; CI, 1.03-2.5) and deep/mixed cerebellar CMBs with a pattern of deep/mixed ICH (odds ratio, 1.8; CI, 1.2-2.7). Pathologically verified CAA was present in 23 of 24 (96%) patients with superficial cerebellar CMBs versus 3 of 12 (25%) patients with deep/mixed cerebellar CMBs ( P<0.001). Conclusions- In ICH patients, cerebellar CMBs are relatively common and often restricted to superficial regions. A strictly superficial distribution of cerebellar CMBs is associated with clinically diagnosed and pathologically verified CAA.

Advances in cerebral amyloid angiopathy imaging

Cerebral amyloid angiopathy (CAA) is a cerebral small vessel disease caused by β -amyloid (Aβ) deposition at the leptomeningeal vessel walls. It is a common cause of spontaneous intracerebral hemorrhage and a frequent comorbidity in Alzheimer’s disease. The high recurrent hemorrhage rate in CAA makes it very important to recognize this disease to avoid potential harmful medication. Imaging studies play an important role in diagnosis and research of CAA. Conventional computed tomography and magnetic resonance imaging (MRI) methods reveal anatomical alterations, and remains as the most reliable tool in identifying CAA according to modified Boston criteria. The vascular injuries of CAA result in both hemorrhagic and ischemic manifestations and related structural changes on MRI, including cerebral microbleeds, cortical superficial siderosis, white matter hyperintensity, MRI-visible perivascular spaces, and cortical microinfarcts. As imaging techniques advance, not only does the resolution of conventional imaging improve, but novel skills in functional and molecular imaging studies also enable in vivo analysis of vessel physiological changes and underlying pathology. These modern tools help in early detection of CAA and may potentially serve as sensitive outcome markers in future clinical trials. In this article, we reviewed past studies of CAA focusing on utilization of various conventional and novel imaging techniques in both research and clinical aspects.

Increased cerebral microbleeds and cortical superficial siderosis in pediatric patients with Down syndrome

BACKGROUND

Patients with Down syndrome carry a third copy of the amyloid precursor protein gene, which is localized on chromosome 21. Consequently, these patients are prone to develop early-onset Alzheimer disease and cerebral amyloid angiopathy. Post-mortem studies suggest increased amyloid deposition to be already detectable in children with Down syndrome. The aim of our study was to evaluate if amyloid-related changes in pediatric Down syndrome patients can be detected in vivo using MRI biomarkers of cerebral microbleeds and cortical superficial siderosis.

MATERIALS AND METHODS

This retrospective study included 12 patients with Down syndrome (mean age = 5.0 years) and 12 age-matched control subjects (mean age = 4.8 years). Frequency and location of microbleeds and siderosis were assessed on blood-sensitive MRI sequences in a consensus reading by two radiologists applying a modified Microbleed Anatomical Rating Scale.

RESULTS

Down syndrome patients showed a significantly higher mean microbleeds count and likelihood of siderosis than age-matched controls. Across groups, the highest microbleeds count was found in lobar regions (gray and white matter of frontal, parietal, temporal, and occipital lobes, and the insula), while fewer microbleeds were located in subcortical and infratentorial regions. The number of microbleeds increased over time in all three Down syndrome patients with a follow-up exam.

CONCLUSION

In vivo MRI biomarkers can support the diagnosis of early-onset cerebral amyloid angiopathy, which might already be present in pediatric Down syndrome patients. This might contribute to clinical decision-making and potentially to the development of therapeutic and prophylactic approaches, as cerebral amyloid angiopathy increases the risk for intracranial hemorrhage and may be associated with increased risk of developing Alzheimer disease.

Cerebral amyloid angiopathy: Review of clinico-radiological features and mimics

Cerebral amyloid angiopathy (CAA) is an important cause of lobar intracerebral haemorrhage (ICH) in the elderly, but has other clinico-radiological manifestations. In the last two decades, certain magnetic resonance imaging (MRI) sequences, namely gradient-recalled echo imaging and the newer and more sensitive susceptibility-weighted imaging, have been utilised to detect susceptibility-sensitive lesions such as cerebral microbleeds and cortical superficial siderosis. These can be utilised sensitively and specifically by the Modified Boston Criteria to make a diagnosis of CAA without the need for 'gold-standard' histopathology from biopsy. However, recently, other promising MRI biomarkers of CAA have been described which may further increase precision of radiological diagnosis, namely chronic white matter ischaemia, cerebral microinfarcts and lobar lacunes, cortical atrophy, and increased dilated perivascular spaces in the centrum semiovale. However, the radiological manifestations of CAA, as well as their clinical correlates, may have other aetiologies and mimics. It is important for the radiologist to be aware of these clinico-radiological features and mimics to accurately diagnose CAA. This is increasingly important in a patient demographic that has a high prevalence for use of antiplatelet and antithrombotic medications for other comorbidities which inherently carries an increased risk of ICH in patients with CAA.

The Impact of Aging on Cardio and Cerebrovascular Diseases

A growing number of evidences report that aging represents the major risk factor for the development of cardio and cerebrovascular diseases. Understanding Aging from a genetic, biochemical and physiological point of view could be helpful to design a better medical approach and to elaborate the best therapeutic strategy to adopt, without neglecting all the risk factors associated with advanced age. Of course, the better way should always be understanding risk-to-benefit ratio, maintenance of independence and reduction of symptoms. Although improvements in treatment of cardiovascular diseases in the elderly population have increased the survival rate, several studies are needed to understand the best management option to improve therapeutic outcomes. The aim of this review is to give a 360° panorama on what goes on in the fragile ecosystem of elderly, why it happens and what we can do, right now, with the tools at our disposal to slow down aging, until new discoveries on aging, cardio and cerebrovascular diseases are at hand.

Identification of neurovascular changes associated with cerebral amyloid angiopathy from subject-specific hemodynamic response functions

Cerebral amyloid angiopathy (CAA) is a small-vessel disease preferentially affecting posterior brain regions. Recent evidence has demonstrated the efficacy of functional MRI in detecting CAA-related neurovascular injury, however, it is unknown whether such perturbations are associated with changes in the hemodynamic response function (HRF). Here we estimated HRFs from two different brain regions from block design activation data, in light of recent findings demonstrating how block designs can accurately reflect HRF parameter estimates while maximizing signal detection. Patients with a diagnosis of probable CAA and healthy controls performed motor and visual stimulation tasks. Time-to-peak (TTP), full-width at half-maximum (FWHM), and area under the curve (AUC) of the estimated HRFs were compared between groups and to MRI features associated with CAA including cerebral microbleed (CMB) count. Motor HRFs in CAA patients showed significantly wider FWHM ( P = 0.006) and delayed TTP ( P = 0.03) compared to controls. In the patient group, visual HRF FWHM was positively associated with CMB count ( P = 0.03). These findings indicate that hemodynamic abnormalities in patients with CAA may be reflected in HRFs estimated from block designs across different brain regions. Moreover, visual FWHM may be linked to structural MR indications associated with CAA.

Cerebral amyloid angiopathy initially occurs in the meningeal vessels

To clarify the frequency of CAA in the brain parenchyma and subarachnoid space (SAS), we counted sections of blood vessels showing positive staining for Aβ in the SAS, cerebral cortex (CC) and cerebral white matter (WM) using paraffin-embedded sections of the frontal, temporal and occipital lobes. The specimens had been taken for routine neuropathological examination from the brains of 105 Japanese patients (aged 40-95 years) selected from among 200 consecutive patients autopsied between 1989 and 2015 at our hospital. We examined the anatomical ratios of blood-vessel sections in the SAS relative to the CC in three selected CAA cases, and those of Aβ-positive blood-vessel sections in CAA cases. CAA was found in 53 of the 105 cases (50.5%), and the youngest patient affected was a 51-year-old man. The incidence of CAA increased with age. The anatomical ratio of blood vessel sections in the SAS relative to the CC was 1/3.70-1/4.37 (mean: 1/3.94). The ordinary CAA group, in which CAA was seen in both the SAS and CC, included 41 cases (77.4%). In 37 of these cases, the SAS/CC ratio of Aβ-positive blood vessels was 1/0.05-1/0.66 (mean: 1/0.26), and in the other four cases the ratio was 1/1-1/1.5. In the ordinary CAA group, the SAS/CC ratio of Aβ-positive blood vessels was smaller than the anatomical ratio. The meningeal CAA group, in which CAA was found only in the SAS, included 12 cases (22.6%). These patients ranged in age from their fifties to their nineties. There was no case in which CAA was limited only to the CC. We concluded that CAA initially develops in the meningeal blood vessels, and not in the cortical blood vessels. CAA in the WM was seen in 10 cases, not only in nine cases that were severe, but also in a mild case.

Cerebral Hypoperfusion and the Energy Deficit in Alzheimer's Disease

There is a perfusion deficit in Alzheimer's disease (AD), commencing in the precuneus and spreading to other parts of the cerebral cortex. The deficit anticipates the development of dementia, contributes to brain damage, and is caused by both functional and structural abnormalities of the cerebral vasculature. Most of the abnormalities are probably secondary to the accumulation of Aβ but the consequent hypoperfusion may, in turn, increase Aβ production. In the early stages of disease, abnormalities that cause vasoconstriction predominate. These include cholinergic vascular denervation, inhibition of endothelial nitric oxide synthase, increased production of endothelin-1 production and possibly also of angiotensin II. Patients with AD also have an increased prevalence of structural disease of cerebral microvessels, particularly CAA and capillary damage, and particularly in the later stages of disease these are likely to make an important contribution to the cerebral hypoperfusion. The metabolic abnormalities that cause early vascular dysfunction offer several targets for therapeutic intervention. However, for intervention to be effective it probably needs to be early. Prolonged cerebral hypoperfusion may induce compensatory circulatory changes that are themselves damaging, including hypertension and small vessel disease. This has implications for the use of antihypertensive drugs once there is accumulation of Aβ within the brain.

Cerebrovascular disease in ageing and Alzheimer's disease

Cerebrovascular disease (CVD) and Alzheimer’s disease (AD) have more in common than their association with ageing. They share risk factors and overlap neuropathologically. Most patients with AD have Aβ amyloid angiopathy and degenerative changes affecting capillaries, and many have ischaemic parenchymal abnormalities. Structural vascular disease contributes to the ischaemic abnormalities in some patients with AD. However, the stereotyped progression of hypoperfusion in this disease, affecting first the precuneus and cingulate gyrus, then the frontal and temporal cortex and lastly the occipital cortex, suggests that other factors are more important, particularly in early disease. Whilst demand for oxygen and glucose falls in late disease, functional MRI, near infrared spectroscopy to measure the saturation of haemoglobin by oxygen, and biochemical analysis of myelin proteins with differential susceptibility to reduced oxygenation have all shown that the reduction in blood flow in AD is primarily a problem of inadequate blood supply, not reduced metabolic demand. Increasing evidence points to non-structural vascular dysfunction rather than structural abnormalities of vessel walls as the main cause of cerebral hypoperfusion in AD. Several mediators are probably responsible. One that is emerging as a major contributor is the vasoconstrictor endothelin-1 (EDN1). Whilst there is clearly an additive component to the clinical and pathological effects of hypoperfusion and AD, experimental and clinical observations suggest that the disease processes also interact mechanistically at a cellular level in a manner that exacerbates both. The elucidation of some of the mechanisms responsible for hypoperfusion in AD and for the interactions between CVD and AD has led to the identification of several novel therapeutic approaches that have the potential to ameliorate ischaemic damage and slow the progression of neurodegenerative disease.

Clinico-Radiological Characteristics and Pathological Diagnosis of Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage

OBJECTIVE

We aim to clarify the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage and to investigate the efficacy of pathological diagnosis using biopsy specimens.

METHOD

We retrospectively reviewed 253 consecutive patients with cortico-subcortical hemorrhage who had been admitted to Aizawa Hospital between January 2006 and July 2013. We had performed craniotomy and hematoma evacuation in 48 patients, as well as biopsy of the evacuated hematoma, cerebral parenchyma adjacent to the hematoma, or both, and they were classified according to the histological results (positive or negative for vascular amyloid deposition) and to the Boston criteria. We compared the clinico-radiological characteristics of cerebral amyloid angiopathy-related intracerebral hemorrhage. We also investigated the detection rate of cerebral amyloid angiopathy with respect to the origins of the specimens.

RESULTS

Pathological examination revealed that 22 subjects were positive for vascular amyloid. The number of the cerebral microbleeds located in the deep or infratentorial region was significantly larger in the negative group than in the positive group (P <.05). There was no significant difference in the distribution of lobar cerebral microbleeds and in the prevalence of hypertension. In the probable cerebral amyloid angiopathy-related intracerebral hemorrhage patients, the probability of having vascular amyloid detected by biopsy of both hematoma and parenchyma was 100%. Rebleeding in the postoperative periods was observed in 2 cases (9.1%) of the positive group.

CONCLUSIONS

Our results demonstrate the importance and safety of biopsy simultaneously performed with hematoma evacuation. Deep or infratentorial microbleeds are less correlated with cerebral amyloid angiopathy-related intracerebral hemorrhage than with noncerebral amyloid angiopathy-related intracerebral hemorrhage.

Cerebral amyloid angiopathy with atypical imagingfindings of subarachnoid hemorrhage

Cerebral amyloid angiopathy (CAA) is observed in most cases of nonhypertensive subcortical hemorrhage involving elderly patients. We herein describe the case of a female in whom a convexal subarachnoid hemorrhage was observed at 55 years of age. The cerebral hemorrhage occurred repeatedly; however, no obvious vascular lesions were observed on a cerebral angiography, and no signs of microbleeding or lesions in the deep white matter were identified on magnetic resonance imaging (MRI). Partial excision of the right frontal cortex and hematoma evacuation were performed, and histopathological examination showed deposition of an acidophilic substance with positive staining for Direct Fast Scarlet (DFS) in the cerebral vascular wall. Finally, brain hemorrhage due to CAA was diagnosed. This case suggests that CAA is an important differential diagnosis in patients with localized non-aneurysmal subarachnoid hemorrhage in the convexity sulcus.

Cerebral amyloid angiopathy: emerging concepts

Cerebral amyloid angiopathy (CAA) involves cerebrovascular amyloid deposition and is classified into several types according to the amyloid protein involved. Of these, sporadic amyloid β-protein (Aβ)-type CAA is most commonly found in older individuals and in patients with Alzheimer's disease (AD). Cerebrovascular Aβ deposits accompany functional and pathological changes in cerebral blood vessels (CAA-associated vasculopathies). CAA-associated vasculopathies lead to development of hemorrhagic lesions [lobar intracerebral macrohemorrhage, cortical microhemorrhage, and cortical superficial siderosis (cSS)/focal convexity subarachnoid hemorrhage (SAH)], ischemic lesions (cortical infarction and ischemic changes of the white matter), and encephalopathies that include subacute leukoencephalopathy caused by CAA-associated inflammation/angiitis. Thus, CAA is related to dementia, stroke, and encephalopathies. Recent advances in diagnostic procedures, particularly neuroimaging, have enabled us to establish a clinical diagnosis of CAA without brain biopsies. Sensitive magnetic resonance imaging (MRI) methods, such as gradient-echo T2^* imaging and susceptibility-weighted imaging, are useful for detecting cortical microhemorrhages and cSS. Amyloid imaging with amyloid-binding positron emission tomography (PET) ligands, such as Pittsburgh Compound B, can detect CAA, although they cannot discriminate vascular from parenchymal amyloid deposits. In addition, cerebrospinal fluid markers may be useful, including levels of Aβ40 for CAA and anti-Aβ antibody for CAA-related inflammation. Moreover, cSS is closely associated with transient focal neurological episodes (TFNE). CAA-related inflammation/angiitis shares pathophysiology with amyloid-related imaging abnormalities (ARIA) induced by Aβ immunotherapies in AD patients. This article reviews CAA and CAA-related disorders with respect to their epidemiology, pathology, pathophysiology, clinical features, biomarkers, diagnosis, treatment, risk factors, and future perspectives.

Genetics of cerebral small vessel disease

Cerebral small vessel disease (SVD) is an important cause of stroke and cognitive impairment among the elderly and is a more frequent cause of stroke in Asia than in the US or Europe. Although traditional risk factors such as hypertension or diabetes mellitus are important in the development of cerebral SVD, the exact pathogenesis is still uncertain. Both, twin and family history studies suggest heritability of sporadic cerebral SVD, while the candidate gene study and the genome-wide association study (GWAS) are mainly used in genetic research. Robust associations between the candidate genes and occurrence of various features of sporadic cerebral SVD, such as lacunar infarction, intracerebral hemorrhage, or white matter hyperintensities, have not yet been elucidated. GWAS, a relatively new technique, overcomes several shortcomings of previous genetic techniques, enabling the detection of several important genetic loci associated with cerebral SVD. In addition to the more common, sporadic cerebral SVD, several single-gene disorders causing cerebral SVD have been identified. The number of reported cases is increasing as the clinical features become clear and diagnostic examinations are more readily available. These include cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy, COL4A1-related cerebral SVD, autosomal dominant retinal vasculopathy with cerebral leukodystrophy, and Fabry disease. These rare single-gene disorders are expected to play a crucial role in our understanding of cerebral SVD pathogenesis by providing animal models for the identification of cellular, molecular, and biochemical changes underlying cerebral small vessel damage.

The relationship between cerebral amyloid angiopathy and cortical microinfarcts in brain ageing and Alzheimer's disease

AIMS

Cerebral amyloid angiopathy (CAA) represents the deposition of amyloid β protein (Aβ) in the meningeal and intracerebral vessels. It is often observed as an accompanying lesion of Alzheimer's disease (AD) or in the brain of elderly individuals even in the absence of dementia. CAA is largely age-dependent. In subjects with severe CAA a higher frequency of vascular lesions has been reported. The goal of our study was to define the frequency and distribution of CAA in a 1-year autopsy population (91 cases) from the Department of Internal Medicine, Rehabilitation, and Geriatrics, Geneva.

MATERIALS AND METHODS

Five brain regions were examined, including the hippocampus, and the inferior temporal, frontal, parietal and occipital cortex, using an antibody against Aβ, and simultaneously assessing the severity of AD-type pathology with Braak stages for neurofibrillary tangles identified with an anti-tau antibody. In parallel, the relationships of CAA with vascular brain lesions were established.

RESULTS

CAA was present in 53.8% of the studied population, even in cases without AD (50.6%). The strongest correlation was seen between CAA and age, followed by the severity of amyloid plaques deposition. Microinfarcts were more frequent in cases with CAA; however, our results did not confirm a correlation between these parameters.

CONCLUSION

The present data show that CAA plays a role in the development of microvascular lesions in the ageing brain, but cannot be considered as the most important factor in this vascular pathology, suggesting that other mechanisms also contribute importantly to the pathogenesis of microvascular changes.

Imaging spectrum of sporadic cerebral amyloid angiopathy: multifaceted features of a single pathological condition

OBJECTIVES

Sporadic cerebral amyloid angiopathy (CAA) is common cause of cerebrovascular disorders that predominantly affect elderly patients. When symptomatic, cortical-subcortical intracerebral haemorrhage (ICH) in the elderly is the most well-known manifestation of CAA. Furthermore, the clinical presentation varies from a sudden neurological deficit to seizures, transient symptoms and acute progressive cognitive decline. Despite its clinical importance, this multifaceted nature poses a diagnostic challenge for radiologists. The aims of this study were to expound the characteristics of neuroimaging modalities, which cover a wide spectrum of CAA-related imaging findings, and to review the various abnormal findings for which CAA could be responsible.

CONCLUSIONS

Radiologically, in addition to typical ICH, CAA leads to various types of abnormal findings, including microbleed, subarachnoid haemorrhage, superficial siderosis, microinfarction, reversible oedema, and irreversible leukoaraiosis. Taking into consideration the clinical importance of CAA-related disorders such as haemorrhagic risks and treatable oedema, it is necessary for radiologists to understand the wide spectrum of CAA-related imaging findings.

TEACHING POINTS

• To describe the characteristics of imaging modalities and findings of CAA-related disorders. • MRI, especially gradient echo sequences, provides the useful information of CAA-related haemosiderin depositions. • To understand the wide spectrum of CAA-related neuroimaging and clinical features is important.

Cerebral Amyloidal Angiopathy--a disease with implications for neurology and psychiatry

Cerebral Amyloidal Angiopathy (CAA), which occurs sporadically in most cases but can also occur hereditarily, belongs to the group amyloidoses and is characterized by the deposition and accumulation of beta-amyloid (Aβ) in smaller arterial vessels of the brain. The deposition of Aβ leads to degenerative changes in the cerebral vessel system (thickening of the vessel wall, microaneurysm, constriction of vascular lumen, dissection), which favour the development of the clinical symptomatology most often associated with CAA. Besides haemorrhages, cerebral ischaemia, transient neurological symptoms, leukoencephalopathy as well as cognitive decline and even dementia may appear in connection with CAA. A definite diagnosis of CAA can only be made on the basis of a pathological assessment, even though diagnostic findings of cerebral neuroimaging and clinical symptoms allow the diagnosis of a probable CAA. At present, no causal therapy options are available. Although CAA is placed within the range of neurological illnesses, psychiatric symptoms such as cognitive impairment, personality change or behavioural problems as well as depression are plausible clinical manifestations of CAA and may even dominate the clinical picture. Apart from epidemiological, pathogenetical, clinical and diagnostical aspects, possible psychiatric implications of CAA are discussed in the review article.

Insulin-degrading enzyme deficiency accelerates cerebrovascular amyloidosis in an animal model

Cerebrovascular amyloidosis (CA) may result in intraparenchymal bleeding and cognitive impairment. It was previously shown that transforming growth factor-β1 (TGF-β1) expression under an astrocyte promoter resulted in congophilic vascular deposits and vascular pathology. A reduction in insulin-degrading enzyme (IDE) activity was previously suggested to play a role in the accumulation of congophilic vascular deposits in the microvasculature of Alzheimer's disease (AD) cases. Here, we aim to investigate the link between TGF-β1 and IDE activity in the development of CA. We found that TGF-β1 can reduce IDE expression in a mouse brain endothelial cell line (ECs). Furthermore, we discovered that IDE activity in the brains of TGF-β1 transgenic (Tg) mice was significantly reduced compared with that of the control mice in an age-dependent manner. In addition, TGF-β1/IDE(-/-) mice showed significantly greater levels of cerebrovascular pathology compared with TGF-β1 mice. We have previously shown that 16-month-old TGF-β1 mice have a significant reduction in synaptophysin protein levels, which may lead to cognitive impairment. Here we discovered a significant reduction in synaptophysin protein already at the age of seven in the hippocampus of TGF-β1/IDE(-/-) mice compared with TGF-β1 mice. Further investigation of TGF-β1-mediated IDE activity in ECs may provide useful therapeutic intervention targets for cerebrovascular diseases such as CA.

Isolation, characterization, and aggregation of a structured bacterial matrix precursor

Biofilms are surface-associated groups of microbial cells that are embedded in an extracellular matrix (ECM). The ECM is a network of biopolymers, mainly polysaccharides, proteins, and nucleic acids. ECM proteins serve a variety of structural roles and often form amyloid-like fibers. Despite the extensive study of the formation of amyloid fibers from their constituent subunits in humans, much less is known about the assembly of bacterial functional amyloid-like precursors into fibers. Using dynamic light scattering, atomic force microscopy, circular dichroism, and infrared spectroscopy, we show that our unique purification method of a Bacillus subtilis major matrix protein component results in stable oligomers that retain their native α-helical structure. The stability of these oligomers enabled us to control the external conditions that triggered their aggregation. In particular, we show that stretched fibers are formed on a hydrophobic surface, whereas plaque-like aggregates are formed in solution under acidic pH conditions. TasA is also shown to change conformation upon aggregation and gain some β-sheet structure. Our studies of the aggregation of a bacterial matrix protein from its subunits shed new light on assembly processes of the ECM within bacterial biofilms.

Prevalence and severity of cerebral amyloid angiopathy: a population-based study on very elderly Finns (Vantaa 85+)

BACKGROUND

Cerebral amyloid angiopathy (CAA) is frequent in patients with Alzheimer's disease while its prevalence in different populations is variable. We investigated the prevalence and severity of CAA in a very elderly Finnish population.

METHODS

Neuropathological investigation was performed on 306 subjects from the population-based Vantaa 85+ Study (253 women, 53 men, mean age at death 92.3 years). The presence of CAA was analysed in six brain regions by using Congo red and immunohistochemistry with an antibody against amyloid beta peptide. The severity of CAA was assessed by counting the percentage of the CAA-positive blood vessels.

RESULTS

In total, 69.6% of the participants (170 women, 43 men) had CAA, with median severity of 1.0%, inter-quartile range (IQR) 0-5.4% and range 0-72.7%. CAA was more prevalent (81.1% vs. 67.2%; P = 0.046) and severe (median 2.7%, IQR 0.4-7.5%, range 0-72.7%) in the men than in the women (median 1.0%, IQR 0-4.6%, range 0-52.8%; P = 0.004). Parietal lobe showed the highest prevalence (57.8%) whereas the severity was highest (median 1.0%, IQR 0-6.0%, range 0-77%) in the frontal lobe. Prevalence of CAA in the six regions was variable, but the severity indices between those regions correlated highly (P < 0.001 for all regions). Meningeal CAA was more prevalent (69.5%) than cortical (59.3%; P < 0.001).

CONCLUSION

CAA was highly prevalent, albeit mild, in the very old. The prevalence and severity of CAA were found to be highest in the frontal and parietal lobes respectively - independent of the staining method used (Congo red or amyloid beta peptide).

Amyloid β-Related Angiitis Causing Coma Responsive to Immunosuppression

Introduction. Amyloid-beta-related angiitis (ABRA) is a form of CNS vasculitis in which perivascular beta-amyloid in the intracerebral vessels is thought to act as a trigger for inflammation mediated by CD68+ macrophages and CD3+ T lymphocytes. Patients with severe ABRA may develop coma responsive to immunosuppressive treatment. Case Presentation. A 57-year-old man presented to the neurological intensive care unit febrile, obtunded, and with a left hemiparesis. He had suffered from intermittent left arm weakness and numbness for several months prior. Serum and cerebrospinal fluid studies showed a lymphocytic leukocytosis in the cerebrospinal fluid (CSF), but no other evidence of infection, and the patient underwent a brain biopsy. Histopathological examination demonstrated amyloid angiopathy, with an extensive perivascular lymphocytic infiltrate, indicative of ABRA. The patient was started on cyclophosphamide and steroids. Following a week of treatment he awakened and over several weeks made a significant neurological recovery. Conclusions. ABRA can have a variety of clinical presentations, including impairments in consciousness and coma. Accurate pathological diagnosis, followed by aggressive immunosuppression, can lead to impressive neurological improvements. This diagnosis should be considered in patients with paroxysmal recurrent neurological symptoms and an accelerated progression.

The amyloid state of proteins in human diseases

Amyloid fibers and oligomers are associated with a great variety of human diseases including Alzheimer's disease and the prion conditions. Here we attempt to connect recent discoveries on the molecular properties of proteins in the amyloid state with observations about pathological tissues and disease states. We summarize studies of structure and nucleation of amyloid and relate these to observations on amyloid polymorphism, prion strains, coaggregation of pathogenic proteins in tissues, and mechanisms of toxicity and transmissibility. Molecular studies have also led to numerous strategies for biological and chemical interventions against amyloid diseases.

Predicting cerebral amyloid angiopathy-related intracerebral hemorrhages and other cerebrovascular disorders in Alzheimer's disease

Cerebral amyloid angiopathy (CAA) of amyloid β-protein (Aβ) type is common in Alzheimer's disease (AD). Aβ immunotherapies have been reported to induce CAA-related intracerebral hemorrhages (ICH) or vasogenic edema. For the purpose of developing a method to predict CAA-related ICH and other cerebrovascular disorders in AD, the biomarkers, and risk factors are reviewed. The biomarkers include (1) greater occipital uptake on amyloid positron emission tomography imaging and a decrease of cerebrospinal fluid Aβ40 levels as markers suggestive of CAA, and (2) symptomatic lobar ICH, lobar microhemorrhages, focal subarachnoidal hemorrhages/superficial siderosis, cortical microinfarcts, and subacute encephalopathy (caused by CAA-related inflammation or angiitis) as imaging findings of CAA-related ICH and other disorders. The risk factors include (1) old age and AD, (2) CAA-related gene mutations and apolipoprotein E genotype as genetic factors, (3) thrombolytic, anti-coagulation, and anti-platelet therapies, hypertension, and minor head trauma as hemorrhage-inducing factors, and (4) anti-amyloid therapies. Positive findings for one or more biomarkers plus one or more risk factors would be associated with a significant risk of CAA-related ICH and other cerebrovascular disorders. To establish a method to predict future occurrence of CAA-related ICH and other cerebrovascular disorders in AD, prospective studies with a large number of AD patients are necessary, which will allow us to statistically evaluate to what extent each biomarker or risk factor would increase the risk. In addition, further studies with progress of technologies are necessary to more precisely detect CAA and CAA-related cerebrovascular disorders.

[A case of cerebral amyloid angiopathy with reversible white matter lesions and multiple cerebral microbleeds]

A 59-year-old woman presented with a 7-year history of headache. She showed no neurological abnormality. T(2) weighted magnetic resonance (MR) images showed a hyperintense signal in the white matter in the bilateral parieto-occipital lobe without abnormal enhancement. A small amount of prednisolone was administered for rheumatoid arthritis. After prednisolone was discontinued, the T(2) weighted images showed an expansion of the hyperintense signal lesions seen in the white matter, and T(2) weighted image showed multiple foci of petechial bleeding in the cortex and subcortex of the bilateral occipital lobe. A brain biopsy specimen from the right occipital lobe revealed deposition of amyloid in the subarachnoidal and cortical vessel walls and transmural infiltration of a few lymphocytes, eosinophils, and giant histiocytes. Subsequently the patient was diagnosed with central nervous system vasculitis associated with cerebral amyloid angiopathy (CAA). After 5 months, the T(2) weighted images showed a remarkable regression of the hyperintense signal lesions in the white matter of the bilateral parieto-occipital lobe without the administration of any maintenance immunosuppressive agents. However, T(2) weighted image showed an increase of multiple cortico-subcortical foci of petechial bleeding. Her headache did not improve during the illness. Thus, we should consider the diagnosis of CAA when patients present with reversible white matter lesions and multiple cerebral microbleeds simultaneously.

Review: sporadic cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) may result from focal to widespread amyloid-β protein (Aβ) deposition within leptomeningeal and intracortical cerebral blood vessels. In addition, pericapillary Aβ refers to Aβ depositions in the glia limitans and adjacent neuropil, whereas in capillary CAA Aβ depositions are present in the capillary wall. CAA may cause lobar intracerebral haemorrhages and microbleeds. Hypoperfusion and reduced vascular autoregulation due to CAA might cause infarcts and white matter lesions. CAA thus causes vascular lesions that potentially lead to (vascular) dementia and may further contribute to dementia by impeding the clearance of solutes out of the brain and transport of nutrients across the blood brain barrier. Severe CAA is an independent risk factor for cognitive decline. The clinical diagnosis of CAA is based on the assessment of associated cerebrovascular lesions. In addition, perivascular spaces in the white matter and reduced concentrations of both Aβ(40) and Aβ(42) in cerebrospinal fluid may prove to be suggestive for CAA. Transgenic mouse models that overexpress human Aβ precursor protein show parenchymal Aβ and CAA, thus corroborating the current concept of CAA pathogenesis: neuronal Aβ enters the perivascular drainage pathway and may accumulate in vessel walls due to increased amounts and/or decreased clearance of Aβ, respectively. We suggest that pericapillary Aβ represents early impairment of the perivascular drainage pathway while capillary CAA is associated with decreased transendothelial clearance of Aβ. CAA plays an important role in the multimorbid condition of the ageing brain but its contribution to neurodegeneration remains to be elucidated.