Cerebrospinal fluid amyloid beta(40) is decreased in cerebral amyloid angiopathy

Free-water imaging of the hippocampus is a sensitive marker of Alzheimer's disease

Validating sensitive markers of hippocampal degeneration is fundamental for understanding neurodegenerative conditions such as Alzheimer's disease. In this paper, we test the hypothesis that free-water in the hippocampus will be more sensitive to early stages of cognitive decline than hippocampal volume, and that free-water in hippocampus will increase across distinct clinical stages of Alzheimer's disease. We examined two separate cohorts (N = 126; N = 112) of cognitively normal controls, early and late mild cognitive impairment (MCI), and Alzheimer's disease. Demographic, clinical, diffusion-weighted and T1-weighted imaging, and positron emission tomography (PET) imaging were assessed. Results indicated elevated hippocampal free-water in early MCI individuals compared to controls across both cohorts. In contrast, there was no difference in volume of these regions between controls and early MCI. ADNI free-water values in the hippocampus was associated with low CSF AB1-42 levels and high global amyloid PET values. Free-water imaging of the hippocampus can serve as an early stage marker for AD and provides a complementary measure of AD neurodegeneration using non-invasive imaging.

Early Aβ reduction prevents progression of cerebral amyloid angiopathy

OBJECTIVE

Clinical trials targeting β-amyloid peptides (Aβ) for Alzheimer disease (AD) failed for arguable reasons that include selecting the wrong stages of AD pathophysiology or Aβ being the wrong target. Targeting Aβ to prevent cerebral amyloid angiopathy (CAA) has not been rigorously followed, although the causal role of Aβ for CAA and related hemorrhages is undisputed. CAA occurs with normal aging and to various degrees in AD, where its impact and treatment is confounded by the presence of parenchymal Aβ deposition.

METHODS

APPDutch mice develop CAA in the absence of parenchymal amyloid, mimicking hereditary cerebral hemorrhage with amyloidosis Dutch type (HCHWA-D). Mice were treated with a β-site amyloid precursor protein cleaving enzyme 1 (BACE1) inhibitor. We used 3-dimensional ultramicroscopy and immunoassays for visualizing CAA and assessing Aβ in cerebrospinal fluid (CSF) and brain.

RESULTS

CAA onset in mice was at 22 to 24 months, first in frontal leptomeningeal and superficial cortical vessels followed by vessels penetrating the cortical layers. CSF Aβ increased with aging followed by a decrease of both Aβ40 and Aβ42 upon CAA onset, supporting the idea that combined reduction of CSF Aβ40 and Aβ42 is a specific biomarker for vascular amyloid. BACE1 inhibitor treatment starting at CAA onset and continuing for 4 months revealed a 90% Aβ reduction in CSF and largely prevented CAA progression and associated pathologies.

INTERPRETATION

This is the first study showing that Aβ reduction at early disease time points largely prevents CAA in the absence of parenchymal amyloid. Our observation provides a preclinical basis for Aβ-reducing treatments in patients at risk of CAA and in presymptomatic HCHWA-D. ANN NEUROL 2019;86:561-571.

Amyloid imaging of dutch-type hereditary cerebral amyloid angiopathy carriers

OBJECTIVE

To determine whether amyloid imaging with the positron emission tomography (PET) agent Pittsburgh compound B (PiB) can detect vascular β-amyloid (Aβ) in the essentially pure form of cerebral amyloid angiopathy associated with the Dutch-type hereditary cerebral amyloid angiopathy (D-CAA) mutation.

METHODS

PiB retention in a cortical composite of frontal, lateral, and retrosplenial regions (FLR) was measured by PiB-PET in 19 D-CAA mutation carriers (M⁺ ; 13 without neurologic symptoms, 6 with prior lobar intracerebral hemorrhage) and 17 mutation noncarriers (M^- ). Progression of PiB retention was analyzed in a subset of 18 serially imaged individuals (10 asymptomatic M⁺ , 8 M^- ). We also analyzed associations between PiB retention and cerebrospinal fluid (CSF) Aβ concentrations in 17 M⁺ and 11 M^- participants who underwent lumbar puncture and compared the findings to PiB-PET and CSF Aβ in 37 autosomal dominant Alzheimer disease (ADAD) mutation carriers.

RESULTS

D-CAA M⁺ showed greater age-dependent FLR PiB retention (p < 0.001) than M^- , and serially imaged asymptomatic M⁺ demonstrated greater longitudinal increases (p = 0.004). Among M⁺ , greater FLR PiB retention associated with reduced CSF concentrations of Aβ40 (r = -0.55, p = 0.021) but not Aβ42 (r = 0.01, p = 0.991). Despite comparably low CSF Aβ40 and Aβ42, PiB retention was substantially less in D-CAA than ADAD (p < 0.001).

INTERPRETATION

Increased PiB retention in D-CAA and correlation with reduced CSF Aβ40 suggest this compound labels vascular amyloid, although to a lesser degree than amyloid deposits in ADAD. Progression in PiB signal over time suggests amyloid PET as a potential biomarker in trials of candidate agents for this untreatable cause of hemorrhagic stroke. ANN NEUROL 2019;86:616-625.

Development of a Multicomponent Intervention to Prevent Alzheimer's Disease

Recent advances in vascular risk management have successfully reduced the prevalence of Alzheimer's Disease (AD) in several epidemiologic investigations. It is now widely accepted that cerebrovascular disease is both directly and indirectly involved in AD pathogenesis. Herein, we review the non-pharmacological and pharmacological therapeutic approaches for AD treatment. MIND [Mediterranean and DASH (Dietary Approaches to Stop Hypertension) Intervention for Neurodegenerative Delay] diet is an important dietary treatment for prevention of AD. Multi domain intervention including diet, exercise, cognitive training, and intensive risk managements also prevented cognitive decline in the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER) study. To confirm these favorable effects of life-style intervention, replica studies are being planned worldwide. Promotion of β-amyloid (Aβ) clearance has emerged as a promising pharmacological approach because insufficient removal of Aβ is more important than excessive Aβ production in the pathogenesis of the majority of AD patients. Most AD brains exhibit accompanying cerebral amyloid angiopathy, and Aβ distribution in cerebral amyloid angiopathy closely corresponds with the intramural periarterial drainage (IPAD) route, emphasizing the importance of Aβ clearance. In view of these facts, promotion of the major vascular-mediated Aβ elimination systems, including capillary transcytosis, the glymphatic system, and IPAD, have emerged as new treatment strategies in AD. In particular, the beneficial effects of cilostazol were shown in several clinical observation studies, and cilostazol facilitated IPAD in a rodent AD model. The COMCID (Cilostazol for prevention of Conversion from MCI to Dementia) trial, evaluating the efficacy of cilostazol for patients with mild cognitive impairment is currently ongoing in Japan. Such therapeutic approaches involving maintenance of cerebrovascular integrity and promotion of vascular-mediated Aβ clearance have the potential to be mainstream treatments for sporadic AD.

Beta-amyloid pathology in human brain microvessel extracts from the parietal cortex: relation with cerebral amyloid angiopathy and Alzheimer's disease

Several pieces of evidence suggest that blood-brain barrier (BBB) dysfunction is implicated in the pathophysiology of Alzheimer's disease (AD), exemplified by the frequent occurrence of cerebral amyloid angiopathy (CAA) and the defective clearance of Aβ peptides. However, the specific role of brain microvascular cells in these anomalies remains elusive. In this study, we validated by Western, ELISA and immunofluorescence analyses a procedure to generate microvasculature-enriched fractions from frozen samples of human cerebral cortex. We then investigated Aβ and proteins involved in its clearance or production in microvessel extracts generated from the parietal cortex of 60 volunteers in the Religious Orders Study. Volunteers were categorized as AD (n = 38) or controls (n = 22) based on the ABC scoring method presented in the revised guidelines for the neuropathological diagnosis of AD. Higher ELISA-determined concentrations of vascular Aβ40 and Aβ42 were found in persons with a neuropathological diagnosis of AD, in apoE4 carriers and in participants with advanced parenchymal CAA, compared to respective age-matched controls. Vascular levels of two proteins involved in Aβ clearance, ABCB1 and neprilysin, were lower in persons with AD and positively correlated with cognitive function, while being inversely correlated to vascular Aβ40. In contrast, BACE1, a protein necessary for Aβ production, was increased in individuals with AD and in apoE4 carriers, negatively correlated to cognitive function and positively correlated to Aβ40 in microvessel extracts. The present report indicates that concentrating microvessels from frozen human brain samples facilitates the quantitative biochemical analysis of cerebrovascular dysfunction in CNS disorders. Data generated overall show that microvessels extracted from individuals with parenchymal CAA-AD contained more Aβ and BACE1 and less ABCB1 and neprilysin, evidencing a pattern of dysfunction in brain microvascular cells contributing to CAA and AD pathology and symptoms.

Novel Therapeutic Potentials of Taxifolin for Amyloid-β-associated Neurodegenerative Diseases and Other Diseases: Recent Advances and Future Perspectives

Amyloid-β (Aβ) has been closely implicated in the pathogenesis of cerebral amyloid angiopathy (CAA) and Alzheimer’s disease (AD), the major causes of dementia. Thus, Aβ could be a target for the treatment of these diseases, for which, currently, there are no established effective treatments. Taxifolin is a bioactive catechol-type flavonoid present in various plants, such as herbs, and it exhibits pleiotropic effects including anti-oxidant and anti-glycation activities. Recently, we have demonstrated that taxifolin inhibits Aβ fibril formation in vitro and have further shown that it improves cerebral blood flow, facilitating Aβ clearance in the brain and suppressing cognitive decline in a mouse model of CAA. These findings suggest the novel therapeutic potentials of taxifolin for CAA. Furthermore, recent extensive studies have reported several novel aspects of taxifolin supporting its potential as a therapeutic drug for AD and metabolic diseases with a high risk for dementia as well as for CAA. In this review, we have summarized the recent advances in taxifolin research based on in vitro, in vivo, and in silico approaches. Furthermore, we have discussed future research directions on the potential of taxifolin for use in novel therapeutic strategies for CAA, AD, and metabolic diseases with an increased risk for dementia.

Decreased CSF Levels of ß-Amyloid in Patients With Cortical Superficial Siderosis

Background: Cortical superficial siderosis (cSS) represents a key neuroimaging marker of cerebral amyloid angiopathy (CAA) that is associated with intracranial hemorrhages and cognitive impairment. Nevertheless, the association between cSS and core cerebrospinal fluid (CSF) biomarkers for dementia remain unclear.

Methods: One hundred and one patients with probable (79%, 80/101) or possible (21%, 21/101) CAA according to the modified Boston criteria and mild cognitive impairment according to Petersen criteria were prospectively included between 2011 and 2016. CSF analyses of ß-amyloid 42, ß-amyloid 40, total tau and phosphorylated tau were performed using sandwich-type enzyme-linked immunosorbent-assay. All patients received MRI and Mini-Mental-State Examination (MMSE). Logistic regression analysis was used to adjust for possible confounders.

Results: cSS was present in 61% (62/101). Of those, 53% (33/62) had disseminated cSS and 47% (29/62) focal cSS. ß-amyloid 42 was lower in patients with cSS than in patients without cSS (OR 0.2; 95% CI 0.08–0.6; p = 0.0052) and lower in patients with disseminated cSS than in those with focal cSS (OR 0.02; 95% CI 0.003–0.2; p = 0.00057). Presence of cSS had no association with regard to ß-amyloid 40, total tau and phosphorylated tau.

Conclusions: Our results demonstrate that the presence and extent of cSS are associated with reduced CSF ß-amyloid 42 levels. Further studies are needed to investigate the underlying mechanisms of this association.

Pyroglutamation of amyloid-βx-42 (Aβx-42) followed by Aβ1-40 deposition underlies plaque polymorphism in progressing Alzheimer's disease pathology

Amyloid-β (Aβ) pathology in Alzheimer's disease (AD) is characterized by the formation of polymorphic deposits comprising diffuse and cored plaques. Because diffuse plaques are predominantly observed in cognitively unaffected, amyloid-positive (CU-AP) individuals, pathogenic conversion into cored plaques appears to be critical to AD pathogenesis. Herein, we identified the distinct Aβ species associated with amyloid polymorphism in brain tissue from individuals with sporadic AD (s-AD) and CU-AP. To this end, we interrogated Aβ polymorphism with amyloid conformation–sensitive dyes and a novel in situ MS paradigm for chemical characterization of hyperspectrally delineated plaque morphotypes. We found that maturation of diffuse into cored plaques correlated with increased Aβ1–40 deposition. Using spatial in situ delineation with imaging MS (IMS), we show that Aβ1–40 aggregates at the core structure of mature plaques, whereas Aβ1–42 localizes to diffuse amyloid aggregates. Moreover, we observed that diffuse plaques have increased pyroglutamated Aβx-42 levels in s-AD but not CU-AP, suggesting an AD pathology–related, hydrophobic functionalization of diffuse plaques facilitating Aβ1–40 deposition. Experiments in tgAPP_Swe mice verified that, similar to what has been observed in human brain pathology, diffuse deposits display higher levels of Aβ1–42 and that Aβ plaque maturation over time is associated with increases in Aβ1–40. Finally, we found that Aβ1–40 deposition is characteristic for cerebral amyloid angiopathy deposition and maturation in both humans and mice. These results indicate that N-terminal Aβx-42 pyroglutamation and Aβ1–40 deposition are critical events in priming and maturation of pathogenic Aβ from diffuse into cored plaques, underlying neurotoxic plaque development in AD.

Clinical and neuropathologic analysis of intracerebral hemorrhage in patients with cerebral amyloid angiopathy

OBJECTIVE

To evaluate the clinical and histopathological features of elderly patients with subcortical intracerebral hemorrhage (ICH), and to analyze the presence of cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) type pathologic changes using amyloid beta (Aβ) and tau immunohistochemistry.

PATIENTS AND METHODS

We retrospectively analyzed cases satisfying the Boston criteria for CAA among patients with subcortical hemorrhage who underwent surgical removal by craniotomy at our hospital. Surgical specimens were subjected to hematoxylin and eosin (HE) staining as well as immunostaining.

RESULTS

A total of 54 patients were included in this study, with a mean age of 74.5 years (range: 72.5-76.5 years, 95% confidence interval [CI]; 51% female). Of these 54 patients, 31 (57%) were hypertensive, 18 (33%) were undergoing antithrombotic therapy, and 12 (22%) had dementia. Strong immunoreactivity for Aβ40 in the cerebral vessels was observed in 30 patients (55.6%), and among these, 27 patients (90%) also showed strong immunoreactivity for Aβ42. Among the 54 patients, 25 (46%) exhibited AD characteristics, including Aβ-positive senile plaques and AT8-positive neurons. Multivariate analysis revealed that strong Aβ40 immunoreactivity in the cerebral vessels was associated with older patients, females, lack of high blood pressure, and the presence of AT8-positive neurons.

CONCLUSION

CAA patients with strong Aβ40 deposition in the cerebral vessels were associated with subcortical hemorrhage in our cohort. Future studies should investigate the pathomechanism of ICH in individuals with CAA.

The growing clinical spectrum of cerebral amyloid angiopathy

PURPOSE OF REVIEW

Cerebral amyloid angiopathy (CAA) is diagnosed primarily as a cause of lobar intracerebral hemorrhages (ICH) in elderly patients. With improving MRI techniques, however, the role of CAA in causing other symptoms has become clear. Recognizing the full clinical spectrum of CAA is important for diagnosis and treatment. In this review we summarize recent insights in clinical CAA features, MRI biomarkers, and management.

RECENT FINDINGS

The rate of ICH recurrence in CAA is among the highest of all stroke subtypes. Cortical superficial siderosis (cSS) and cortical subarachnoid hemorrhage (cSAH) are important imaging predictors for recurrent ICH. CAA also causes cognitive problems in multiple domains. In patients with nondemented CAA, the risk of developing dementia is high especially after ICH. CAA pathology probably starts years before the first clinical manifestations. The first signs in hereditary CAA are white matter lesions, cortical microinfarcts, and impaired occipital cerebral vasoreactivity. Visible centrum semiovale perivascular spaces, lobar located lacunes, and cortical atrophy are new nonhemorrhagic MRI markers.

SUMMARY

CAA should be in the differential diagnosis of elderly patients with lobar ICH but also in those with cognitive decline and episodic transient neurological symptoms. Physicians should be aware of the cognitive effects of CAA. In patients with a previous ICH, cSS, or cSAH, anticoagulation should be considered risky. The increasing number of MRI markers may help to discriminate CAA from other small vessel diseases and dementia subtypes.

Cerebrospinal fluid and blood biomarkers for neurodegenerative dementias: An update of the Consensus of the Task Force on Biological Markers in Psychiatry of the World Federation of Societies of Biological Psychiatry

In the 12 years since the publication of the first Consensus Paper of the WFSBP on biomarkers of neurodegenerative dementias, enormous advancement has taken place in the field, and the Task Force takes now the opportunity to extend and update the original paper. New concepts of Alzheimer's disease (AD) and the conceptual interactions between AD and dementia due to AD were developed, resulting in two sets for diagnostic/research criteria. Procedures for pre-analytical sample handling, biobanking, analyses and post-analytical interpretation of the results were intensively studied and optimised. A global quality control project was introduced to evaluate and monitor the inter-centre variability in measurements with the goal of harmonisation of results. Contexts of use and how to approach candidate biomarkers in biological specimens other than cerebrospinal fluid (CSF), e.g. blood, were precisely defined. Important development was achieved in neuroimaging techniques, including studies comparing amyloid-β positron emission tomography results to fluid-based modalities. Similarly, development in research laboratory technologies, such as ultra-sensitive methods, raises our hopes to further improve analytical and diagnostic accuracy of classic and novel candidate biomarkers. Synergistically, advancement in clinical trials of anti-dementia therapies energises and motivates the efforts to find and optimise the most reliable early diagnostic modalities. Finally, the first studies were published addressing the potential of cost-effectiveness of the biomarkers-based diagnosis of neurodegenerative disorders.

Updates on Prevention of Hemorrhagic and Lacunar Strokes

Intracerebral hemorrhage (ICH) and lacunar infarction (LI) are the major acute clinical manifestations of cerebral small vessel diseases (cSVDs). Hypertensive small vessel disease, cerebral amyloid angiopathy, and hereditary causes, such as Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL), constitute the three common cSVD categories. Diagnosing the underlying vascular pathology in these patients is important because the risk and types of recurrent strokes show significant differences. Recent advances in our understanding of the cSVD-related radiological markers have improved our ability to stratify ICH risk in individual patients, which helps guide antithrombotic decisions. There are general good-practice measures for stroke prevention in patients with cSVD, such as optimal blood pressure and glycemic control, while individualized measures tailored for particular patients are often needed. Antithrombotic combinations and anticoagulants should be avoided in cSVD treatment, as they increase the risk of potentially fatal ICH without necessarily lowering LI risk in these patients. Even when indicated for a concurrent pathology, such as nonvalvular atrial fibrillation, nonpharmacological approaches should be considered in the presence of cSVD. More data are emerging regarding the presentation, clinical course, and diagnostic markers of hereditary cSVD, allowing accurate diagnosis, and therefore, guiding management of symptomatic patients. When suspicion for asymptomatic hereditary cSVD exists, the pros and cons of prescribing genetic testing should be discussed in detail in the absence of any curative treatment. Recent data regarding diagnosis, risk stratification, and specific preventive approaches for both sporadic and hereditary cSVDs are discussed in this review article.

APP Mutations in Cerebral Amyloid Angiopathy with or without Cortical Calcifications: Report of Three Families and a Literature Review

BACKGROUND

Specific APP mutations cause cerebral amyloid angiopathy (CAA) with or without Alzheimer's disease (AD).

OBJECTIVE

We aimed at reporting APP mutations associated with CAA, describe the clinical, cerebrospinal fluid AD biomarkers, and neuroimaging features, and compare them with the data from the literature.

METHODS

We performed a retrospective study in two French genetics laboratories by gathering all clinical and neuroimaging data from patients referred for a genetic diagnosis of CAA with an age of onset before 66 years and fulfilling the other Boston revised criteria. We studied the segregation of mutations in families and performed a comprehensive literature review of all cases reported with the same APP mutation.

RESULTS

We screened APP in 61 unrelated French patients. Three mutations, located in the Aβ coding region, were detected in five patients from three families: p.Ala692Gly (Flemish), p.Glu693Lys (Italian), and p.Asp694Asn (Iowa). Patients exhibited CAA and progressive cognitive impairment associated with cortical calcifications in the Iowa and Italian mutation carriers, but not the patient carrying the Flemish mutation.

CONCLUSIONS

This is the first evidence of cortical calcification in patients with an APP mutation other than the Iowa mutation. We discuss the radiological, cerebrospinal fluid, and clinical phenotype of patients carrying these mutations in the literature.

Neurodegenerative disease biomarkers Aβ1-40, Aβ1-42, tau, and p-tau181 in the vervet monkey cerebrospinal fluid: Relation to normal aging, genetic influences, and cerebral amyloid angiopathy

Background

The Caribbean vervet monkey (Chlorocebus aethiops sabaeus) is a potentially valuable animal model of neurodegenerative disease. However, the trajectory of aging in vervets and its relationship to human disease is incompletely understood.

Methods

To characterize biomarkers associated with neurodegeneration, we measured cerebrospinal fluid (CSF) concentrations of Aβ1-40, Aβ1-42, total tau, and p-tau181 in 329 members of a multigenerational pedigree. Linkage and genome-wide association were used to elucidate a genetic contribution to these traits.

Results

Aβ1-40 concentrations were significantly correlated with age, brain total surface area, and gray matter thickness. Levels of p-tau181 were associated with cerebral volume and brain total surface area. Among the measured analytes, only CSF Aβ1-40 was heritable. No significant linkage (LOD > 3.3) was found, though suggestive linkage was highlighted on chromosomes 4 and 12. Genome-wide association identified a suggestive locus near the chromosome 4 linkage peak.

Conclusions

Overall, these results support the vervet as a non-human primate model of amyloid-related neurodegeneration, such as Alzheimer's disease and cerebral amyloid angiopathy, and highlight Aβ1-40 and p-tau181 as potentially valuable biomarkers of these processes.

Senile Dementia from Neuroscientific and Islamic Perspectives

Diseases involving the nervous system drastically change lives of victims and commonly increase dependency on others. This paper focuses on senile dementia from both the neuroscientific and Islamic perspectives, with special emphasis on the integration of ideas between the two different disciplines. This would enable effective implementation of strategies to address issues involving this disease across different cultures, especially among the world-wide Muslim communities. In addition, certain incongruence ideas on similar issues can be understood better. The former perspective is molded according to conventional modern science, while the latter on the analysis of various texts including the holy Qur'an, sunnah [sayings and actions of the Islamic prophet, Muhammad (pbuh)] and writings of Islamic scholars. Emphasis is particularly given on causes, symptoms, treatments and prevention of dementia.

Core cerebrospinal fluid biomarker profile in cerebral amyloid angiopathy: A meta-analysis

OBJECTIVE

To perform a meta-analysis of 4 core CSF biomarkers (β-amyloid [Aβ]42, Aβ40, total tau [t-tau], and phosphorylated tau [p-tau]) to assess which of these are most altered in sporadic cerebral amyloid angiopathy (CAA).

METHODS

We systematically searched PubMed for eligible studies reporting data on CSF biomarkers reflecting amyloid precursor protein metabolism (Aβ42, Aβ40), neurodegeneration (t-tau), and tangle pathology (p-tau) in symptomatic sporadic CAA cohorts vs controls and patients with Alzheimer disease (AD). Biomarker performance was assessed in random-effects meta-analysis based on ratio of mean (RoM) biomarker concentrations: (1) in patients with CAA vs healthy controls and (2) in patients with CAA vs patients with AD. RoM >1 indicates higher biomarker concentration in patients with CAA vs comparison population and RoM <1 indicates higher concentration in comparison groups.

RESULTS

Three studies met inclusion criteria. These comprised 5 CAA patient cohorts (n = 59 patients) vs healthy controls (n = 94 cases) and AD cohorts (n = 158). Three core biomarkers differentiated CAA from controls: CSF Aβ42 (RoM 0.49, 95% confidence interval [CI] 0.38-0.64, p < 0.003), Aβ40 (RoM 0.70, 95% CI 0.63-0.78, p < 0.0001), and t-tau (RoM 1.54, 95% CI 1.15-2.07, p = 0.004); p-tau was marginal (RoM 1.24, 95% CI 0.99-1.54, p = 0.062). Differentiation between CAA and AD was strong for CSF Aβ40 (RoM 0.76, 95% CI 0.69-0.83, p < 0.0001), but not Aβ42 (RoM 1.00; 95% CI 0.81-1.23, p = 0.970). For t-tau and p-tau, average CSF ratios in patients with CAA vs patients with AD were 0.63 (95% CI 0.54-0.74, p < 0.0001) and 0.60 (95% CI 0.50-0.71, p < 0.0001), respectively.

CONCLUSION

Specific CSF patterns of Aβ42, Aβ40, t-tau, and p-tau might serve as molecular biomarkers of CAA, but analyses in larger CAA cohorts are needed.

Cerebrospinal Fluid Alzheimer's Disease Biomarkers in Isolated Supratentorial Cortical Superficial Siderosis

We evaluated cerebrospinal fluid amyloid-β 1-40 (Aβ40), amyloid-β 1-42 (Aβ42), total and phosphorylated-tau (t-tau and p-tau) in patients with symptomatic isolated cortical supratentorial superficial siderosis (SS), by prospectively recruiting ten patients with SS in the absence of pre-existing cognitive dysfunction, and comparing biomarkers with lobar hematoma cerebral amyloid angiopathy patients (LH-CAA, n = 13), Alzheimer's disease patients (AD, n = 42), and controls (n = 16). Compared to controls, SS patients showed statistically significant higher t-tau (p = 0.019) and lower Aβ42 (p = 0.0084). Compared to other groups, SS showed statistically significant lower t-tau, p-tau, and Aβ40 compared to AD (p = 0.0063, p = 0.0004, and p = 0022, respectively), and higher p-tau compared to LH-CAA (p = 0.012).

The increasing impact of cerebral amyloid angiopathy: essential new insights for clinical practice

Cerebral amyloid angiopathy (CAA) has never been more relevant. The last 5 years have seen a rapid increase in publications and research in the field, with the development of new biomarkers for the disease, thanks to advances in MRI, amyloid positron emission tomography and cerebrospinal fluid biomarker analysis. The inadvertent development of CAA-like pathology in patients treated with amyloid-beta immunotherapy for Alzheimer's disease has highlighted the importance of establishing how and why CAA develops; without this information, the use of these treatments may be unnecessarily restricted. Our understanding of the clinical and radiological spectrum of CAA has continued to evolve, and there are new insights into the independent impact that CAA has on cognition in the context of ageing and intracerebral haemorrhage, as well as in Alzheimer's and other dementias. While the association between CAA and lobar intracerebral haemorrhage (with its high recurrence risk) is now well recognised, a number of management dilemmas remain, particularly when considering the use of antithrombotics, anticoagulants and statins. The Boston criteria for CAA, in use in one form or another for the last 20 years, are now being reviewed to reflect these new wide-ranging clinical and radiological findings. This review aims to provide a 5-year update on these recent advances, as well as a look towards future directions for CAA research and clinical practice.

Cerebral amyloid angiopathy as a cause of neurodegeneration

Sporadic, age-related cerebral amyloid angiopathy (CAA) is most commonly recognized clinically as a cause of hemorrhagic stroke and transient focal neurological episodes in older persons. But a growing body of research in the last 5 years shows that the pathophysiology of CAA is much more complex than previously believed, leading to many different types of brain injury. CAA has now been linked with brain atrophy in regions remote from those directly affected by intracerebral hematomas, and with risk for progressive cognitive decline in the absence of new hemorrhagic strokes. Therefore, CAA is associated with features - brain atrophy and progressive cognitive decline - that are typically considered hallmarks of neurodegenerative disease. Although CAA is usually accompanied by some degree of Alzheimer's disease pathology, the profiles of cortical thinning and cognitive impairment do not fully overlap with those seen in Alzheimer's disease, suggesting that there are CAA-specific pathways of neurodegeneration. CAA-related brain ischemia may be an important mechanism that leads to brain injury, cortical disconnection, and cognitive impairment. This article is part of the Special Issue "Vascular Dementia".

Cerebral Amyloid Angiopathy: Diagnosis, Clinical Implications, and Management Strategies in Atrial Fibrillation

With an aging population, clinicians are more frequently encountering patients with atrial fibrillation who are also at risk of intracerebral hemorrhage due to cerebral amyloid angiopathy, the result of β-amyloid deposition in cerebral vessels. Cerebral amyloid angiopathy is common among elderly patients, and is associated with an increased risk of intracerebral bleeding, especially with the use of anticoagulation. Despite this association, this entity is absent in current risk-benefit analysis models, which may result in underestimation of the chance of bleeding in the subset of patients with this disease. Determining the presence and burden of cerebral amyloid angiopathy is particularly important when planning to start or restart anticoagulation after an intracerebral hemorrhage. Given the lack of randomized trial data to guide management strategies, we discuss a heart-brain team approach that includes clinician-patient shared decision making for the use of pharmacologic and nonpharmacologic approaches to diminish stroke risk.

Elevated Plasma Aβ42 in Cognitively Impaired Individuals Taking ACE Inhibitor Antihypertensives

BACKGROUND/RATIONALE

Accumulating evidence suggests that the use of angiotensin-converting enzyme inhibitor (ACE-I) medication protects against cognitive decline in the elderly patients. We investigated whether ACE-I use was associated with higher plasma levels of amyloid-β (Aβ), possibly indicating improved Aβ clearance from brain to blood.

METHODS

We measured and compared plasma concentrations of Aβ42, Aβ40, and creatinine in cognitively impaired individuals with amnestic mild cognitive impairment, probable Alzheimer's disease (AD) dementia, and mixed probable AD/vascular dementia.

RESULTS

Plasma Aβ42 levels and Aβ42/Aβ40 ratios of participants taking ACE-Is (n = 11) significantly exceeded ( t = 3.1, df = 19, P = .006; U = 24, P = .029, respectively) those not taking ACE-Is (n = 10).

CONCLUSIONS

This study is the first to show an association between ACE-I use and increased plasma Aβ42 level and Aβ42/Aβ40 ratio in cognitively impaired individuals. Future investigations should assess whether a possible ACE-I-induced increase in plasma Aβ42 indicates improved Aβ42 clearance from brain that contributes to protection from cognitive decline.

Alzheimer's disease CSF biomarkers: clinical indications and rational use

This review focusses on the validation and standardization of Alzheimer's disease (AD) cerebrospinal fluid (CSF) biomarkers, as well as on the current clinical indications and rational use of CSF biomarkers in daily clinical practice. The validated AD CSF biomarkers, Aβ1-42, T-tau, and P-tau181, have an added value in the (differential) diagnosis of AD and related disorders, including mixed pathologies, atypical presentations, and in case of ambiguous clinical dementia diagnosis. CSF biomarkers should not be routinely used in the diagnostic work-up of dementia and cannot be used to diagnose non-AD dementias. In cognitively healthy subjects, CSF biomarkers can only be applied for research purposes, e.g., to identify pre-clinical AD in the context of clinical trials with potentially disease-modifying drugs. Therefore, biomarker-based early diagnosis of AD offers great opportunities for preventive treatment development in the near future.

18F-AV-1451 PET Imaging in Three Patients with Probable Cerebral Amyloid Angiopathy

Cerebrovascular deposition of amyloid-β, known as cerebral amyloid angiopathy (CAA), is associated with MRI findings of lobar hemorrhage, cerebral microbleeds, and cortical superficial siderosis. Although pathological studies suggest that tau may co-localize with vascular amyloid, this has not yet been investigated in CAA in vivo. Three patients with probable CAA underwent 11C-Pittsburgh Compound B (PiB) PET or 18F-florbetaben PET to evaluate amyloid burden, and 18F-AV-1451 PET to evaluate paired helical filament tau burden. Regions that had cerebral microbleeds or cortical superficial siderosis largely overlapped with those showing increased 18F-AV-1451. Our preliminary study raised the possibility that lobar cerebral microbleeds, and cortical superficial siderosis, which are characteristic markers of vascular amyloid, may be associated with local production of paired helical filament tau.

Vascular Cognitive Impairment

Cerebrovascular disease typically manifests with stroke, cognitive impairment, or both. Vascular cognitive impairment refers to all forms of cognitive disorder associated with cerebrovascular disease, regardless of the specific mechanisms involved. It encompasses the full range of cognitive deficits from mild cognitive impairment to dementia. In principle, any of the multiple causes of clinical stroke can cause vascular cognitive impairment. Recent work further highlights a role of microinfarcts, microhemorrhages, strategic white matter tracts, loss of microstructural tissue integrity, and secondary neurodegeneration. Vascular brain injury results in loss of structural and functional connectivity and, hence, compromise of functional networks within the brain. Vascular cognitive impairment is common both after stroke and in stroke-free individuals presenting to dementia clinics, and vascular pathology frequently coexists with neurodegenerative pathology, resulting in mixed forms of mild cognitive impairment or dementia. Vascular dementia is now recognized as the second most common form of dementia after Alzheimer's disease, and there is increasing awareness that targeting vascular risk may help to prevent dementia, even of the Alzheimer type. Recent advances in neuroimaging, neuropathology, epidemiology, and genetics have led to a deeper understanding of how vascular disease affects cognition. These new findings provide an opportunity for the present reappraisal of vascular cognitive impairment. We further briefly address current therapeutic concepts.

MRI-visible perivascular space location is associated with Alzheimer's disease independently of amyloid burden

Perivascular spaces that are visible on magnetic resonance imaging (MRI) are a neuroimaging marker of cerebral small vessel disease. Their location may relate to the type of underlying small vessel pathology: those in the white matter centrum semi-ovale have been associated with cerebral amyloid angiopathy, while those in the basal ganglia have been associated with deep perforating artery arteriolosclerosis. As cerebral amyloid angiopathy is an almost invariable pathological finding in Alzheimer's disease, we hypothesized that MRI-visible perivascular spaces in the centrum semi-ovale would be associated with a clinical diagnosis of Alzheimer's disease, whereas those in the basal ganglia would be associated with subcortical vascular cognitive impairment. We also hypothesized that MRI-visible perivascular spaces in the centrum semi-ovale would be associated with brain amyloid burden, as detected by amyloid positron emission tomography using 11C-Pittsburgh B compound (PiB-PET). Two hundred and twenty-six patients (Alzheimer's disease n = 110; subcortical vascular cognitive impairment n = 116) with standardized MRI and PiB-PET imaging were included. MRI-visible perivascular spaces were rated using a validated 4-point visual rating scale, and then categorized by severity ('none/mild', 'moderate' or 'frequent/severe'). Univariable and multivariable regression analyses were performed. Those with Alzheimer's disease-related cognitive impairment were younger, more likely to have a positive PiB-PET scan and carry at least one apolipoprotein E ɛ4 allele; those with subcortical vascular cognitive impairment were more likely to have hypertension, diabetes mellitus, hyperlipidaemia, prior stroke, lacunes, deep microbleeds, and carry the apolipoprotein E ɛ3 allele. In adjusted analyses, the severity of MRI-visible perivascular spaces in the centrum semi-ovale was independently associated with clinically diagnosed Alzheimer's disease (frequent/severe grade odds ratio 6.26, 95% confidence interval 1.66-23.58; P = 0.017, compared with none/mild grade), whereas the severity of MRI-visible perivascular spaces in the basal ganglia was associated with clinically diagnosed subcortical vascular cognitive impairment and negatively predicted Alzheimer's disease (frequent/severe grade odds ratio 0.03, 95% confidence interval 0.00-0.44; P = 0.009, compared with none/mild grade). MRI-visible perivascular space severity in either location did not predict PiB-PET. These findings provide further evidence that the anatomical distribution of MRI-visible perivascular spaces may reflect the underlying cerebral small vessel disease. Using MRI-visible perivascular space location and severity together with other imaging markers may improve the diagnostic value of neuroimaging in memory clinic populations, in particular in differentiating between clinically diagnosed Alzheimer's and subcortical vascular cognitive impairment.

Cerebral microbleeds topography and cerebrospinal fluid biomarkers in cognitive impairment

Cerebral microbleeds, a marker of small vessel disease, are thought to be of importance in cognitive impairment. We aimed to study topographical distribution of cerebral microbleeds, and their involvement in disease pathophysiology, reflected by cerebrospinal fluid biomarkers; 1039 patients undergoing memory investigation underwent lumbar puncture and a brain magnetic resonance imaging scan. Cerebrospinal fluid samples were analyzed for amyloid β(Aβ)42, total tau(T-tau), tau phosphorylated at threonine 18(P-tau) and cerebrospinal fluid/serum albumin ratios. Magnetic resonance imaging sequences were evaluated for small vessel disease markers, including cerebral microbleeds, white matter hyperintensities and lacunes. Low Aβ42 levels were associated with lobar cerebral microbleeds in the whole cohort and Alzheimer's disease ( P < 0.001). High cerebrospinal fluid/serum albumin ratios were seen with increased number of cerebral microbleeds in the brainstem ( P < 0.001). There were tendencies for increased Aβ42 levels and decreased Tau levels with deep and infratentorial cerebral microbleeds ( P < 0.05). Lobar cerebral microbleeds were associated with white matter hyperintensities and lacunes ( P < 0.001). Probable cerebral amyloid angiopathy-related cerebral microbleeds were associated with low Aβ42 levels and lacunes, whereas probable cerebral amyloid angiopathy-unrelated cerebral microbleeds were associated with white matter hyperintensities ( P < 0.001). Our findings show that cerebral microbleed distribution is associated with different patterns of cerebrospinal fluid biomarkers, supporting different pathogenesis of deep/infratentorial and lobar cerebral microbleeds.

Association of Plasma Aβ40 Peptides, But Not Aβ42, with Coronary Artery Disease and Diabetes Mellitus

BACKGROUND/OBJECTIVE

Plasma levels of amyloid-beta (Aβ) 1-40 peptide have been proposed to be associated with cardiovascular mortality in patients with coronary artery disease (CAD). Therefore, we aimed to investigate the association of plasma Aβ levels with CAD, cardiovascular risk factors (CVRF), and APOE genotype in non-demented elderly individuals.

METHODS

Plasma Aβ1 - 40 and Aβ1 - 42 levels of 526 individuals (mean age of 63.0±7.3 years) were quantified with the INNO-BIA plasma Aβ forms assay based on multiplextrademark technique. APOE genotype was determined with an established protocol. Presence of CAD and CVRFs were ascertained using a questionnaire and/or medical records.

RESULTS

Plasma Aβ1 - 40 levels were significantly higher in individuals with CAD (p = 0.043) and, independently, in individuals with diabetes mellitus (DM) type 2 (p = 0.001) while accounting for age- and gender-effects. Plasma Aβ1 - 42 levels were higher in APOEɛ4 carriers (p = 0.004), but were neither relevantly associated with CAD nor with any CVRF. Plasma Aβ1 - 40 showed no association with APOE genotype.

DISCUSSION

Our findings argue for an association of circulating plasma Aβ1 - 40 peptides with incident CAD and DM. Further investigations are needed to entangle the role of Aβ1 - 40 role in the pathophysiology of cardiovascular disease independent of its known role in Alzheimer's disease.

Thrombolysis-related Multiple Lobar Hemorrhaging in Cerebral Amyloid Angiopathy with Extensive Strictly Lobar Cerebral Microbleeding

A hemi-paralyzed 86-year-old man was diagnosed with ischemic stroke and underwent thrombolysis. Pre-thrombolysis brain magnetic resonance imaging revealed extensive strictly lobar cerebral microbleeding (CMB). Post-thrombolytic computed tomography revealed asymptomatic multiple intracerebral hemorrhaging (ICH). His age, CMB topography, and decreased cerebral spinal fluid amyloid-β 40 and 42 levels were compatible with a diagnosis of cerebral amyloid angiopathy (CAA). There is no consensus on the safety of thrombolysis for acute stroke patients with CAA. Patients with CAA might have a higher incidence of thrombolysis-related ICH than those without CAA.

β-Amyloid in CSF: Biomarker for preclinical cerebral amyloid angiopathy

OBJECTIVE

To investigate CSF biomarkers in presymptomatic and symptomatic mutation carriers with hereditary cerebral hemorrhage with amyloidosis-Dutch type (HCHWA-D), a model for sporadic cerebral amyloid angiopathy, and to determine the earliest deposited form of β-amyloid (Aβ).

METHODS

HCHWA-D mutation carriers and controls were enrolled in the cross-sectional EDAN (Early Diagnosis of Amyloid Angiopathy Network) study. The HCHWA-D group was divided into symptomatic carriers with a previous intracerebral hemorrhage and presymptomatic carriers. CSF concentrations of Aβ₄₀, Aβ₄₂, total tau, and phosphorylated tau₁₈₁ proteins were compared to those of controls of a similar age. Correlations between CSF biomarkers, MRI markers, and age were investigated with multivariate linear regression analyses.

RESULTS

We included 10 symptomatic patients with HCHWA-D (mean age 55 ± 6 years), 5 presymptomatic HCHWA-D carriers (mean age 36 ± 13 years), 31 controls <50 years old (mean age 31 ± 7 years), and 50 controls ≥50 years old (mean age 61 ± 8 years). After correction for age, CSF Aβ₄₀ and Aβ₄₂ were significantly decreased in symptomatic carriers vs controls (median Aβ₄₀ 1,386 vs 3,867 ng/L, p < 0.001; median Aβ₄₂ 289 vs 839 ng/L, p < 0.001) and in presymptomatic carriers vs controls (median Aβ₄₀ 3,501 vs 4,684 ng/L, p = 0.011; median Aβ₄₂ 581 vs 1,058 ng/L, p < 0.001). Among mutation carriers, decreasing CSF Aβ₄₀ was associated with higher lobar microbleed count (p = 0.010), increasing white matter hyperintensity volume (p = 0.008), and presence of cortical superficial siderosis (p = 0.02).

CONCLUSIONS

Decreased levels of CSF Aβ₄₀ and Aβ₄₂ occur before HCHWA-D mutation carriers develop clinical symptoms, implicating vascular deposition of both Aβ species as early steps in cerebral amyloid angiopathy pathogenesis. CSF Aβ₄₀ and Aβ₄₂ may serve as preclinical biomarkers of cerebral amyloid angiopathy pathology.

Cerebrospinal Fluid Alzheimer's Disease Biomarkers in Cerebral Amyloid Angiopathy-Related Inflammation

BACKGROUND

Decreased cerebrospinal fluid (CSF) amyloid-β 1-40 (Aβ40) and amyloid-β 1-42 (Aβ42) and increased total and phosphorylated tau (t-tau, p-tau) concentrations have been described in cerebral amyloid angiopathy (CAA).

OBJECTIVE

Our aim was to analyze these biomarkers in patients with CAA-related inflammation (CAA-I).

METHODS

We prospectively recruited nine patients with acute phase CAA-I fulfilling Chung criteria. CSF was analyzed for t-tau, p-tau, Aβ42, and Aβ40. Data were compared to controls (n = 14), patients with Alzheimer's disease (AD, n = 42), CAA (n = 10), and primary angiitis of the central nervous system (PACNS, n = 3).

RESULTS

For the CAA-I group, statistically significant differences were: lower Aβ42 (p = 0.00053) compared to the control group; lower t-tau (p = 0.018), p-tau (p <  0.001), and Aβ40 (p <  0.001) compared to AD; lower Aβ42 (p = 0.027) compared to CAA; lower Aβ42 (p = 0.012) compared to PACNS. Nearly significantly lower Aβ40 (p = 0.051) and higher t-tau (p = 0.051) were seen in CAA-I compared to controls.

CONCLUSION

CSF biomarkers profile similar to that of CAA was observed in CAA-I (with even lower levels of Aβ42 compared to CAA). Based on our findings, high p-tau seems more specific for AD, whereas low Aβ42 differentiates CAA-I from CAA, PACNS, and controls, and low Aβ40 differentiates CAA-I from AD.

Florbetapir-PET to diagnose cerebral amyloid angiopathy: A prospective study

OBJECTIVE

We hypothesized that florbetapir, a Food and Drug Administration-approved PET tracer, could distinguish cerebral amyloid angiopathy (CAA)-related intracerebral hemorrhage (ICH) from hypertensive ICH (HTN-ICH).

METHODS

We prospectively enrolled survivors of primary ICH related to probable CAA (per Boston Criteria, n = 10) and HTN-ICH (n = 9) without dementia. All patients underwent florbetapir-PET and multimodal MRI, and patients with CAA had additional Pittsburgh compound B (PiB) PET. Amyloid burden was assessed quantitatively (standard uptake value ratio [SUVR]) and visually classified as positive or negative.

RESULTS

The CAA and HTN-ICH groups had similar age (66.9 vs 67.1), sex, and leukoaraiosis volumes (31 vs 30 mL, all p > 0.8). Florbetapir uptake and PiB retention strongly correlated in patients with CAA both globally within cerebral cortex (r = 0.96, p < 0.001) and regionally in lobar cortices (all r > 0.8, all p ≤ 0.01). Mean global cortical florbetapir uptake was substantially higher in CAA than HTN-ICH (SUVR: 1.41 ± 0.17 vs 1.15 ± 0.08, p = 0.001), as was mean occipital SUVR (1.44 ± 0.12 vs 1.17 ± 0.08, p < 0.001), even after correcting for global SUVR (p = 0.03). Visual rating for positive/negative florbetapir demonstrated perfect interrater agreement (k = 1) and was positive for all 10 patients with CAA vs 1 of 9 HTN-ICH patients (sensitivity 100%, specificity 89%).

CONCLUSIONS

Florbetapir appears to label vascular amyloid in patients with CAA-related ICH. The approved florbetapir binary visual reading method can have diagnostic value in appropriate clinical settings.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that florbetapir-PET provides a sensitivity of 100% (95% confidence interval [CI] 66%-100%) and specificity of 89% (95% CI 51%-99%) for determination of probable CAA among cognitively normal patients.

Pre-critical MRI findings of an Alzheimer's disease patient with pathologically proven cerebral amyloid angiopathy related lobar hemorrhage

An 85-year-old woman with untreated hypertension was admitted with a disturbance of consciousness. On admission, brain CT revealed a lobar intracerebral hemorrhage with a midline shift. An intracranial hematoma was evacuated via a life-saving craniotomy. Definite pathological findings of amyloid-β deposition in the excised hematoma (strong in anti-amyloid β40 immunostain, but weak in anti- amyloid β42) indicated cerebral amyloid angiopathy (CAA). She had been diagnosed with Alzheimer's disease at a regional memory clinic one month before symptom onset based on MRI findings of medial temporal lobe atrophy as well as CAA-related features of multiple strictly lobar cerebral microbleeds in the occipital lobe, cortical superficial siderosis and >20 enlarged perivascular spaces in the centrum semiovale. This experience suggests that comprehensive interpretation of such CAA-related findings on MRI might help to improve the management of cardiovascular risk factors for Alzheimer's disease.

Cerebrospinal fluid profiles with increasing number of cerebral microbleeds in a continuum of cognitive impairment

Cerebral microbleeds (CMBs) are hypothesised to have an important yet unknown role in the dementia disease pathology. In this study we analysed increasing number of CMBs and their independent associations with routine cerebrospinal fluid (CSF) biomarkers in a continuum of cognitive impairment. A total of 1039 patients undergoing dementia investigation were analysed and underwent lumbar puncture, and an MRI scan. CSF samples were analysed for amyloid β (Aβ) 42, total tau (T-tau), tau phosphorylated at threonine 18 (P-tau) and CSF/serum albumin ratios. Increasing number of CMBs were independently associated with low Aβ42 levels, in the whole cohort, Alzheimer's disease and mild cognitive impairment (p < 0.05). CSF/serum albumin ratios were high with multiple CMBs (p < 0.001), reflecting accompanying blood-brain barrier dysfunction. T-tau and P-tau levels were lower in Alzheimer's patients with multiple CMBs when compared to zero CMBs, but did not change in the rest of the cohort. White matter hyperintensities were associated with low Aβ42 in the whole cohort and Alzheimer's disease (p < 0.05). Aβ42 is the routine CSF-biomarker mainly associated with CMBs in cognitive impairment, and there is an accumulative effect with increasing number of CMBs.

Cerebral white matter lesions - associations with Aβ isoforms and amyloid PET

Small vessel disease (SVD) and amyloid deposition may promote each other, with a potential association between SVD and altered production or clearance of β-amyloid (Aβ) affecting its cleavage products. We investigated the relationship between SVD, multiple isoforms of Aβ in cerebrospinal fluid (CSF) and cortical Aβ in 831 subjects with cognitive performance ranging from normal to Alzheimer’s disease (AD) (the Swedish BioFINDER study). SVD was estimated as white matter lesions (WML) and lacunes. 18F-flutemetamol PET was performed in 321 subjects. Lower CSF levels of Aβ38 and Aβ40 were consistently associated with increased WML in all subgroups, while lower levels of CSF Aβ42 were associated with WML mainly in AD. CSF Aβ38 and Aβ40 were associated with regional WML in all regions, while CSF Aβ42 was associated with temporal WML only. A composite measure of 18F-flutemetamol uptake was not associated with WML, and regional 18F-flutemetamol uptake only with temporal WML. Lacunes were not associated with Aβ isoforms nor 18F-flutemetamol uptake. Our results suggest that WML may be associated with alterations in the production or clearance of Aβ species, particularly of Aβ38 and Aβ40. However, in AD cases, Aβ42 pathology might be associated with WML, especially in the temporal lobe.

Pseudotumoral presentation of cerebral amyloid angiopathy-related inflammation

OBJECTIVE

To identify the clinical and radiologic features that should raise suspicion for the pseudotumoral presentation of cerebral amyloid angiopathy-related inflammation (CAA-I).

METHODS

We retrospectively reviewed the characteristics of 5 newly diagnosed and 23 previously reported patients in whom the CAA-I imaging findings were initially interpreted as CNS neoplasms.

RESULTS

Most cases (85%) occurred in patients >60 years old. The clinical characteristics at presentation included subacute cognitive decline (50%), confusion (32%), focal deficits (32%), seizures (25%), and headaches (21%). Brain MRI demonstrated infiltrative white matter lesions that exhibited a loco-regional mass effect without parenchymal enhancement (93%). In general, these findings were interpreted as low-grade glioma or lymphoma. Eighteen patients (64%) underwent a biopsy, which was nondiagnostic in 4 patients (14%), and 6 patients (21%) underwent a surgical resection. The primary reason for the misinterpretation of the imaging findings was the absence of T2*-weighted gradient recalled echo (T2*-GRE) sequences on initial imaging (89%). When subsequently performed (39%), the T2*-GRE sequences demonstrated multiple characteristic cortical and subcortical microhemorrhages in all cases. Perfusion MRI and magnetic resonance spectroscopy (MRS), which were performed on a subset of patients, indicated markedly reduced relative cerebral blood flow and a normal metabolic ratio.

CONCLUSION

The identification of one or several nonenhancing space-occupying lesions, especially in elderly patients presenting with cognitive impairment, should raise suspicion for the pseudotumoral presentation of CAA-I and lead to T2*-GRE sequences. Perfusion MRI and MRS appear to be useful techniques for the differential diagnosis of this entity.

Revisiting supersaturation as a factor determining amyloid fibrillation

Amyloid fibrils involved in various diseases are formed by a nucleation-growth mechanism, similar to the crystallization of solutes from solution. Solubility and supersaturation are two of the most important factors determining crystallization of solutes. Moreover, crystallization competes with glass formation in which solutes collapse into amorphous aggregates. Recent studies on the formation of amyloid fibrils and amorphous aggregates indicate that the partition between distinct types of aggregates can be rationally explained by a kinetic and thermodynamic competition between them. Understanding the role of supersaturation in determining aggregation-based phase transitions of denatured proteins provides an important complementary point of view to structural studies of protein aggregates.

Spontaneous convexity subarachnoid haemorrhage: Clinical series of 3 patients with associated cerebral amyloid angiopathy

INTRODUCTION

Convexity subarachnoid haemorrhage (cSAH) is a rare type of spontaneous, non-traumatic, and nonaneurysmal SAH characterised by blood collections in one or more cortical sulci in the convexity of the brain; the aetiology varies. We report a clinical case series of 3 patients with cSAH associated with probable cerebral amyloid angiopathy (CAA) who presented with focal sensory seizures and responded well to corticosteroid treatment.

PATIENTS

Case 1 was a 67-year-old man reporting right-sided paroxysmal sensory episodes with Jacksonian progression, cheiro-oral symptoms, and motor dysphasia. Case 2 was a 79-year-old man reporting left-sided paroxysmal episodes with cheiro-oral signs and dysarthria. Case 3 was a 71-year-old woman also reporting recurrent left cheiro-oral signs and dysarthria. None of the patients had headache or clinical dementia. Aneurysms were ruled out using MR angiography.

RESULTS

Brain CT scan detected an isolated hyperintensity in a sulcus of the frontal convexity; brain gradient echo T2-weighted MRI sequences showed meningeal haemosiderosis and microbleeds. However, no atrophy was identified in medial temporal lobes including the hippocampal formation. All patients had low levels of beta-amyloid in CSF, low values on the Hulstaert index and high levels of phosphorylated tau protein. Patients were initially treated with prednisone and levetiracetam, but symptoms recurred in 2 patients after prednisone was discontinued.

CONCLUSIONS

We present a series of 3 patients with cSAH associated with CAA, characterised by a stereotypical syndrome responding well to corticoid treatment; there were no cases of headache or clinical dementia.

Diagnostic value of cerebrospinal fluid Aβ ratios in preclinical Alzheimer's disease

INTRODUCTION

In this study of preclinical Alzheimer's disease (AD) we assessed the added diagnostic value of using cerebrospinal fluid (CSF) Aβ ratios rather than Aβ42 in isolation for detecting individuals who are positive on amyloid positron emission tomography (PET).

METHODS

Thirty-eight community-recruited cognitively intact older adults (mean age 73, range 65-80 years) underwent (18)F-flutemetamol PET and CSF measurement of Aβ1-42, Aβ1-40, Aβ1-38, and total tau (ttau). (18)F-flutemetamol retention was quantified using standardized uptake value ratios in a composite cortical region (SUVRcomp) with reference to cerebellar grey matter. Based on a prior autopsy validation study, the SUVRcomp cut-off was 1.57. Sensitivities, specificities and cut-offs were defined based on receiver operating characteristic analysis with CSF analytes as variables of interest and (18)F-flutemetamol positivity as the classifier. We also determined sensitivities and CSF cut-off values at fixed specificities of 90 % and 95 %.

RESULTS

Seven out of 38 subjects (18 %) were positive on amyloid PET. Aβ42/ttau, Aβ42/Aβ40, Aβ42/Aβ38, and Aβ42 had the highest accuracy to identify amyloid-positive subjects (area under the curve (AUC) ≥ 0.908). Aβ40 and Aβ38 had significantly lower discriminative power (AUC = 0.571). When specificity was fixed at 90 % and 95 %, Aβ42/ttau had the highest sensitivity among the different CSF markers (85.71 % and 71.43 %, respectively). Sensitivity of Aβ42 alone was significantly lower under these conditions (57.14 % and 42.86 %, respectively).

CONCLUSION

For the CSF-based definition of preclinical AD, if a high specificity is required, our data support the use of Aβ42/ttau rather than using Aβ42 in isolation.