Prevalence of cerebral amyloid angiopathy: A systematic review and meta-analysis

Seizures in Cerebral Amyloid Angiopathy: A Systematic Review and Meta-Analysis

Purpose of Review

Cerebral amyloid angiopathy (CAA) is a disease of the cerebral vasculature that can result in microhemorrhages, as well as intraparenchymal and subarachnoid hemorrhage, superficial siderosis (SS), and/or secondary infarct/inflammation. CAA may be encountered as an isolated pathology or with Alzheimer disease and has been demonstrated to be associated with an increased risk of seizures. However, the overall rates of seizures and specific pathologies related to CAA and their subsequent risk of seizures have not been elucidated.

Recent findings

Prior studies of CAA and seizures are predominantly case reports or small case series, and larger studies have focused primarily on smaller subgroups of patients with CAA. Only 2 prior studies assessed larger heterogeneous populations of patients with CAA. One study focused on long-term outcomes and evaluated the impact of seizures on cognitive and survival outcomes retrospectively, although it did not delineate the effects of acute and chronic seizure disorders (epilepsy) and did not find an association. Long-term prospective or retrospective studies on outcomes regarding seizures/epilepsy and CAA are therefore lacking.

Summary

A total of 1,376 articles were identified, with 48 (34 case reports/series and 14 cohort studies) included in this review. Acute symptomatic seizures (ASyS) and epilepsy were poorly defined, and the overall prevalence of seizures in cohort studies was 22.8%, with significant heterogeneity (I 2 = 77%; p < 0.01). Epilepsy was diagnosed in 34.4% and ASyS in 10.6% of patients in heterogeneous cohorts. Most of the studies assessed seizures in specific subgroups of CAA with variable prevalence, including CAA with related inflammation (CAA-ri): 56.9%; lobar intracranial hemorrhage (ICH): 17.1%; and cortical SAH (cSAH) or SS: 8.7%. In heterogeneous cohorts, SS (p < 0.001 and p = 0.03, respectively) and CAA-ri (p = 0.005 and p = 0.04, respectively) were significantly associated with epilepsy/seizures. In 1 study, cSAH (p = 0.03) and acute lobar ICH (p = 0.002) were associated with seizures, likely related to inclusion of ASyS. Status epilepticus (14/125) and drug resistance (6/89) were infrequent. Clinical pathologic entities associated with a risk of seizures include cSAH, CAA-ri, SS, and acute ICH.

Vascular and glymphatic dysfunction as drivers of cognitive impairment in Alzheimer's disease: Insights from computational approaches

Alzheimer's disease (AD) is driven by complex interactions between vascular dysfunction, glymphatic system impairment, and neuroinflammation. Vascular aging, characterized by arterial stiffness and reduced cerebral blood flow (CBF), disrupts the pulsatile forces necessary for glymphatic clearance, exacerbating amyloid-beta (Aβ) accumulation and cognitive decline. This review synthesizes insights into the mechanistic crosstalk between these systems and explores their contributions to AD pathogenesis. Emerging machine learning (ML) tools, such as DeepLabCut and Motion sequencing (MoSeq), offer innovative solutions for analyzing multimodal data and enhancing diagnostic precision. Integrating ML with imaging and behavioral analyses bridges gaps in understanding vascular-glymphatic dysfunction. Future research must prioritize these interactions to develop early diagnostics and targeted interventions, advancing our understanding of neurovascular health in AD.

Lecanemab for early Alzheimer's disease: Appropriate use recommendations from the French federation of memory clinics

Lecanemab, a monoclonal antibody targeting β-amyloid protofibrils, has shown promising results in a Phase III clinical trial for the treatment of early stages of Alzheimer's disease (AD) and has been approved by the European Medicines Agency. An Early Market Authorization could be submitted to the French regulatory agencies, potentially allowing for the drug's use in clinical practice in France in 2025. To guide French clinicians in administering lecanemab in a standardized way, the French Federation of Memory Clinics has developed appropriate use recommendations for lecanemab that highlight relevant questions established to ensure an optimal risk-benefit ratio. The recommendations emphasize that lecanemab treatment requires a comprehensive individualized evaluation of the risk-benefit ratio, which should occur in multidisciplinary meetings. When approved, the guidelines support the use of blood biomarkers, proposing specific cutoffs for patients eligible for lecanemab under restricted conditions. In addition to the European Medicines Agency restrictions in patients on anticoagulants, and APOE4 homozygotes, the guidelines recommend against lecanemab treatment for patients with high amyloid-related hemorrhagic risk such as probable cerebral amyloid angiopathy (Boston criteria v1.5) until further data become available. Additionally, we recommend that MRI monitoring be started before the third infusion to account for early Amyloid Related Imaging Abnormalities (ARIA) occurring on lecanemab. It is recommended to establish a specific clinical care pathway with protocols for patients with ARIA, with trained physicians and radiologists with expertise in neurological emergency and intensive care. Finally, a discontinuation protocol based on dementia severity assessment after 18 months of lecanemab treatment is suggested. Access to lecanemab requires a personalized biological and genetic diagnosis of AD, which is currently not necessary in most cases. Therefore, the healthcare system must rapidly adjust to new diagnostic procedures and treatment delivery to ensure equal access for all individuals.

The relationship between Alzheimer's disease and intracerebral hemorrhage based on Mendelian randomization

BackgroundTraditional epidemiologic studies suggest that Alzheimer's disease (AD) may be associated with intracerebral hemorrhage (ICH).ObjectiveTo explore whether there is a causal relationship between AD and ICH and the underlying mechanisms involved.MethodsMendelian randomization (MR) approach was used to explore causal relationships. The genetic instrumental variables of the candidate genetic instrumental variable AD were obtained from genome-wide association studies. The inverse variance weighted method was the primary method for MR analysis and meta-analysis. The obtained single nucleotide polymorphisms were analyzed for corresponding genes for subsequent pathway enrichment and protein-protein interaction analysis.ResultsFor the single AD dataset, our MR analysis of the AD datasets versus the ICH datasets revealed a genetically predicted causal relationship between AD and ICH (OR 5.947, 95%CI 1.165-30.356, pIVW = 0.032). In addition, the MR-Egger method and MR-PRESSO method revealed no horizontal pleiotropic effect of AD on the risk of ICH. Meta-analysis of each dataset using IVW revealed a final calculated OR of 1.08 (95%CI 1.02-1.15, p = 0.01). Subsequent pathway enrichment analysis revealed that the corresponding genes were involved mainly in the metabolic process of amyloid-β (Aβ) and negatively regulated Aβ formation. In the PPI network analysis, proteins such as ApoE, SROL1, CLU, ABCA7, and AβPP were found to be closely related and located in the key position of the center.ConclusionsWe verified the causal relationship between AD and ICH via MR, and identified the possible pathological mechanisms involved. We also discovered that Aβ plays an important role in this process.

Prevalence of cerebral amyloid angiopathy and its correlation with Alzheimer's disease and cognition in an autopsy-confirmed cohort from China

BACKGROUND

We aimed to investigate the prevalence of cerebral amyloid angiopathy (CAA) and its correlations with Alzheimer's disease (AD) and cognitive impairment in an autopsy-confirmed cohort donated to a human brain bank in Beijing, China.

METHODS

A total of 483 subjects were neuropathologically evaluated based on standardized protocols. Descriptive statistics and ordinal logistic regression models were used to estimate the correlation between CAA, AD, apolipoprotein E (APOE) genotyping, and cognitive function proximal to death.

RESULTS

Neuropathological assessment revealed that 53 of 483 subjects (11%) had CAA without AD, 78 of 483 (16%) had AD without CAA, 98 of 483 (20%) had both CAA and AD, and 254 of 483 (53%) had neither condition. A significant correlation was confirmed between CAA severity and AD. Subjects with both CAA and AD exhibited aggravated cognitive impairment.

DISCUSSION

Our results indicate a substantial prevalence of CAA that is frequently comorbid with AD and may exacerbate cognitive decline in the elderly population in China.

Highlights

First reporting of cerebral amyloid angiopathy (CAA) based on an autopsy-confirmed cohort from China.The prevalence of CAA was high in the elderly Chinese sample.Age and apolipoprotein E (APOE) ε4 allele were related to the prevalence of CAA.CAA and Alzheimer's disease (AD) were frequently co-occurred and significantly associated.Subjects with both CAA and AD exhibited aggravated cognitive impairment.

Perivascular brain clearance as a therapeutic target in cerebral amyloid angiopathy and Alzheimer's disease

Although distinct diseases, both cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD) are characterized by the aggregation and accumulation of amyloid-β (Aβ). This is thought to be due, in part, to impaired perivascular Aβ clearance from the brain. This shared failure in both diseases presents a common opportunity for therapeutic intervention. In this review we discuss the idea that promoting perivascular brain clearance could be an effective strategy for safely reducing Aβ levels in CAA and AD thereby improving clinical outcomes, most notably hemorrhagic stroke and cognitive decline. We will explore the evidence for the different forces that are thought to drive perivascular brain clearance, review the literature on potential strategies for potentiating these driving forces, and finally we will discuss the substantial translational challenges and considerations that would accompany such an intervention.

Proteinopathies and the Neurodegenerative Aftermath of Stroke: Potential Biomarkers and Treatment Targets

Stroke remains a predominant cause of death and long-term disability among adults worldwide. Emerging evidence suggests that proteinopathies, characterized by the aggregation and accumulation of misfolded proteins, may play a significant role in the aftermath of stroke and the progression of neurodegenerative disorders. In this review, we explore preclinical and clinical research on key proteinopathies associated with stroke, including tau, Aβ (amyloid-β), TDP-43 (TAR DNA-binding protein 43), α-synuclein, and UCH-L1 (ubiquitin C-terminal hydrolase-L1). We focus on their potential as biomarkers for recovery management and as novel treatment targets that may enhance neuronal repair and mitigate secondary neurodegeneration. The involvement of these proteinopathies in various aspects of stroke, including neuroinflammation, oxidative stress, neuronal damage, and vascular dysfunction, underscores their potential. However, further investigations are essential to validate the clinical utility of these biomarkers, elucidate the mechanisms connecting proteinopathies to poststroke neurodegeneration, and develop targeted interventions. Identifying specific protein signatures associated with stroke outcomes could facilitate the advancement of precision medicine tailored to individual patient needs, significantly enhancing the quality of life for stroke survivors.

Developing and validating a prediction tool for cerebral amyloid angiopathy neuropathological severity

INTRODUCTION

Cerebral amyloid angiopathy (CAA) is a cerebrovascular condition, the severity of which can only be determined post mortem. Here, we developed machine learning models, the Florey CAA Score (FCAAS), to predict CAA severity (none/mild/moderate/severe).

METHODS

Building on an auto-score-ordinal algorithm, the FCAAS models were developed and validated using data collected by three cohort studies of aging and dementia. The developed FCAAS models were digitized as a web-based tool. A pilot trial was conducted using this web-based tool.

RESULTS

The FCAAS-4 achieved a mean area under the receiver operating characteristic curve (AUC-ROC) of 0.74 (95% confidence interval: 0.71-0.77) and a Harrell generalized c-index of 0.72 (0.70-0.75). Pilot trial results obtained a mean AUC-ROC of 0.82 (0.71-0.85) and Harrell generalized c-index 0.79 (0.73-0.82).

DISCUSSION

The FCAAS models demonstrate a promising performance in predicting CAA severity. This framework holds the potential for predicting development of amyloid-related imaging abnormalities (ARIAs), given the CAA-ARIAs link.

HIGHLIGHTS

The severity of cerebral amyloid angiopathy (CAA) can only be determined post mortem. A web tool, the Florey CAA Score (FCAAS), was developed to predict CAA severity. The FCAAS holds the potential to be used for CAA risk stratification in clinics. CAA is linked to increased risk of amyloid-related imaging abnormalities (ARIAs). The framework used by FCAAS can possibly be adapted to predict ARIAs risk.

Cerebral Amyloid Angiopathy: Clinical Presentation, Sequelae and Neuroimaging Features-An Update

The prevalence of cerebral amyloid angiopathy (CAA) has been shown to increase with age, with rates reported to be around 50-60% in individuals over 80 years old who have cognitive impairment. The disease often presents as spontaneous lobar intracerebral hemorrhage (ICH), which carries a high risk of recurrence, along with transient focal neurologic episodes (TFNE) and progressive cognitive decline, potentially leading to Alzheimer's disease (AD). In addition to ICH, neuroradiologic findings of CAA include cortical and subcortical microbleeds (MB), cortical subarachnoid hemorrhage (cSAH) and cortical superficial siderosis (cSS). Non-hemorrhagic pathologies include dilated perivascular spaces in the centrum semiovale and multiple hyperintense lesions on T2-weighted magnetic resonance imaging (MRI). A definitive diagnosis of CAA still requires histological confirmation. The Boston criteria allow for the diagnosis of a probable or possible CAA by considering specific neurological and MRI findings. The recent version, 2.0, which includes additional non-hemorrhagic MRI findings, increases sensitivity while maintaining the same specificity. The characteristic MRI findings of autoantibody-related CAA-related inflammation (CAA-ri) are similar to the so-called "amyloid related imaging abnormalities" (ARIA) observed with amyloid antibody therapies, presenting in two variants: (a) vasogenic edema and leptomeningeal effusions (ARIA-E) and (b) hemorrhagic lesions (ARIA-H). Clinical and MRI findings enable the diagnosis of a probable or possible CAA-ri, with biopsy remaining the gold standard for confirmation. In contrast to spontaneous CAA-ri, only about 20% of patients treated with monoclonal antibodies who show proven ARIA on MRI also experience clinical symptoms, including headache, confusion, other psychopathological abnormalities, visual disturbances, nausea and vomiting. Recent findings indicate that treatment should be continued in cases of mild ARIA, with ongoing MRI and clinical monitoring. This review offers a concise update on CAA and its associated consequences.

Plasma biomarkers distinguish Boston Criteria 2.0 cerebral amyloid angiopathy from healthy controls

INTRODUCTION

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of beta-amyloid (Aβ) in small vessels leading to hemorrhagic stroke and dementia. This study examined whether plasma Aβ42/40, phosphorylated-tau (p-tau), neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) differ in CAA and their potential to discriminate Boston Criteria 2.0 probable CAA from healthy controls.

METHODS

Plasma Aβ42/40, p-tau-181, NfL, and GFAP were quantified using single molecule array (Simoa) and Aβ42/40 was also independently quantified using immunoprecipitation liquid chromatography mass-spectrometry (IPMS).

RESULTS

Forty-five participants with CAA and 47 healthy controls had available plasma. Aβ42/40 ratios were significantly lower in CAA than healthy controls. While p-tau-181 and NfL were elevated in CAA, GFAP was similar. A combination of Aβ42/40 (Simoa), p-tau-181, and NfL resulted in an area under the curve of 0.90 (95% confidence interval: 0.80, 0.95).

DISCUSSION

Plasma Aβ42/40, p-tau-181, and NfL differ in those with CAA and together can discriminate CAA from healthy controls.

HIGHLIGHTS

Participants with CAA had reduced plasma Aβ42/40 ratios compared to controls. Plasma p-tau-181 and NfL concentrations are elevated in CAA compared to controls. Plasma GFAP was similar in CAA and controls. Together, plasma Aβ42/40, p-tau-181, and NfL had excellent discriminability for CAA.

Exploring epidemiological risk factors for cerebral amyloid angiopathy: Considerations for monoclonal antibody therapy in people with Alzheimer's disease

INTRODUCTION

Cerebral amyloid angiopathy (CAA) increases the risk of amyloid-related imaging abnormalities in Alzheimer's disease (AD) patients receiving anti-amyloid-beta therapies, emphasizing the need to identify its risk factors.

METHODS

Data were collected from three cohort studies, and a machine learning model was developed to predict CAA occurrence using the selected risk factors.

RESULTS

The AD neuropathologic changes (ADNC)-CAA association was significantly positive in the cross-sectional analysis. When stratified by selected risk factors, this association was generally stronger among females, smokers, people with a history of stroke/memory complaints, apolipoprotein E (APOE)-ε4 carriers, and those without diabetes/heart conditions. In the longitudinal analysis of the association between potential risk factors and CAA, a higher risk of CAA was observed among males, older individuals, smokers, people with diabetes/heart conditions, lower Mini-Mental State Examination (MMSE) scores, and APOE-ε4 carriers compared to their respective reference groups.

DISCUSSION

Our study identified risk factors for cerebral amyloid angiopathy, informing potential prevention strategies.

HIGHLIGHTS

ADNC were significantly positively associated with the risk of CAA. The ADNC-CAA association was generally stronger among females, smokers, people with a history of stroke/memory complaints, APOE-ε4 carriers, and those without diabetes or heart conditions. Longitudinally, higher CAA risk was observed among males, older individuals, smokers, people with diabetes/heart conditions/lower MMSE scores, and APOE-ε4 carriers compared to their reference groups.

Calcineurin inhibition may prevent Alzheimer disease in people with Down syndrome

Virtually all people with Down syndrome will develop Alzheimer disease pathology during their lifetime. As Alzheimer disease is the third leading cause of death and a significant factor in end-of-life complications for adults with Down syndrome, identifying interventions is a medical necessity. Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, has recently been investigated as a possible Alzheimer treatment. This review explores the histories behind Down syndrome and Alzheimer disease, and their intersecting pathologies. This is followed by the role that calcineurin and its U.S. Food and Drug Administration-approved pharmacological inhibitor, tacrolimus, may play in the prevention or treatment of Alzheimer disease. Finally, this review discusses the gap in the literature surrounding the role of calcineurin, its regulators, and calcineurin inhibitors in the context of Down syndrome and comorbid Alzheimer disease. Future studies investigating the role that calcineurin plays in this pathology will be essential in determining the viability of calcineurin inhibitors to treat Alzheimer disease in people with Down syndrome. HIGHLIGHTS: Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, has become prominent as a possible therapeutic target to treat Alzheimer disease. People with Down syndrome develop Alzheimer pathology as they age, requiring novel therapeutics for treatment. People with Down syndrome may exhibit contraindications to calcineurin inhibition-based therapy, as they overexpress RCAN1 and DYRK1A, regulators of calcineurin. There is a significant gap in the literature involving the expression of calcineurin, RCAN1 and DYRK1A, in people with Down syndrome and Alzheimer disease, which must be addressed to determine the efficacy and safety of newly developed therapeutics.

Downregulation of Parahippocampal Copper Chaperone for Superoxide Dismutase in Alzheimer's Disease

BACKGROUND/OBJECTIVES

Proper regulation of copper is essential for maintaining neuronal stability and is facilitated by several chaperone proteins, protecting cells from oxidative damage that would otherwise be caused by improperly regulated copper ions. Oxidative stress, resulting from such dysregulation, is hypothesized to play a significant role in the pathogenesis of Alzheimer's disease (AD).

METHODS

In this study, we evaluated the concentrations of the copper chaperones CCS, DCTN4, and ATOX1 in control and AD cases via Western blotting and ELISA, and quantified the copper concentrations in fractionated neurons using ICP-MS.

RESULTS

Our findings reveal a significant reduction in CCS levels in AD cases (p = 0.0085), with a progressive decline observed with advancing age. This decline was more pronounced in women, although the difference did not reach statistical significance (p = 0.0768). No significant differences were observed in copper concentrations within synaptosomal (p = 0.3869) or cytosolic fractions (p = 0.4461) between the AD and control cases. Additionally, comprehensive analyses of the effects of sex and age showed no significant impact on the levels of copper chaperones or copper distribution across cellular compartments.

CONCLUSIONS

These results suggest a strong association between reduced CCS levels and AD pathology, highlighting a potential role for CCS in the redistribution of copper ions within neurons. This redistribution may contribute to oxidative stress and neuronal dysfunction, offering new insights into the mechanisms underlying AD pathogenesis.

A review of the use of oral anticoagulants in individuals with atrial fibrillation who had experienced intracranial hemorrhage in the past

Atrial fibrillation (AF) is the most prevalent arrhythmia, significantly increasing the risk of stroke and thromboembolism. Oral anticoagulants (OACs), including direct oral anticoagulants (DOACs) and vitamin K antagonists (VKAs), have been shown to reduce these risks effectively. However, the administration of OACs carries a notable risk of spontaneous intracranial hemorrhage (ICH), a severe complication associated with high morbidity and mortality. Patients with a history of ICH face a complex decision regarding the resumption of anticoagulation therapy, as the likelihood of recurrence is heightened in this population. Current literature reveals inconsistencies in research findings regarding the safety and efficacy of restarting OACs after ICH. A lack of definitive guidelines addressing this issue leaves clinicians uncertain about optimal management strategies. This systematic review aims to analyze existing observational studies and randomized controlled trials (RCTs) to evaluate the safety and effectiveness of resuming OACs in patients with AF who have experienced ICH. The review underscores the urgent need for high-quality research to inform clinical practices and develop comprehensive guidelines for managing anticoagulation therapy in this vulnerable group.

Vascular amyloidβ load in the meningeal arterial network correlates with loss of cerebral blood flow and pial collateral vessel enlargement in the J20 murine model of Alzheimer's disease

INTRODUCTION

Global reduction in cerebral blood flow (CBF) is an early pathology in Alzheimer's disease, preceding significant plaque accumulation and neurological decline. Chronic reduced CBF and subsequent reduction in tissue oxygenation and glucose may drive neurodegeneration, yet the underlying cause of globally reduced CBF remains unclear.

METHODS

Using premortem delivery of Methoxy-XO4 to label Aβ, and arterial vascular labeling, we assessed Aβ burden on the pial artery/arteriole network and cerebral blood flow in aged male and female WT and J20 AD mice.

RESULTS

The pial artery/arteriole vascular network selectively displayed extensive vascular Aβ burden. Pial collateral arteriole vessels, the by-pass system that reroutes blood flow during occlusion, displayed significant enlargement in J20 mice. Despite this, CBF was decreased by approximately 15% in 12-month J20 mice when compared to WT littermates.

DISCUSSION

Significant Aβ burden on the meningeal arterial network may contribute to the restriction of CBF. Redistribution of CBF through enlarged pial collateral vessels may serve as a compensatory mechanism to alter CBF during disease progression in cases of CAA.

Cerebral amyloid angiopathy: one single entity?

PURPOSE OF REVIEW

Cerebral amyloid angiopathy (CAA) is a common brain disorder among the elderly and individuals with Alzheimer's disease, where accumulation of amyloid-ß can lead to intracerebral hemorrhage and dementia. This review discusses recent developments in understanding the pathophysiology and phenotypes of CAA.

RECENT FINDINGS

CAA has a long preclinical phase starting decades before symptoms emerge. Its pathophysiology follows consecutive stages of amyloid-ß deposition, decreased vascular reactivity, nonhemorrhagic changes, and ultimately hemorrhages. Although impaired perivascular clearance is the leading hypothesis underlying CAA, several lines of evidence suggest that glymphatic dysfunction also plays a significant role in the disease process. Despite its common pathway, the disease course is variable. Some patients develop more microbleeds, while others develop larger hemorrhages, suggesting a differentiation in vascular remodeling. Some patients with CAA develop a symptomatic immune response, and inflammation could be an important contributor to vascular damage in CAA in general. Furthermore, the prion-like transmission of amyloid-β has been identified as a cause of iatrogenic CAA occurring decades after neurosurgical procedures involving cadaveric dura mater.

SUMMARY

Emerging evidence of sporadic, hereditary, inflammatory, and iatrogenic CAA suggests a complex interplay between brain clearance, inflammation and vascular remodeling leading to a diverse clinical phenotype.

Cerebral Amyloid Angiopathy in Alzheimer Disease: A Comparison Between Different Versions of the Boston Criteria

OBJECTIVES

Cerebral amyloid angiopathy (CAA) is the main driver of amyloid-related imaging abnormalities (ARIAs) in Alzheimer disease (AD). We compared different versions of the Boston criteria for CAA diagnosis in AD.

METHODS

This article presents a single-center analysis (outpatient neurodegenerative clinic) of patients with AD with mild cognitive impairment (MCI) or early dementia, meeting NIA-AA criteria and having biological amyloid confirmation (CSF or imaging). Two raters analyzed hemorrhagic (cerebral microbleeds, CMBs; cortical superficial siderosis, cSS) and nonhemorrhagic (severe centrum semiovale perivascular spaces, CSO-PVSs; multispot pattern white matter hyperintensities (WMHs)) markers following the original (V1.0), modified (V1.5), and latest (V2.0) Boston criteria.

RESULTS

We included 75 patients (mean age 71.6 ± 8.1 years, 53% female, mean disease duration 2.6 ± 2.0 years, 91% MCI). White matter CAA markers were more common than hemorrhagic markers: 41 (55%) had severe CSO-PVSs, 28 (37%) had multispot WHMs, 12 (16%) had 1 lobar CMB, 9 had ≥2 lobar CMBs (12%), 1 (1.3%) had focal cSS, and 5 (6.7) had disseminated cSS. The prevalence of possible and probable CAA was lowest with V1.0 (14.7% and 9.3%) than with V1.5 (13.3% and 13.3%) and V2.0 (42.7% and 26.7%) criteria.

DISCUSSION

More than 1 in 4 patients with AD had probable CAA according to the V2.0 Boston criteria. These findings might inform future trials.

Subarachnoid hemorrhage and finger-like projection predict recurrence in patients with lobar intracerebral hemorrhage

BACKGROUND AND PURPOSE

Lobar intracerebral hemorrhage (ICH) is associated with a high risk of recurrence, particularly in elderly patients, where cerebral amyloid angiopathy (CAA) is often the primary cause. Diagnostic markers of CAA-related ICH, including subarachnoid hemorrhage (SAH) and finger-like projection (FLP), have recently been developed. Here, we aimed to explore the associations between SAH, FLP and the risk of ICH recurrence in lobar ICH patients.

METHODS

We analyzed data from consecutive lobar ICH patients using the method of cohort study. We divided them into 4 groups on the basis of the presence or absence of SAH and FLP on CT imaging. The Cox regression model and competing risk model were used to analyze the associations of SAH and FLP with the risk of ICH recurrence at 1 year.

RESULTS

In total, 353 patients with lobar ICH (median age 74 [62, 81] years, 57.2% male) were included in our study. During follow-up, recurrence occurred in 34 patients (10.6%), and 90 patients (28.1%) died. The competing risk model revealed that patients in the SAH + FLP- (HR 2.88, 95% CI 1.12-7.44, p = 0.03) and SAH + FLP + (HR 8.38, 95% CI 3.40-20.66, p < 0.001) groups had higher risks of ICH recurrence within 1 year than did those in the SAH-FLP- group.

CONCLUSION

SAH is an important predictor of ICH recurrence, and this predictive ability is further enhanced when FLP is present. These findings suggest that SAH, especially with FLP, can be a valuable tool for assessing prognosis in lobar ICH patients.

Anti-Amyloid Therapies for Alzheimer's Disease and Amyloid-Related Imaging Abnormalities: Implications for the Emergency Medicine Clinician

Alzheimer's disease is the neurodegenerative disorder responsible for approximately 60% to 70% of all cases of dementia and is expected to affect 152 million by 2050. Recently, anti-amyloid therapies have been developed and approved by the Food and Drug Administration as disease-modifying treatments given as infusions every 2 to 5 weeks for Alzheimer's disease. Although this is an important milestone in mitigating Alzheimer's disease progression, it is critical for emergency medicine clinicians to understand what anti-amyloid therapies are and how they work to recognize, treat, and mitigate their adverse effects. Anti-amyloid therapies may be underrecognized contributors to emergency department visits because they carry the risk of adverse effects, namely amyloid-related imaging abnormalities. Amyloid-related imaging abnormalities are observed as abnormalities on magnetic resonance imaging as computed tomography is not sensitive enough to detect the microvasculature abnormalities causing vasogenic edema (amyloid-related imaging abnormalities-E) microhemorrhages and hemosiderin deposits (amyloid-related imaging abnormalities-H). Patients presenting with amyloid-related imaging abnormalities may have nonspecific neurologic symptoms, including headache, lethargy, confusion, and seizures. Anti-amyloid therapies may increase risk of hemorrhagic conversion of ischemic stroke patients receiving thrombolytics and complicate the initiation of anticoagulation. Given the novelty of anti-amyloid therapies and limited real-world data pertaining to amyloid-related imaging abnormalities, it is important for emergency medicine clinicians to be aware of these agents.

The cerebral blood flow response to neuroactivation is reduced in cognitively normal men with β-amyloid accumulation

BACKGROUND

Accumulation of β-amyloid (Aβ) in the brain is a hallmark of Alzheimer's Disease (AD). Cerebral deposition of Aβ initiates deteriorating pathways which eventually can lead to AD. However, the exact mechanisms are not known. A possible pathway could be that Aβ affects the cerebral vessels, causing inadequate cerebrovascular function. In the present study, we examined if Aβ accumulation is associated with a reduced cerebral blood flow response (CBF) to neuronal activation by visual stimulation (ΔCBFVis.Act.) in cognitively normal subjects from the Metropolit Danish Male Birth Cohort.

METHODS

64 subjects participated in the present study. ΔCBFVis.Act. was measured using arterial spin labelling (ASL) combined with blood-oxygen-level-dependent (BOLD) MRI. Neuronal activation was obtained by visual stimulation by a flickering checkerboard presented on a screen in the MRI-scanner. Brain Aβ accumulation and cerebral glucose metabolism were assessed by PET imaging using the radiotracers [11C]Pittsburgh Compound-B (PiB) and [18F]Fluorodeoxyglucose (FDG), respectively. Cortical thickness was measured from structural MRI.

RESULTS

ΔCBFVis.Act. correlated negatively ( β = -32.1 [95% confidence interval (CI): -60.2; -4.1], r = -0.30, p = 0.025) with PiB standardized uptake value ratio (SUVr) in the brain regions activated by visual stimulation. ΔCBFVis.Act. did not correlate with FDG SUVr ( β = 1.9 [CI: -23.8; 27.6], r = 0.02, p = 0.88) or cortical thickness ( β = 10.3 [CI: -8.4; 29.0], r = 0.15, p = 0.27) in the activated brain regions. Resting CBF did not correlate with PiB SUVr neither in the regions activated by visual stimulation ( β = -17.8 [CI:-71.9; 36.2], r =- 0.09, p = 0.51) nor in the remaining cortex ( β = 5.2 [CI:-3.9; 14.2], r = 0.15, p = 0.26).

CONCLUSION

We found a correlation between high PiB SUVr and reduced CBF response to neuronal activation, indicating a link between Aβ accumulation and impaired cerebrovascular function. The impairment was not associated with cortical thinning or hypometabolism, suggesting that Aβ accumulation affecting brain vessel function could be a very early pathology leading to neurodegenerative disease.

An older man with progressive short-term memory loss and confusion

ABSTRACT

A 72-year-old man with progressive memory loss and confusion presented to a neurology clinic for evaluation. He initially had difficulty remembering names and misplaced objects; however, his memory deficits had progressed, and more recently he had numerous car accidents and difficulty managing his own medications and finances. Cognitive testing revealed significant memory deficits reflecting moderate-stage dementia, and his brain MRI showed several cortical microbleeds and an area of siderosis consistent with the diagnosis of cerebral amyloid angiopathy (CAA). This case report provides an overview of a classic case of CAA and its potential treatment options.

Study on the Therapeutic Effects of Bisdemethoxycurcumin on a Cerebral Amyloid Angiopathy Mouse Model Established via Chronic Treatment With Five Vascular Risk Factors

BACKGROUND AND PURPOSE

Cerebral amyloid angiopathy (CAA) is recognized as a major contributor to progressive cognitive decline and cerebral hemorrhages in the elderly population. Currently, there is a global shortage of safe and effective treatments for this condition. Bisdemethoxycurcumin (BDMC) has been demonstrated to exhibit pharmacological effects with anti-Aβ toxicity properties. Thus, the present study mainly focused on the potential therapeutic effects of BDMC on CAA.

METHOD

The 30 male C57BL/6 mice were subjected to chronic treatment with five vascular risk factors (lipopolysaccharide, social stress, streptozotocin, high-cholesterol diet, and copper-containing drinking water) for 35 weeks to establish a CAA mouse model. Of these, 15 CAA mice received oral administration of BDMC (50 mg/kg) for two consecutive weeks as an intervention, while the remaining 15 CAA mice received an equal volume of physiological saline by gavage. The study observed the levels of Aβ40 and proinflammatory factors in brain tissue and plasma, Aβ deposition in cerebral blood vessels, microbleeds in brain tissue, expression of proteins related to the cGAS/STING signaling pathway in brain tissue, as well as the contents of p-RIPK-1, p-RIPK-3, p-MLKL, neuronal morphology, and learning and memory abilities in mice.

RESULT

The therapeutic administration of BDMC demonstrates a pronounced efficacy in alleviating Aβ burden and cerebral microbleeding in CAA mice, concurrently enhancing learning and memory capabilities. Interestingly, BDMC may inhibits neuroinflammatory responses by reducing the expression of cGAS/STING signaling pathway proteins and suppresses necroptosis.

CONCLUSION

Our research findings demonstrate that BDMC exerts therapeutic effects in a mouse model of CAA established through chronic treatment involving five vascular risk factors.

Updated imaging markers in cerebral amyloid angiopathy: What radiologists need to know

Cerebral amyloid angiopathy (CAA) is an age-related small vessel disease pathologically characterized by the progressive accumulation of amyloid-beta (Aβ) peptide in cerebrovascular walls, affecting both cortical and leptomeningeal vessels. Amyloid deposition results in fragile vessels, which may lead to lobar intracerebral hemorrhage (ICH) and cognitive impairment. To evaluate the probability and severity of CAA, the imaging markers depicted on CT and MRI techniques are crucial, as brain pathological examination is highly invasive. Although the Boston criteria have established diagnostic value and have been updated to version 2.0, due to an aging population, the patients with CAA should also be assessed for their risk of future ICH or cognitive impairment. Furthermore, an increased awareness of CAA is essential when introducing anticoagulants for infarct in elderly patients or anti-amyloid antibodies for Alzheimer's disease, as these may worsen CAA-related hemorrhagic lesions. However, the radiological literature on CAA has not been comprehensively updated. Here, we review the imaging markers of CAA and clinical significance. We also discuss the clinical and imaging characteristics of CAA-related inflammation, amyloid-related imaging abnormalities, and iatrogenic-CAA.

Cerebral amyloid angiopathy-related inflammation (CAA-ri): A case report

RATIONALE

Cerebral amyloid angiopathy-related inflammation (CAA-ri) is a treatable condition characterized by an acute or subacute onset, with its primary pathological hallmark being the deposition of amyloid, predominantly β-amyloid (Aβ), within intracranial microvessels. Despite its potential for treatment, CAA-ri is a rare disorder that is frequently underrecognized by clinicians in practice. This article provides a comprehensive overview of the clinical manifestations and therapeutic approaches associated with CAA-ri, aiming to enhance awareness among healthcare professionals.

PATIENT CONCERNS

A 67-year-old male patient who suffered from a sudden decline in cognitive functioning, intermittent headache, and dysphoria underwent brain magnetic resonance imaging, susceptibility weighted imaging, and cerebrospinal fluid analysis and was considered probable CAA-ri.

DIAGNOSIS INTERVENTIONS

During the course of disease development, the patient suffered from a sudden decline in cognitive functioning, mainly in the form of unresponsiveness, decreased comprehension, and increased repetitive language, accompanied by intermittent headaches and dysphoria. Brain magnetic resonance imaging showed numerous white matter in both hemispheres. Susceptibility weighted imaging showed multiple spots of hypointensity in the bilateral cerebral and cerebellar hemispheres, a hypointensity signal in the left occipital lobe, and extensive zones of hypointensity in bilateral sulci. Cerebrospinal fluid analysis was abnormal with elevated levels of protein and low levels of P-tau, Aβ42, and Aβ1-42/Aβ1-40. The use of glucocorticoids greatly reduced his symptoms. This lends credence to the probable CAA-ri diagnosis. The symptoms can be successfully alleviated by administering methylprednisolone sodium succinate.

OUTCOMES

During the patient's hospitalization, immunosuppressive therapy, primarily consisting of methylprednisolone sodium succinate and methylprednisolone, was administered, resulting in a significant improvement in symptoms. Post-discharge, the patient was monitored regularly, revealing a gradual enhancement in cognitive function without recurrence. Consequently, immunosuppressive therapy was discontinued 1 year following the patient's discharge.

LESSONS

CAA-ri is a rare clinical condition, and timely diagnosis and early treatment are very critical for patient prognosis.

Divergent brain solute clearance in rat models of cerebral amyloid angiopathy and Alzheimer's disease

Brain waste clearance from the interstitial fluid environment is challenging to measure, which has contributed to controversy regarding the significance of glymphatic transport impairment for neurodegenerative processes. Dynamic contrast enhanced MRI (DCE-MRI) with cerebrospinal fluid administration of Gd-tagged tracers is often used to assess glymphatic system function. We previously quantified glymphatic transport from DCE-MRI data utilizing regularized optimal mass transport (rOMT) analysis, however, information specific to glymphatic clearance was not directly derived. To fill this knowledge gap, we here implemented unbalanced rOMT analysis which allows for assessment of both influx and clearance. Dynamic influx/clearance brain maps were derived from rTg-DI rats with cerebral amyloid angiopathy (CAA) and TgSD-AD rats with Alzheimer's disease (AD). The rTg-DI rats with severe CAA disease exhibited abnormal influx/clearance kinetics, while TgSD-AD rats with a moderate Aβ plaque load exhibited normal transport suggesting that different Aβ lesions and their overall burden differentially impact glymphatic system function.

Left atrial appendage occlusion in patients with atrial fibrillation and intracerebral haemorrhage associated with cerebral amyloid angiopathy: a multicentre observational study and pooled analysis of published studies

BACKGROUND

Cerebral amyloid angiopathy (CAA) is a common cause of intracerebral haemorrhage (ICH) with a high recurrence risk. Left atrial appendage occlusion (LAAO) is a method for ischaemic stroke prevention in patients with atrial fibrillation (AF), potentially reducing the risk of intracranial bleeding in CAA-associated ICH. We aimed to determine the outcomes of patients with AF with CAA-associated ICH undergoing LAAO.

METHODS

We conducted a multicentre study of patients with CAA-associated ICH who underwent LAAO for stroke prevention. We pooled our findings with data from a systematic review of relevant published studies of LAAO for AF in ICH survivors reporting CAA diagnosis.

RESULTS

We included data from two published studies (n=65) with CAA-specific data and our cohort study (n=37), providing a total of 102 participants (mean age 76.2±8.0 years, 74.6% male) with CAA-related symptomatic ICH and AF treated with LAAO. The median follow-up period was 9.4 months (IQR 4.2-20.6). Postprocedural antithrombotic regimens varied between single (73.0%) or dual antiplatelet therapy (16.2%), or direct oral anticoagulant (DOAC) (10.8%), with a median duration of 42 days (IQR 35-74). Postprocedural complications were uncommon, but included transient arrhythmias (2.1%) and non-life-threatening tamponade (2.1%). Pooled incidence rates of ischaemic stroke and ICH during follow-up were 5.16 (95% CI 1.36 to 17.48) and 2.73 (95% CI 0.41 to 13.94) per 100 patient years, respectively.

CONCLUSIONS

LAAO followed by short-term antithrombotic therapy might be a safe and effective ischaemic stroke preventive strategy in people with CAA-associated ICH and AF. However, randomised controlled trials are needed to determine how LAAO compares with long-term DOAC in this population.

PROSPERO REGISTRATION NUMBER

CRD42023415354.

Intracerebral haemorrhage - mechanisms, diagnosis and prospects for treatment and prevention

Intracerebral haemorrhage (ICH) is a devastating condition associated with high mortality and substantial residual disability among survivors. Effective treatments for the acute stages of ICH are limited. However, promising findings from randomized trials of therapeutic strategies, including acute care bundles that target anticoagulation therapies, blood pressure control and other physiological parameters, and trials of minimally invasive neurosurgical procedures have led to renewed optimism that patient outcomes can be improved. Currently ongoing areas of research for acute treatment include anti-inflammatory and haemostatic treatments. The implementation of effective secondary prevention strategies requires an understanding of the aetiology of ICH, which involves vascular and brain parenchymal imaging; the use of neuroimaging markers of cerebral small vessel disease improves classification with prognostic relevance. Other data underline the importance of preventing not only recurrent ICH but also ischaemic stroke and cardiovascular events in survivors of ICH. Ongoing and planned randomized controlled trials will assess the efficacy of prevention strategies, including antiplatelet agents, oral anticoagulants or left atrial appendage occlusion (in patients with concomitant atrial fibrillation), and optimal management of long-term blood pressure and statin use. Together, these advances herald a new era of improved understanding and effective interventions to reduce the burden of ICH.

Vascular Cognitive Impairment

OBJECTIVE

Vascular cognitive impairment is a major contributor to age-associated cognitive decline, both independently and as a contributor to mixed dementia syndromes. This article reviews the current understanding of how vascular dysfunction contributes to cognitive impairment and dementia risk in older individuals and includes updated diagnostic criteria and treatment recommendations.

LATEST DEVELOPMENTS

Clinical and research criteria have been evolving to more accurately determine the full prevalence of vascular cognitive impairment. The Boston Criteria version 2.0 for cerebral amyloid angiopathy now includes multiple punctate MRI T2 white matter hyperintensities and MR-visible perivascular spaces in addition to previously described T2* hemorrhagic signatures. MR-visible perivascular spaces are associated with both vascular cognitive impairment and Alzheimer disease, potentially linking cerebrovascular dysfunction to neurodegenerative disorders through its role in brain waste clearance. The American Heart Association's goal for cardiovascular health promotion, "Life's Essential 8," has been updated to include sleep health and acknowledges psychological well-being and social determinants of health as fundamental components necessary to achieve optimal cardiovascular health for all adults.

ESSENTIAL POINTS

Vascular cognitive impairment is a common and often underrecognized contributor to cognitive impairment in older individuals, with heterogeneous etiologies requiring individualized treatment strategies. Effective cerebrovascular disease risk factor modification starting in midlife is critical to reducing the risk of Alzheimer disease and related dementias, with the goal of preventing vascular brain injury and maintaining cognitive reserve in the presence of nonvascular age-related brain pathologies.

The role of neuroinflammation in cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a cerebrovascular disease characterized by vascular amyloid-β (Aβ) deposition. CAA is often seen in the brains of elderly individuals and in a majority of patients with Alzheimer's disease. The molecular pathways triggered by vascular Aβ, causing vessel wall breakdown and ultimately leading to intracerebral haemorrhage and cognitive decline, remain poorly understood. The occurrence of CAA-related inflammation (CAA-ri) and Amyloid-Related Imaging Abnormalities (ARIA) have sparked interest for a role of neuroinflammation in CAA pathogenesis. This review discusses prior studies of neuroinflammation in CAA and outlines potential future research directions targeting candidates such as matrix metalloproteinases, complement activation, microglial activation, reactive astrocytes and parenchymal border macrophages. Understanding the role of neuroinflammation in CAA pathogenesis could help identify new therapeutic strategies.

Integrating epigenetic modification and stem cell therapy strategies: A novel approach for advancing Alzheimer's disease treatment - A literature review

Alzheimer's disease (AD) is the most frequent form of dementia and represents an increasing global burden, particularly in countries like Indonesia, where the population has begun to age significantly. Current medications, including cholinesterase inhibitors and NMDA receptor antagonists, have modest effects on clinical symptoms in the early to middle stages, but there is no curative treatment available so far despite progress. Activating or repressing epigenetic modifications, including DNA methylation, histone modification and microRNA regulation, appears to play an important role in AD development. These alterations further enact transcriptional changes relevant to the signature AD pathologies of amyloid-β deposition, tau protein malfunctioning, neuroinflammation, and neuronal death. Here, we discuss the feasibility of targeting these epigenetic alterations as a new treatment strategy due to the reversibility of epigenetics and their ability to correct faulty gene expression. We also review the combined promise of stem cell therapies and epigenetic modulation in neurodegeneration, inflammation and cognitive decline. This combined approach may provide a multifaceted strategy to slow disease progression, replace lost neurons, and restore neural function. Despite challenges, including ethical, financial, and methodological barriers, ongoing research in epigenetic modulation and stem cell therapy holds promise for pioneering therapies in AD.

Decreased microvascular claudin-5 levels in cerebral amyloid angiopathy associated with intracerebral haemorrhage

Decreased microvascular levels of claudin-5 in the occipital and temporal lobe of patients with cerebral amyloid angiopathy are associated with intracerebral haemorrhage.

Cerebrospinal fluid in the differential diagnosis of Alzheimer's disease: an update of the literature

INTRODUCTION

The importance of cerebrospinal fluid (CSF) biomarkers in Alzheimer's disease (AD) diagnosis is rapidly increasing, and there is a growing interest in the use of CSF biomarkers in monitoring the response to therapy, especially in the light of newly available approaches to the therapy of neurodegenerative diseases.

AREAS COVERED

In this review we discuss the most relevant measures of neurodegeneration that are being used to distinguish patients with AD from healthy controls and individuals with mild cognitive impairment, in order to provide an overview of the latest information available in the scientific literature. We focus on markers related to amyloid processing, markers associated with neurofibrillary tangles, neuroinflammation, neuroaxonal injury and degeneration, synaptic loss and dysfunction, and markers of α-synuclein pathology.

EXPERT OPINION

In addition to neuropsychological evaluation, core CSF biomarkers (Aβ42, t-tau, and p-tau181) have been recommended for improvement of timely, accurate and differential diagnosis of AD, as well as to assess the risk and rate of disease progression. In addition to the core CSF biomarkers, various other markers related to synaptic dysfunction, neuroinflammation, and glial activation (neurogranin, SNAP-25, Nfl, YKL-40, TREM2) are now investigated and have yet to be validated for future potential clinical use in AD diagnosis.

Core CSF Biomarker Profile in Cerebral Amyloid Angiopathy: Updated Meta-Analysis

BACKGROUND AND OBJECTIVES

There is a clear need to characterize and validate molecular biomarkers of cerebral amyloid angiopathy (CAA), in an effort to improve diagnostics, especially in the context of patients with Alzheimer disease (AD) receiving immunotherapies (for whom underlying CAA is the driver of amyloid-related imaging abnormalities). We performed an updated meta-analysis of 5 core CSF biomarkers (Aβ42, Aβ40, Aβ438, total tau [T-tau], and phosphorylated tau [P-tau]) to assess which of these are most altered in sporadic CAA.

METHODS

We systematically searched PubMed for eligible studies reporting data on CSF biomarkers reflecting APP metabolism (Aβ42, Aβ40, Aβ38), neurodegeneration (T-tau), and tangle pathology (P-tau), in symptomatic sporadic CAA cohorts (based on the Boston criteria) vs control groups and/or vs patients with AD. Biomarker performance was assessed in random-effects meta-analysis based on ratio of mean (RoM) biomarker concentrations in (1) patients with CAA to controls and (2) CAA to patients with AD. RoM >1 indicates higher biomarker concentration in CAA vs comparison population, and RoM <1 indicates higher concentration in comparison groups.

RESULTS

8 studies met inclusion criteria: a total of 11 CAA cohorts (n = 289), 9 control cohorts (n = 310), and 8 AD cohorts (n = 339). Overall included studies were of medium quality based on our assessment tools. CAA to controls had lower mean level of all amyloid markers with CSF Aβ42, Aβ40, and Aβ38 RoMs of 0.46 (95% CI 0.38-0.55, p < 0.0001), 0.70 (95% CI 0.63-0.78, p < 0.0001), and 0.71 (95% CI 0.56-0.89, p = 0.003), respectively. CSF T-tau and P-tau RoMs of patients with CAA to controls were both greater than 1: 1.56 (95% CI 1.32-1.84, p < 0.0001) and 1.31 (95% CI 1.13-1.51, p < 0.0001), respectively. Differentiation between CAA and AD was strong for CSF Aβ40 (RoM 0.76, 95% CI 0.69-0.83, p < 0.0001) and Aβ38 (RoM 0.55, 95% CI 0.38-0.81, 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 AD were 0.64 (95% CI 0.58-0.71, p < 0.0001) and 0.64 (95% CI 0.58-0.71, p < 0.0001), respectively.

DISCUSSION

Specific CSF patterns of Aβ42, Aβ40, Aβ38, T-tau, and P-tau might serve as molecular biomarkers of CAA, in research and clinical settings, offering the potential to improve the clinical diagnostic approach pathway in specific scenarios.

Cerebral Proteomic Changes in the rTg-D Rat Model of Cerebral Amyloid Angiopathy Type-2 With Cortical Microhemorrhages and Cognitive Impairments

Cerebral amyloid angiopathy (CAA) is a common disorder of the elderly, a prominent comorbidity of Alzheimer's disease, and causes vascular cognitive impairment and dementia. Previously, we generated a novel transgenic rat model (rTg-D) that produces human familial CAA Dutch E22Q mutant amyloid β-protein (Aβ) in brain and develops arteriolar CAA type-2. Here, we show that deposition of fibrillar Aβ promotes arteriolar smooth muscle cell loss and cerebral microhemorrhages that can be detected by magnetic resonance imaging and confirmed by histopathology. Aged rTg-D rats also present with cognitive deficits. Cerebral proteomic analyses revealed 241 proteins that were significantly elevated with an increase of >50% in rTg-D rats presenting with CAA compared to wild-type rats. Fewer proteins were significantly decreased in rTg-D rats. Of note, high temperature requirement peptidase A (HTRA1), a proteinase linked to transforming growth factor beta 1 (TGF-β1) signaling, was elevated and found to accumulate in cerebral vessels harboring amyloid deposits. Pathway analysis indicated elevation of the TGF-β1 pathway and increased TGF-β1 levels were detected in rTg-D rats. In conclusion, the present findings provide new molecular insights into the pathogenesis of CAA and suggest a role for interactions between HTRA1 and TGF-β1 in the disease process.

Clinical and neuroimaging precursors in cerebral amyloid angiopathy: impact of the Boston criteria version 2.0

BACKGROUND AND PURPOSE

Although the Boston criteria version 2.0 facilitates the sensitivity of cerebral amyloid angiopathy (CAA) diagnosis, there are only limited data about precursor symptoms. This study aimed to determine the impact of neurological and imaging features in relation to the time of CAA diagnosis.

METHODS

Patients diagnosed with probable CAA according to the Boston criteria version 1.5, treated between 2010 and 2020 in our neurocentre, were identified through a keyword search in our medical database. Neuroimaging was assessed using Boston criteria versions 1.5 and 2.0. Medical records with primary focus on the clinical course and the occurrence of transient focal neurological episodes were prospectively evaluated.

RESULTS

Thirty-eight out of 81 patients (46.9%) exhibited transient focal neurological episodes, most often sensory (13.2%) or aphasic disorders (13.2%), or permanent deficits at a mean time interval of 31.1 months (SD ±26.3; range 1-108 months) before diagnosis of probable CAA (Boston criteria version 1.5). If using Boston criteria version 2.0, all patients receiving magnetic resonance imaging (MRI) met the criteria for probable CAA, and diagnosis could have been made on average 44 months earlier. Four patients were younger than 50 years, three of them with supporting pathology. Cognitive deficits were most common (34.6%) at the time of diagnosis.

CONCLUSIONS

Non-haemorrhagic MRI markers enhance the sensitivity of diagnosing probable CAA; however, further prospective studies are proposed to establish a minimum age for inclusion. As the neurological overture of CAA may occur several years before clinical diagnosis, early clarification by MRI including haemosensitive sequences are suggested.

Beta-Amyloid Related Neurodegenerative and Neurovascular Diseases: Potential Implications for Transfusion Medicine

Cerebral amyloid angiopathy (CAA) is a progressive cerebrovascular and neurodegenerative disorder that is caused by the aberrant accumulation of soluble beta-amyloid isoforms in the small vessel walls of the cerebral and cerebellar cortices and the leptomeninges. Vascular beta-amyloid deposition increases vulnerability to intracerebral hemorrhage (ICH). Clinically, CAA can be the underlying cause of up to half of spontaneous lobar ICHs and can also present with convexity subarachnoid hemorrhage, transient focal neurologic episodes and progressive cognitive decline leading to dementia. The majority of CAA is sporadic, with increasing prevalence with age and often coexists with Alzheimer's Disease (AD). Genetic and iatrogenic etiologies are rare. Cases of CAA and AD have been linked to the use of cadaveric pituitary hormone and later life iatrogenic CAA has also been described following early-life neurosurgical procedures with cadaveric dura grafts. Together these data suggest a capacity of beta-amyloid transmissibility. A recent study found that in over 1 million transfusion recipients from donors who later developed (i) >1 ICH or (ii) one ICH event and dementia, had an elevated risk of developing future ICH. Considering prior reports of transfusion associated variant-Creutzfeldt Jakob Disease in humans and in vivo evidence in sheep, coupled with emerging data supporting beta-amyloid's prion-like properties, raises the question of whether CAA could be transmissible by blood transfusion. This would also have implications for screening, especially in an era of emerging plasma biomarkers of cerebral amyloidosis. Given the public health concerns raised by this biologically plausible question, there is a need for future studies with well-characterized definitions - and temporal ascertainment - of CAA exposure and outcomes to examine whether CAA is transfusion-transmissible, and, if so, with what frequency and timing of onset.

Atherosclerotic burden and cerebral small vessel disease: exploring the link through microvascular aging and cerebral microhemorrhages

Cerebral microhemorrhages (CMHs, also known as cerebral microbleeds) are a critical but frequently underestimated aspect of cerebral small vessel disease (CSVD), bearing substantial clinical consequences. Detectable through sensitive neuroimaging techniques, CMHs reveal an extensive pathological landscape. They are prevalent in the aging population, with multiple CMHs often being observed in a given individual. CMHs are closely associated with accelerated cognitive decline and are increasingly recognized as key contributors to the pathogenesis of vascular cognitive impairment and dementia (VCID) and Alzheimer's disease (AD). This review paper delves into the hypothesis that atherosclerosis, a prevalent age-related large vessel disease, extends its pathological influence into the cerebral microcirculation, thereby contributing to the development and progression of CSVD, with a specific focus on CMHs. We explore the concept of vascular aging as a continuum, bridging macrovascular pathologies like atherosclerosis with microvascular abnormalities characteristic of CSVD. We posit that the same risk factors precipitating accelerated aging in large vessels (i.e., atherogenesis), primarily through oxidative stress and inflammatory pathways, similarly instigate accelerated microvascular aging. Accelerated microvascular aging leads to increased microvascular fragility, which in turn predisposes to the formation of CMHs. The presence of hypertension and amyloid pathology further intensifies this process. We comprehensively overview the current body of evidence supporting this interconnected vascular hypothesis. Our review includes an examination of epidemiological data, which provides insights into the prevalence and impact of CMHs in the context of atherosclerosis and CSVD. Furthermore, we explore the shared mechanisms between large vessel aging, atherogenesis, microvascular aging, and CSVD, particularly focusing on how these intertwined processes contribute to the genesis of CMHs. By highlighting the role of vascular aging in the pathophysiology of CMHs, this review seeks to enhance the understanding of CSVD and its links to systemic vascular disorders. Our aim is to provide insights that could inform future therapeutic approaches and research directions in the realm of neurovascular health.

Sex differences in histopathological markers of cerebral amyloid angiopathy and related hemorrhage

BACKGROUND

Men with cerebral amyloid angiopathy (CAA) may have an earlier onset of intracerebral hemorrhage and a more hemorrhagic disease course compared to women. In this cohort study, we investigated sex differences in histopathological markers associated with amyloid-β burden and hemorrhage in cognitively impaired individuals and patients with CAA, using neuropathological data from two autopsy databases.

METHODS

First, we investigated presence of parenchymal (Thal score) and vascular amyloid-β (CAA severity score) in cognitively impaired individuals from the National Alzheimer's Coordinating Center (NACC) neuropathology database. Next, we examined sex differences in hemorrhagic ex vivo magnetic resonance imaging (MRI) markers and local cortical iron burden and the interaction of sex on factors associated with cortical iron burden (CAA percentage area and vessel remodeling) in patients with pathologically confirmed clinical CAA from the Massachusetts General Hospital (MGH) CAA neuropathology database.

RESULTS

In 6120 individuals from the NACC database (45% women, mean age 80 years), the presence of parenchymal amyloid-β (odds ratio (OR) (95% confidence interval (CI)) =0.68 (0.53-0.88)) but not vascular amyloid-β was less in men compared to women. In 19 patients with definite CAA from the MGH CAA database (35% women, mean age 75 years), a lower microbleed count (p < 0.001) but a higher proportion of cortical superficial siderosis and a higher local cortical iron burden was found in men (p < 0.001) compared to women. CAA percentage area was comparable in men and women (p = 0.732). Exploratory analyses demonstrated a possible stronger negative relation between cortical CAA percentage area and cortical iron density in men compared to women (p = 0.03).

CONCLUSION

Previously observed sex differences in hemorrhage onset and progression in CAA patients are likely not due to differences in global CAA severity between men and women. Other factors, such as vascular remodeling, may contribute, but future studies are necessary to replicate our findings in larger data sets and to further investigate the underlying mechanisms behind these complex sex differences.

Utility of cerebrovascular imaging biomarkers to detect cerebral amyloidosis

INTRODUCTION

The relationship between cerebrovascular disease (CVD) and amyloid beta (Aβ) in Alzheimer's disease (AD) is understudied. We hypothesized that magnetic resonance imaging (MRI)-based CVD biomarkers-including cerebral microbleeds (CMBs), lacunar infarction, and white matter hyperintensities (WMHs)-would correlate with Aβ positivity on positron emission tomography (Aβ-PET).

METHODS

We cross-sectionally analyzed data from the Alzheimer's Disease Neuroimaging Initiative (ADNI, N = 1352). Logistic regression was used to calculate odds ratios (ORs), with Aβ-PET positivity as the standard-of-truth.

RESULTS

Following adjustment, WMHs (OR = 1.25) and superficial CMBs (OR = 1.45) remained positively associated with Aβ-PET positivity (p < 0.001). Deep CMBs and lacunes exhibited a varied relationship with Aβ-PET in cognitive subgroups. The combined diagnostic model, which included CVD biomarkers and other accessible measures, significantly predicted Aβ-PET (pseudo-R2 = 0.41).

DISCUSSION

The study highlights the translational value of CVD biomarkers in diagnosing AD, and underscores the need for more research on their inclusion in diagnostic criteria.

CLINICALTRIALS

gov: ADNI-2 (NCT01231971), ADNI-3 (NCT02854033).

HIGHLIGHTS

Cerebrovascular biomarkers linked to amyloid beta (Aβ) in Alzheimer's disease (AD). White matter hyperintensities and cerebral microbleeds reliably predict Aβ-PET positivity. Relationships with Aβ-PET vary by cognitive stage. Novel accessible model predicts Aβ-PET status. Study supports multimodal diagnostic approaches.

Lead Acetate Exposure and Cerebral Amyloid Accumulation: Mechanistic Evaluations in APP/PS1 Mice

BACKGROUND

The role of environmental factors in Alzheimer's disease (AD) pathogenesis remains elusive. Mounting evidence suggests that acute and past exposure to the environmental toxicant lead (Pb) is associated with longitudinal decline in cognitive function, brain atrophy, and greater brain β -amyloid (A β ) deposition. However, the nature of Pb-induced amyloid deposition and how it contributes to AD development remain unclear.

OBJECTIVES

This study investigates the role of Pb in the pathogenesis of cerebral amyloid angiopathy (CAA) and whether plasminogen activator inhibitor-1 (PAI-1) contributes to this process in the APP/PS1 mouse model.

METHODS

Female APP/PS1 mice at 8 wk of age were administered either 50 mg / kg Pb-acetate (PbAc) (i.e., 27 mg   Pb / kg ) or an equivalent molar concentration of sodium acetate (NaAc) via oral gavage once daily for 8 wk. Amyloid deposition and vascular amyloid were determined by immunostaining. In addition, A β perivascular drainage, vascular binding assay, and microglial endocytosis were examined to determine underlying mechanisms. Furthermore, magnetic resonance imaging demyelination imaging was performed in vivo measure the level of demyelination. Finally, Y-maze and Morris water maze tests were assessed to evaluate the cognitive function of mice.

RESULTS

APP/PS1 mice (an AD mice model) exposed to PbAc demonstrated more vascular amyloid deposition less neocortical myelination, and lower cognitive function, as well as greater vascular binding to A β 40 , higher A β 40 / A β 42 ratios, strikingly lower A β 40 levels in the perivascular drainage, and microglial endocytosis. Importantly, exposure to a specific PAI-1 inhibitor, tiplaxtinin, which previously was reported to lower CAA pathology in mice, resulted in less CAA-related outcomes following PbAc exposure.

DISCUSSION

Our findings suggest that PbAc induced CAA/AD pathogenesis via the PAI-1 signaling in the APP/PS1 mouse model, and the inhibition of PAI-1 could be a potential therapeutic target for PbAc-mediated CAA/AD disorders. https://doi.org/10.1289/EHP14384.

A 73-Year-Old Woman With Confusion, Visual Field Disturbances, and Edematous White Matter Lesions: From the National Multiple Sclerosis Society Case Conference Proceedings

We describe the case of a 73-year-old woman presenting with headaches, confusion, and vision disturbances. Brain MRI showed a large T2-hyperintense lesion in the right temporo-occipital region with vasogenic edema and leptomeningeal enhancement. A leptomeningeal biopsy was performed, which led to a definitive diagnosis.

Genetic Determinants of Vascular Dementia

Vascular dementia (VaD) is a prevalent form of cognitive impairment with underlying vascular etiology. In this review, we examine recent genetic advancements in our understanding of VaD, encompassing a range of methodologies including genome-wide association studies, polygenic risk scores, heritability estimates, and family studies for monogenic disorders revealing the complex and heterogeneous nature of the disease. We report well known genetic associations and highlight potential pathways and mechanisms implicated in VaD and its pathological risk factors, including stroke, cerebral small vessel disease, and cerebral amyloid angiopathy. Moreover, we discuss important modifiable risk factors such as hypertension, diabetes, and dyslipidemia, emphasizing the importance of a multifactorial approach in prevention, treatment, and understanding the genetic basis of VaD. Last, we outline several areas of scientific advancements to improve clinical care, highlighting that large-scale collaborative efforts, together with an integromics approach can enhance the robustness of genetic discoveries. Indeed, understanding the genetics of VaD and its pathophysiological risk factors hold the potential to redefine VaD on the basis of molecular mechanisms and to generate novel diagnostic, prognostic, and therapeutic tools.

The presence of circulating human apolipoprotein J reduces the occurrence of cerebral microbleeds in a transgenic mouse model with cerebral amyloid angiopathy

BACKGROUND

Cerebral amyloid angiopathy (CAA) is characterized by amyloid-β (Aβ) deposition in cerebral vessels, leading to lobar cerebral microbleeds (CMB) and intracerebral hemorrhages (ICH). Apolipoprotein J (ApoJ) is a multifunctional chaperone related to Aβ aggregation and clearance. Our study investigated the vascular impact of chronic recombinant human Apolipoprotein J (rhApoJ) treatment in a transgenic mouse model of β-amyloidosis with prominent CAA.

METHODS

Twenty-month-old APP23 C57BL/6 mice received 25 doses of rhApoJ (1 mg/kg) (n = 9) or saline (n = 8) intraperitoneally for 13 weeks, while Wild-type (WT) mice received saline (n = 13). Postmortem brains underwent T2*-weighted magnetic resonance imaging (MRI) to detect hemorrhagic lesions. Aβ levels and distribution, cerebral fibrinogen leakage, brain smooth muscle actin (sma), and plasma matrix metalloproteinases and inflammatory markers were analyzed after treatments. Additionally, plasma samples from 22 patients with lobar ICH were examined to determine the clinical relevance of the preclinical findings.

RESULTS

rhApoJ-treated APP23 presented fewer cortical CMBs (50-300 μm diameter) (p = 0.012) and cortical larger hemorrhages (> 300 μm) (p = 0.002) than saline-treated mice, independently of Aβ brain levels. MRI-detected hemorrhagic lesions correlated with fibrinogen cerebral extravasation (p = 0.011). Additionally, rhApoJ-treated mice presented higher number of sma-positive vessels than saline-treated mice (p = 0.038). In rhApoJ-treated mice, human ApoJ was detected in plasma and in occasional leptomeningeal vessels, but not in the parenchyma, suggesting that its mechanism of action operates through the periphery. The administration of rhApoJ induced an increase in plasma Groα (p = 0.035) and MIP-1α (p = 0.035) levels, while lower MMP-12 (p = 0.046) levels, compared to the saline-treated group. In acute lobar ICH patients, MMP-12 plasma levels correlated with larger hemorrhage volume (p = 0.040) and irregular ICH shape (p = 0.036).

CONCLUSIONS

Chronic rhApoJ treatment in aged APP23 mice ameliorated CAA-related neurovascular damage by reducing the occurrence of CMB. We propose that rhApoJ may prevent blood-brain barrier (BBB) leakage and CMB appearance partly through circulating MMP-12 modulation.

Amyloid-β peptide signature associated with cerebral amyloid angiopathy in familial Alzheimer's disease with APPdup and Down syndrome

Alzheimer's disease (AD) is characterized by extracellular amyloid plaques containing amyloid-β (Aβ) peptides, intraneuronal neurofibrillary tangles, extracellular neuropil threads, and dystrophic neurites surrounding plaques composed of hyperphosphorylated tau protein (pTau). Aβ can also deposit in blood vessel walls leading to cerebral amyloid angiopathy (CAA). While amyloid plaques in AD brains are constant, CAA varies among cases. The study focuses on differences observed between rare and poorly studied patient groups with APP duplications (APPdup) and Down syndrome (DS) reported to have higher frequencies of elevated CAA levels in comparison to sporadic AD (sAD), most of APP mutations, and controls. We compared Aβ and tau pathologies in postmortem brain tissues across cases and Aβ peptides using mass spectrometry (MS). We further characterized the spatial distribution of Aβ peptides with MS-brain imaging. While intraparenchymal Aβ deposits were numerous in sAD, DS with AD (DS-AD) and AD with APP mutations, these were less abundant in APPdup. On the contrary, Aβ deposits in the blood vessels were abundant in APPdup and DS-AD while only APPdup cases displayed high Aβ deposits in capillaries. Investigation of Aβ peptide profiles showed a specific increase in Aβx-37, Aβx-38 and Aβx-40 but not Aβx-42 in APPdup cases and to a lower extent in DS-AD cases. Interestingly, N-truncated Aβ2-x peptides were particularly increased in APPdup compared to all other groups. This result was confirmed by MS-imaging of leptomeningeal and parenchymal vessels from an APPdup case, suggesting that CAA is associated with accumulation of shorter Aβ peptides truncated both at N- and C-termini in blood vessels. Altogether, this study identified striking differences in the localization and composition of Aβ deposits between AD cases, particularly APPdup and DS-AD, both carrying three genomic copies of the APP gene. Detection of specific Aβ peptides in CSF or plasma of these patients could improve the diagnosis of CAA and their inclusion in anti-amyloid immunotherapy treatments.

Profiling amyloid-β peptides as biomarkers for cerebral amyloid angiopathy

Brain amyloid-β (Aβ) deposits are key pathological hallmarks of both cerebral amyloid angiopathy (CAA) and Alzheimer's disease (AD). Microvascular deposits in CAA mainly consist of the Aβ40 peptide, whereas Aβ42 is the predominant variant in parenchymal plaques in AD. The relevance in pathogenesis and diagnostic accuracy of various other Aβ isoforms in CAA remain understudied. We aimed to investigate the biomarker potential of various Aβ isoforms in cerebrospinal fluid (CSF) to differentiate CAA from AD pathology. We included 25 patients with probable CAA, 50 subjects with a CSF profile indicative of AD pathology (AD-like), and 23 age- and sex-matched controls. CSF levels of Aβ1-34, Aβ1-37, Aβ1-38, Aβ1-39, Aβ1-40, and Aβ1-42 were quantified by liquid chromatography mass spectrometry. Lower CSF levels of all six Aβ peptides were observed in CAA patients compared with controls (p = 0.0005-0.03). Except for Aβ1-42 (p = 1.0), all peptides were decreased in CAA compared with AD-like subjects (p = 0.007-0.03). Besides Aβ1-42, none of the Aβ peptides were decreased in AD-like subjects compared with controls. All Aβ peptides combined differentiated CAA from AD-like subjects better (area under the curve [AUC] 0.84) than individual peptide levels (AUC 0.51-0.75). Without Aβ1-42 in the model (since decreased Aβ1-42 served as AD-like selection criterion), the AUC was 0.78 for distinguishing CAA from AD-like subjects. CAA patients and AD-like subjects showed distinct disease-specific CSF Aβ profiles. Peptides shorter than Aβ1-42 were decreased in CAA patients, but not AD-like subjects, which could suggest different pathological mechanisms between vascular and parenchymal Aβ accumulation. This study supports the potential use of this panel of CSF Aβ peptides to indicate presence of CAA pathology with high accuracy.

Apolipoprotein E in Alzheimer's disease trajectories and the next-generation clinical care pathway

Alzheimer's disease (AD) is a complex, progressive primary neurodegenerative disease. Since pivotal genetic studies in 1993, the ε4 allele of the apolipoprotein E gene (APOE ε4) has remained the strongest single genome-wide associated risk variant in AD. Scientific advances in APOE biology, AD pathophysiology and ApoE-targeted therapies have brought APOE to the forefront of research, with potential translation into routine AD clinical care. This contemporary Review will merge APOE research with the emerging AD clinical care pathway and discuss APOE genetic risk as a conduit to genomic-based precision medicine in AD, including ApoE's influence in the ATX(N) biomarker framework of AD. We summarize the evidence for APOE as an important modifier of AD clinical-biological trajectories. We then illustrate the utility of APOE testing and the future of ApoE-targeted therapies in the next-generation AD clinical-diagnostic pathway. With the emergence of new AD therapies, understanding how APOE modulates AD pathophysiology will become critical for personalized AD patient care.

Non-hemorrhagic imaging markers of cerebral amyloid angiopathy in memory clinic patients

INTRODUCTION

The Boston criteria v2.0 for cerebral amyloid angiopathy (CAA) incorporated non-hemorrhagic imaging markers. Their prevalence and significance in patients with cognitive impairment remain uncertain.

METHODS

We studied 622 memory clinic patients with available magnetic resonance imaging (MRI) and cerebrospinal fluid (CSF) biomarkers. Two raters assessed non-hemorrhagic markers, and we explored their association with clinical characteristics through multivariate analyses.

RESULTS

Most patients had mild cognitive impairment; median age was 71 years and 50% were female. Using the v2.0 criteria, possible or probable CAA increased from 75 to 383 patients. Sixty-eight percent of the sample had non-hemorrhagic CAA markers, which were independently associated with age (odds ratio [OR] = 1.04, 95% confidence interval [CI] = 1.01-1.07), female sex (OR = 1.68, 95% CI = 1.11-2.54), and hemorrhagic CAA markers (OR = 2.11, 95% CI = 1.02-4.35).

DISCUSSION

Two-thirds of patients from a memory clinic cohort had non-hemorrhagic CAA markers, increasing the number of patients meeting the v2.0 CAA criteria. Longitudinal approaches should explore the implications of these markers, particularly the hemorrhagic risk in this population.

HIGHLIGHTS

The updated Boston criteria for cerebral amyloid angiopathy (CAA) now include non-hemorrhagic markers. The prevalence of non-hemorrhagic CAA markers in memory clinic patients is unknown. Two-thirds of patients in our memory clinic presented non-hemorrhagic CAA markers. The presence of these markers was associated with age, female sex, and hemorrhagic CAA markers. The hemorrhagic risk of patients presenting these type of markers remains unclear.

Altered brain expression and cerebrospinal fluid levels of TIMP4 in cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a highly prevalent and progressive pathology, involving amyloid-β (Aβ) deposition in the cerebral blood vessel walls. CAA is associated with an increased risk for intracerebral hemorrhages (ICH). Insight into the molecular mechanisms associated with CAA pathology is urgently needed, to develop additional diagnostic tools to allow for reliable and early diagnosis of CAA and to obtain novel leads for the development of targeted therapies. Tissue inhibitor of matrix metalloproteinases 4 (TIMP4) is associated with cardiovascular functioning and disease and has been linked to vascular dementia. Using immunohistochemistry, we studied occipital brain tissue samples of 57 patients with CAA (39 without ICH and 18 with ICH) and 42 controls, and semi-quantitatively assessed expression levels of TIMP4. Patients with CAA had increased vascular expression of TIMP4 compared to controls (p < 0.001), and in these patients, TIMP4 expression correlated with CAA severity (τb = 0.38; p = 0.001). Moreover, TIMP4 expression was higher in CAA-ICH compared to CAA-non-ICH cases (p = 0.024). In a prospective cross-sectional study of 38 patients with CAA and 37 age- and sex-matched controls, we measured TIMP4 levels in cerebrospinal fluid (CSF) and serum using ELISA. Mean CSF levels of TIMP4 were decreased in patients with CAA compared to controls (3.36 ± 0.20 vs. 3.96 ± 0.22 ng/ml, p = 0.033), whereas median serum levels were increased in patients with CAA (4.51 ng/ml [IQR 3.75-5.29] vs 3.60 ng/ml [IQR 3.11-4.85], p-9.013). Moreover, mean CSF TIMP4 levels were lower in CAA patients who had experienced a symptomatic hemorrhage compared to CAA patients who did not (2.13 ± 0.24 vs. 3.57 ± 0.24 ng/ml, p = 0.007). CSF TIMP4 levels were associated with CSF levels of Aβ40 (spearman r (rs) = 0.321, p = 0.009). In summary, we show that TIMP4 is highly associated with CAA and CAA-related ICH, which is reflected by higher levels in the cerebral vasculature and lower levels in CSF. With these findings we provide novel insights into the pathophysiology of CAA, and more specifically in CAA-associated ICH.