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 (GWAS), polygenic risk scores (PRS), 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 diseases 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. Lastly, 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 based on molecular mechanisms and generate novel diagnostic, prognostic, and therapeutic tools.

Remote intracerebral hemorrhage following craniotomy for an intracerebral hematoma: A case report

Remote intracerebral hemorrhage (RICH) is a rare yet highly consequential complication that can occur after a craniotomy performed for the evacuation of an intracerebral hemorrhage (ICH). In this case report, we present the clinical details of a 74-year-old female patient who underwent a supratentorial craniotomy to address an ICH, and subsequently developed RICH. A 74-year-old woman was admitted to our department with a severe headache, onset of dysarthria, and left-sided brachio-crural hemiparesis. The patient had a history of arterial hypertension and a previous cerebral ischemia incident 2 years prior, potentially due to cerebral amyloid angiopathy. Despite the immediate surgical intervention and intensive care, she succumbed to respiratory distress after developing a contralateral ICH. RICH following craniotomy for an intracerebral hematoma is a rare but potentially devastating complication. Close monitoring, prompt recognition of neurological deterioration, and timely intervention are imperative to optimize patient outcomes. Further research is needed to better understand the underlying mechanisms and risk factors associated with this complication, allowing for improved prevention and management strategies in the future.

Retinal arterial Aβ40 deposition is linked with tight junction loss and cerebral amyloid angiopathy in MCI and AD patients

INTRODUCTION

Vascular amyloid beta (Aβ) protein deposits were detected in retinas of mild cognitively impaired (MCI) and Alzheimer's disease (AD) patients. We tested the hypothesis that the retinal vascular tight junctions (TJs) were compromised and linked to disease status.

METHODS

TJ components and Aβ expression in capillaries and larger blood vessels were determined in post mortem retinas from 34 MCI or AD patients and 27 cognitively normal controls and correlated with neuropathology.

RESULTS

Severe decreases in retinal vascular zonula occludens-1 (ZO-1) and claudin-5 correlating with abundant arteriolar Aβ40 deposition were identified in MCI and AD patients. Retinal claudin-5 deficiency was closely associated with cerebral amyloid angiopathy, whereas ZO-1 defects correlated with cerebral pathology and cognitive deficits.

DISCUSSION

We uncovered deficiencies in blood-retinal barrier markers for potential retinal imaging targets of AD screening and monitoring. Intense retinal arteriolar Aβ40 deposition suggests a common pathogenic mechanism of failed Aβ clearance via intramural periarterial drainage.

[A case of multiple small cerebral infarcts in the cerebellum and bilateral cerebrum, diagnosed with amyloid angiopathy by brain biopsy]

An 82-year-old woman had been suffering from progressive forgetfulness and abnormal speech and behavior for One month. Findings of the MRI of the head indicated scattered small cerebral infarcts in the cerebellum and in bilateral cerebral cortex/subcortical white matter. After admission, she experienced a subcortical hemorrhage, and the percentage of small cerebral infarcts increased over time. Based on the suspicion of central primary vasculitis or malignant lymphoma, we performed a brain biopsy targeting the right temporal lobe hemorrhage site, and the patient was diagnosed with cerebral amyloid angiopathy (CAA). We conclude that CAA can cause multiple small progressive cerebral infarcts.

Neuropathological lesions and their contribution to dementia and cognitive impairment in a heterogeneous clinical population

INTRODUCTION

Alzheimer disease (AD) and related dementias are characterized by damage caused by neuropathological lesions in the brain. These include AD lesions (plaques and tangles) and non-AD lesions such as vascular injury or Lewy bodies. We report here an assessment of lesion association to dementia in a large clinic-based population.

METHODS

We identified 5272 individuals with neuropathological data from the National Alzheimer's Coordinating Center. Individual lesions, as well as a neuropathological composite score (NPCS) were tested for association with dementia, and both functional and neurocognitive impairment using regression models.

RESULTS

Most individuals exhibited mixed pathologies, especially AD lesions in combination with non-AD lesions. All lesion types were associated with one or more clinical outcomes; most even while controlling for AD pathology. The NPCS was also associated with clinical outcomes.

DISCUSSION

These data suggest mixed-type pathologies are extremely common in a clinic-based population and may contribute to dementia and cognitive impairment.

Cerebrovascular disease lesions are additive and tied to vascular risk factors and cognitive impairment

Cerebrovascular lesions are prevalent in late life and frequently co-occur but the relationship to cognitive impairment is complicated by the lack of consensus around which lesions represent hallmark pathologies for vascular impairment, particularly in the presence of Alzheimer's disease (AD). We developed an easily applicable model of cerebrovascular disease (CVD), defined as the presence of two or more lesions: moderate to severe cerebral amyloid angiopathy, moderate to severe arteriolosclerosis, infarcts (large, lacunar, or micro), and/or hemorrhages. AD was defined as intermediate or high AD neuropathologic change. The contribution of vascular risk factors such as atherosclerosis and/or a health history of heart disease, hyperlipidemia, stroke events, diabetes, or hypertension was also assessed. Logistic regression analysis reported the association of CVD with increasing age, vascular risk factors, AD, and cognitive impairment in this study of 1,485 autopsied individuals. Cerebrovascular lesions were present in 48% and 16% had CVD. Increasing age associated with all lesions (p<0.001), except hemorrhages (p=0.41). CVD was more likely in individuals with vascular risk factors or AD (p<0.01). CVD, but not individual cerebrovascular lesions, associated with impairment in cases without AD (p<0.01), but not in cases with AD (p>0.61). From this, we conclude that a simple, additive model of CVD is 1) age and AD-associated, 2) is associated with vascular risk factors, and 3) clinically correlates with cognitive decline independent of AD.

Imaging Markers of Subcortical Vascular Dementia in Patients With Multiple-Lobar Cerebral Microbleeds

Background and Purpose: Small vessel disease (SVD) imaging markers are related to ischemic and hemorrhage stroke and to cognitive dysfunction. This study aimed to clarify the relationship between SVD imaging markers and subcortical vascular dementia in severe SVD burden.

Methods: A total of 57 subjects with multiple lobar cerebral microbleeds (CMBs) and four established SVD imaging markers were enrolled from the dementia and stroke registries of a single center. Visual rating scales that are used to semi-quantify SVD imaging changes were analyzed individually and compositely to make correlations with cognitive domains and subcortical vascular dementia.

Results: Dementia group had higher subcortical and total white matter hyperintensities (WMHs) and SVD composite scores than non-dementia group. Individual imaging markers correlated differently with one another and had distinct cognitive correlations. After adjusting for demographic factors, multivariate logistic regression indicated associations of subcortical WMHs (odds ratio [OR] 2.03, CI 1.24–3.32), total WMHs (OR 1.43, CI 1.09–1.89), lacunes (OR 1.18, CI 1.02–1.35), cerebral amyloid angiopathy-SVD scores (OR 2.33, CI 1.01–5.40), C₁ scores (imaging composite scores of CMB and WMH) (OR 1.41, CI 1.09–1.83), and C₂ scores (imaging composite scores of CMB, WMH, perivascular space, and lacune) (OR 1.38, CI 1.08–1.76) with dementia.

Conclusions: SVD imaging markers might have differing associations with cognitive domains and dementia. They may provide valuable complementary information in support of personalized treatment planning against cognitive impairment, particularly in patients with a heavy SVD load.

Blinded potency comparison of transthyretin kinetic stabilisers by subunit exchange in human plasma

Transthyretin (TTR) tetramer dissociation is rate limiting for aggregation and subunit exchange. Slowing of TTR tetramer dissociation via kinetic stabiliser binding slows cardiomyopathy progression. Quadruplicate subunit exchange comparisons of the drug candidate AG10, and the drugs tolcapone, diflunisal, and tafamidis were carried out at 1, 5, 10, 20 and 30 µM concentrations in 4 distinct pooled wild type TTR (TTRwt) human plasma samples. These experiments reveal that the concentration dependence of the efficacy of each compound at inhibiting TTR dissociation was primarily determined by the ratio between the stabiliser's dissociation constants from TTR and albumin, which competes with TTR to bind kinetic stabilisers. The best stabilisers, tafamidis (80 mg QD), AG10 (800 mg BID), and tolcapone (3 x 100 mg over 12 h), exhibit very similar kinetic stabilisation at the plasma concentrations resulting from these doses. At a 10 µM plasma concentration, AG10 is slightly more potent as a kinetic stabiliser vs. tolcapone and tafamidis (which are similar), which are substantially more potent than diflunisal. Dissociation of TTR can be limited to 10% of its normal rate at concentrations of 5.7 µM AG10, 10.3 µM tolcapone, 12.0 µM tafamidis, and 188 µM diflunisal. The potency similarities revealed by our study suggest that differences in safety, adsorption and metabolism, pharmacokinetics, and tissue distribution become important for kinetic stabiliser clinical use decisions.

Clinical usefulness of Edinburgh CT criteria in patients with lobar intracerebral hemorrhage

Background

Identifying the cause of intracerebral hemorrhage (ICH) is relevant to optimize its management. We aimed to assess the applicability and utility of the Edinburgh CT criteria for cerebral amyloid angiopathy (CAA) in an unselected cohort of hospitalized patients.

Patients and Methods

We retrospectively applied the Edinburgh criteria to the first available brain CTs of patients hospitalized for a first-ever lobar ICH in the district of L'Aquila from 2011 to 2017. ICH characteristics and outcomes were compared according to the presence of the Edinburgh CT criteria, including associated subarachnoid hemorrhage (aSAH) and finger-like projections (FLPs). The outcome of ICH in-hospital mortality was assessed with multivariate logistic regression analysis. We adopted the Edinburgh criteria, age, NIHSS and Glasgow Coma Scale scores, systolic blood pressure, antiplatelet treatment, ICH volume, and intraventricular extension on admission as covariates.

Results

Of 178 patients with lobar ICH, 52 (29.2%) had aSAH+FLPs, 60 (33.7%) aSAH only, 1 (0.6%) FLPs, and 65 (36.5%) none. Patients with aSAH+FLPs were older (79.0 ± 9.2 years) than those with only one criterion or none (74.0 ± 15.3 and 72.2 ± 13.8 years, respectively; P = 0.020). Patients with aSAH+FLPs also had more severe ICH at onset, higher in-hospital case-fatality (log rank test P = 0.003) and higher mRS scores at discharge (P < 0.001) as compared to those fulfilling one or none of the Edinburgh criteria. Low Glasgow Coma Scale score was the only factor independently associated to in-hospital case-fatality (odds ratio per point increase 0.51; 95% confidence interval, 0.32-0.91; P = 0.021).

Discussion

Our data suggest the applicability of the Edinburgh CT criteria in a hospital setting. The presence of those criteria reflects ICH clinical severity.

Conclusions

Applying the Edinburgh CT criteria might help refining the diagnosis and improving the management of patients with lobar ICH.

A Pictorial Review of Intracranial Haemorrhage Revisited

BACKGROUND

The many causes of Intracerebral Haemorrhage (IH) can be difficult to differentiate. However, there are imaging features that can provide useful clues. This paper aims to provide a pictorial review of the common causes of IH, to identify some distinguishing diagnostic features and to provide guidance on subsequent imaging and follow up. It is hoped that this review would benefit radiology and non-radiology consultants, multi-professional workers and trainees who are commonly exposed to unenhanced CT head studies but are not neuroradiology specialists.

DISCUSSION

In the absence of trauma, Spontaneous Intracerebral Haemorrhage (SIH) can be classified as idiopathic or secondary. Secondary causes of IH include hypertension and amyloid angiopathy (75-80%) and less common pathologies such as vascular malformations (arteriovenous malformations, aneurysms and cavernomas), malignancy , venous sinus thrombosis and infection. SIH causes between 10 to 15% of all strokes and has a higher mortality than ischaemic stroke. Trauma is another cause of IH with significant mortality and some of the radiological features will be reviewed.

CONCLUSION

Unenhanced CT is a mainstay of acute phase imaging due to its availability and, sensitivity and specificity for detecting acute haemorrhage. Several imaging features can be identified on CT and, along with clinical information, can provide some certainty in diagnosis. For those suitable and where diagnostic uncertainty remains CT angiogram, time-resolved CT angiography and catheter angiography can help identify underlying AVMs, aneurysms, cavernomas and vasculitides. MRI is more sensitive for the detection of subacute and chronic haemorrhage and identification of underlying mass lesions.

High-grade Glioma Masquerading as a Small Cerebral Hemorrhage: A Case Report

We report a rare case of a high-grade glioma masquerading as a small subcortical hemorrhage. A 71-year-old woman came to a local hospital with sudden right upper extremity numbness. Computed tomography revealed a small subcortical hemorrhage with faint perifocal edema in the left postcentral gyrus. Conservative treatment was initiated, and she was discharged from the hospital with no neurological deficits. Six months later after discharge, she suffered an acute partial seizure of the right upper extremity. Magnetic resonance imaging with gadolinium demonstrated a ring-enhancing mass surrounded by severe perifocal edema in the hemorrhagic scar. We performed complete resection of the tumor, and the histological diagnosis was anaplastic oligodendroglioma. The diagnosis of a high-grade glioma was delayed due to intratumoral hemorrhages mimicking a small subcortical hemorrhage; consequently, we suspected the hemorrhage was induced by cerebral amyloid angiopathy. It may be important to repeat radiological follow up, if necessary, and to maintain clinical observance of possible intracranial neoplasm, even when the hemorrhage is small, particularly when the cause of bleeding is unknown.

Prevalence and Evolution of Susceptibility-Weighted Imaging Lesions in Patients With Artificial Heart Valves

Background

In patients with mechanical heart valves, cerebral susceptibility‐weighted imaging (SWI) lesions on magnetic resonance imaging, postulated to be caused by degenerative metallic abrasion, are frequently referred to as valve abrasion. It remains unclear whether valve implantation not requiring cardiopulmonary bypass or biological heart valves also shows those lesions.

Methods and Results

Two blinded readers rated SWI lesions and cerebral amyloid angiopathy probability according to established criteria on brain magnetic resonance imaging pre‐ and postinterventionally. We assessed the association between valve type/cardiopulmonary bypass use and SWI lesion count on the first postinterventional scan using multivariable logistic regression. On postinterventional magnetic resonance imaging, 57/58 (98%) patients with mechanical heart valves had at least 1 and 46/58 (79%) 3 or more SWI lesions, while 92/97 (95%) patients with biological heart valves had at least 1 and 72/97 (74%) 3 or more SWI lesions. On multivariate analysis, duration of cardiopulmonary bypass during implantation significantly increased the odds of having SWI lesions on the first postinterventional magnetic resonance imaging (β per 10 minutes 0.498; 95% CI, 0.116–0.880; P=0.011), whereas valve type showed no significant association (P=0.338). Thirty‐seven of 155 (23.9%) patients fulfilled the criteria of possible/probable cerebral amyloid angiopathy.

Conclusions

SWI lesions in patients with artificial heart valves evolve around the time point of valve implantation and the majority of patients had multiple lesions. The missing association with the valve type weakens the hypothesis of degenerative metallic abrasion and highlights cardiopulmonary bypass as the main risk factor for SWI occurrence. SWI lesions associated with cardiac procedures can mimic cerebral amyloid angiopathy. Further research needs to clarify whether those lesions are associated with intracranial hemorrhage after intravenous thrombolysis or anticoagulation.

Multiple Cerebral Hemorrhagic Lesions Depicted by Susceptibility-Weighted Imaging in a Patient with Down Syndrome: Case Report

Our objective is to study a 53-year-old woman with Down syndrome presented with massive lobar hematoma in the left fronto-parietal lobe, and who underwent craniotomy and hematoma evacuation. Histopathological diagnosis of surgical specimen was amyloid angiopathy. Postoperative magnetic resonance studies were performed. The lesion this time showed mixed intensity on susceptibility-weighted imaging. In addition, multiple hypointense lesions were evident. An old previously unidentified hemorrhage in the right temporo-parietal lobe was accompanied by superficial cortical siderosis. Old bleeds were apparent in subcortical areas. These various kinds of hemorrhagic lesion were consistent with findings of amyloid angiopathy reported in the elderly. Most reported cases of Down syndrome associated with intracerebral hemorrhage have involved middle-aged patients. Magnetic resonance studies for Down syndrome patients before old age may disclose the degree to which amyloid angiopathy progresses in the brain of these patients.

Cerebral Microbleeds in Advanced Dementia: Clinical and Pathological Correlates

OBJECTIVE

We conducted a longitudinal study to explore the clinical and pathological correlates of cerebral microbleeds (CMBs) in institutionalized patients with dementia.

METHODS

Clinical and magnetic resonance imaging (MRI) data were extracted from 182 nursing home patients (mean age [standard deviation]: 81.3 [6.9], 78.0% female, and 83.4% moderate to severe dementia), which were divided according to the CMBs number and location. One-year follow-up data were obtained from 153 patients, and postmortem pathological diagnosis was available in 40 patients.

RESULTS

Cerebral microbleeds were observed in 42.9% of patients and were associated with MRI ischemic lesions ( P < .0005). In the adjusted analysis, lobar CMB predicted worsening of parkinsonism (standardized β: 0.43) and gait (standardized β: 0.24). A pathological diagnosis of Alzheimer's disease was less frequent in the brains of patients with lobar and deep CMB (33.3% vs 85.3%; P < .05).

CONCLUSION

Cerebral microbleeds were linked to cerebrovascular disease and predicted motor deterioration in institutionalized people with advanced dementia.

Lack of P-glycoprotein Results in Impairment of Removal of Beta-Amyloid and Increased Intraparenchymal Cerebral Amyloid Angiopathy after Active Immunization in a Transgenic Mouse Model of Alzheimer's Disease

BACKGROUND

Immunization against beta-amyloid (Aβ) reduces cerebral Aβ deposits and improves cognitive capacities in transgenic mouse models, and thus has been considered a promising disease- modifying therapeutic approach for Alzheimer's disease (AD). Although clinical trials in AD patients have yielded evidence for clearance of parenchymal Aβ plaques, Aβ increases in blood vessels of treated patients. We hypothesize that an age-related decline in the mechanisms that clear Aβ from the brain might be at least in part responsible for the failure to purge and re-distribute Aβ. The expulsion of Aβ via the blood-brain barrier is mediated by specialized transport proteins such as P-glycoprotein (P-gp, ABCB1/MDR1).

OBJECTIVE

The objective of this study is to investigate the influence of the absence of P-gp at the bloodbrain barrier on the effectiveness of Aβ peptide immunization in APP/PS1+/- P-gp ko mice.

METHODS

Male APP/PS1+/- P-gp wt (n = 8) and APP/PS1+/- P-gp ko (n = 8) mice were actively immunized with human Aβ42. After behavioral testing animals were sacrificed at the age of 395 days (+/- 5 days) and antibody titres against Aβ were measured. Brains were dissected and soluble/insoluble cerebral Aβ was quantified, additionally the number of amyloid plaques and severity of amyloid angiopathy were evaluated.

RESULTS

In immunized mice with intact P-gp, our results showed a significant reduction of soluble and insoluble Aβ40 and Aβ42. Furthermore, immunization significantly reduced Aβ plaque burden. In contrast, immunized APP/PS1+/- P-gp ko mice lacking functional P-gp did not show a reduction of Aβ40 or Aβ42 accumulation in the brain except for the soluble form of Aβ42. Furthermore, after active immunization these mice displayed a stronger intracerebral amyloid angiopathy.

CONCLUSION

The results show that the absence of P-gp results in a significant disturbance of Aβ removal from the brain and increased intraparenchymal cerebral amyloid angiopathy after immunization against Aβ. Our data indicate that the selective up-regulation of P-gp could enhance the efficacy of Aβ immunization in the treatment or prevention of AD.

Progression of Brain Network Alterations in Cerebral Amyloid Angiopathy

BACKGROUND AND PURPOSE

We recently showed that cerebral amyloid angiopathy (CAA) is associated with functionally relevant brain network impairments, in particular affecting posterior white matter connections. Here we examined how these brain network impairments progress over time.

METHODS

Thirty-three patients with probable CAA underwent multimodal brain magnetic resonance imaging at 2 time points (mean follow-up time: 1.3±0.4 years). Brain networks of the hemisphere free of intracerebral hemorrhages were reconstructed using fiber tractography and graph theory. The global efficiency of the network and mean fractional anisotropies of posterior-posterior, frontal-frontal, and posterior-frontal network connections were calculated. Patients with moderate versus severe CAA were defined based on microbleed count, dichotomized at the median (median=35).

RESULTS

Global efficiency of the intracerebral hemorrhage-free hemispheric network declined from baseline to follow-up (-0.008±0.003; P=0.029). The decline in global efficiency was most pronounced for patients with severe CAA (group×time interaction P=0.03). The decline in global network efficiency was associated with worse executive functioning (β=0.46; P=0.03). Examination of subgroups of network connections revealed a decline in fractional anisotropies of posterior-posterior connections at both levels of CAA severity (-0.006±0.002; P=0.017; group×time interaction P=0.16). The fractional anisotropies of posterior-frontal and frontal-frontal connections declined in patients with severe but not moderate CAA (group×time interaction P=0.007 and P=0.005). Associations were independent of change in white matter hyperintensity volume.

CONCLUSIONS

Brain network impairment in patients with CAA worsens measurably over just 1.3-year follow-up and seem to progress from posterior to frontal connections with increasing disease severity.

Cerebral Microbleeds and Cortical Superficial Siderosis in Patients Presenting With Minor Cerebrovascular Events

BACKGROUND AND PURPOSE

Transient focal neurological episodes occur in cerebral amyloid angiopathy (CAA) and can mimic transient ischemic attack (TIA). Risk factors and outcomes of minor ischemic stroke or TIA might differ in patients with and without cerebral microbleeds (CMBs), including CAA-consistent lobar CMB.

METHODS

Baseline magnetic resonance imaging (MRI) was analyzed for CMBs and cortical superficial siderosis in 416 patients in the prospective computed tomography and MRI in the CATCH study (Triage of TIA and Minor Cerebrovascular Events to Identify High Risk Patients). Clinical symptoms, baseline characteristics, recurrence, and 90-day modified Rankin Scale were prospectively collected. MRI white-matter hyperintensity was measured using the Fazekas scale.

RESULTS

CMBs were detected in 65 (15.6%) and cortical superficial siderosis in 11 patients (2.6%). Lobar CMBs were present in 49 (11.8%). In multivariable logistic regression adjusted for risk factors and age, subcortical Fazekas score was associated with lobar CMB (odds ratio, 2.07; 95% confidence interval, 1.23-3.48; P=0.006). Forty-two patients (10.1%) had lobar-only CMBs with or without cortical superficial siderosis consistent with modified Boston criteria for possible/probable CAA. The possible/probable CAA pattern was not predictive of recurrent TIA (odds ratio, 0.42; 95% confidence interval, 0.05-3.31; P=0.41), stroke (odds ratio, 1.24; 95% confidence interval, 0.26-5.99; P=0.79), or 90-day modified Rankin Scale score ≥2 (odds ratio, 1.38; 95% confidence interval, 0.62-3.07; P=0.42).

CONCLUSIONS

CMBs in TIA and minor stroke are moderately common but do not predict recurrence or 90-day outcome. CAA-related transient focal neurological episodes and TIA have overlapping clinical symptoms, suggesting that MRI may be needed for differentiation.

Multiple Spontaneous Cerebral Microbleeds and Leukoencephalopathy in PSEN1-Associated Familial Alzheimer's Disease: Mirror of Cerebral Amyloid Angiopathy?

Cerebral microbleeds (CMB) might reflect specific underlying vascular pathologies like cerebral amyloid angiopathy (CAA). In the present study we report the gradient-echo MRI pattern of two siblings with P284S PSEN1 mutation. T2* gradient-echo images of the two subjects demonstrated multiple microbleeds in lobar regions. The role and causes of CMB in sporadic Alzheimer's disease (AD) patients have not been clearly established and useful contributions could derive from familial AD studies. Furthermore, since CAA is a potential risk factor for developing adverse events in AD immunization trials, the identification in vivo of CAA through non-invasive MRI methods could be useful to monitoring side effects.

Cerebral amyloid angiopathy severity is linked to dilation of juxtacortical perivascular spaces

Perivascular spaces are an emerging marker of small vessel disease. Perivascular spaces in the centrum semiovale have been associated with cerebral amyloid angiopathy. However, a direct topographical relationship between dilated perivascular spaces and cerebral amyloid angiopathy severity has not been established. We examined this association using post-mortem magnetic resonance imaging in five cases with evidence of cerebral amyloid angiopathy pathology. Juxtacortical perivascular spaces dilation was evaluated on T2 images and related to cerebral amyloid angiopathy severity in overlying cortical areas on 34 tissue sections stained for Amyloid β. Degree of perivascular spaces dilation was significantly associated with cerebral amyloid angiopathy severity (odds ratio = 3.3, 95% confidence interval 1.3-7.9, p = 0.011). Thus, dilated juxtacortical perivascular spaces are a promising neuroimaging marker of cerebral amyloid angiopathy severity.

Ischemic brain injury in cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) is a common form of cerebral small vessel disease and an important risk factor for intracerebral hemorrhage and cognitive impairment. While the majority of research has focused on the hemorrhagic manifestation of CAA, its ischemic manifestations appear to have substantial clinical relevance as well. Findings from imaging and pathologic studies indicate that ischemic lesions are common in CAA, including white-matter hyperintensities, microinfarcts, and microstructural tissue abnormalities as detected with diffusion tensor imaging. Furthermore, imaging markers of ischemic disease show a robust association with cognition, independent of age, hemorrhagic lesions, and traditional vascular risk factors. Widespread ischemic tissue injury may affect cognition by disrupting white-matter connectivity, thereby hampering communication between brain regions. Challenges are to identify imaging markers that are able to capture widespread microvascular lesion burden in vivo and to further unravel the etiology of ischemic tissue injury by linking structural magnetic resonance imaging (MRI) abnormalities to their underlying pathophysiology and histopathology. A better understanding of the underlying mechanisms of ischemic brain injury in CAA will be a key step toward new interventions to improve long-term cognitive outcomes for patients with CAA.

A Novel Liposomal Nanoparticle for the Imaging of Amyloid Plaque by Magnetic Resonance Imaging

Amyloid binding molecules with greater hydrophilicity than existing ligands were synthesized. The lead candidate ET6-21 bound amyloid fibrils, and amyloid deposits in dog brain and human brain tissue ex vivo. The ligand was used to prepare novel amyloid-targeted liposomal nanoparticles. The preparation was tested in the Tg2576 and TetO/APP mouse models of amyloid deposition. Gd chelates and Indocyanine green were included in the particles for visualization by MRI and near-infrared microscopy. Upon intravenous injection, the particles successfully traversed the blood-brain barrier in these mice, and bound to the plaques. Magnetic resonance imaging (T1-MRI) conducted 4 days after injection demonstrated elevated signal in the brains of mice with amyloid plaques present. No signal was observed in amyloid-negative mice, or in amyloid-positive mice injected with an untargeted version of the same agent. The MRI results were confirmed by immunohistochemical and fluorescent microscopic examination of mouse brain sections, showing colocalization of the fluorescent tags and amyloid deposits.

Cerebral Amyloid Angiopathy Associated with Inflammation: Report of 3 Cases and Systematic Review

INTRODUCTION

Cerebral amyloid angiopathy associated with inflammatory process (CAA-I) is a rare potentially treatable encephalopathy, characterized by an inflammatory response to vascular deposits of β-amyloid. We aimed to describe 3 clinical cases and perform a systematic review of all neuropathologically proved CAA-I case reports to describe its clinical and pathologic features and outcome under different treatments.

METHODS

We searched PubMed and Cochrane Library and screened references of included studies and review articles for additional citations. Outcome was classified at the last available follow-up by the modified Rankin Scale (mRS).

RESULTS

A total of 67 publications, reporting on 155 patients, were included. Mean age was 66.9 years, and 53.5% were men. The most common clinical presentation was cognitive dysfunction (48.0%) followed by headaches (38.7%), seizures (36.7%), and pyramidal signs (20.0%). Perivascular and vasculitic inflammation with granuloma was the most common pathologic pattern (27.5%). Eighty-six percent were treated with corticosteroids and 33.9% with cyclophosphamide. Forty-two percent regained independence (mRS score 0-2), whereas 20.5% were left with a severe handicap (mRS score 3-5) and 37.5% died. There were no statistically significant differences in outcome between patients treated with therapy with corticosteroids alone comparing with those treated with combination corticosteroids with cytostatic agents.

CONCLUSIONS

The most common clinical manifestation of CAA-I was cognitive dysfunction. The functional outcome was unfavorable in the majority of the patients, with death or severe disability in almost two third of the cases, despite treatment. No differences in outcome could be detected between patients treated with corticosteroids versus patients treated with cytostatics, combined with corticosteroids.

Cerebral amyloid angiopathy increases susceptibility to infarction after focal cerebral ischemia in Tg2576 mice

BACKGROUND AND PURPOSE

We and others have shown that soluble amyloid β-peptide (Aβ) and cerebral amyloid angiopathy (CAA) cause significant cerebrovascular dysfunction in mutant amyloid precursor protein (APP) mice, and that these deficits are greater in aged APP mice having CAA compared with young APP mice lacking CAA. Amyloid β-peptide in young APP mice also increases infarction after focal cerebral ischemia, but the impact of CAA on ischemic brain injury is unknown.

METHODS

To determine this, we assessed cerebrovascular reactivity, cerebral blood flow (CBF), and extent of infarction and neurological deficits after transient middle cerebral artery occlusion in aged APP mice having extensive CAA versus young APP mice lacking CAA (and aged-matched littermate controls).

RESULTS

We found that aged APP mice have more severe cerebrovascular dysfunction that is CAA dependent, have greater CBF compromise during and immediately after middle cerebral artery occlusion, and develop larger infarctions after middle cerebral artery occlusion.

CONCLUSIONS

These data indicate CAA induces a more severe form of cerebrovascular dysfunction than amyloid β-peptide alone, leading to intra- and postischemic CBF deficits that ultimately exacerbate cerebral infarction. Our results shed mechanistic light on human studies identifying CAA as an independent risk factor for ischemic brain injury.

The relationship between cerebral amyloid angiopathy and cortical microinfarcts in brain ageing and Alzheimer's disease

AIMS

Cerebral amyloid angiopathy (CAA) represents the deposition of amyloid β protein (Aβ) in the meningeal and intracerebral vessels. It is often observed as an accompanying lesion of Alzheimer's disease (AD) or in the brain of elderly individuals even in the absence of dementia. CAA is largely age-dependent. In subjects with severe CAA a higher frequency of vascular lesions has been reported. The goal of our study was to define the frequency and distribution of CAA in a 1-year autopsy population (91 cases) from the Department of Internal Medicine, Rehabilitation, and Geriatrics, Geneva.

MATERIALS AND METHODS

Five brain regions were examined, including the hippocampus, and the inferior temporal, frontal, parietal and occipital cortex, using an antibody against Aβ, and simultaneously assessing the severity of AD-type pathology with Braak stages for neurofibrillary tangles identified with an anti-tau antibody. In parallel, the relationships of CAA with vascular brain lesions were established.

RESULTS

CAA was present in 53.8% of the studied population, even in cases without AD (50.6%). The strongest correlation was seen between CAA and age, followed by the severity of amyloid plaques deposition. Microinfarcts were more frequent in cases with CAA; however, our results did not confirm a correlation between these parameters.

CONCLUSION

The present data show that CAA plays a role in the development of microvascular lesions in the ageing brain, but cannot be considered as the most important factor in this vascular pathology, suggesting that other mechanisms also contribute importantly to the pathogenesis of microvascular changes.

Nontraumatic convexity subarachnoid hemorrhage: different etiologies and outcomes

BACKGROUND

Nontraumatic convexity subarachnoid hemorrhage (cSAH) is a rarely reported condition with multiple etiologies. We report the clinical presentation, imaging findings, etiologies, and long-term outcomes of a case series of cSAH.

METHODS

We retrospectively analyzed consecutive cases of cSAH, admitted at a Stroke Unit of a tertiary hospital (January 2006 to March 2012). Recorded variables were demographics, clinical presentation, complementary investigation, etiology, and outcome.

RESULTS

We included 15 patients (9 men, median age of 65 years), 7% of the 210 nontraumatic SAH patients in this period. The most common clinical manifestation was a focal neurologic deficit. Predominant location of the cSAH was frontal. In 5 cases, there was a clinical significant internal carotid artery (ICA) atheromatous stenosis, ipsilateral to cSAH. Two patients had a possible cerebral amyloid angiopathy (CAA) at presentation. There were 2 cases of reversible cerebral vasoconstriction syndrome, 1 cerebral venous thrombosis, 2 dural fistulae, and 3 undetermined. Short-term outcomes were good in most patients. At follow-up (24.3 months), 2 of the patients with undetermined etiology had a lobar hematoma conferring a severe disability, and the diagnosis of CAA was made. There were no other relevant events or added disability in the other patients.

CONCLUSIONS

Significant ICA atherosclerotic stenosis was the most frequent cause of cSAH in our series, reinforcing that cSAH should prompt vascular imagiological evaluation including cervical vessels. Outcomes in cSAH seem to be related to etiology. Patients with undetermined etiology should be followed up because cSAH may be the first manifestation of CAA.

Assessing white matter ischemic damage in dementia patients by measurement of myelin proteins

White matter ischemia is difficult to quantify histologically. Myelin-associated glycoprotein (MAG) is highly susceptible to ischemia, being expressed only adaxonally, far from the oligodendrocyte cell body. Myelin-basic protein (MBP) and proteolipid protein (PLP) are expressed throughout the myelin sheath. We compared MAG, MBP, and PLP levels in parietal white matter homogenates from 17 vascular dementia (VaD), 49 Alzheimer's disease (AD), and 33 control brains, after assessing the post-mortem stability of these proteins. Small vessel disease (SVD) and cerebral amyloid angiopathy (CAA) severity had been assessed in paraffin sections. The concentration of MAG remained stable post-mortem, declined with increasing SVD, and was significantly lower in VaD than controls. The concentration of MBP fell progressively post-mortem, limiting its diagnostic utility in this context. Proteolipid protein was stable post-mortem and increased significantly with SVD severity. The MAG/PLP ratio declined significantly with SVD and CAA severity. The MAG and PLP levels and MAG/PLP did not differ significantly between AD and control brains. We validated the utility of MAG and MAG/PLP measurements on analysis of 74 frontal white matter samples from an Oxford cohort in which SVD had previously been scored. MAG concentration and the MAG/PLP ratio are useful post-mortem measures of ante-mortem white matter ischemia.

Hereditary gelsolin amyloidosis

Hereditary gelsolin amyloidosis (HGA) is an autosomally dominantly inherited form of systemic amyloidosis, characterized mainly by cranial and sensory peripheral neuropathy, corneal lattice dystrophy, and cutis laxa. HGA, originally reported from Finland and now increasingly from other countries in Europe, North and South America, and Asia, may still be underdiagnosed worldwide. It is the first and so-far only known disorder caused by a gelsolin gene defect, namely a G654A or G654T mutation. Gelsolin is a principal actin-modulating protein, implicated in multiple biological processes, also in the nervous system, e.g. axonal transport, myelination, neurite outgrowth, and neuroprotection. The gelsolin gene defect causes expression of variant gelsolin, followed by systemic deposition of gelsolin amyloid (AGel) in HGA patients and even other consequences on the metabolism and function of gelsolin. In HGA, specific therapy is not yet available but correct diagnosis enables adequate symptomatic treatment which decisively improves the quality of life in these patients. A transgenic murine model of HGA expressing AGel is available, in anticipation of new treatment options targeted toward this slowly progressive but devastating amyloidosis. Present and future lessons learned from HGA may be applicable even in diagnosis and treatment of other hereditary and sporadic amyloidoses.

Perivascular neuritic dystrophy associated with cerebral amyloid angiopathy in Alzheimer's disease

Cerebral amyloid angiopathy (CAA) affects both leptomeningeal and parenchymal blood vessels and is common in Alzheimer's disease (AD). In some vessels, CAA is accompanied by localized neuritic dystrophy around the affected blood vessel. The aim of this study was to assess the distribution and severity of perivascular neuritic dystrophy in primary visual and visual association cortices. The severity of perivascular neuritic dystrophy and Abeta deposition was scored in an association cortex (Brodmann area 18) and a primary cortex (Brodmann area 17) with double labeling immunohistochemistry for tau and Abeta in 31 cases of AD with severe CAA. The perivascular tau neuritic dystrophy score was significantly worse in visual association cortex than in primary visual cortex. On the other hand, there was no difference in the perivascular Abeta score between the two cortices. There were positive correlations between the severity of perivascular tau and perivascular Abeta scores for both primary and association cortices. The results suggest that the local neuronal environment determines the severity and nature of the perivascular neuritic pathology more than the severity of the intrinsic vascular disease and suggest a close association between perivascular amyloid deposits, so-called dyshoric angiopathy, and perivascular neuritic dystrophy.