Cerebral amyloid angiopathy in the aged

Cerebral amyloid angiopathy in East and West

Cerebral amyloid angiopathy, a vasculopathy characterised by the deposition of amyloid fibrils in the arteries and arterioles in the cerebral cortex and meninges, has been reported to be associated with intracerebral haemorrhage and cognitive impairment in the elderly. Advances in neuroimaging and validation of the clinical diagnostic criteria aid in making a correct clinical diagnosis. Associations with Alzheimer's disease, asymptomatic microbleeds and white matter changes on neuroimaging have an influence on the clinical treatment for patients with probable cerebral amyloid angiopathy. Reviewing the reports from Asian countries, we found that patients with cerebral amyloid angiopathy have a strong age-related prevalence and a consistent association with dementia, but a weaker correlation with intracerebral haemorrhage, most likely due to a higher incidence of hypertensive intracerebral haemorrhage. Involvement of the occipital lobe arteries by CAA is common in all races and ethnicities, while frontal lobe arteries may be more frequently involved in the East compared to the West. The clinical impact of cerebral amyloid angiopathy on intracerebral haemorrhage and cognitive impairment could be increasingly obvious in Asian countries with ageing populations, especially with improving control of hypertension, the leading cause of intracerebral haemorrhage.

Cerebral amyloid angiopathy pathology and cognitive domains in older persons

OBJECTIVE

To examine the relation of cerebral amyloid angiopathy (CAA) to cognitive domains in older community-dwelling persons with and without dementia.

METHODS

Subjects were 404 persons in the Religious Orders Study, a cohort study of aging, who underwent annual clinical evaluations, including 19 neuropsychological tests from which 5 cognitive domain and global summary scores were derived, and brain autopsy at time-of-death (mean age-at-death 86). Using amyloid-β immunostaining, CAA severity was graded in 5 regions (midfrontal, inferior temporal, angular, calcarine, and hippocampal cortices), as 0 = none, 1 = mild, 2 = moderate, 3 = severe, and 4 = very severe. Because severity was related across regions (all r(s) > 0.63), and almost all persons had some CAA, we averaged regional CAA scores and created class variable predictors for no-to-minimal (<0.5), mild-to-moderate (0.5-2.5) and moderate-to-very severe CAA (>2.5).

RESULTS

CAA was very common (84.9%; 94 had no-to-minimal, 233 mild-to-moderate, and 76 moderate-to-very severe disease) and was related to AD pathology (r(s) = 0.68). In linear regression analyses controlling for age, sex, education, AD pathology, infarcts, and Lewy bodies, moderate-to-very severe CAA was associated with lower perceptual speed (p = 0.012) and episodic memory (p = 0.047), but not semantic memory, working memory, visuospatial skills, or a composite of all cognitive measures. No associations of mild-to-moderate CAA with cognition were found. Dementia did not modify these findings.

INTERPRETATION

CAA pathology is very common in older community-dwelling persons and is associated with AD pathology. Moderate-to-very severe CAA, but not mild-to-moderate CAA, is associated with lower performance in specific cognitive domains, most notably perceptual speed, separately from the effect of AD pathology.

Prevalence of dementia disorders in the oldest-old: an autopsy study

The prevalence of Alzheimer disease (AD) and vascular dementia (VD) increases with advancing age, but less so after age 90 years. A retrospective hospital-based study of the relative prevalence of different disorders was performed in 1,110 consecutive autopsy cases of demented elderly in Vienna, Austria (66% females, MMSE <20; mean age 83.3 +/- 5.4 SD years). It assessed clinical, general autopsy data and neuropathology including immunohistochemistry. Neuropathologic diagnosis followed current consensus criteria. Four age groups (7-10th decade) were evaluated. In the total cohort AD pathology was seen in 82.9% ("pure" AD 42.9%; AD + other pathologies 39.9%), VD in 10.8% (mixed dementia, MIX, i.e. AD + vascular encephalopathy in 5.5%); other disorders in 5.7%, and negative pathology in 0.8%. The relative prevalence of AD increased from age 60 to 89 years and decreased slightly after age 90+, while "pure" VD diagnosed in the presence of vascular encephalopathy of different types with low neuritic AD pathology (Braak stages <3; mean 1.2-1.6) decreased progressively from age 60 to 90+; 85-95% of these patients had histories of diabetes, morphologic signs of hypertension, 65% myocardial infarction/cardiac decompensation, and 75% a history of stroke(s). Morphologic subtypes, subcortical arteriosclerotic (the most frequent), multi-infarct encephalopathy, and strategic infarct dementia showed no age-related differences. The relative prevalence of AD + Lewy pathology remained fairly constant with increasing age. Mixed dementia and AD with minor cerebrovascular lesions increased significantly with age, while other dementias decreased. This retrospective study using strict morphologic criteria confirmed increased prevalence of AD with age, but mild decline at age 90+, and progressive decline of VD, while AD + vascular pathologies including MIX showed considerable age-related increase, confirming that mixed pathologies account for most dementia cases in very old persons. A prospective clinicopathologic study in oldest-old subjects showed a significant increase in both AD and cerebral amyloid angiopathy (CAA), but decrease in VD over age 85, while in a small group of old subjects CAA without considerable AD pathology may be an independent risk factor for cognitive decline.

Steroid responsive encephalopathy in cerebral amyloid angiopathy: a case report and review of evidence for immunosuppressive treatment

Cerebral amyloid angiopathy (CAA) is a common but often asymptomatic disease, characterized by deposition of amyloid in cerebral blood vessels. We describe the successful treatment of CAA encephalopathy with dexamethasone in a patient with CAA-related inflammation causing subacute progressive encephalopathy and seizures, which is an increasingly recognized subtype of CAA. The two pathological subtypes of CAA-related inflammation are described and a review of the literature is performed concerning immunosuppressive treatment of CAA-related inflammation with special attention to its pathological subtypes. Immunosuppressive therapy appears to be an appropriate treatment for CAA encephalopathy.

Clinical features of non-hypertensive lobar intracerebral hemorrhage related to cerebral amyloid angiopathy

BACKGROUND AND PURPOSE

The present study aims to clarify the clinical features of non-hypertensive cerebral amyloid angiopathy-related lobar intracerebral hemorrhage (CAA-L-ICH).

METHODS

We investigated clinical, laboratory, and neuroimaging findings in 41 patients (30, women; 11, men) with pathologically supported CAA-L-ICH from 303 non-hypertensive Japanese patients aged >OR=55, identified via a nationwide survey as symptomatic CAA-L-ICH.

RESULTS

The mean age of patients at onset of CAA-L-ICH was 73.2 +/- 7.4 years; the number of patients increased with age. The corrected female-to-male ratio for the population was 2.2, with significant female predominance. At onset, 7.3% of patients received anti-platelet therapy. In brain imaging studies, the actual frequency of CAA-L-ICHs was higher in the frontal and parietal lobes; however, after correcting for the estimated cortical volume, the parietal lobe was found to be the most frequently affected. CAA-L-ICH recurred in 31.7% of patients during the average 35.3-month follow-up period. The mean interval between intracerebral hemorrhages (ICHs) was 11.3 months. The case fatality rate was 12.2% at 1 month and 19.5% at 12 months after initial ICH. In 97.1% of patients, neurosurgical procedures were performed without uncontrollable intraoperative or post-operative hemorrhage.

CONCLUSIONS

Our study revealed the clinical features of non-hypertensive CAA-L-ICH, including its parietal predilection, which will require further study with a larger number of patients with different ethnic backgrounds.

Descriptive analysis of the Boston criteria applied to a Dutch-type cerebral amyloid angiopathy population

BACKGROUND AND PURPOSE

Validation of the Boston criteria for the in vivo diagnosis of cerebral amyloid angiopathy (CAA) is challenging, because noninvasive diagnostic tests do not exist. Hereditary cerebral hemorrhage with amyloidosis-Dutch type is an accepted monogenetic model of CAA and diagnosis can be made with certainty based on DNA analysis. The aim of this study was to analyze and refine the existing Boston criteria in patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type.

METHODS

We performed T2*-weighted MRI in 27 patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type to assess the presence and location of microbleeds, intracranial hemorrhages, and superficial siderosis. Using the Boston criteria, subjects were categorized as having: no hemorrhages, possible CAA, probable CAA, and hemorrhagic lesions not qualifying for CAA. The sensitivity of the Boston criteria was calculated separately using intracranial hemorrhages only and using intracranial hemorrhages and microbleeds.

RESULTS

The sensitivity of the Boston criteria for probable CAA increased from 48% to 63% when microbleeds were included. For symptomatic subjects only, the sensitivity was 100%. No hemorrhages were identified in the deep white matter, basal ganglia, thalamus, or brainstem. Superficial siderosis, observed in 6 patients, did not increase the sensitivity of the Boston criteria in our study group.

CONCLUSIONS

Our data show that using T2*-weighted MRI and including microbleeds increase the sensitivity of the Boston criteria. The exclusion of hemorrhages in the deep white matter, basal ganglia, thalamus, and brainstem does not lower the sensitivity of the Boston criteria.

Human apolipoprotein E4 targeted replacement mice show increased prevalence of intracerebral hemorrhage associated with vascular amyloid deposition

Previous studies show that APOE *4 carriers are at increased risk for ischemic stroke and intracerebral hemorrhage (ICH). The APOE *4 gene is also linked to increased incidence of cerebral amyloid angiopathy. It has been suggested that apolipoprotein E4 expression leads to increased vascular amyloid deposition, which may explain the increased incidence of ICH in APOE *4 carriers. Here we show a significant increase in ICH in apoE4 targeted replacement mice compared with apoE3 mice. In all, 89% of the vessels in the apoE4 mice that showed evidence for hemorrhage contained fibrillar amyloid beta based on thioflavine-S staining. Aged apoE4 mice contained predominantly vascular amyloid deposits in the frontal cortex and hippocampus, but also showed evidence for parenchymal amyloid deposits. Most of the parenchymal amyloid appeared diffuse in nature; however, a small fraction was thioflavine-S positive, indicating presence of fibrillar amyloid. Electron microscopy further revealed evidence for fibrillar deposits in the vessel walls of apoE4 mice, but not apoE3 mice. The apoE4 targeted replacement mice do not harbor any mutation in the amyloid precursor protein gene and, therefore, are similar to the majority of humans susceptible to cerebral amyloid angiopathy and ICH, where the APOE genetic polymorphism is the only known genetic risk factor.

Population studies of sporadic cerebral amyloid angiopathy and dementia: a systematic review

BACKGROUND

Deposition of amyloid-beta (Abeta) in vessel walls of the brain as cerebral amyloid angiopathy (CAA) could be a major factor in the pathogenesis of dementia. Here we investigate the relationship between dementia and the prevalence of CAA in older populations. We searched the literature for prospective population-based epidemiological clinicopathological studies, free of the biases of other sampling techniques, which were used as a comparison.

METHODS

To identify population-based studies assessing CAA and dementia, a previous systematic review of population-based clinicopathological studies of ageing and dementia was employed. To identify selected-sample studies, PsychInfo (1806-April Week 3 2008), OVID MEDLINE (1950-April Week 2 2008) and Pubmed (searched 21 April 2008) databases were searched using the term "amyloid angiopathy". These databases were also employed to search for any population-based studies not included in the previous systematic review. Studies were included if they reported the prevalence of CAA relative to a dementia classification (clinical or neuropathological).

RESULTS

Four population-based studies were identified. They showed that on average 55-59% of those with dementia displayed CAA (of any severity) compared to 28-38% of the non-demented. 37-43% of the demented displayed severe CAA in contrast to 7-24% of the non-demented. There was no overlap in the range of these averages and they were less variable and lower than those reported in 38 selected sample studies (demented v non-demented: 32-100 v 0-77% regardless of severity; 0-50 v 0-11% for severe only).

CONCLUSION

CAA prevalence in populations is consistently higher in the demented as compared to the non-demented. This supports a significant role for CAA in the pathogenesis of dementia.

Topographical distribution of cerebral amyloid angiopathy and its effect on cognitive decline are influenced by Alzheimer disease pathology

Cerebral amyloid angiopathy (CAA) is defined by beta-amyloid peptide (Abeta) depositions in cerebral vessels and is associated with Alzheimer disease (AD). It has been suggested that severe CAA is an independent risk factor for cognitive decline. 171 autopsy brains underwent standardized neuropathological assessment, the patients age ranged from 54 to 104 years (mean age: 83.9 years, +/-9.2, 59.6% female, 56.1% clinically demented). Using immunohistochemistry, the severity of Abeta depositions in vessels was assessed semiquantitatively in the frontal, frontobasal, hippocampal, and occipital region, respectively. CAA was present in 117 cases (68.4%), with the occipital region being affected significantly stronger than other regions. The overall incidence of CAA was significantly higher in cases with high grade neuritic AD pathology (ADP) compared to those with low grade or no ADP. The severity of CAA significantly increased with increasing ADP, with CAA in the occipital region increasing significantly stronger than that in other regions. The association of CAA and clinical dementia failed to remain statistically significant when adjusting for concomitant ADP. However, in cases devoid of any ADP CAA was significantly associated with the presence of clinical dementia. These results indicate a strong association of AD with CAA, but do not unequivocally support reports suggesting CAA to be an independent risk factor for cognitive decline, except for a subgroup of demented patients lacking any ADP.

Angiopathie amyloïde cérébrale sporadique

INTRODUCTION

Sporadic cerebral amyloid angiopathy (CAA) is a microangiopathy identified by neuropathological examination in more than 30 percent of patients over 85 years of age.

STATE OF ART

Boston criteria for diagnosis of CAA--related hemorrhage are as follows: "definite CAA", "Probable CAA with supporting pathology", "Probable CAA" and "Possible CAA". Clinical manifestations of CAA are either lobar, cortical, corticosubcortical or cerebellar hemorrhages associated with progressive dementia. Dementia, corresponding either to Alzheimer disease, vascular or mixed dementia, precedes hemorrhages in 25 to 40 percent of cases. Brain MRI can demonstrate microbleeding.

PERSPECTIVES

This review compares data regarding CAA prevalence, intracranial hemorrhages, and their risk factors in old patients. Diagnosis and preventive strategies are discussed. It would be useful to identify those affected by CAA among elderly demented patients with atrial fibrillation requiring anticoagulation therapy.

CONCLUSIONS

CAA is suspected in the presence of recurrent lobar or cerebellar hemorrhages, and moreover if associated with pre-existing dementia. In elderly demented patients, MRI criteria to detect CAA should be considered in order to prevent hemorrhage risk, particularly after anticoagulation therapy.

Cerebral Amyloid Angiopathy: CT and MR Imaging Findings

Cerebral amyloid angiopathy (CAA) is an important but underrecognized cause of cerebrovascular disorders that predominantly affect elderly patients. CAA results from deposition of beta-amyloid protein in cortical, subcortical, and leptomeningeal vessels. This deposition is responsible for the wide spectrum of clinical symptoms and neuroimaging findings. Many cases of CAA are asymptomatic. However, when cases are symptomatic, patients can present with transient neurologic events, progressive cognitive decline, or potentially devastating intracranial hemorrhage. Computed tomography is the imaging study of choice for evaluation of suspected acute cortical hemorrhage, which may be accompanied by subarachnoid, subdural, or intraventricular hemorrhage. Magnetic resonance imaging is best suited for identification of small or chronic cortical hemorrhages and ischemic sequelae of this disease, exclusion of other causes of acute cortical-subcortical hemorrhage, and assessment of disease progression. Accurate recognition of imaging findings is important in guiding clinical decision making in patients with CAA.

Senile systemic amyloidosis, cerebral amyloid angiopathy, and dementia in a very old Finnish population

Senile systemic amyloidosis (SSA) and cerebral amyloid angiopathy (CAA) are amyloid disorders, which typically manifest with old age. The aim of our study was to examine the possible association of these disorders in very old Finns. We performed a prospective, population-based post mortem study and used histological and immunohistochemical staining methods to verify the presence of these types of amyloid. All 63 subjects (59% of the 107 individuals 95 years of age or more, who died during the 10-year follow-up study), 53 women and 10 men), had been neurologically examined. The prevalence of SSA and its association with CAA, dementia, and neuropathologically verified AD was analyzed. Overall SSA occurred in 23 (37%) and CAA in 28 (44%) of the 63 subjects. At clinical examination 41 individuals (65%) were demented; 24 (38%) had Alzheimer's disease. SSA showed no association with the presence of CAA (P = 0.45), clinical dementia (P = 0.09), or Alzheimer's disease (P = 0.21), or sex (P = 0.53). Our prospective population based study shows that SSA and CAA are frequent in very old Finns, but they do not associate.

White matter alterations in cerebral amyloid angiopathy measured by diffusion tensor imaging

BACKGROUND AND PURPOSE

Cerebral amyloid angiopathy (CAA) represents beta-amyloid deposition in the small- and medium-sized vessels of the brain and meninges. CAA contributes to altered vessel function and is associated with white matter damage, cognitive impairment, and most salient, hemorrhagic stroke. We used diffusion tensor imaging to evaluate the anatomic distribution of white matter degeneration in participants diagnosed with advanced CAA.

METHODS

Diffusion tensor imaging was obtained from 11 participants diagnosed with CAA-related intracerebral hemorrhage and 13 matched healthy control participants. Fractional anisotropy (FA) and diffusivity maps were compared using voxel based t test and region-of-interest analyses.

RESULTS

FA was reduced in CAA in temporal white matter and in the splenium of the corpus callosum (P<0.001 with approximately 17% reduction in temporal white matter and 15% reduction in the splenium). FA was marginally increased in CAA in the posterior limb of the internal capsule and subthalamic gray matter regions (approximately 7% increase in subthalamic gray). FA changes were bilateral, remained significant in cluster analysis controlling for multiple comparisons, and did not depend on the hemisphere of the cerebral hemorrhage. Diffusivity was not substantially altered.

CONCLUSIONS

These findings suggest that a pattern of regional brain tissue degeneration is a characteristic feature of advanced CAA.

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.

Sporadic cerebral amyloid angiopathy: pathology, clinical implications, and possible pathomechanisms

Cerebral amyloid angiopathy (CAA) was observed for the first time nearly 100 years ago and systematically described in 1938. It is a common finding in elderly individuals, defined by beta-amyloid peptide (Abeta) depositions in cerebral blood vessels, and associated with Alzheimer's disease (AD). A variety of genetic mutations cause hereditary forms of CAA; in this review, however, only the sporadic variant of CAA is considered. In CAA, Abeta depositions primarily occur in the abluminal portion of the tunica media, and with increasing severity all layers of the blood vessel wall are infiltrated and an additional spread of Abeta into the surrounding neuropil may be seen (i.e., dyshoric changes). CAA is most pronounced in the occipital lobe and its distribution is usually patchy. The relationship between CAA and AD is poorly understood; however, low positive correlations between the severity of both CAA and AD pathology have been observed. CAA is a frequent cause of (warfarin-associated) intracerebral hemorrhage, and the diagnosis of probable CAA-related hemorrhage can be made during life with high accuracy. Both APOE-epsilon4 and APOE-epsilon2 are risk factors for CAA, while only APOE-epsilon2 increases the risk for hemorrhage in CAA. Although the role of CAA as an independent risk factor for cognitive decline is unclear, severe CAA is likely to lower the threshold for clinically overt dementia in neurodegenerative diseases. As for the origin of Abeta in CAA, it may be both produced by smooth muscle cells (vessel wall) and derived from neurons in the course of perivascular drainage.

Alzheimer's disease pathology influences severity and topographical distribution of cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is defined by beta-amyloid peptide (Abeta) depositions in cerebral vessels and is associated with Alzheimer's disease (AD). The relationship between sporadic CAA and AD, and the origin of Abeta in CAA are poorly understood. The aim of our study was to investigate the relationship between CAA and AD. Autopsy brains (n=113, 61.1% female, 55.8% clinically demented, age range 54-102 years, mean +/- SE 83.5+/-0.93 years) underwent standardized neuropathological assessment. CAA was evaluated in frontal, frontobasal, hippocampal, and occipital regions. Using immunohistochemistry, the severity of Abeta deposition in vessels was assessed semiquantitatively for each region separately. Evaluation of APOE genotype in 53 cases using real-time PCR showed significant correlations with severe AD pathology and CAA. CAA was present in 77 cases (68.1%), with the occipital region being affected significantly more often and more severely than other regions (P<0.01). Of brains without AD pathology 23.5% revealed CAA, whereas 24% with AD pathology showed no CAA. In concordance with other studies, the severity of both AD pathology and CAA showed a low, but significant correlation. This correlation, however, was only caused by the significant increase of occipital CAA with increasing AD pathology (P<0.01), and was independent of APOE genotype. Our results suggest that progressing AD pathology not only increases the severity of CAA, but also shifts its topographical distribution towards the occipital cortex.

Association of a polymorphism of the transforming growth factor-beta1 gene with cerebral amyloid angiopathy

BACKGROUND

A recent study showed that transforming growth factor-beta1 (TGF-beta1) induces amyloid-beta deposition in cerebral blood vessels and meninges of a transgenic mouse model of Alzheimer's disease (AD), and that TGF-beta1 mRNA levels are correlated with cerebral amyloid angiopathy (CAA) in human AD brains. A T/C polymorphism at codon 10 in exon 1 of the TGF-beta1 gene has been reported to be associated with the serum TGF-beta1 concentration. We investigated whether the TGF-beta1 polymorphism is associated with the risk of CAA.

METHODS

The association between the severity of CAA and the T/C polymorphism at codon 10 in exon 1 of the TGF-beta1 was investigated in 167 elderly Japanese autopsy cases, including 73 patients with AD. The apolipoprotein E (APOE) genotype was also determined.

RESULTS

The genotypes (TT/ TC/ CC) were associated with the severity of CAA significantly in all patients (p = 0.0026), in non-AD patients (p = 0.011), and APOE non-epsilon4 carriers (p = 0.0099), but not in AD patients or APOE epsilon4 carriers. The number of the T alleles positively correlated with the severity of CAA in all patients (p = 0.0011), non-AD patients (p = 0.0026), and APOE non-epsilon4 carriers (p = 0.0028), but not in AD patients or APOE epsilon4 carriers. The polymorphism was not significantly associated with AD.

CONCLUSIONS

Our results suggest that the polymorphism in TGF-beta1 is associated with the severity of CAA, especially in non-AD patients and APOE non-epsilon4 carriers.

Stroke subtypes and lesion sites in Akita, Japan

Stroke patients who underwent computed tomography (CT) were enrolled in a stroke registry in Akita, Japan, which comprised 7288 first-ever stroke cases during 1999 to 2001. Differences in age and sex were evaluated with respect to type-specific incidences and lesion sites. The incidence increased with age, except for subarachnoid hemorrhage (SAH) in men after age 40. The incidence of intracerebral hemorrhage (IH) and cerebral infarction (CI) was higher in men than in women, whereas that for SAH was lower. The mean age of putaminal hemorrhage was lower than that of thalamic hemorrhage, and the mean age of cortical infarction was higher than that of CI in perforator regions, the cerebellum, and the pons. In subjects age 70 years and older, the proportion of thalamic hemorrhage in IH was larger in women than in men; for those age 50 years and older, the proportion of cortical infarction in CI was larger in men than in women. The proportions of anterior communicating artery aneurysms in men and internal carotid artery aneurysms in women were largest in SAH for all age groups. In conclusion, thalamic hemorrhage was most common in elderly women and cortical infarction was most common in middle-aged and elderly men. The feature of SAH occurring at a higher incidence in women than in men, with a sexual difference in aneurysmal distribution, was also observed.

Cerebral amyloid angiopathy and thrombolysis-related intracerebral haemorrhage

Intracerebral haemorrhage is a complication of thrombolytic therapy for acute myocardial infarction, pulmonary embolism, and ischaemic stroke. There is increasing evidence that cerebral amyloid angiopathy (CAA), which itself can cause haemorrhage (CAAH), may be a risk factor for thrombolysis-related intracerebral haemorrhage. CAAH and thrombolysis-related intracerebral haemorrhage share some clinical features, such as predisposition to lobar or superficial regions of the brain, multiple haemorrhages, increasing frequency with age, and an association with dementia. In vitro work showed that accumulation of amyloid-beta peptide causes degeneration of cells in the walls of blood vessels, affects vasoactivity, and improves proteolytic mechanisms, such as fibrinolysis, anticoagulation, and degradation of the extracellular matrix. In a mouse model of CAA there is a low haemorrhagic threshold after thrombolytic therapy compared with that in wild-type mice. To date only a small number of anecdotal clinicopathological relations have been reported; neuroimaging advances and further study of the frequency and role of CAA in patients with thrombolysis-related intracerebral haemorrhage are required.

Vascular Pathology in Alzheimer Disease: Correlation of Cerebral Amyloid Angiopathy and Arteriosclerosis/Lipohyalinosis with Cognitive Decline

Sporadic, late-onset Alzheimer disease (AD) constitutes the most frequent cause of dementia in the elderly population. AD-related pathology is often accompanied by vascular changes. The predominant vascular lesions in AD are cerebral amyloid angiopathy (CAA) and arteriosclerosis/lipohyalinosis (AS/LH). The present study was carried out to examine the coincidence of these small vessel pathologies during the development of cognitive deficits, amyloid beta-protein (A beta) deposition, and neurofibrillary tangle (NFT) formation in sporadic late-onset AD. We correlated the clinical dementia rating (CDR) score, the sequential extension of AD-related A beta deposition into different parts of the brain, and the extension of NFTs to involve more brain regions with the distribution of CAA and AS/LH in 52 human autopsy brains. The extension of CAA and AS/LH to involve different areas of the brain was associated with a rise of CDR scores and an increase in the extension of A beta deposition and NFT generation. AD cases showed a higher number of regions with CAA and AS/LH compared to nondemented patients with AD-related pathology and controls. Moreover, we demonstrated a hierarchical sequence in which the different regions of the brain exhibited CAA and AS/LH-affected vessels, allowing the distinction of 3 stages in the development of CAA and AS/LH. The first stage of CAA involved leptomeningeal and neocortical vessels. The second stage was characterized by additional A beta deposition in allocortical and midbrain vessels. Finally, in a third stage, CAA was observed in the basal ganglia, the thalamus, and in the lower brainstem. In contrast, AS/LH initially affected the basal ganglia in stage A. In stage B this pathology made inroads into the deep white matter, the leptomeningeal arteries of the cortex, the cerebellum, and into the thalamus. Stage C was characterized by AS/LH in brainstem vessels. Our results demonstrate widespread CAA and AS/LH to be associated with the development of cognitive deficits in AD. A combination of both CAA and AS/LH may, therefore, contribute to neurodegeneration in AD. These data also suggest that small vessel disease due to arteriosclerosis and fibrolipohyalinosis is a potential target for the treatment of AD.

APOE and cerebral amyloid angiopathy in the elderly

Over 30% of normal elderly people have cerebral amyloid angiopathy (CAA). Possession of APOE epsilon4 is associated with increased prevalence and severity of CAA in Alzheimer's disease (AD) and in cerebral haemorrhage. We examined CAA in relation to APOE genotype in brains from 152 people aged 60-102 years, without AD or cerebral haemorrhage. Prevalence of CAA increased with age (p = 0.003). CAA was not associated with APOE genotype. The frequency of epsilon4 showed a significant negative association with age (p = 0.016). Age at death was significantly lower in those with than without epsilon4 (p = 0.028). Possession of epsilon4 does not by itself confer an increased risk of CAA but may be associated with reduced longevity even in the absence of AD or cerebral haemorrhage.

Cerebral amyloid angiopathy in aged Chinese: a clinico-neuropathological study

To investigate the prevalence and clinico-neuropathological characteristics of cerebral amyloid angiopathy (CAA) in aged Chinese and its relationship to dementia and cerebrovascular lesions, we examined 362 archived brains of elderly with immunohistochemical staining for beta-amyloid peptide and Congo red, Bodian and Luxol fast blue stains. We found that: (1) CAA appeared in 31.7% examined brains without sexual preponderance, and the incidence increased with age; (2) the frontal lobe was most frequently involved in CAA, followed by occipital and parietal lobe; (3) subcortical white matter and cerebellum dentate nucleus areas may also be affected by CAA; (4) CAA has a close relationship to Alzheimer's disease and multiple cerebrovascular lesions; (5) CAA alone may result in dementia.

Association of neprilysin polymorphism with cerebral amyloid angiopathy

OBJECTIVES

The risk of sporadic cerebral amyloid angiopathy (CAA) may be associated with genetic polymorphisms of molecules related to anabolism or catabolism of amyloid beta protein (Abeta). The authors investigated whether a polymorphism of the gene (NEP) coding for neprilysin, an enzyme catabolising Abeta, is associated with CAA.

METHODS

The study analysed the GT repeat polymorphism in the enhancer/promoter region of NEP and severity of CAA in 164 necropsied elderly Japanese subjects.

RESULTS

The subjects had NEP polymorphisms with 19 to 23 GT repeats and were classified into nine genotypes. CAA severity was significantly higher in the subjects with up to 40 repeats in total than those with more than 40 repeats (p=0.005). There was a significant correlation between the number of the shorter alleles (19 or 20 repeats) and CAA severity (p=0.024). In addition, there was no interaction between the NEP polymorphism and apolipoprotein E genotype.

CONCLUSIONS

These results suggest the association between the NEP polymorphism and the risk of CAA. Further study using more samples from populations with different ethnic backgrounds is necessary.

Risk factors for cerebral amyloid angiopathy in the elderly

To elucidate risk factors for cerebral amyloid angiopathy (CAA) in the elderly, we have investigated 201 autopsy cases of elderly Japanese (ages: 62-104 years), including 82 patients with Alzheimer's disease (AD). Severity of CAA showed no relationship with the history of hypertension, hyperlipidemia, or diabetes mellitus, nor with severity of atherosclerosis of cerebral and systemic arteries, indicating that common vascular risk factors would not be related to CAA. Incidence and severity of CAA were significantly higher in the AD cases compared with the non-AD cases (p < 0.0001). Severity of CAA correlated with densities of senile plaques and neurofibrillary tangles in total and non-AD cases, although the correlations were not significant within the AD cases. Associations of genetic polymorphisms with CAA have been investigated for genes of apolipoprotein E (APOE), presenilin 1 (PS1), alpha1-antichymotrypsin (ACT), butyrylcholinesterase, alpha2-macroglobulin, and paraoxonase. Severity of CAA in APOE epsilon4 carriers is significantly higher than that in non-epsilon4 carriers in total cases, although no significant difference was found in the CAA severity between the epsilon4 carriers and non-epsilon4 carriers within the AD or non-AD group. An intronic polymorphism of PS1 was significantly associated with the severity of CAA, indicating that the PS1 2/2 genotype may be related to lower risk of CAA. A polymorphism in the signal peptide sequence of ACT was significantly associated with the CAA severity in the AD group. Our results suggest that CAA shares risk factors with AD and that multiple genetic factors would be associated with the risk of CAA in the elderly.

Declining expression of neprilysin in Alzheimer disease vasculature: possible involvement in cerebral amyloid angiopathy

Molecular, genetic, and pharmacological studies have shown that neprilysin (also called NEP) catabolizes amyloid beta peptides (A beta) in healthy conditions. However, in Alzheimer disease (AD), A beta accumulates forming senile plaques in brain parenchyma and amyloid deposition around blood vessels. In this study, we tested at cellular level the relationship between neprilysin and A beta in human healthy and AD brain. Our results provided evidence for declining levels of neprilysin in AD brains as compared to healthy controls in parallel with increasing deposition of A beta. In hippocampus of AD individuals we observed a significant down-regulation of neprilysin expression in pyramidal neurons, consistent with the possibility that neprilysin controls the level of A beta accumulation and plaque formation in this area. In the cortex and leptomeninges, neprilysin was expressed in the smooth muscle cells of blood vessels. In sections from AD patients we observed a clear inverse relationship between neprilysin and A beta peptide levels in the vasculature, implicating neprilysin in cerebral amyloid angiopathy.

No association of paraoxonase genotype or atherosclerosis with cerebral amyloid angiopathy

BACKGROUND AND PURPOSE

Both cerebral amyloid angiopathy (CAA) and paraoxonase have been reported to be related to lipid metabolism and atherosclerosis. We investigated whether the paraoxonase gene (PON1) polymorphism and atherosclerosis are associated with risk of CAA.

METHODS

Associations of the PON1 polymorphism and atherosclerosis of the aorta and coronary and cerebral arteries with the severity of CAA were investigated in 154 elderly Japanese individuals, including 47 patients with Alzheimer's disease.

RESULTS

The PON1 polymorphism or severity of atherosclerosis of the arteries was not associated with the severity of CAA.

CONCLUSIONS

The PON1 polymorphism and atherosclerosis would not appear to be associated with risk of CAA in the elderly, although further study with larger samples is necessary for confirmation.

Two types of sporadic cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a type of beta-amyloidosis that occurs in leptomeningeal and cortical vessels of the elderly. In a sample of 41 CAA cases including 16 Alzheimer disease (AD) cases and 28 controls, we show that 2 types of sporadic CAA exist: The first type is characterized by immunohistochemically detectable amyloid beta-protein (Abeta) in cortical capillaries, leptomeningeal and cortical arteries, arterioles, veins, and venules. It is referred to here as CAA-Type 1. The second type of CAA also exhibits immunohistochemically detectable Abeta deposits in leptomeningeal and cortical vessels, with the exception of cortical capillaries. This type is termed CAA-Type 2. In cases with CAA-Type 1, the frequency of the apolipoprotein E (ApoE) epsilon4 allele is more than 4 times greater than in CAA-Type 2 cases and in controls. CAA-Type 2 cases have a higher epsilon2 allele frequency than CAA-Type 1 cases and controls. The ratio of CAA-Type 2 to CAA-Type 1 cases does not shift significantly with respect to the severity of AD-related beta-amyloidosis, with respect to degrees of CAA-severity, or with increasing age. Therefore, CAA-Type 1 is unlikely to be the late stage of CAA-Type 2; rather, they represent 2 different entities. Since both the ApoE epsilon2 and the epsilon4 allele are known to be risk factors for CAA, we can assign the risk factor ApoE epsilon4 to a distinct morphological type of CAA. The ApoE epsilon4 allele constitutes a risk factor for CAA-Type 1 and, as such, for neuropil-associated dyshoric vascular Abeta deposition in capillaries, whereas the e2 allele does not. CAA-Type 2 is not associated with the epsilon4 allele as a risk factor but shows a higher epsilon2 allele frequency than CAA-Type 1 cases and controls in our sample.

Dementia in hereditary cerebral hemorrhage with amyloidosis-Dutch type is associated with cerebral amyloid angiopathy but is independent of plaques and neurofibrillary tangles

Cerebral amyloid angiopathy is frequently found in demented and nondemented elderly persons, but its contribution to the causation of dementia is unknown. Therefore, we investigated the relation between the amount of cerebral amyloid angiopathy and the presence of dementia in 19 patients with hereditary cerebral hemorrhage with amyloidosis-Dutch type. The advantage of studying hereditary cerebral hemorrhage in amyloidosis-Dutch type is that patients with this disease consistently have severe cerebral amyloid angiopathy with minimal neurofibrillary pathology. The amount of cerebral amyloid angiopathy, as quantified by computerized morphometry, was strongly associated with the presence of dementia independent of neurofibrillary pathology, plaque density, or age. The number of cortical amyloid beta-laden severely stenotic vessels, vessel-within-vessel configurations, and cerebral amyloid angiopathy-associated microvasculopathies was associated with the amount of cerebral amyloid angiopathy and dementia. A semiquantitative score, based on the number of amyloid beta-laden severely stenotic vessels, completely separated demented from nondemented patients. These results suggest that extensive (more than 15 amyloid beta-laden severely stenotic vessels in five frontal cortical sections) cerebral amyloid angiopathy alone is sufficient to cause dementia in hereditary cerebral hemorrhage with amyloidosis-Dutch type. This may have implications for clinicopathological correlations in Alzheimer's disease and other dementias with cerebral amyloid angiopathy.

The diagnostic relevance of cerebral amyloid angiopathy in the setting of forensic pathology - a report of two cases and review of the literature

The neuropathological features seen in two cases with cerebral amyloid angiopathy (CAA) are presented. An 85-year-old woman was found comatose at home and died on the way to the hospital. The cause of death was an intracerebral hemorrhage (ICH) in the right parietal lobe. A 93-year-old woman with a history of traumatic subarachnoid hemorrhage was operated on for a chronic subdural hematoma. Intraoperatively, she developed severe ICH and died. The cause of death was an ICH in the parieto-occipital lobe. The morphology of the vessels was studied on differently stained sections and the neuropathological findings of the surrounding brain tissue were investigated. The affected vessels showed the characteristic alterations seen in CAA and included vascular amyloid deposition, fibrinoid necrosis, double-barrel lumen, splitting of the internal elastic lamina, defects of the vessel wall, and microaneurysms. Visualization of beta-amyloid protein was performed by histological and immunohistochemical methods. The immunohistochemistry for beta-amyloid was more sensitive and yielded better results compared with Congo red. In cases of ICH, CAA has to be considered in the differential diagnosis. Besides the use of Congo red stain, the application of beta-amyloid immunohistochemistry is requested to reliably make the diagnosis of CAA. Additional staining with a modified silver impregnation technique (AgNOR) is useful to detect associated neurodegenerative changes.

Spontaneous hemorrhagic stroke in a mouse model of cerebral amyloid angiopathy

A high risk factor for spontaneous and often fatal lobar hemorrhage is cerebral amyloid angiopathy (CAA). We now report that CAA in an amyloid precursor protein transgenic mouse model (APP23 mice) leads to a loss of vascular smooth muscle cells, aneurysmal vasodilatation, and in rare cases, vessel obliteration and severe vasculitis. This weakening of the vessel wall is followed by rupture and bleedings that range from multiple, recurrent microhemorrhages to large hematomas. Our results demonstrate that, in APP transgenic mice, the extracellular deposition of neuron-derived beta-amyloid in the vessel wall is the cause of vessel wall disruption, which eventually leads to parenchymal hemorrhage. This first mouse model of CAA-associated hemorrhagic stroke will now allow development of diagnostic and therapeutic strategies.

Apolipoprotein E genotype and cerebral amyloid angiopathy-related hemorrhage

Following the identification of the role of the apolipoprotein E (APOE) gene polymorphism in Alzheimer's disease (AD), this gene was examined in cerebral amyloid angiopathy (CAA). As in AD, the APOE epsilon 4 allele was found to be associated with CAA. Lobar intracerebral hemorrhage is the major clinical manifestation of CAA. Initial studies on a small number of patients with CAA-related hemorrhage (CAAH) identified overrepresentation of APOE epsilon 4. However, it became clear that confounding bias from concomitant AD and the need for pathologically confirmed cases of CAAH would also have to be considered. A larger series of pathologically confirmed cases of CAAH, also assessed for AD pathology, found a surprising overrepresentation of the APOE epsilon 2 allele. Because of the association between CAA and AD, it might have been predicted that patients with CAAH would have a low, rather than a high, epsilon 2 frequency. The overrepresentation of APOE epsilon 2 was present both in patients with and without AD, whereas a high epsilon 4 frequency correlated with concomitant AD. Further studies found that overrepresentation of APOE epsilon 2 is specific for CAAH and is not found in intracranial hemorrhages due to other causes. In CAAH, APOE epsilon 2 may interact with putative risk factors for hemorrhage, including antiplatelet/anticoagulant medication, minor head trauma, and hypertension. Several microvascular abnormalities in amyloid-laden blood vessels have been assumed to antedate CAAH and increase its likelihood. APOE epsilon 2 has now been found to be associated with some of these vascular abnormalities, specifically a "double-barrel" appearance and fibrinoid necrosis. The currently favored interpretation is that APOE epsilon 4 enhances deposition of amyloid-beta protein in the walls of cerebral blood vessels, whereas epsilon 2 is a risk factor for hemorrhage from amyloid-laden blood vessels by promoting specific "CAA-associated vasculopathies."

Mechanisms of cerebrovascular amyloid deposition. Lessons from mouse models

Cerebrovascular deposition of amyloid is a frequent observation in Alzheimer's disease patients. It can also be detected sporadically in normal aged individuals and is further found in familial diseases linked to specific gene mutations. The source and mechanism of this pathology are still unknown. It has been suggested that amyloidogenic proteins are derived from blood, the vessel wall itself, or from the central nervous system. In this article evidence is reviewed for and against each of these hypotheses, including new data obtained from transgenic mouse models. In APP23 transgenic mice that develop cerebral amyloid angiopathy (CAA) in addition to amyloid plaques, the transport and drainage of neuronally produced amyloid-beta (A beta) seem to be responsible for CAA rather than vascular A beta production or blood uptake. Although a number of mechanisms may contribute to CAA in humans, these results suggest that a neuronal source of A beta is sufficient to induce vascular amyloid deposition. The possibility to cross genetically defined mouse models of CAA with other mutant mice now has the potential to identify molecular mechanisms of CAA.

Cerebral amyloid angiopathy: an overview

Cerebral amyloid angiopathy (CAA) is characterized by amyloid deposition in cortical and leptomeningeal vessels. Several cerebrovascular amyloid proteins (amyloid beta-protein (Abeta), 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 Abeta 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.

A deletion polymorphism of alpha(2)-macroglobulin gene and cerebral amyloid angiopathy

BACKGROUND AND PURPOSE

alpha(2)-Macroglobulin may be implicated in amyloid beta protein deposition. A deletion in the exon 18 splice acceptor of the alpha(2)-macroglobulin gene (A2M) has been reported to be associated with risk for Alzheimer's disease (AD). In search of genetic risk factors for cerebral amyloid angiopathy (CAA), we investigated association of the A2M deletion polymorphism with CAA.

METHODS

The association between the severity of CAA and A2M deletion polymorphism was investigated in 178 autopsy cases of the elderly including 68 patients with AD.

RESULTS

There was no significant difference in the severity of CAA between individuals with the A2M deletion allele and those without in the AD, non-AD, or total cases. Status for the epsilon4 allele of the apolipoprotein E gene did not influence the results.

CONCLUSIONS

Our results suggest that the A2M deletion polymorphism may not be a definitive risk factor of CAA in the elderly, although further study with larger samples is necessary to confirm this.

Transient hyperemia immediately after rapid decompression of chronic subdural hematoma

OBJECTIVE

Intracerebral hemorrhage occurring after removal of a chronic subdural hematoma (CSH) is a rare but usually devastating postoperative complication. In patients with CSH, we determined cerebral blood flow immediately after surgical decompression to clarify the pathogenic mechanism of this complication.

METHODS

In 22 patients with unilateral CSH, a catheter was inserted into the hematoma cavity through a single burr hole without leakage of the contents. Cerebral blood flow was measured using single-photon emission computed tomography 1 day before surgery, immediately after rapid decompression by opening the catheter, and 3 days after surgery.

RESULTS

Single-photon emission computed tomography imaging immediately after decompression demonstrated areas of hyperemia in nine patients (41%). In all nine patients, hyperemia was observed in the cortex beneath the CSH, and it disappeared on the 3rd postoperative day. The patients with hyperemia were significantly older than those without hyperemia. Other variables, including preoperative cerebral blood flow, intrahematoma pressure before decompression, and mean arterial blood pressure during decompression had no significant effect on the occurrence of hyperemia.

CONCLUSION

In elderly patients, rapid decompression of CSH frequently results in transient hyperemia in the cerebral cortex beneath the hematoma.

The influence of coincidental vascular pathology on symptomatology and course of Alzheimer's disease

The aim of this review is to determine the influence of coincidental cerebrovascular pathology on the symptomatology and course of Alzheimer's disease (AD). The link between stroke and AD is probably higher than expected by chance for the following reasons: (i) both pathologies share genetic risk factors such as the epsilon 4 allele of the apolipoprotein E gene; (ii) AD patients have changes in the brain vessels that may lead to either ischemic or hemorrhagic stroke or white matter changes or both; (iii) there is evidence of an increased risk of stroke in AD patients; (iv) there is evidence of a frequent association of AD and stroke at autopsy. Because of the summation of the various types of lesions, stroke lesions may lead to an increase progression of cognitive decline in AD patients. Recognition of a vascular component in a dementia syndrome is therefore useful for the management of AD patients. Whether an optimal management of risk factors for stroke may delay the clinical expression of dementia in patients with preclinical Alzheimer pathology should be evaluated.

Butyrylcholinesterase K variant and cerebral amyloid angiopathy

BACKGROUND AND PURPOSE

Cholinesterases are found histochemically in the vessels affected with cerebral amyloid angiopathy (CAA). A gene for the K variant of butyrylcholinesterase (BCHE-K) may be associated with late-onset Alzheimer's disease (AD). In search of genetic risk factors for CAA, we investigated the association of BCHE-K with CAA.

METHODS

The association between the severity of CAA and BCHE-K was investigated in 155 autopsy cases of the elderly, including 48 patients with AD.

RESULTS

There was no significant association of BCHE-K with the severity of CAA in the total, AD, or non-AD cases. Status of the epsilon4 allele of apolipoprotein E gene did not influence the results.

CONCLUSIONS

Our results may suggest that BCHE-K is not a definitive risk factor for CAA in the elderly, although further study with larger samples is necessary to confirm this.

Aging and cerebrovascular disease

Aging influences cerebrovascular disease expression by a variety of mechanisms. Age-related changes in cerebral autoregulation, cellular metabolism, the blood-brain barrier, and autonomic function may leave the cerebrovascular system vulnerable to injury. Certain cerebrovascular disease, such as atrial fibrillation, watershed infarctions, carotid artery atherosclerosis, cerebral hemorrhages, subdural hematomas, and transient global amnesia manifest in the elderly. Vascular dementia and white matter disease are better understood with newer neuroimaging studies, careful neuropsychological and histopathologic examinations. Atherosclerosis and cerebral amyloid angiopathy may have larger roles than previously understood in Alzheimer's disease.

Association of alpha1-antichymotrypsin polymorphism with cerebral amyloid angiopathy

In search of genetic risk factors of sporadic cerebral amyloid angiopathy (CAA), we investigated the association of a polymorphism in the signal peptide sequence of alpha1-antichymotrypsin (ACT) with the severity of CAA in 155 autopsy cases of the elderly, including 48 patients with Alzheimer's disease. In the total cases, there was no significant association of the ACT genotypes (AA, AT, and TT) with the severity of CAA. Within the Alzheimer's disease group, however, a significant correlation was found between the ACT A allele frequency and the severity of CAA.

An immunohistochemical study of centenarian brains: a comparison

To evaluate the pathology of centenarian brains, which would reflect the ultimate stage of the aging process, 13 centenarians (M:F=1:12; mean+/-SD, 101.5+/-1.5 years) from the consecutive autopsy series were studied. None had severe dementia compatible with Alzheimer's disease (AD). As younger controls, 20 nondemented (ND) individuals (79.8+/-3.2 years) and 20 AD patients (80.8+/-3.0 years) were selected. In addition to the routine examination including methenamine-Bodian staining, an immunohistochemical study was performed, using antibodies to amyloid beta protein, tau, ubiquitin, glial fibrillary acidic protein (GFAP), synaptophysin, and Ki-MIP (a marker of the microglial and perivascular cells). No centenarian subjects satisfied the neuropathological criteria for definite AD. The densities of senile plaques and neurofibrillary tangles (NFTs) were significantly lower in almost all examined subdivisions than the AD patients, and tended to be higher than the ND subjects. Cerebral amyloid angiopathy of the centenarian was less severe than the AD patients, as well as the proliterations of GFAP-positive astrocytes and Ki-MIP-positive microglial cells, and the loss of synaptic terminal density. The relative mildness of the age-related morphological changes in the centenarians compared with the AD patients supports the idea that AD would not be the ultimate condition of the aging process, but would develop through the switching to the pathological process.

Association of presenilin-1 polymorphism with cerebral amyloid angiopathy in the elderly

BACKGROUND AND PURPOSE

An intronic polymorphism of presenilin-1 (PS-1), a gene responsible for early-onset familial Alzheimer's disease, has been reported to be associated with late-onset sporadic Alzheimer's disease. In a search for a genetic risk factor of sporadic cerebral amyloid angiopathy (CAA), we investigated the association of the polymorphism of PS-1 with CAA.

METHODS

The association between the severity of CAA and genotypes of a polymorphism in intron 8 of PS-1 was investigated in 137 autopsy cases of the elderly.

RESULTS

A significant decrease of PS-1 2/2 genotype frequency was associated with severe or moderate CAA.

CONCLUSIONS

Our results suggest that PS-1 intronic polymorphism may be associated with the severity of CAA in the elderly.

Animal models of cerebral beta-amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a significant risk factor for hemorrhagic stroke in the elderly, and occurs as a sporadic disorder, as a frequent component of Alzheimer's disease, and in several rare, hereditary conditions. The most common type of amyloid found in the vasculature of the brain is beta-amyloid (A beta), the same peptide that occurs in senile plaques. A paucity of animal models has hindered the experimental analysis of CAA. Several transgenic mouse models of cerebral beta-amyloidosis have now been reported, but only one appears to develop significant cerebrovascular amyloid. However, well-characterized models of naturally occurring CAA, particularly aged dogs and non-human primates, have contributed unique insights into the biology of vascular amyloid in recent years. Some non-human primate species have a predilection for developing CAA; the squirrel monkey (Saimiri sciureus), for example, is particularly likely to manifest beta-amyloid deposition in the cerebral blood vessels with age, whereas the rhesus monkey (Macaca mulatta) develops more abundant parenchymal amyloid. These animals have been used to test in vivo beta-amyloid labeling strategies with monoclonal antibodies and radiolabeled A beta. Species-differences in the predominant site of A beta deposition also can be exploited to evaluate factors that direct amyloid selectively to a particular tissue compartment of the brain. For example, the cysteine protease inhibitor, cystatin C, in squirrel monkeys has an amino acid substitution that is similar to the mutant substitution found in some humans with a hereditary form of cystatin C amyloid angiopathy, possibly explaining the predisposition of squirrel monkeys to CAA. The existing animal models have shown considerable utility in deciphering the pathobiology of CAA, and in testing strategies that could be used to diagnose and treat this disorder in humans.

Human choroid plexus is an uniquely involved area of the brain in amyloidosis: a histochemical, immunohistochemical and ultrastructural study

To better understand the characteristics of amyloid deposition in the choroid plexus, we examined autopsied brain by routine histology, immunohistochemistry, and electron microscopy in three group of patients: primary systemic amyloidosis (n = 7), cerebral amyloid angiopathy (CAA, n = 6), and controls (n = 3). Three of the CAA patients had Alzheimer's disease. Congophilic, birefringent amyloid deposits of the choroid plexus were seen in six of the seven cases of systemic light chain amyloidosis. Immunohistochemistry revealed that the deposited amyloids had reactivity for immunoglobulin light chain and amyloid P component. Accumulation of macrophages labeled with monoclonal antibodies against CD 68 and major histocompatibility complex class II antigens were observed around the massive amyloid deposits. The presence of approximately 10 nm amyloid fibrils along the epithelial basement membrane as well as in the vascular walls was ascertained by electron microscopy. In CAA, Congo red-positive amyloid deposits were consistently present in meningeal blood vessels and were often found in senile plaques of the cerebral parenchyma; congophilic amyloid deposits were absent in the choroid plexus. Choroid plexus epithelial cells exhibited immunostaining for beta amyloid precursor protein (APP) with N-terminal- and C-terminal-specific antibodies; in particular, consistent staining was obtained for the latter antibody. Immunoreactivity for amyloid beta protein (A beta) with monoclonal antibodies (6E10, 4G8) was often found in choroid plexus epithelial cells. These findings suggest that amyloid deposition of the choroid plexus depends on the major component protein in amyloidosis, and that the choroid plexus may produce APP and A beta protein although A beta amyloidosis is not evident in the choroid plexus.

Non-traumatic cerebral hemorrhage in Saudi Arabs: a hospital-based study of 243 cases

This is a retrospective study involving 243 Saudi Arabs with non-traumatic cerebral hemorrhages confirmed by CT scan. Intracerebral hemorrhages accounted for about 20% of all strokes in this population. THe male to female ratio was 2.74 which is slightly higher than those reported from elsewhere. Peak frequency was around 60 years. Hypertension was the most common cause accounting for 64% of the cases, hemopathies/coagulopathies for 10% and arteriovenous malformations (AVMs) for 6%. THe cause was undetermined in 21% of patients. Amyloid angiopathy was probably underrepresented due to lack of autopsy correlation. The etiologies were, however, age-related with a clear predominance of AVMs and coagulation disorders before the age of 40 years. Hypertensive hemorrhages were located in the putamen in 46% of cases compared to 20% in non-hypertensive patients while 52% of non-hypertensive hemorrhages were lobar in location compared to 20.5% in hypertensives. Early mortality (19%) in our series was relatively low compared to reports from the industrialized world.