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Alzheimer's disease (AD) is characterized pathologically by amyloid-beta (Aβ) deposition in brain parenchyma and blood vessels (as cerebral amyloid angiopathy (CAA)) and by neurofibrillary tangles of hyperphosphorylated tau. Compelling genetic and biomarker evidence supports Aβ as the root cause of AD. We previously reported human transmission of Aβ pathology and CAA in relatively young adults who had died of iatrogenic Creutzfeldt-Jakob disease (iCJD) after childhood treatment with cadaver-derived pituitary growth hormone (c-hGH) contaminated with both CJD prions and Aβ seeds. This raised the possibility that c-hGH recipients who did not die from iCJD may eventually develop AD. Here we describe recipients who developed dementia and biomarker changes within the phenotypic spectrum of AD, suggesting that AD, like CJD, has environmentally acquired (iatrogenic) forms as well as late-onset sporadic and early-onset inherited forms. Although iatrogenic AD may be rare, and there is no suggestion that Aβ can be transmitted between individuals in activities of daily life, its recognition emphasizes the need to review measures to prevent accidental transmissions via other medical and surgical procedures. As propagating Aβ assemblies may exhibit structural diversity akin to conventional prions, it is possible that therapeutic strategies targeting disease-related assemblies may lead to selection of minor components and development of resistance., (© 2024. The Author(s).)

Background: Cerebral amyloid angiopathy (CAA) is an age-related small vessel disease, characterised pathologically by progressive deposition of amyloid β in the cerebrovascular wall. The Boston criteria are used worldwide for the in-vivo diagnosis of CAA but have not been updated since 2010, before the emergence of additional MRI markers. We report an international collaborative study aiming to update and externally validate the Boston diagnostic criteria across the full spectrum of clinical CAA presentations., Methods: In this multicentre, hospital-based, retrospective, MRI and neuropathology diagnostic accuracy study, we did a retrospective analysis of clinical, radiological, and histopathological data available to sites participating in the International CAA Association to formulate updated Boston criteria and establish their diagnostic accuracy across different populations and clinical presentations. Ten North American and European academic medical centres identified patients aged 50 years and older with potential CAA-related clinical presentations (ie, spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes), available brain MRI, and histopathological assessment for CAA diagnosis. MRI scans were centrally rated at Massachusetts General Hospital (Boston, MA, USA) for haemorrhagic and non-haemorrhagic CAA markers, and brain tissue samples were rated by neuropathologists at the contributing sites. We derived the Boston criteria version 2.0 (v2.0) by selecting MRI features to optimise diagnostic specificity and sensitivity in a prespecified derivation cohort (Boston cases 1994-2012, n=159), then externally validated the criteria in a prespecified temporal validation cohort (Boston cases 2012-18, n=59) and a geographical validation cohort (non-Boston cases 2004-18; n=123), comparing accuracy of the new criteria to the currently used modified Boston criteria with histopathological assessment of CAA as the diagnostic standard. We also assessed performance of the v2.0 criteria in patients across all cohorts who had the diagnostic gold standard of brain autopsy., Findings: The study protocol was finalised on Jan 15, 2017, patient identification was completed on Dec 31, 2018, and imaging analyses were completed on Sept 30, 2019. Of 401 potentially eligible patients presenting to Massachusetts General Hospital, 218 were eligible to be included in the analysis; of 160 patient datasets from other centres, 123 were included. Using the derivation cohort, we derived provisional criteria for probable CAA requiring the presence of at least two strictly lobar haemorrhagic lesions (ie, intracerebral haemorrhages, cerebral microbleeds, or foci of cortical superficial siderosis) or at least one strictly lobar haemorrhagic lesion and at least one white matter characteristic (ie, severe visible perivascular spaces in centrum semiovale or white matter hyperintensities in a multispot pattern). The sensitivity and specificity of these criteria were 74·8% (95% CI 65·4-82·7) and 84·6% (71·9-93·1) in the derivation cohort, 92·5% (79·6-98·4) and 89·5% (66·9-98·7) in the temporal validation cohort, 80·2% (70·8-87·6) and 81·5% (61·9-93·7) in the geographical validation cohort, and 74·5% (65·4-82·4) and 95·0% (83·1-99·4) in all patients who had autopsy as the diagnostic standard. The area under the receiver operating characteristic curve (AUC) was 0·797 (0·732-0·861) in the derivation cohort, 0·910 (0·828-0·992) in the temporal validation cohort, 0·808 (0·724-0·893) in the geographical validation cohort, and 0·848 (0·794-0·901) in patients who had autopsy as the diagnostic standard. The v2.0 Boston criteria for probable CAA had superior accuracy to the current Boston criteria (sensitivity 64·5% [54·9-73·4]; specificity 95·0% [83·1-99·4]; AUC 0·798 [0·741-0854]; p=0·0005 for comparison of AUC) across all individuals who had autopsy as the diagnostic standard., Interpretation: The Boston criteria v2.0 incorporate emerging MRI markers of CAA to enhance sensitivity without compromising their specificity in our cohorts of patients aged 50 years and older presenting with spontaneous intracerebral haemorrhage, cognitive impairment, or transient focal neurological episodes. Future studies will be needed to determine generalisability of the v.2.0 criteria across the full range of patients and clinical presentations., Funding: US National Institutes of Health (R01 AG26484)., Competing Interests: Declaration of interests AC reports receiving funding from the Bodossaki Foundation and the Frechette Family Foundation and consulting fees from Imperative Care. MPF reports receiving funding from Biogen and Voyager Therapeutics. Gba reports receiving funding from the Rosetrees Trust, Alzheimer's Research UK, NIHR, and the Stroke Association. CC reports receiving funding from the French Ministry of Health and honoraria from Amgen, and participating in data safety monitoring, advisory, or steering committees for the University of Glasgow, University of Caen, Op2Lysis, AstraZeneca, Bristol Myers Squibb, and Biogen. MD reports receiving funding from Deutsche Forschungsgemeinschaft under Germany's Excellence Strategy within the framework of the Munich Cluster for Systems Neurology and the Vascular Dementia Research Foundation. JH reports receiving funding from the German Research Foundation and German Center for Neurodegenerative Diseases and tissue from Neurobiobank Munich. JL reports serving on a serving on an advisory board for Biogen and Mediaire. LP reports receiving honoraria from Daiichi Sankyo Ireland. FP reports receiving funding from the Alzheimer's Association (AARG-18-561699), participation on an Advisory Board for Roche, and leadership of the CAA Study Group of the Italia Society of Neurology-Dementia and the iCAB International Network. SR reports receiving funding from the German Research Foundation and brain tissue from Neurobiobank Munich. MAR reports receiving funding from the Wellcome Trust. JAS reports receiving funding from the US National Institutes of Health, consulting fees from Alnylam Pharmaceuticals, Apellis Pharmaceuticals, and Avid Radiopharmaceuticals, honoraria from Weil Cornell University, payment for expert testimony from the National Hockey League, support for travel from the US National Institutes for Health, serving on safety monitoring or advisory boards for the Framingham Heart Study, DISCOVERY, University of Kansas, Boston University, and University of California Irvine, and serving in leadership positions for the Alzheimer's Association and Foundation Alzheimer France. CSm reports receiving funding from the Medical Research Council UK. LS reports receiving funding from the Hungarian Academy of Sciences and Ministry for Innovation and Technology of Hungary from the source of the National Research. JMW reports receiving funding from the UK Dementia Research Institute funded by the UK Medical Research Council, Alzheimer's Society, and Alzheimer's Research UK, and a leadership role for the European Stroke Organization SVD Guidelines. FAW reports receiving honoraria from Alexion Pharm. MEG reports receiving funding from Avid Radiopharmaceuticals, Pfizer, and Boston Scientific. AV reports receiving funding from the US National Institutes of Health and consulting fees from Alnylam Pharmaceuticals and Biogen Pharmaceuticals. RA-SS reports receiving funding from the UK Medical Research Council and the Stroke Association. EES reports receiving funding from the Canadian Institutes of Health Research, Brain Canada, and Biogen, and consulting fees from Biogen and Eli Lily. DJW reports receiving consulting fees from Alnylam and Novo Nordisk, honoraria from Bayer and Alexion, participation on a safety monitoring board for the OXHARP study, and serving in leadership for the British Association of Stroke Physicians. SMG reports receiving funding from the US National Institutes of Health, royalties from Up-To-Date, consulting fees from Eli Lily, and serving on data safety monitoring committees for Washington University, Bayer, Biogen, and Roche. All other authors declare no competing interests., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Amyloid-β transmission has been described in patients both with and without iatrogenic Creutzfeldt-Jakob disease; however, there is little information regarding the clinical impact of this acquired amyloid-β pathology during life. Here, for the first time, we describe in detail the clinical and neuroimaging findings in 3 patients with early onset symptomatic amyloid-β cerebral amyloid angiopathy following childhood exposure to cadaveric dura (by neurosurgical grafting in 2 patients and tumor embolization in a third). Our observations provide further in vivo evidence that cerebral amyloid angiopathy might be caused by transmission of amyloid-β seeds (prions) present in cadaveric dura and have diagnostic relevance for younger patients presenting with suspected cerebral amyloid angiopathy. Ann Neurol 2019; 1-7 ANN NEUROL 2019;85:284-290., (© 2018 The Authors. Annals of Neurology published by Wiley Periodicals, Inc. on behalf of American Neurological Association.)

Amyloid-β (Aβ) is a peptide deposited in the brain parenchyma in Alzheimer's disease and in cerebral blood vessels, causing cerebral amyloid angiopathy (CAA). Aβ pathology is transmissible experimentally in animals and through medical procedures in humans, such as contaminated growth hormone or dura mater transplantation in the context of iatrogenic prion disease. Here, we present four patients who underwent neurosurgical procedures during childhood or teenage years and presented with intracerebral haemorrhage approximately three decades later, caused by severe CAA. None of these patients carried pathogenic mutations associated with early Aβ pathology development. In addition, we identified in the literature four patients with a history of neurosurgical intervention and subsequent development of CAA. These findings raise the possibility that Aβ pathology may be transmissible, as prion disease is, through neurosurgical procedures.

More than two hundred individuals developed Creutzfeldt-Jakob disease (CJD) worldwide as a result of treatment, typically in childhood, with human cadaveric pituitary-derived growth hormone contaminated with prions. Although such treatment ceased in 1985, iatrogenic CJD (iCJD) continues to emerge because of the prolonged incubation periods seen in human prion infections. Unexpectedly, in an autopsy study of eight individuals with iCJD, aged 36-51 years, in four we found moderate to severe grey matter and vascular amyloid-β (Aβ) pathology. The Aβ deposition in the grey matter was typical of that seen in Alzheimer's disease and Aβ in the blood vessel walls was characteristic of cerebral amyloid angiopathy and did not co-localize with prion protein deposition. None of these patients had pathogenic mutations, APOE ε4 or other high-risk alleles associated with early-onset Alzheimer's disease. Examination of a series of 116 patients with other prion diseases from a prospective observational cohort study showed minimal or no Aβ pathology in cases of similar age range, or a decade older, without APOE ε4 risk alleles. We also analysed pituitary glands from individuals with Aβ pathology and found marked Aβ deposition in multiple cases. Experimental seeding of Aβ pathology has been previously demonstrated in primates and transgenic mice by central nervous system or peripheral inoculation with Alzheimer's disease brain homogenate. The marked deposition of parenchymal and vascular Aβ in these relatively young patients with iCJD, in contrast with other prion disease patients and population controls, is consistent with iatrogenic transmission of Aβ pathology in addition to CJD and suggests that healthy exposed individuals may also be at risk of iatrogenic Alzheimer's disease and cerebral amyloid angiopathy. These findings should also prompt investigation of whether other known iatrogenic routes of prion transmission may also be relevant to Aβ and other proteopathic seeds associated with neurodegenerative and other human diseases.

Objective: We investigated whether severe, MRI-visible perivascular spaces (PVS) in the cerebral hemisphere white matter (centrum semiovale) are more common in patients with pathology-proven cerebral amyloid angiopathy (CAA) than in those with pathology-proven non-CAA-related intracerebral hemorrhage (ICH)., Methods: Using a validated 4-point scale on axial T2-weighted MRI, we compared PVS in patients with pathology-proven CAA to PVS in those with spontaneous ICH but no histopathologic evidence of CAA. In a preliminary analysis restricted to patients with T2*-weighted gradient-recalled echo MRI, we also investigated whether including severe centrum semiovale PVS increases the sensitivity of existing diagnostic criteria for probable CAA., Results: Fourteen patients with CAA and 10 patients with non-CAA-related ICH were included. Eight of the patients with CAA were admitted for symptomatic, spontaneous lobar ICH, 1 because of ischemic stroke, 1 with transient focal neurologic episodes, and 4 due to cognitive decline. Severe (>20) centrum semiovale PVS were more frequent in patients with CAA compared to controls (12/14 [85.7%; 95% confidence interval (CI): 57.2%-98.2%] vs 0/10 [1-sided 95% CI: 0%-30.8%], p < 0.0005); this was robust to adjustment for age. The original Boston criteria for probable CAA showed a sensitivity of 76.9% (95% CI: 46.2%-95%), which increased to 92.3% (95% CI: 64%-99.8%), without loss of specificity, after including severe centrum semiovale PVS., Conclusions: Severe centrum semiovale PVS on MRI may be a promising new neuroimaging marker for the in vivo diagnosis of CAA. However, our findings are preliminary and require confirmation and external validation in larger cohorts of pathology-proven CAA.

Here we show that a significant tau pathology, similar to that seen in patients with Alzheimer's disease, can develop in patients with iatrogenic A pathology after incubation periods exceeding 3 decades. °For case 1 it is unknown if a cadaver-derived dural graft was used during neurosurgery Whilst this study cannot answer if the tauopathy was transmitted or is a consequence of A pathology, the observations described here are important as they show that tau pathology can develop in patients with iatrogenically transmitted A . Whilst tau seeds were also found in these hcGH vials [[7], [19]], to date, no substantial tau pathology has been observed in patients with iCJD, iatrogenically transmitted A pathology or both. Human (iatrogenic) transmission of amyloid- (A ) pathology has been shown in brain biopsy or autopsy tissues in patients with and without iatrogenic Creutzfeldt-Jakob disease (iCJD) [[1], [5]-[18], [20]-[22]] and these A seeds have been detected in the archival vials containing human cadaver-derived growth hormone (hcGH) [[7], [19]]. [Extracted from the article]

A correction to the article "Evidence for human transmission of amyloid-β pathology and cerebral amyloid angiopathy" which was published in issue #525 is presented.