Clearance of interstitial fluid (ISF) and CSF (CLIC) group-part of Vascular Professional Interest Area (PIA), updates in 2022-2023. Cerebrovascular disease and the failure of elimination of Amyloid-ß from the brain and retina with age and Alzheimer's disease: Opportunities for therapy.

This editorial summarizes advances from the Clearance of Interstitial Fluid and Cerebrospinal Fluid (CLIC) group, within the Vascular Professional Interest Area (PIA) of the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment (ISTAART). The overarching objectives of the CLIC group are to: (1) understand the age-related physiology changes that underlie impaired clearance of interstitial fluid (ISF) and cerebrospinal fluid (CSF) (CLIC); (2) understand the cellular and molecular mechanisms underlying intramural periarterial drainage (IPAD) in the brain; (3) establish novel diagnostic tests for Alzheimer's disease (AD), cerebral amyloid angiopathy (CAA), retinal amyloid vasculopathy, amyloid-related imaging abnormalities (ARIA) of spontaneous and iatrogenic CAA-related inflammation (CAA-ri), and vasomotion; and (4) establish novel therapies that facilitate IPAD to eliminate amyloid ß (Aß) from the aging brain and retina, to prevent or reduce AD and CAA pathology and ARIA side events associated with AD immunotherapy.

The Venular Side of Cerebral Amyloid Angiopathy: Proof of Concept of a Neglected Issue.

Small vessel diseases (SVD) is an umbrella term including several entities affecting small arteries, arterioles, capillaries, and venules in the brain. One of the most relevant and prevalent SVDs is cerebral amyloid angiopathy (CAA), whose pathological hallmark is the deposition of amyloid fragments in the walls of small cortical and leptomeningeal vessels. CAA frequently coexists with Alzheimer's Disease (AD), and both are associated with cerebrovascular events, cognitive impairment, and dementia. CAA and AD share pathophysiological, histopathological and neuroimaging issues. The venular involvement in both diseases has been neglected, although both animal models and human histopathological studies found a deposition of amyloid beta in cortical venules. This review aimed to summarize the available information about venular involvement in CAA, starting from the biological level with the putative pathomechanisms of cerebral damage, passing through the definition of the peculiar angioarchitecture of the human cortex with the functional organization and consequences of cortical arteriolar and venular occlusion, and ending to the hypothesized links between cortical venular involvement and the main neuroimaging markers of the disease.

Neurovascular Manifestations of Iron-Deficient Anemia: Narrative Review and Practical Reflections through a Teaching Case.

Anemia is one of the most frequent diseases worldwide, affecting one-third of the general population. Anemia in general and in particular, iron-deficient anemia (IDA), has been associated to a higher risk of thrombotic manifestations, including ischemic stroke and cerebral venous thrombosis (CVT), as well as systemic extra-cerebral arterial and venous thrombosis. Despite these data, anemia is seldom considered as an etiological factor of stroke. An individual case encompassing all known neurovascular and systemic arterial and venous thrombotic manifestations related to IDA is presented with the focus on clinical reasoning issues in the diagnostic pathways, starting from the neuroradiological signs. The main questions have been identified and addressed in a narrative review of the most relevant data in the literature from a pragmatic and clinical viewpoint. The presented case concerns a 46-year-old man admitted to the Stroke Unit because of acute ischemic stroke with multiple thrombi in large intracranial and extracranial vessels, multifocal ischemic lesions in several arterial territories and the concurrent finding of asymptomatic CVT, pulmonary embolism with lung infarction and aortic thrombosis. An extended diagnostic work-up excluded the main etiologies (arterial dissection, cardiac embolism, genetic and acquired prothrombotic disorders, such as cancer and antiphospholipid syndrome), except for a severe IDA, such as to require blood transfusions followed by anticoagulant therapy for the several thrombotic manifestations. Neuroimaging and systemic vascular findings have been analyzed, and the main issues proposed by the case in the diagnostic pathway have been identified and discussed in a pragmatic clinical road map reviewing the data provided by the literature. Conclusions: IDA is a common but treatable condition that, independently or synergically, may increase the risk of thrombotic events. The diagnostic and therapeutic approach has not yet been defined, and each case should be individually addressed in a pragmatic clinical road map.

Association of Microglial Activation With Spontaneous ARIA-E and CSF Levels of Anti-Aß Autoantibodies.

BACKGROUND AND OBJECTIVES: Amyloid-related imaging abnormalities suggestive of vasogenic edema or sulcal effusion (ARIA-E) are the most common adverse events complicating Alzheimer disease (AD) immunotherapy with anti-ß-amyloid (Aß) monoclonal antibodies. ARIA-E can also occur spontaneously in cerebral amyloid angiopathy-related inflammation (CAA-ri), a rare autoimmune encephalopathy associated with increased CSF levels of anti-Aß autoantibodies. Although the pathophysiologic mechanisms of ARIA-E remain to be fully elucidated, experimental evidence from ex vivo studies suggests that gantenerumab and aducanumab enable microglial activation. However, the in vivo evidence for a direct association between neuroinflammation and ARIA-E in patients with high CSF anti-Aß (auto)antibody levels has never been demonstrated. METHODS: The spatial distribution and temporal variations of microglial activation associated with levels of anti-Aß autoantibodies at (sub)acute presentation of ARIA-E and after corticosteroid therapy were evaluated in a longitudinal case series of patients with CAA-ri, the spontaneous variant of the iatrogenic ARIA-E reported in Aß-lowering immunotherapy with monoclonal antibodies. Multimodal and multiparametric MRI was used for CAA and ARIA-E severity quantification, according to validated scoring system; CSF testing for anti-Aß autoantibodies and AD biomarkers; 11C-PK11195 PET for activated microglia. RESULTS: At (sub)acute presentation, we found focal peaks of microglial activation having a greater spatial colocalization with ARIA-E compared with chronic age-related white matter change imaging abnormalities. The severity of ARIA-E and the magnitude of the associated microglial activation were greater in patients having AD and severe CAA concomitant disease compared with patients having CAA only. CSF anti-Aß autoantibodies at presentation were high in all patients and markedly decreased at posttreatment follow-up, in parallel with clinical resolution of acute symptoms, reduced ARIA-E severity, and reduced microglial activation. DISCUSSION: Our findings extend the current notion of ARIA-E by providing the first in vivo 11C-PK11195 PET evidence for an association between microglial activation and the magnitude and severity of ARIA-E in patients with increased CSF concentration of anti-Aß autoantibodies and comorbid AD and CAA disease. Our results highlight CSF testing for anti-Aß autoantibodies as a promising diagnostic, prognostic, and therapy response biomarker to help guide future treatment and management decisions in real clinical practice and clinical trials.

The Boston criteria version 2.0 for cerebral amyloid angiopathy: a multicentre, retrospective, MRI-neuropathology diagnostic accuracy study.

BACKGROUND: Cerebral amyloid angiopathy (CAA) is an age-related small vessel disease, characterised pathologically by progressive deposition of amyloid ß in the cerebrovascular wall. The Boston criteria are used worldwide for the in-vivo diagnosis of CAA but have not been updated since 2010, before the emergence of additional MRI markers. We report an international collaborative study aiming to update and externally validate the Boston diagnostic criteria across the full spectrum of clinical CAA presentations. METHODS: In this multicentre, hospital-based, retrospective, MRI and neuropathology diagnostic accuracy study, we did a retrospective analysis of clinical, radiological, and histopathological data available to sites participating in the International CAA Association to formulate updated Boston criteria and establish their diagnostic accuracy across different populations and clinical presentations. Ten North American and European academic medical centres identified patients aged 50 years and older with potential CAA-related clinical presentations (ie, spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes), available brain MRI, and histopathological assessment for CAA diagnosis. MRI scans were centrally rated at Massachusetts General Hospital (Boston, MA, USA) for haemorrhagic and non-haemorrhagic CAA markers, and brain tissue samples were rated by neuropathologists at the contributing sites. We derived the Boston criteria version 2.0 (v2.0) by selecting MRI features to optimise diagnostic specificity and sensitivity in a prespecified derivation cohort (Boston cases 1994-2012, n=159), then externally validated the criteria in a prespecified temporal validation cohort (Boston cases 2012-18, n=59) and a geographical validation cohort (non-Boston cases 2004-18; n=123), comparing accuracy of the new criteria to the currently used modified Boston criteria with histopathological assessment of CAA as the diagnostic standard. We also assessed performance of the v2.0 criteria in patients across all cohorts who had the diagnostic gold standard of brain autopsy. FINDINGS: The study protocol was finalised on Jan 15, 2017, patient identification was completed on Dec 31, 2018, and imaging analyses were completed on Sept 30, 2019. Of 401 potentially eligible patients presenting to Massachusetts General Hospital, 218 were eligible to be included in the analysis; of 160 patient datasets from other centres, 123 were included. Using the derivation cohort, we derived provisional criteria for probable CAA requiring the presence of at least two strictly lobar haemorrhagic lesions (ie, intracerebral haemorrhages, cerebral microbleeds, or foci of cortical superficial siderosis) or at least one strictly lobar haemorrhagic lesion and at least one white matter characteristic (ie, severe visible perivascular spaces in centrum semiovale or white matter hyperintensities in a multispot pattern). The sensitivity and specificity of these criteria were 74·8% (95% CI 65·4-82·7) and 84·6% (71·9-93·1) in the derivation cohort, 92·5% (79·6-98·4) and 89·5% (66·9-98·7) in the temporal validation cohort, 80·2% (70·8-87·6) and 81·5% (61·9-93·7) in the geographical validation cohort, and 74·5% (65·4-82·4) and 95·0% (83·1-99·4) in all patients who had autopsy as the diagnostic standard. The area under the receiver operating characteristic curve (AUC) was 0·797 (0·732-0·861) in the derivation cohort, 0·910 (0·828-0·992) in the temporal validation cohort, 0·808 (0·724-0·893) in the geographical validation cohort, and 0·848 (0·794-0·901) in patients who had autopsy as the diagnostic standard. The v2.0 Boston criteria for probable CAA had superior accuracy to the current Boston criteria (sensitivity 64·5% [54·9-73·4]; specificity 95·0% [83·1-99·4]; AUC 0·798 [0·741-0854]; p=0·0005 for comparison of AUC) across all individuals who had autopsy as the diagnostic standard. INTERPRETATION: The Boston criteria v2.0 incorporate emerging MRI markers of CAA to enhance sensitivity without compromising their specificity in our cohorts of patients aged 50 years and older presenting with spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes. Future studies will be needed to determine generalisability of the v.2.0 criteria across the full range of patients and clinical presentations. FUNDING: US National Institutes of Health (R01 AG26484).

In silico exploration of amyloid-related imaging abnormalities in the gantenerumab open-label extension trials using a semi-mechanistic model.

Introduction: Amyloid-related imaging abnormalities with edema/effusion (ARIA-E) are commonly observed with anti-amyloid therapies in Alzheimer's disease. We developed a semi-mechanistic, in silico model to understand the time course of ARIA-E and its dose dependency. Methods: Dynamic and statistical analyses of data from 112 individuals that experienced ARIA-E in the open-label extension of SCarlet RoAD (a study of gantenerumab in participants with prodromal Alzheimer's disease) and Marguerite RoAD (as study of Gantenerumab in participants with mild Alzheimer's disease) studies were used for model building. Gantenerumab pharmacokinetics, local amyloid removal, disturbance and repair of the vascular wall, and ARIA-E magnitude were represented in the novel vascular wall disturbance (VWD) model of ARIA-E. Results: The modeled individual-level profiles provided a good representation of the observed pharmacokinetics and time course of ARIA-E magnitude. ARIA-E dynamics were shown to depend on the interplay between drug-mediated amyloid removal and intrinsic vascular repair processes. Discussion: Upon further refinement and validation, the VWD model could inform strategies for dosing and ARIA monitoring in individuals with an ARIA-E history.

Spontaneous ARIA-like Events in Cerebral Amyloid Angiopathy-Related Inflammation: A Multicenter Prospective Longitudinal Cohort Study.

BACKGROUND AND OBJECTIVES: The goal of this work was to investigate the natural history and outcomes after treatment for spontaneous amyloid-related imaging abnormalities (ARIA)-like in cerebral amyloid angiopathy-related inflammation (CAA-ri). METHODS: This was a multicenter, hospital-based, longitudinal, prospective observational study of inpatients meeting CAA-ri diagnostic criteria recruited through the Inflammatory Cerebral Amyloid Angiopathy and Alzheimer's Disease ßiomarkers International Network from January 2013 to March 2017. A protocol for systematic data collection at first-ever presentation and at subsequent in-person visits, including T1-weighted, gradient recalled echo-T2*, fluid-suppressed T2-weighted (fluid-attenuated inversion recovery), and T1 postgadolinium contrast-enhanced images acquired on 1.5T MRI, was used at the 3-, 6-, 12-, and 24-month follow-up. Centralized reads of MRIs were performed by investigators blinded to clinical, therapeutic, and time-point information. Main outcomes were survival, clinical and radiologic recovery, intracerebral hemorrhage (ICH), and recurrence of CAA-ri. RESULTS: The study enrolled 113 participants (10.6% definite, 71.7% probable, and 17.7% possible CAA-ri). Their mean age was 72.9 years; 43.4% were female; 37.1% were APOEε4 carriers; 36.3% had a history of Alzheimer disease; and 33.6% had a history of ICH. A history of ICH and the occurrence of new ICH at follow-up were more common in patients with cortical superficial siderosis at baseline (52.6% vs 14.3%, p < 0.0001 and 19.3% vs 3.6%, p < 0.009, respectively). After the first-ever presentation of CAA-ri, 70.3% (95% confidence interval [CI] 61.6%-78.5%) and 84.1% (95% CI 76.2%-90.6%) clinically recovered within 3 and 12 months, followed by radiologic recovery in 45.1% (95% CI 36.4%-54.8%) and 77.4% (95% CI 67.7%-85.9%), respectively. After clinicoradiologic resolution of the first-ever episode, 38.3% (95% CI 22.9%-59.2%) had at least 1 recurrence within the following 24 months. Recurrence was more likely if IV high-dose corticosteroid pulse therapy was suddenly stopped compared to slow oral tapering off (hazard ratio 4.68, 95% CI 1.57-13.93; p = 0.006). DISCUSSION: These results from the largest longitudinal cohort registry of patients with CAA-ri support the transient and potentially relapsing inflammatory nature of the clinical-radiologic acute manifestations of the disease and the effectiveness of slow oral tapering off after IV corticosteroid pulse therapy in preventing recurrences. Our results highlight the importance of differential diagnosis for spontaneous ARIA-like events in ß-amyloid-driven diseases, including treatment-related ARIA in patients with Alzheimer disease exposed to immunotherapy drugs.

Hemostasis components in cerebral amyloid angiopathy and Alzheimer's disease.

Increased cerebrovascular amyloid-ß (Aß) deposition represents the main pathogenic mechanisms characterizing Alzheimer's disease (AD) and cerebral amyloid angiopathy (CAA). Whereas an increasing number of studies define the contribution of fibrin(ogen) to neurodegeneration, how other hemostasis factors might be pleiotropically involved in the AD and CAA remains overlooked. Although traditionally regarded as pertaining to hemostasis, these proteins are also modulators of inflammation and angiogenesis, and exert cytoprotective functions. This review discusses the contribution of hemostasis components to Aß cerebrovascular deposition, which settle the way to endothelial and blood-brain barrier dysfunction, vessel fragility, cerebral bleeding, and the associated cognitive changes. From the primary hemostasis, the process that refers to platelet aggregation, we discuss evidence regarding the von Willebrand factor (vWF) and its regulator ADAMTS13. Then, from the secondary hemostasis, we focus on tissue factor, which triggers the extrinsic coagulation cascade, and on the main inhibitors of coagulation, i.e., tissue factor pathway inhibitor (TFPI), and the components of protein C pathway. Last, from the tertiary hemostasis, we discuss evidence on FXIII, involved in fibrin cross-linking, and on components of fibrinolysis, including tissue-type plasminogen activator (tPA), urokinase-type plasminogen activator (uPA) and its receptor uPA(R), and plasminogen activator inhibitor-1 (PAI-1). Increased knowledge on contributors of Aß-related disease progression may favor new therapeutic approaches for early modifiable risk factors.

Clearance of interstitial fluid (ISF) and CSF (CLIC) group-part of Vascular Professional Interest Area (PIA): Cerebrovascular disease and the failure of elimination of Amyloid-ß from the brain and retina with age and Alzheimer's disease-Opportunities for Therapy.

Two of the key functions of arteries in the brain are (1) the well-recognized supply of blood via the vascular lumen and (2) the emerging role for the arterial walls as routes for the elimination of interstitial fluid (ISF) and soluble metabolites, such as amyloid beta (Aß), from the brain and retina. As the brain and retina possess no conventional lymphatic vessels, fluid drainage toward peripheral lymph nodes is mediated via transport along basement membranes in the walls of capillaries and arteries that form the intramural peri-arterial drainage (IPAD) system. IPAD tends to fail as arteries age but the mechanisms underlying the failure are unclear. In some people this is reflected in the accumulation of Aß plaques in the brain in Alzheimer's disease (AD) and deposition of Aß within artery walls as cerebral amyloid angiopathy (CAA). Knowledge of the dynamics of IPAD and why it fails with age is essential for establishing diagnostic tests for the early stages of the disease and for devising therapies that promote the clearance of Aß in the prevention and treatment of AD and CAA. This editorial is intended to introduce the rationale that has led to the establishment of the Clearance of Interstitial Fluid (ISF) and CSF (CLIC) group, within the Vascular Professional Interest Area of the Alzheimer's Association International Society to Advance Alzheimer's Research and Treatment.

Discovering the Italian phenotype of cerebral amyloid angiopathy (CAA): the SENECA project.

Cerebral amyloid angiopathy (CAA) is one of the major types of cerebral small vessel disease, and a leading cause of spontaneous intracerebral hemorrhage and cognitive decline in elderly patients. Although increasingly detected, a number of aspects including the pathophysiology, the clinical and neuroradiological phenotype, and the disease course are still under investigation. The incomplete knowledge of the disease limits the implementation of evidence-based guidelines on patient's clinical management and the development of treatments able to prevent or reduce disease progression. The SENECA (SEarchiNg biomarkErs of Cerebral Angiopathy) project is the first Italian multicenter cohort study aimed at better defining the disease natural history and identifying clinical and neuroradiological markers of disease progression. By a multidisciplinary approach and the collection of a large and well-phenotyped series and biorepository of CAA patients, the study is ultimately expected to improve the diagnosis and the knowledge of CAA pathophysiological mechanisms.

Idiopathic infratentorial superficial siderosis of the central nervous system: case report and review of literature.

The superficial siderosis (SS) of the central nervous system (CNS) is a rare condition characterized by a wide range of neurological manifestations directly linked to an acquired iron-mediated neurodegeneration. First described more than 100 years ago, only recently SS has been divided into two distinct entities, according to the distribution of iron deposition in the CNS: cortical superficial siderosis (cSS) and infratentorial superficial siderosis (iSS). Here we describe an adult case of iSS, with detailed clinical and radiological features. Moreover, we extensively review the literature of SS, particularly focusing on the pathogenesis, clinical-radiological classification, diagnostic algorithm and treatment options of this rare condition.

Amyloid-Related Imaging Abnormalities (ARIA) in Immunotherapy Trials for Alzheimer's Disease: Need for Prognostic Biomarkers?

At the 8th International Conference on Clinical Trials in Alzheimer's Disease held November 5-7, 2015 in Barcelona, Spain, promising data were presented on two candidate Alzheimer's disease immunotherapeutic agents, gantenerumab and aducanumab. Trial results demonstrated that the implementation of cerebrospinal fluid and Aß-PET biomarkers improves trial enrichment and outcome, which has led to a change in targeting strategy as clinical trials would be conducted with earlier, even presymptomatic, stages of the disease. Promising findings of outcomes, as measured by Aß-PET and cerebrospinal fluid tau and P-tau, were, nevertheless, associated with antibody dose-dependent increased risk of severe adverse effects, specifically amyloid-related imaging abnormalities (ARIA). Aducanumab was associated with concomitant time-, dose-, and APOE-related incidence of ARIA in more than one-half of the patients within the high-dose arm. The future challenge will thus be to find biomarkers more favorably balanced between effective dosing of antibody to remove Aß versus dosing to limit deleterious side effects. Interest was shown by Roche and Biogen, which promoted high-dose phase 3 trials. However, this generated some concerns related to a reasonable expected further increase in the incidence of severe side effects. What has been learned is challenging primary industry strategies for following-up and monitoring safety and effectiveness of anti-Aß antibodies in clinical trials. Here, we debate the issue of what is an acceptable balance of treatment side effects, i.e., therapeutic-induced ARIA, versus the positive prospects. Indeed, implementation of biomarkers for ARIA might increase value and reduce waste in the design of immunotherapy trials of Alzheimer's disease.

Validation of Clinicoradiological Criteria for the Diagnosis of Cerebral Amyloid Angiopathy-Related Inflammation.

IMPORTANCE: Cerebral amyloid angiopathy-related inflammation (CAA-ri) is an important diagnosis to reach in clinical practice because many patients with the disease respond to immunosuppressive therapy. Reliable noninvasive diagnostic criteria for CAA-ri would allow some patients to avoid the risk of brain biopsy. OBJECTIVE: To test the sensitivity and specificity of clinical and neuroimaging-based criteria for CAA-ri. DESIGN, SETTING, AND PARTICIPANTS: We modified the previously proposed clinicoradiological criteria and retrospectively analyzed clinical medical records and magnetic resonance imaging fluid-attenuated inversion recovery and gradient-echo scans obtained from individuals with CAA-ri and noninflammatory CAA. At 2 referral centers between October 1, 1995, and May 31, 2013, and between January 1, 2009, and December 31, 2011, participants included 17 individuals with pathologically confirmed CAA-ri and 37 control group members with pathologically confirmed noninflammatory CAA. The control group was further divided into those with past lobar intracerebral hemorrhage (ICH) (n = 21) and those with cerebral microbleeds only and no history of ICH (n = 16). The dates of our analysis were September 1, 2012, to August 31, 2015. MAIN OUTCOMES AND MEASURES: The sensitivity and specificity of prespecified criteria for probable CAA-ri (requiring asymmetric white matter hyperintensities extending to the subcortical white matter) and possible CAA-ri (not requiring the white matter hyperintensities to be asymmetric). RESULTS: The 17 patients in the CAA-ri group were a mean (SD) of 68 (8) years and 8 (47%) were women. In the CAA-ri group, 14 of 17 (82%) met the criteria for both probable and possible CAA-ri. In the control group having noninflammatory CAA with lobar ICH, 1 of 21 (5%) met the criteria for possible CAA-ri, and none met the criteria for probable CAA-ri. In the control group having noninflammatory CAA with no ICH, 11 of 16 (69%) met the criteria for possible CAA-ri, and 1 of 16 (6%) met the criteria for probable CAA-ri. These findings yielded a sensitivity and specificity of 82% and 97%, respectively, for the probable criteria and a sensitivity and specificity of 82% and 68%, respectively, for the possible criteria. CONCLUSIONS AND RELEVANCE: Our data suggest that a reliable diagnosis of CAA-ri can be reached from basic clinical and magnetic resonance imaging information alone, with good sensitivity and excellent specificity.

Cerebrospinal Fluid Anti-Amyloid-ß Autoantibodies and Amyloid PET in Cerebral Amyloid Angiopathy-Related Inflammation.

We report a biomarker and genetic evaluation of four patients with cerebral amyloid angiopathy-related inflammation (CAA-ri) treated with corticosteroids. Patients presented with focal symptomatology and cognitive impairment. MRI revealed cortical microbleeds and asymmetrical hyperintense white matter lesions (WML). Cerebrospinal fluid (CSF) biomarker analyses showed increased anti-Aß autoantibodies, t-Tau, and p-Tau and decreased Aß40 and Aß42. After treatment, focal symptomatology disappeared, and WML and anti-Aß autoantibodies decreased. The APOEɛ4 allele was overrepresented. Florbetapir-PET showed cortical deposition with lower retention in swollen areas. In the case of suspected CAA-ri, both CSF anti-Aß autoantibodies levels and Florbetapir-PET could provide highly useful data to guide the correct diagnosis.

Anti-Aß Autoantibodies in Amyloid Related Imaging Abnormalities (ARIA): Candidate Biomarker for Immunotherapy in Alzheimer's Disease and Cerebral Amyloid Angiopathy.

Amyloid-related imaging abnormalities (ARIA) represent the major severe side effect of amyloid-beta (Aß) immunotherapy for Alzheimer's disease (AD). Early biomarkers of ARIA represent an important challenge to ensure safe and beneficial effects of immunotherapies, given that different promising clinical trials in prodromal and subjects at risk for AD are underway. The recent demonstration that cerebrospinal fluid (CSF) anti-Aß autoantibodies play a key role in the development of the ARIA-like events characterizing cerebral amyloid angiopathy-related inflammation generated great interest in the field of immunotherapy. Herein, we critically review the growing body of evidence supporting the monitoring of CSF anti-Aß autoantibody as a promising candidate biomarker for ARIA in clinical trials.

Cerebral Amyloid Angiopathy-Related Inflammation: Report of a Case with Very Difficult Therapeutic Management.

Background. Cerebral amyloid angiopathy-related inflammation (CAA-ri) results from autoimmune response to beta-amyloid deposits in cerebral vessels. Its clinical course and complications have seldom been described in literature. Case Report. In a patient presenting with delirium and left hemiparesis the diagnosis of CAA-ri was supported by the finding of elevated anti-amyloid autoantibodies in the cerebrospinal fluid (CSF). Steroid therapy produced significant improvements in clinical and investigational assessments, but after two months, it caused Acute Respiratory Distress Syndrome. After steroid therapy discontinuation the patient presented a rapidly progressive dementia, Guillain-Barré syndrome, new cerebral ischemic lesions, and thrombosis of the right cephalic and subclavian veins that were treated with subcutaneous heparin. After a week the patient died because of brain hemorrhage. Conclusion. This case suggests caution in steroid therapy discontinuation and antithrombotic therapy administration in patients with CAA-ri. The CSF search of anti-amyloid autoantibodies could be helpful to support the diagnosis.

Recurrence of Cerebral Amyloid Angiopathy-Related Inflammation: A Report of Two Cases from the iCAß International Network.

BACKGROUND: Cerebral amyloid angiopathy-related inflammation (CAA-ri) represents the most readily responsive form of CAA, if diagnosed and treated early. Although CAA-ri typically presents with a monophasic pattern, recurrences have been occasionally reported. OBJECTIVES: To describe the evolution of the clinical and neuroradiological features of CAA-ri recurrence. METHODS: From the 60 CAA-ri cases recruited through the iCAß International Network, we identified those patients who experienced a CAA-ri recurrence at more than 12 months after the first inflammatory event. Neuroradiological evidence of cerebral inflammation (vasogenic edema) and sulcal superficial siderosis or multiple areas of cortical/subcortical microhemorrhages (MHs) were evaluated based upon fluid-attenuated inversion recovery and T2 *-weighted gradient echo or susceptibility weighted imaging, respectively. In one patient, the deposition of amyloid-ß was evaluated using 11C-Pittsburgh Compound B-positron emission tomography (PiB-PET). RESULTS: Of the 60 cases, two were identified as having experienced a late CAA-ri recurrence, at two and seven years after the first presentation, respectively. At recurrence, the inflammatory lesions colocalized with the appearance of new MHs and were observed in brain areas different from those where the first onset occurred. PiB-PET four months after remission showed particularly low amyloid-ß deposition in the left frontal lobe, while no change was observed in the area of the inflammatory relapse. CONCLUSIONS: Our observations highlight the importance of not underestimating any new neurological symptoms in patients who have already experienced an episode of CAA-ri. Although the frequency of CAA-ri recurrences is rare, in cases of suspected relapse, a prompt clinical and radiological follow-up should be considered in order to obtain a timely diagnosis and treatment, having a potential strong impact on patients' clinical outcome.