Neuropathologic analysis of hematomas evacuated from patients with spontaneous intracerebral hemorrhage

Spontaneous intracerebral hemorrhage (ICH) is a devastating cause of morbidity and mortality. Intraparenchymal hematomas are often surgically evacuated. This generates fragments of perihematoma brain tissue that may elucidate their etiology. The goal of this study is to analyze the value of these specimens in providing a possible etiology for spontaneous ICH as well as the utility of using immunohistochemical markers to identify amyloid angiopathy. Surgically resected hematomas from 20 individuals with spontaneous ICH were examined with light microscopy. Hemorrhage locations included 11 lobar and nine basal ganglia hemorrhages. Aβ immunohistochemistry and Congo red stains were used to confirm the presence of amyloid angiopathy, when this was suspected. Evidence of cerebral amyloid angiopathy (CAA) was observed in eight of the 20 specimens, each of which came from lobar locations. Immunohistochemistry confirmed CAA in the brain fragments from these eight individuals. Patients with immunohistochemically confirmed CAA were older than patients without CAA, and more likely to have lobar hemorrhages (OR 3.0 and 3.7, respectively). Evidence of CAA was not found in any of the basal ganglia specimens. One specimen showed evidence of CAA‐associated angiitis, with formation of a microaneurysm in an inflamed segment of a CAA‐affected arteriole, surrounded by acute hemorrhage. In another specimen, Aβ immunohistochemistry showed the presence of senile plaques suggesting concomitant Alzheimer's disease (AD) changes. Surgically evacuated hematomas from patients with spontaneous ICH should be carefully examined, paying special attention to any fragments of included brain parenchyma. These fragments can provide evidence of the etiology of the hemorrhage. Markers such as Aβ 1–40 can help to identify underlying CAA, and should be utilized when microangiopathy is suspected. Given the association of (Aβ) CAA with AD, careful examination of entrapped brain fragments may also provide evidence of AD in a given patient.     

Stroke related to cerebral amyloid angiopathy: the significance of systemic vascular disease

Summary A retrospective postmortem analysis of 25 cases of cerebral amyloid angiopathy (CAA) in the setting of Alzheimer's disease or senile dementia of the Alzheimer type (AD/SDAT) is reported. Seven patients experienced clinically significant cerebral infarcts or hemorrhages or both. There was no statistically significant difference in the incidence of infarcts or hemorrhages in hypertensive and nonhypertensive patients. Hypertension does not appear to be an additional risk factor in the causation of cerebral infarct or hemorrhage associated with CAA in the setting of AD/SDAT. Just over half of patients with CAA and significant ischemic and/or hemorrhagic brain lesions showed atherosclerosis of the circle of Willis, sometimes in the context of severe disseminated atheromatous disease.     

Alzheimer disease and cerebrovascular pathology: an update

Summary. Recent epidemiological and clinico-pathologic data suggest overlaps between Alzheimer disease (AD) and cerebrovascular lesions that may magnify the effect of mild AD pathology and promote progression of cognitive decline or even may precede neuronal damage and dementia.Vascular pathology in the aging brain and in AD includes: 1. cerebral amyloid angiopathy (CAA) with an incidence of 82–98% often associated with ApoEε2 and causing a) cerebral mass hemorrhages (around 70%, mainly in the frontal and parieal lobes), b) multiple or recurrent microhemorrhages (15%), and c) ischemic (micro-)infarcts or lacunes (around 20%). The frequency of these lesions increases with the severity of CAA and shows no correlation with that of senile amyloid plaques. CAA, significantly more frequent in patients with cerebral hemorrhages or infarcts than in aged controls, is an important risk factor for cerebrovascular lesions in AD. 2. Microvascular changes with decreased density and structural abnormalities causing regional metabolic and blood-brain barrier dysfunctions with ensuing neuronal damage. In large autopsy series of demented aged subjects, around 80% show Alzheimer type pathology, 20–40% with additional, often minor vascular lesions, 7–10% “pure” vascular dementia, and 3–5% “mixed” dementia (combination of AD and vascular encephalopathy). AD cases with additional minor cerebrovascular lesions have significantly more frequent histories of hypertension or infarcts than “pure” AD patients. Vascular lesions in AD include cortical microinfarcts, subcortial lacunes, white matter lesions / leukoencephalopathy, small hemorrhages and corticosubcortical infarcts, while in mixed type dementia multiple larger or hemispheral infarcts are more frequent. Small infarcts in AD patients have no essential impact on global cognitive decline which mainly depends on the severity of Alzheimer pathology, but in early stage of AD they may influence and promote the development of dementia. Recent studies showed lower density of plaques and tangles in brains with cerebrovascular lesions, and similar severity of dementia was related to fewer AD lesions in brains with than in those without small vascular lesions. Further studies will help to elucidate the risk factors and impact of cerebrovascular lesions on the development and progression of dementia in AD. Received November 2, 2001; accepted January 16, 2002     

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.     

Cerebral amyloid angiopathy: An overview

Cerebral amyloid angiopathy (CAA) is characterized by amyloid deposition in cortical and leptomeningeal vessels. Several cerebrovascular amyloid proteins (amyloid β‐protein (Aβ), cystatin C (ACys), prion protein (AScr), transthyretin (ATTR), gelsolin (AGel), and ABri (or A‐WD)) have been identified, leading to the classification of several types of CAA. Sporadic CAA of Aβ type is commonly found in elderly individuals and patients with Alzheimer’s disease. Cerebral amyloid angiopathy is an important cause of cerebrovascular disorders including lobar cerebral hemorrhage, leukoencephalopathy, and small cortical hemorrhage and infarction. We review the clinicopathological and molecular aspects of CAA and discuss the pathogenesis of CAA with future perspectives.     

Multiple cerebral infarcts with a few vasculitic lesions in the chronic stage of cerebral amyloid angiopathy‐related inflammation

We report a 75‐year‐old man with a 3.5‐year history of cerebral amyloid angiopathy (CAA)‐related inflammation. His initial symptom was headache and sensory aphasia appeared 1 month later. Brain MRI revealed features compatible with meningoencephalitis involving the right frontal, parietal and temporooccipital lobes. A brain biopsy sample from the right parietal lobe showed thickening of the leptomeninges, and granulomatous vasculitis with multinucleated giant cells and vascular Aβ deposits. No vascular lesions were evident by cerebral angiography. Serological examination revealed an elevated level of proteinase 3 anti‐neutrophil cytoplasmic autoantibodies (PR3‐ANCA). The patient was treated with corticosteroids, but this was only partially and temporarily effective. Autopsy revealed marked leptomeningeal thickening with inflammatory cell infiltrates and hemosiderin deposits, many superficial predominantly small infarcts at various stages in the cerebral cortex and only a few cerebral active vasculitic lesions. Immunohistochemically, CAA showing widespread Aβ‐positive blood vessels with double‐barrel formations was demonstrated. In conclusion, we consider that, although the association of PR3‐ANCA with the pathogenesis of Aβ‐associated vasculitis remained unclear, the present case represents a rare example of CAA‐related inflammation at the chronic stage.     

Amyloid-β plaques may be reduced in advanced stages of cerebral amyloid angiopathy in the elderly

We examined 29 cases in which cerebral amyloid angiopathy (CAA) was detected among routine aged autopsies. Most cases with severe CAA had many amyloid-β (Aβ) plaques in the occipital cortex. Nonetheless, two cases had few Aβ plaques with many small vessels and capillaries with CAA. In the two cases, severe CAA was widely distributed, except in the frontal lobes. Aβ deposits in capillaries often showed the characteristic pattern of dysphoric amyloid angiopathy. A few naked plaques were present. Although Aβ plaques were sparse near small vessels with CAA, there were many Aβ plaques distant from small vessels with CAA. Some of the remaining plaques had a moth-eaten appearance. Based on Aβ-positive star-like appearance and results of double immunohistochemistry for glial fibrillary acidic protein and Aβ_1–42, some astrocytes appeared to contain Aβ. Ionized calcium-binding adapter molecule 1 (Iba1)-positive microglia were scattered within the neuropil, with some present around small vessels with CAA. Iba1-positive microglia also seemed to phagocytose Aβ in several senile plaques by double immunostaining. Neurons and neurites identified with a monoclonal antibody against phosphorylated tau (clone AT8) were occasionally detected in sparse plaque areas, with AT8-identified dot-like structures present around capillaries with CAA. Accumulation of T lymphocytes was detected around vessels in the subarachnoid space in one case. The morphological changes detected in our two cases were similar to those of morphological markers of plaque clearance after Aβ immunotherapy. Nonetheless, our cases did not receive Aβ immunotherapy, but similar pathologies were observed. Overall, advanced CAA cases, including our two cases, may be examples of plaque clearance without Aβ immunotherapy. Further studies are needed to resolve the mechanism of Aβ plaque clearance using these cases.     

The impact of cerebral amyloid angiopathy on the occurrence of cerebrovascular lesions in demented patients with Alzheimer features: a neuropathological study

Objective: The aim of this neuropathological study was to determine the prevalence of the different cerebrovascular lesions to be attributed to cerebral amyloid angiopathy (CAA) and of those associated with the severity of the Alzheimer dementia (AD) itself. Patients and methods: The cerebrovascular lesions were compared separately in 40 brains of patients with mild and 50 with severe AD features. In the two groups, the number of lesions were compared between the brains with severe and those with mild of absent CAA. Results: The age of the patients, the vascular risk factors and antithrombotic treatment were similar in all the compared groups. The brains with mild and severe AD features and with CAA contained more haematomas, cortical micro‐infarcts and micro‐bleeds, and more severe white matter changes, and cortico‐subcortical and white matter mini‐bleeds. In the CAA brains with severe AD features, also more cortical territorial infarcts were observed, compared to those with mild AD features. Conclusions: The increase in cortical infarcts cannot be attributed to the CAA alone, but also to the severity of the degenerative features, implying additional vascular factors in the pathogenesis of AD.     

Human apolipoprotein E2 promotes parenchymal amyloid deposition and neuronal loss in vasculotropic mutant amyloid-β protein Tg-SwDI mice

Human apolipoprotein (ApoE) genotype influences the development of Alzheimer's disease and cerebral amyloid angiopathy (CAA), where the ε4 allele increases and the ε2 allele decreases the risk for developing disease. Specific mutations within the amyloid-β (Aβ) peptide have been identified that cause familial forms of CAA. However, the influence of APOE genotype on accumulation of CAA mutant Aβ in brain is not well understood. Earlier, we showed that human ApoE4 redistributes fibrillar amyloid deposition from the cerebral microvasculature to parenchymal plaques in Tg-SwDI mice, a model that accumulates human Dutch/Iowa (E22Q/D23N) CAA mutant Aβ in brain (Xu et al., J Neurosci 28, 5312-5320, 2008). Human ApoE2 can reduce Aβ pathology in transgenic models of parenchymal plaques. Here we determined if human ApoE2 can influence the location and severity of amyloid pathology in Tg-SwDI mice. Comparing Tg-SwDI mice bred onto a human APOE2/2 or human APOE4/4 background, we found there was no change in the brain levels of total Aβ(40) and Aβ(42) compared to mice on the endogenous mouse APOE background. In Tg-SwDI mice on either human APOE background, there was a similarly strong reduction in the levels of microvascular CAA and emergence of extensive parenchymal plaque amyloid. In both Tg-SwDI-hAPOE2/2 and Tg-SwDI-hAPOE4/4 mice, the distribution of ApoE proteins and neuronal loss were associated with parenchymal amyloid plaques. These findings suggest that compared with human ApoE4, human ApoE2 does not beneficially influence the quantitative or spatial accumulation of human Dutch/Iowa CAA mutant amyloid or associated pathology in transgenic mice.     

An azobenzene photoswitch sheds light on turn nucleation in amyloid-β self-assembly

Amyloid-β (Aβ) self-assembly into cross-β amyloid fibrils is implicated in a causative role in Alzheimer's disease pathology. Uncertainties persist regarding the mechanisms of amyloid self-assembly and the role of metastable prefibrillar aggregates. Aβ fibrils feature a sheet-turn-sheet motif in the constituent β-strands; as such, turn nucleation has been proposed as a rate-limiting step in the self-assembly pathway. Herein, we report the use of an azobenzene β-hairpin mimetic to study the role turn nucleation plays on Aβ self-assembly. [3-(3-Aminomethyl)phenylazo]phenylacetic acid (AMPP) was incorporated into the putative turn region of Aβ42 to elicit temporal control over Aβ42 turn nucleation; it was hypothesized that self-assembly would be favored in the cis-AMPP conformation if β-hairpin formation occurs during Aβ self-assembly and that the trans-AMPP conformer would display attenuated fibrillization propensity. It was unexpectedly observed that the trans-AMPP Aβ42 conformer forms fibrillar constructs that are similar in almost all characteristics, including cytotoxicity, to wild-type Aβ42. Conversely, the cis-AMPP Aβ42 congeners formed nonfibrillar, amorphous aggregates that exhibited no cytotoxicity. Additionally, cis-trans photoisomerization resulted in rapid formation of native-like amyloid fibrils and trans-cis conversion in the fibril state reduced the population of native-like fibrils. Thus, temporal photocontrol over Aβ turn conformation provides significant insight into Aβ self-assembly. Specifically, Aβ mutants that adopt stable β-turns form aggregate structures that are unable to enter folding pathways leading to cross-β fibrils and cytotoxic prefibrillar intermediates.     

Astrocytic Aβ1‐42 uptake is determined by Aβ‐aggregation state and the presence of amyloid‐associated proteins

Intracerebral accumulation of amyloid‐β (Aβ) leading to Aβ plaque formation, is the main hallmark of Alzheimer's disease and might be caused by defective Aβ‐clearance. We previously found primary human astrocytes and microglia able to bind and ingest Aβ1‐42 in vitro, which appeared to be limited by Aβ1‐42 fibril formation. We now confirm that astrocytic Aβ‐uptake depends on size and/or composition of Aβ‐aggregates as astrocytes preferably take up oligomeric Aβ over fibrillar Aβ. Upon exposure to either fluorescence‐labelled Aβ1‐42 oligomers (Aβ_oligo) or fibrils (Aβ_fib), a larger (3.7 times more) proportion of astrocytes ingested oligomers compared to fibrils, as determined by flow cytometry. Aβ‐internalization was verified using confocal microscopy and live‐cell imaging. Neither uptake of Aβ_oligo nor Aβ_fib, triggered proinflammatory activation of the astrocytes, as judged by quantification of interleukin‐6 and monocyte‐chemoattractant protein‐1 release. Amyloid‐associated proteins, including α1‐antichymotrypsin (ACT), serum amyloid P component (SAP), C1q and apolipoproteins E (ApoE) and J (ApoJ) were earlier found to influence Aβ‐aggregation. Here, astrocytic uptake of Aβ_fib increased when added to the cells in combination with SAP and C1q (SAP/C1q), but was unchanged in the presence of ApoE, ApoJ and ACT. Interestingly, ApoJ and ApoE dramatically reduced the number of Aβ_oligo‐positive astrocytes, whereas SAP/C1q slightly reduced Aβ_oligo uptake. Thus, amyloid‐associated proteins, especially ApoJ and ApoE, can alter Aβ‐uptake in vitro and hence may influence Aβ clearance and plaque formation in vivo. © 2010 Wiley‐Liss, Inc.     

Intracisternal injection of beta-amyloid seeds promotes cerebral amyloid angiopathy

Beta amyloid (Aβ) is a key component of parenchymal Aβ plaques and vascular Aβ fibrils, which lead to cerebral amyloid angiopathy (CAA) in Alzheimer’s disease (AD). Recent studies have revealed that Aβ contained in the cerebrospinal fluid (CSF) can re-enter into brain through paravascular spaces. However, whether Aβ in CSF may act as a constant source of pathogenic Aβ in AD is still unclear. This study aimed to examine whether Aβ pathology could be worsened when CSF Aβ level was enhanced by intra-cisternal infusion of aged brain extract containing abundant Aβ in TgCRND8 host mice. TgCRND8 mouse is an AD animal model which develops predominant parenchymal Aβ plaques in the brain at as early as 3 months of age. Here, we showed that single intracisternal injection of Aβ seeds into TgCRND8 mice before the presence of Aβ pathology induced robust prion-like propagation of CAA within 90 days. The induced CAA is mainly distributed in the cerebral cortex, hippocampus and thalamus of TgCRND8 mice. Surprisingly, despite the robust increase in CAA levels, the TgCRND8 mice had a marked decrease in parenchymal Aβ plaques and the plaques related neuroinflammation in the brains compared with the control mice. These results amply indicate that Aβ in CSF may act as a source of Aβ contributing to the growth of vascular Aβ deposits in CAA. Our findings provide experimental evidence to unravel the mechanisms of CAA formation and the potential of targeting CSF Aβ for CAA.     

Cerebral amyloid β(42) deposits and microvascular pathology in ageing baboons

M. Ndung'u, W. Härtig, F. Wegner, J. M. Mwenda, R. W. C. Low, R. O. Akinyemi and R. N. Kalaria (2012) Neuropathology and Applied Neurobiology 38, 487–499 Cerebral amyloid β(42) deposits and microvascular pathology in ageing baboons Background: Previous studies have extensively reported the deposition of amyloid β (Aβ) peptide with carboxyl‐ and amino‐terminal heterogeneity in cortical and cerebrovascular deposits in Alzheimer's disease (AD) and in non‐human primates except baboons. Methods: We examined the immunocytochemical distribution of Aβ peptides and Aβ oligomers in brain tissue from three subspecies of 18‐ to 28‐year‐old baboons (Papio) and in other monkeys including the squirrel (Saimiri sciureus) and rhesus (Macaca mulatta) for comparison. Results: A general preponderance of Aβ(42) in parenchymal deposits and many vascular deposits in all cortical lobes was evident in the baboons. Aβ oligomeric immunoreactivity was also apparent like to amyloid plaques. We found that the amino acid sequence of the Aβ domain of the baboon amyloid precursor protein is similar to that of man. In contrast to Aβ, immunoreactivity to hyperphosphorylated tau protein was largely intracellular and rare in these baboons. Brain tissues from squirrel and rhesus monkeys examined in parallel exhibited mostly vascular and parenchymal deposits containing Aβ(42) peptides. Our results were comparable to AD, but showed that even in younger monkeys exhibiting few deposits, Aβ(42) was evident in both parenchymal deposits and cerebral amyloid angiopathy. Perivascular amyloid deposits were frequent and often accompanied by microvascular abnormalities in the form of collapsed degenerated capillaries. Conclusions: Similar to other primates above and below in the phylogenetic order, our observations and evaluation of the literature implicate pathogenicity of Aβ(42) peptide associated with microvascular degeneration in baboons. We suggest baboons are useful animals to investigate the dynamics of AD‐related pathology.     

Cerebral amyloid angiopathy: the vascular pathology and complications

Twenty-five cases with cerebral amyloid angiopathy (CAA) were studied. Senile plaques (SP) were present in all cases. In only eight cases which also displayed either SP (two cases), or both SP and Alzheimer's neurofibrillary tangles (NFT) (six cases), was there a history of dementia. In five cases, SP and NFT were observed without a history of dementia. Seven cases had significant cerebral hemorrhage, single or multiple, which could be related to CAA. Ten cases had cerebral infarcts, but only in seven of these cases could the infarcts be related to CAA. In five cases, with moderate to severe CAA and no history of dementia other distinctive vascular changes were also noted in the brain. These CAA-associated vasculopathies (CAA-AV) consisted of: clusters of multiple arteriolar lumina, the so-called "glomerular" formations, with various degrees of amyloid infiltration; aneurysmal vessels with amyloid infiltration; obliterative intimal changes; "double barreling", chronic inflammatory perivascular or transmural infiltrates; hyaline (nonamyloid) arteriolar degeneration, with or without aneurysmal dilatation; and fibrinoid necrotizing vascular change. In all five cases with CAA-AV, there were cerebral infarcts or hemorrhages which were considered to be direct complications of amyloid angiopathy, or of the vasculopathies developing secondary to the amyloid infiltration of vessel walls. It is possible that the associated vasculopathies represented secondary vascular changes that followed amyloid deposition in the blood vessel walls.     

Blocking the apolipoprotein E/amyloid-β interaction reduces fibrillar vascular amyloid deposition and cerebral microhemorrhages in TgSwDI mice

The accumulation of amyloid-β (Aβ) peptides as toxic oligomers, amyloid plaques, and cerebral amyloid angiopathy (CAA) is critical in the pathogenesis of Alzheimer's disease (AD). The binding of Aβ peptides to apolipoprotein E (ApoE) plays an important role in modulation of amyloid deposition and clearance. We have shown that blocking the Aβ/ApoE interaction with Aβ(12-28P), a nontoxic blood-brain-barrier permeable and non-fibrillogenic synthetic peptide, constitutes a novel therapeutic approach for AD by reducing Aβ parenchymal deposition. In the present study, we investigate this therapeutic effect on CAA in the transgenic (Tg) AD mice model (TgSwDI), which expresses Swedish (K670N/M671L), Dutch (E693Q)/Iowa (D694N) AβPP mutations. These mice develop abundant CAA beginning at the age of 6 months. Behavioral results show that Aβ(12-28P) treated TgSwDI AD mice performed the same as wild-type mice, whereas vehicle treated TgSwDI were impaired in spatial memory. Furthermore, this treatment resulted in a significant reduction of total amyloid burden, especially the fibrillar vascular amyloid burden, which importantly was accompanied by a reduction in microhemorrhages and neuroinflammation. Measurement of Aβ levels in the brain homogenate revealed a significant decrease in both the total amount of Aβ and Aβ oligomer levels in Aβ(12-28P) treated TgSwDI mice. These findings suggest that blocking the Aβ/ApoE interaction is a highly effective therapeutic approach for vascular amyloid deposition, in contrast to some other therapeutic approaches.     

Cerebral amyloid angiopathy in a 95+ cohort: complement activation and apolipoprotein E (ApoE) genotype

There is growing evidence that in Alzheimer's disease (AD) amyloid beta-protein (Abeta) triggers a chronic inflammatory reaction in cerebral amyloid plaques, including complement proteins. Abeta also accumulates cerebrovascularly in age- and AD-associated cerebral amyloid angiopathy (CAA). We investigated complement proteins in CAA in a population-based series using histological and immunohistochemical staining methods. The 74 subjects, aged 95 years or more, had undergone clinical neurological examination and apolipoprotein E (ApoE) genotyping. The brains had been studied for AD post-mortem, allowing us to relate the histopathological findings to clinical and genetic conditions. CAA with congophilic amyloid was found in 36/74 individuals (48.6%). The vascular amyloid deposits immunoreacted with antibodies to Abeta and complements 3d (C3d) and 9 (C9). The positivity in complement stains increased with growing severity of CAA (P = 0.001). The presence of CAA associated with ApoE epsilon4 (P = 0.0005) and overrepresentation of epsilon4 among those with moderate or severe vs. mild CAA (P = 0.03) was demonstrated. The presence of CAA associated with dementia (P = 0.01), which was contributed by both epsilon4+ (P = 0.02) and epsilon4- (P = 0.06) subjects. Our study shows that complement proteins are deposited in the affected vessels in Abeta-associated CAA. They may solely represent the cerebral Abeta- burden associated to inflammatory stimuli, or signal a contribution in the clearance of cerebral Abeta, thereby contributing to the events associated with evolution of clinical dementia. Our results demonstrate a strong association between CAA and ApoE epsilon4 as well as dementia and suggest that the contribution of CAA to dementia is largely independent of ApoE epsilon4.     

Pathologic processes leading to cerebral hemorrhage in amyloid angiopathy

This report concerns a study undertaken to eluidate the pathogenesis of arterial rupture related to amyloid deposition. For this purpose, histochemical and immunohistochemical analyses were carried out on brain tissue specimens of a case of cerebral amyloid angiopathy (CAA) with multiple cortical hemorrhages. A small amount of amyloid β-protein was found in the tunica media vasorum in which the smooth muscle cells were well preserved. with increases in amyloiod deposition, the entire arteriolar wall became concenmtrically thick, with amyloid largely occupying the tunica media; the number of smooth muscle cells was decreased and these cells were located in the intimal side of the vessel wall. Under these conditions, the elastic fibers and endothhelial cells were relatively well preserved. In the advanced stage of amyloid deposition, the arterioles became devoid of smooth muscle cells and underwent wither fibrous luminal occlusionor aneurysmal dilatation with fibrinoid necrosis and loss of elastic fibers; the latterwould eventually rupture causing the hemorrhage. These findings suggest that amyloid β-protein-related loss of arteriolar smooth muscle cells could be the initial event, with the subsequent damage of the vascular wall leading to cerebral hemorrhages in CAA patients.     

Clinical and neuropathological findings in a patient with familial Alzheimer disease showing a mutation in the PSEN1 gene

Over 100 mutations have been described in the presenilin‐1 gene (PSEN1), resulting in familial Alzheimer disease (AD). However, of the limited number of autopsy cases, only one has been reported from an AD family with an L420R PSEN1 mutation. We describe here clinical and neuropathological features of a patient with dementia‐parkinsonism from a family with a PSEN1 mutation (L420R). A 43‐year‐old Japanese woman was autopsied 12 years after the onset of her progressive dementia and 4 years after the onset of parkinsonism. Throughout the neocortex and hippocampus, cotton wool plaques were identified, densely packed, in almost all the cortical layers along with neuronal loss, gliosis, NFT and neuropil threads. In addition, CAA affecting meningeal, subpial and cortical arterioles was found, as well as amyloid β‐protein (Aβ)‐deposition in the capillaries (capillary CAA) in the neocortex and subcortical nuclei. There was loss of pigmented neurons in the substantia nigra. The putamen was densely packed with diffuse plaques and rarely showed capillary CAA, whereas the globus pallidus showed extensive capillary CAA but no plaques. This differential distribution is similar to that reported for a previous patient with a mutation in PSEN1. It is concluded that neuropathological changes in the substantia nigra and lenticular nuclei were responsible for the patient's parkinsonism. Capillary transport of Aβ unique to the respective tissue of the patient may result in the differential distribution of Aβ between the putamen and globus pallidus seen in individuals with a PSEN1 mutation.     

Cerebral amyloid angiopathy in the aged

Summary Cerebral amyloid angiopathy (CAA) was found in 57% of 123 autopsy brains removed from patients aged 59–101 years. The incidence of CAA increased with age. CAA was seen most frequently in the occipital cortex. Immunohistochemically, amyloid of CAA was positive for amyloid P component and negative for human AA protein and human prealbumin. The presence and severity of CAA were significantly correlated with the number of senile plaques and neurofibrillary tangles. The incidence of CAA in 17 patients with dementia of Alzheimer type (DAT) was estimated to be 88% and was significantly higher than that in 26 patients with dementia of non-Alzheimer type. CAA had a pathogenetic relationship with both brain ageing and DAT. Lobar cerebral haemorrhage was found in 3 patients with CAA of marked or moderate degree. Lobar cerebral haemorrhage in the aged and in patients with DAT suggest the presence of CAA.