Publications
663 results found
Huang J, Gill D, Zuber V, et al., 2023, Circulatory proteins relate cardiovascular disease to cognitive performance: a Mendelian randomisation study, Frontiers in Genetics, Vol: 14, Pages: 1-11, ISSN: 1664-8021
Background and objectives: Mechanistic research suggests synergistic effects of cardiovascular disease (CVD) and dementia pathologies on cognitive decline. Interventions targeting proteins relevant to shared mechanisms underlying CVD and dementia could also be used for the prevention of cognitive impairment.Methods: We applied Mendelian randomisation (MR) and colocalization analysis to investigate the causal relationships of 90 CVD-related proteins measured by the Olink CVD I panel with cognitive traits. Genetic instruments for circulatory protein concentrations were obtained using a meta-analysis of genome-wide association studies (GWAS) from the SCALLOP consortium (N = 17,747) based on three sets of criteria: 1) protein quantitative trait loci (pQTL); 2) cis-pQTL (pQTL within ±500 kb from the coding gene); and 3) brain-specific cis-expression QTL (cis-eQTL) which accounts for coding gene expression based on GTEx8. Genetic associations of cognitive performance were obtained from GWAS for either: 1) general cognitive function constructed using Principal Component Analysis (N = 300,486); or, 2) g Factor constructed using genomic structural equation modelling (N = 11,263–331,679). Findings for candidate causal proteins were replicated using a separate protein GWAS in Icelanders (N = 35,559).Results: A higher concentration of genetically predicted circulatory myeloperoxidase (MPO) was nominally associated with better cognitive performance (p < 0.05) using different selection criteria for genetic instruments. Particularly, brain-specific cis-eQTL predicted MPO, which accounts for protein-coding gene expression in brain tissues, was associated with general cognitive function (βWald = 0.22, PWald = 2.4 × 10−4). The posterior probability for colocalization (PP.H4) of MPO pQTL with the g Factor was 0.577. Findings for MPO were replicated using the Icelandic GWAS. Although we did not find evidence for colocalization, we found that higher gene
Huang J, Su B, Karhunen V, et al., 2023, Inflammatory diseases, inflammatory biomarkers, and Alzheimer disease: an observational analysis and mendelian randomization, Neurology, Vol: 100, Pages: e568-e581, ISSN: 0028-3878
OBJECTIVES: Whether chronic autoimmune inflammatory diseases causally affect the risk of AD is controversial. We characterised the relationship between inflammatory diseases and the risk of AD and explore the role of circulating inflammatory biomarkers in the relationships between inflammatory diseases and AD. METHODS: We performed observational analyses for chronic autoimmune inflammatory diseases and risk of AD using data from 2,047,513 participants identified in the UK Clinical Practice Research Datalink (CPRD). Using data of a total of more than 1,100,000 individuals from 15 large scale genome-wide association study (GWAS) datasets, we performed two-sample Mendelian randomisation (MR) to investigate the relationships between chronic autoimmune inflammatory diseases, circulating inflammatory biomarker levels, and risk of AD. RESULTS: Cox regression models using CPRD data showed that overall incidence of AD was higher among patients with inflammatory bowel disease (IBD) (hazard ratio (HR)=1.17; 95%CI 1.15 to 1.19; P-value=2.1×10-4), other inflammatory polyarthropathies & systematic connective tissue disorders (OID) (HR=1.13; 95%CI 1.12 to 1.14; P-value=8.6×10-5), psoriasis (HR=1.13; 95%CI 1.10 to 1.16; P-value=2.6×10-4), rheumatoid arthritis (RA) (HR=1.08; 95%CI 1.06 to 1.11; P-value=4.0×10-4), and multiple sclerosis (MS) (HR=1.06; 95%CI 1.04 to 1.07; P-value=2.8×10-4) compared to the age (± 5 years) and sex-matched comparison groups free from all inflammatory diseases under investigation. Bidirectional MR analysis identified relationships between chronic autoimmune inflammatory diseases and circulating inflammatory biomarkers. Particularly, circulating monokine induced by gamma interferon (MIG) level was suggestively associated with a higher risk of AD (odds ratio from inverse variance weighted (ORIVW)=1.23; 95%CI 1.06 to 1.42; PIVW=0.007), and lower risk of Crohn's disease (ORIVW=0.73; 95%CI -0.62, 0.86; PIVW=1.3×10
Tadros R, Zheng SL, Grace C, et al., 2023, Large scale genome-wide association analyses identify novel genetic loci and mechanisms in hypertrophic cardiomyopathy., medRxiv
Hypertrophic cardiomyopathy (HCM) is an important cause of morbidity and mortality with both monogenic and polygenic components. We here report results from the largest HCM genome-wide association study (GWAS) and multi-trait analysis (MTAG) including 5,900 HCM cases, 68,359 controls, and 36,083 UK Biobank (UKB) participants with cardiac magnetic resonance (CMR) imaging. We identified a total of 70 loci (50 novel) associated with HCM, and 62 loci (32 novel) as sociated with relevant left ventricular (LV) structural or functional traits. Amongst the common variant HCM loci, we identify a novel HCM disease gene, SVIL , which encodes the actin-binding protein supervillin, showing that rare truncating SVIL variants cause HCM. Mendelian randomization analyses support a causal role of increased LV contractility in both obstructive and non-obstructive forms of HCM, suggesting common disease mechanisms and anticipating shared response to therapy. Taken together, the findings significantly increase our understanding of the genetic basis and molecular mechanisms of HCM, with potential implications for disease management.
Montalban X, Matthews PM, Simpson A, et al., 2023, Real-world evaluation of ocrelizumab in multiple sclerosis: A systematic review, ANNALS OF CLINICAL AND TRANSLATIONAL NEUROLOGY, ISSN: 2328-9503
Pillinger T, Osimo EF, de Marvao A, et al., 2023, Effect of polygenic risk for schizophrenia on cardiac structure and function: a UK Biobank observational study, The Lancet Psychiatry, Vol: 10, Pages: 98-107, ISSN: 2215-0366
BACKGROUND: Cardiovascular disease is a major cause of excess mortality in people with schizophrenia. Several factors are responsible, including lifestyle and metabolic effects of antipsychotics. However, variations in cardiac structure and function are seen in people with schizophrenia in the absence of cardiovascular disease risk factors and after accounting for lifestyle and medication. Therefore, we aimed to explore whether shared genetic causes contribute to these cardiac variations. METHODS: For this observational study, we used data from the UK Biobank and included White British or Irish individuals without diagnosed schizophrenia with variable polygenic risk scores for the condition. To test the association between polygenic risk score for schizophrenia and cardiac phenotype, we used principal component analysis and regression. Robust regression was then used to explore the association between the polygenic risk score for schizophrenia and individual cardiac phenotypes. We repeated analyses with fibro-inflammatory pathway-specific polygenic risk scores for schizophrenia. Last, we investigated genome-wide sharing of common variants between schizophrenia and cardiac phenotypes using linkage disequilibrium score regression. The primary outcome was principal component regression. FINDINGS: Of 33 353 individuals recruited, 32 279 participants had complete cardiac MRI data and were included in the analysis, of whom 16 625 (51·5%) were female and 15 654 (48·5%) were male. 1074 participants were excluded on the basis of incomplete cardiac MRI data (for all phenotypes). A model regressing polygenic risk scores for schizophrenia onto the first five cardiac principal components of the principal components analysis was significant (F=5·09; p=0·00012). Principal component 1 captured a pattern of increased cardiac volumes, increased absolute peak diastolic strain rates, and reduced ejection fractions; polygenic risk
Davenport F, Gallacher J, Kourtzi Z, et al., 2023, Neurodegenerative disease of the brain: a survey of interdisciplinary approaches, JOURNAL OF THE ROYAL SOCIETY INTERFACE, Vol: 20, ISSN: 1742-5689
Dehghan A, Pinto RC, Karaman I, et al., 2022, Metabolome-wide association study on ABCA7 indicates a role of ceramide metabolism in Alzheimer's disease., Proceedings of the National Academy of Sciences of USA, Vol: 119, Pages: 1-12, ISSN: 0027-8424
Genome-wide association studies (GWASs) have identified genetic loci associated with the risk of Alzheimer's disease (AD), but the molecular mechanisms by which they confer risk are largely unknown. We conducted a metabolome-wide association study (MWAS) of AD-associated loci from GWASs using untargeted metabolic profiling (metabolomics) by ultraperformance liquid chromatography-mass spectrometry (UPLC-MS). We identified an association of lactosylceramides (LacCer) with AD-related single-nucleotide polymorphisms (SNPs) in ABCA7 (P = 5.0 × 10-5 to 1.3 × 10-44). We showed that plasma LacCer concentrations are associated with cognitive performance and genetically modified levels of LacCer are associated with AD risk. We then showed that concentrations of sphingomyelins, ceramides, and hexosylceramides were altered in brain tissue from Abca7 knockout mice, compared with wild type (WT) (P = 0.049-1.4 × 10-5), but not in a mouse model of amyloidosis. Furthermore, activation of microglia increases intracellular concentrations of hexosylceramides in part through induction in the expression of sphingosine kinase, an enzyme with a high control coefficient for sphingolipid and ceramide synthesis. Our work suggests that the risk for AD arising from functional variations in ABCA7 is mediated at least in part through ceramides. Modulation of their metabolism or downstream signaling may offer new therapeutic opportunities for AD.
Basaran B, Matthews PM, Bai W, 2022, New lesion segmentation for multiple sclerosis brain images with imaging and lesion-aware augmentation, Frontiers in Neuroscience, Vol: 16, ISSN: 1662-453X
Multiple sclerosis (MS) is an inflammatory and demyelinating neurological disease of the central nervous system. Image-based biomarkers, such as lesions defined on magnetic resonance imaging (MRI), play an important role in MS diagnosis and patient monitoring. The detection of newly formed lesions provides crucial information for assessing disease progression and treatment outcome. Here, we propose a deep learning-based pipeline for new MS lesion detection and segmentation, which is built upon the nnU-Net framework. In addition to conventional data augmentation, we employ imaging and lesion-aware data augmentation methods, axial subsampling and CarveMix, to generate diverse samples and improve segmentation performance. The proposed pipeline is evaluated on the MICCAI 2021 MS new lesion segmentation challenge (MSSEG-2) dataset. It achieves an average Dice score of 0.510 and F1 score of 0.552 on cases with new lesions, and an average false positive lesion number nFP of 0.036 and false positive lesion volume VFP of 0.192 mm3 on cases with no new lesions. Our method outperforms other participating methods in the challenge and several state-of-the-art network architectures.
Coales I, Tsartsalis S, Nurun F, et al., 2022, Alzheimer’s disease related transcriptional sex differences in myeloid cells, Journal of Neuroinflammation, Vol: 19, ISSN: 1742-2094
Sex differences have been identified in many diseases associated with dysregulated immune responses, including Alzheimer’s disease (AD), for which approximately two-thirds of patients are women. An accumulating body of research indicates that microglia may play a causal role in the pathogenesis of this disease. We hypothesised that sex differences in the transcriptome of human myeloid cells may contribute to the sex difference observed in AD prevalence. To explore this, we assessed bulk and single-nuclear RNA sequencing data sets generated from four human derived myeloid cell populations: post-mortem microglial nuclei, peripheral monocytes, monocyte-derived macrophages (MDMs) and induced pluripotent stem cell derived microglial-like cells (MGLs). We found that expression of AD risk genes, gene signatures associated with the inflammatory response in AD, and genes related to proinflammatory immune responses were enriched in microglial nuclei isolated from aged female donors without ante-mortem neurological disease, relative to those from males. In addition, these inflammation-associated gene sets were found to be enriched in peripheral monocytes isolated from postmenopausal women and in MDMs obtained from premenopausal individuals relative to age-matched males. Expression of these gene sets did not differ in MDMs derived from women whose blood was sampled across the menstrual cycle or in MGLs cultured with 17β-oestradiol. This suggests that the observed gene set enrichments in myeloid cells from women were not being driven by acute hormonal influences. Together, these data support the hypothesis that the increased prevalence of AD in women may be partly explained by a myeloid cell phenotype biased towards expression of biological processes relevant to AD.
Basaran BD, Qiao M, Matthews P, et al., 2022, Subject-specific lesion generation and pseudo-healthy synthesis for multiple sclerosis brain images, SASHIMI: Simulation and Synthesis in Medical Imaging, Publisher: Springer, ISSN: 0302-9743
Understanding the intensity characteristics of brain lesions is key for defining image-based biomarkers in neurological studies and for predicting disease burden and outcome. In this work, we present a novel foreground-based generative method for modelling the local lesion characteristics that can both generate synthetic lesions on healthy images and synthesize subject-specific pseudo-healthy images from pathological images. Furthermore, the proposed method can be used as a data augmentation module to generate synthetic images for training brain image segmentation networks. Experiments on multiple sclerosis (MS) brain images acquired on magnetic resonance imaging (MRI) demonstrate that the proposed method can generate highly realistic pseudo-healthy and pseudo-pathological brain images. Data augmentation using the synthetic images improves the brain image segmentation performance compared to traditional data augmentation methods as well as a recent lesion-aware data augmentation technique, CarveMix. The code will be released at https://github.com/dogabasaran/lesion-synthesis.
Curtis EM, Codd V, Nelson C, et al., 2022, Telomere Length and Risk of Incident Fracture and Arthroplasty: Findings From UK Biobank, JOURNAL OF BONE AND MINERAL RESEARCH, Vol: 37, Pages: 1997-2004, ISSN: 0884-0431
Dobson R, Craner M, Waddingham E, et al., 2022, EVALUATING THE FEASIBILITY OF A REAL WORLD PHARMACOVIGILANCE STUDY (OPTIMISE:MS), Association-of-British-Neurologists (ABN) Annual Meeting, Publisher: BMJ PUBLISHING GROUP, ISSN: 0022-3050
Owen D, 2022, Human pharmacokinetics of XBD173 and etifoxine distinguish their potential for pharmacodynamic effects mediated by TSPO, British Journal of Clinical Pharmacology, Vol: 88, Pages: 4230-4236, ISSN: 0306-5251
XBD173 and etifoxine are translocator protein (TSPO) ligands that modulate inflammatory responses in preclinical models. Limited human pharmacokinetic data is available for either molecule, and the binding affinity of etifoxine for human TSPO is unknown. To allow for design of human challenge experiments, we derived pharmacokinetic data for orally administered etifoxine (50 mg 3 times daily) and XBD173 (90 mg once daily) and determined the binding affinity of etifoxine for TSPO. For XBD173, maximum plasma concentration and free fraction measurements predicted a maximal free concentration of 1.0 nM, which is similar to XBD173 binding affinity. For etifoxine, maximum plasma concentration and free fraction measurements predicted a maximal free concentration of 0.31 nM, substantially lower than the Ki for etifoxine in human brain derived here (7.8 μM, 95% CI 4.5–14.6 μM). We conclude that oral XBD173 dosing at 90 mg once daily will achieve pharmacologically relevant TSPO occupancy. However, the occupancy is too low for TSPO mediated effects after oral dosing of etifoxine at 50 mg 3 times daily.
Venkataraman A, Mansur A, Rizzo G, et al., 2022, Widespread cell stress and mitochondrial dysfunction occur in patients with early Alzheimer’s Disease, Science Translational Medicine, Vol: 14, Pages: 1-11, ISSN: 1946-6234
Cell stress and impaired oxidative phosphorylation are central to mechanisms of synaptic loss and neurodegeneration in the cellular pathology of Alzheimer’s disease (AD). In this study, we quantified the in vivo expression of the endoplasmic reticulum stress marker, sigma 1 receptor (S1R), using [11C]SA4503 PET, the mitochondrial complex I (MC1) with [18F]BCPP-EF and the pre-synaptic vesicular protein SV2A with [11C]UCB-J in 12 patients with early AD and in 16 cognitively normal controls. We integrated these molecular measures with assessments of regional brain volumes and cerebral blood flow (CBF) measured with magnetic resonance imaging (MRI) arterial spin labelling. Eight patients with AD were followed longitudinally to estimate the rate of change of the physiological and structural pathology markers with disease progression. The patients showed widespread increases in S1R (≤ 27%) and regional reduction in MC1 (≥ -28%) and SV2A (≥ -25%) radioligand binding, brain volume (≥ -23%), and CBF (≥ -26%). [18F]BCPP-EF PET MC1 binding (≥ -12%) and brain volumes (≥ -5%) showed progressive reductions over 12-18 months, suggesting that they both could be used as pharmacodynamic indicators in early-stage therapeutics trials. Associations of reduced MC1 and SV2A and increased S1R radioligand binding with reduced cognitive performance in AD, although exploratory, suggested a loss of metabolic functional reserve with disease. Our study thus provides in vivo evidence for widespread, clinically relevant cellular stress and bioenergetic abnormalities in early AD.
Francis C, Futschik M, Huang J, et al., 2022, Genome-wide associations of aortic distensibility suggest causality for aortic aneurysms and brain white matter hyperintensities, Nature Communications, Vol: 13, ISSN: 2041-1723
Aortic dimensions and distensibility are key risk factors for aortic aneurysms and dissections, as well as for other cardiovascular and cerebrovascular diseases. We present genome-wide associations of ascending and descending aortic distensibility and area derived from cardiac magnetic resonance imaging (MRI) data of up to 32,590 Caucasian individuals in UK Biobank. We identify 102 loci (including 27 novel associations) tagging genes related to cardiovascular development, extracellular matrix production, smooth muscle cell contraction and heritable aortic diseases. Functional analyses highlight four signalling pathways associated with aortic distensibility (TGF-, IGF, VEGF and PDGF). We identify distinct sex-specific associations with aortic traits. We develop co-expression networks associated with aortic traits and apply phenome-wide Mendelian randomization (MR-PheWAS), generating evidence for a causal role for aortic distensibility in development of aortic aneurysms. Multivariable MR suggests a causal relationship between aortic distensibility and cerebral white matter hyperintensities, mechanistically linking aortic traits and brain small vessel disease.
Fancy N, Willumsen N, Tsartsalis S, et al., 2022, Mechanisms contributing to differential genetic risks for <i>TREM2 R47H</i> and <i>R62H</i> variants in Alzheimer’s Disease
<jats:title>SUMMARY</jats:title><jats:p>Coding variants in the microglial <jats:italic>TREM2</jats:italic> ectodomain differentially (<jats:italic>R47H</jats:italic>> <jats:italic>R62H</jats:italic>) increase the risk of Alzheimer’s disease (AD). To define mechanisms responsible, we characterised neuropathology and transcriptomic responses in heterozygotes for these <jats:italic>TREM2</jats:italic> variant alleles (<jats:italic>TREM2var</jats:italic>) and for common allele homozygotes (<jats:italic>CV</jats:italic>) in non-diseased and AD brain cortical tissue from 58 donors. Increased neurodegeneration in the <jats:italic>TREM2var</jats:italic> AD cortex was associated with genotype-dependent reductions in expression of Disease Associated Microglia (DAM) genes and increased expression of complement and Type I and II interferon pathways in microglia, phagocytosis and amyloid binding pathways and Disease Associated Astrocyte (DAA) genes in astrocytes, and growth factor, ubiquitination and apoptotic pathways in neurons. The microglial phenotypes and secondary differences in tissue β-amyloid deposition and in astrocyte and neuronal responses describe a variably partial loss of TREM2 function with variant alleles (<jats:italic>R47H</jats:italic>><jats:italic>R62H</jats:italic>) relative to CV and suggest mechanisms that could account for differences in genetic risks conferred.</jats:p>
Kaufmann M, Schaupp A-L, Sun R, et al., 2022, Identification of early neurodegenerative pathways in progressive multiple sclerosis, NATURE NEUROSCIENCE, Vol: 25, Pages: 944-+, ISSN: 1097-6256
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- Citations: 7
Dobson R, Craner M, Ed Waddingham E, et al., 2022, Evaluating the feasibility of a real world pharmacovigilance study (OPTIMISE:MS), MULTIPLE SCLEROSIS AND RELATED DISORDERS, Vol: 63, ISSN: 2211-0348
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- Citations: 1
Mishra A, Duplaa C, Vojinovic D, et al., 2022, Gene-mapping study of extremes of cerebral small vessel disease reveals TRIM47 as a strong candidate, BRAIN, Vol: 145, Pages: 1992-2007, ISSN: 0006-8950
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Douaud G, Lee S, Alfaro-Almagro F, et al., 2022, SARS-CoV-2 is associated with changes in brain structure in UK Biobank., Nature, Vol: 604, Pages: 697-707
There is strong evidence of brain-related abnormalities in COVID-191-13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51-81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans-with 141 days on average separating their diagnosis and the second scan-as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.
Waddingham E, Miller A, Dobson R, et al., 2022, Challenges and opportunities of real-world data: Statistical analysis plan for the Optimise: MS multicentre prospective cohort pharmacovigilance study, Frontiers in Neurology, Vol: 13, ISSN: 1664-2295
Introduction: Optimise:MS is an observational pharmacovigilance study aimed at characterising the safety profile of disease-modifying therapies (DMTs) for multiple sclerosis (MS) in a real world population. The study will categorise and quantify the occurrence of serious adverse events (SAEs) in a cohort of MS patients recruited from clinical sites around the UK. The study was motivated particularly by a need to establish the safety profile of newer DMTs, but will also gather data on outcomes among treatment-eligible but untreated patients and those receiving established DMTs (interferons and glatiramer acetate),. It will also explore the impact of treatment switching. Methods: Causal pathway confounding between treatment selection and outcomes, together with the variety and complexity of treatment and disease patterns observed among MS patients in the real world, present statistical challenges to be addressed in the analysis plan. We developed an approachfor analysis of the OPTIMISE:MS data that will include disproportionality-based signal detection methods adapted to the longitudinal structure of the data and a longitudinal time-series analysis of a cohort of participants receiving second-generation DMT for the first time. The time-series analyses will use a number of exposure definitions in order to identify temporal patterns, carryover effects and interactions with prior treatments. Time-dependent confounding will be allowed for via inverse probability-of-treatment weighting (IPTW). Additional analyses will examine rates and outcomes of pregnancies and explore interactions of these with treatment type and duration. Results: To date 13 hospitals have joined the study and over 2000 participants have been recruited.A statistical analysis plan has been developed and is described here. Conclusion: Optimise:MS is expected to be a rich source of data on the outcomes of DMTs in real world conditions over several years of follow-up in an inclusive sample of UK MS patient
Douaud G, Lee S, Alfaro-Almagro F, et al., 2022, SARS-CoV-2 is associated with changes in brain structure in UK Biobank, NATURE, Vol: 604, Pages: 697-+, ISSN: 0028-0836
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- Citations: 286
Livingston NR, Calsolaro V, Hinz R, et al., 2022, Relationship between astrocyte reactivity, using novel C-11-BU99008 PET, and glucose metabolism, grey matter volume and amyloid load in cognitively impaired individuals, MOLECULAR PSYCHIATRY, Vol: 27, Pages: 2019-2029, ISSN: 1359-4184
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- Citations: 3
Jiwaji Z, Tiwari SS, Aviles-Reyes RX, et al., 2022, Reactive astrocytes acquire neuroprotective as well as deleterious signatures in response to Tau and A beta pathology, NATURE COMMUNICATIONS, Vol: 13
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- Citations: 20
Venkataraman AV, Bai W, Whittington A, et al., 2021, Boosting the diagnostic power of amyloid-β PET using a data-driven spatially informed classifier for decision support, Alzheimer's Research and Therapy, Vol: 13, Pages: 1-12, ISSN: 1758-9193
BackgroundAmyloid-β (Aβ) PET has emerged as clinically useful for more accurate diagnosis of patients with cognitive decline. Aβ deposition is a necessary cause or response to the cellular pathology of Alzheimer’s disease (AD). Usual clinical and research interpretation of amyloid PET does not fully utilise all information regarding the spatial distribution of signal. We present a data-driven, spatially informed classifier to boost the diagnostic power of amyloid PET in AD.MethodsVoxel-wise k-means clustering of amyloid-positive voxels was performed; clusters were mapped to brain anatomy and tested for their associations by diagnostic category and disease severity with 758 amyloid PET scans from volunteers in the AD continuum from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). A machine learning approach based on this spatially constrained model using an optimised quadratic support vector machine was developed for automatic classification of scans for AD vs non-AD pathology.ResultsThis classifier boosted the accuracy of classification of AD scans to 81% using the amyloid PET alone with an area under the curve (AUC) of 0.91 compared to other spatial methods. This increased sensitivity to detect AD by 15% and the AUC by 9% compared to the use of a composite region of interest SUVr.ConclusionsThe diagnostic classification accuracy of amyloid PET was improved using an automated data-driven spatial classifier. Our classifier highlights the importance of considering the spatial variation in Aβ PET signal for optimal interpretation of scans. The algorithm now is available to be evaluated prospectively as a tool for automated clinical decision support in research settings.
Venkataraman A, Bishop C, Mansur A, et al., 2021, Imaging synaptic microstructure and synaptic loss in vivo in early Alzheimer’s Disease, Publisher: Cold Spring Harbor Laboratory
Background Synaptic loss and neurite dystrophy are early events in Alzheimer’s Disease (AD). We aimed to characterise early synaptic microstructural changes in vivo.Methods MRI neurite orientation dispersion and density imaging (NODDI) and diffusion tensor imaging (DTI) were used to image cortical microstructure in both sporadic, late onset, amyloid PET positive AD patients and healthy controls (total n = 28). We derived NODDI measures of grey matter extracellular free water (FISO), neurite density (NDI) and orientation dispersion (ODI), which provides an index of neurite branching and orientation, as well as more conventional DTI measures of fractional anisotropy (FA), mean/axial/radial diffusivity (MD, AD, RD, respectively). We also performed [11C]UCB-J PET, which provides a specific measure of the density of pre-synaptic vesicular protein SV2A. Both sets of measures were compared to regional brain volumes.Results The AD patients showed expected relative decreases in regional brain volumes (range, -6 to - 23%) and regional [11C]UCB-J densities (range, -2 to -25%). Differences between AD and controls were greatest in the hippocampus. NODDI microstructural measures showed greater FISO (range, +26 to +44%) in AD, with little difference in NDI (range, -1 to +7%) and mild focal changes in ODI (range, -4 to +3%). Regionally greater FISO and lower [11C]UCB-J binding were correlated across grey matter in patients (most strongly in the caudate, r2 = 0.37, p = 0.001). FISO and DTI RD were strongly positively associated, particularly in the hippocampus (r2 = 0.98, p < 7.4 × 10−9). After 12-18 months we found a 5% increase in FISO in the temporal lobe, but little change across all ROIs in NDI and ODI. An exploratory analysis showed higher parietal lobe FISO was associated with lower language scores in people with AD.Conclusions We interpreted the increased extracellular free water as a possible consequence of glial activation. The dynamic range of disease
Smith AM, Davey K, Tsartsalis S, et al., 2021, Diverse human astrocyte and microglial transcriptional responses to Alzheimer's pathology, ACTA NEUROPATHOLOGICA, Vol: 143, Pages: 75-91, ISSN: 0001-6322
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Bai W, Raman B, Petersen SE, et al., 2021, Longitudinal Changes of Cardiac and Aortic Imaging Phenotypes Following COVID-19 in the UK Biobank Cohort
<jats:title>Abstract</jats:title><jats:p>Case studies conducted after recovery from acute infection with SARS-CoV-2 have frequently identified abnormalities on CMR imaging, suggesting the possibility that SARS-CoV-2 infection commonly leads to cardiac pathology. However, these observations have not been able to distinguish between associations that reflect pre-existing cardiac abnormalities (that might confer a greater likelihood of more severe infection) from those that arise as consequences of infection. To address this question, UK Biobank volunteers (n=1285; 54.5% women; mean age at baseline, 59.8 years old; 96.3% white) who attended an imaging assessment including cardiac magnetic resonance (CMR) before the start of the COVID-19 pandemic were invited to attend a second imaging assessment in 2021. Cases with evidence of previous SARS-CoV-2 infection were identified through linkage to PCR-testing or other medical records, or a positive antibody lateral flow test; n=640 in data available on 22 Sep 2021) and were matched to controls with no evidence of previous infection (n=645). The majority of these infections were milder and did not involve hospitalisation. Measures of cardiac and aortic structure and function were derived from the CMR images obtained on the cases before and after SARS-CoV-2 infection from images for the controls obtained over the same time interval using a previously validated, automated algorithm. Cases and controls had similar cardiac and aortic imaging phenotypes at their first imaging assessment. Changes between CMR imaging measures in cases before and after infection were not significantly different from those in the matched control group. Additional adjustment for comorbidities made no material difference to the results. While these results are preliminary and limited to imaging metrics derived from automated analyses, they do not suggest clinically significant persistent cardiac pathology in the UK Biobank population af
Dobson R, Craner M, Waddingham E, et al., 2021, OPTIMISE: MS study protocol: a pragmatic, prospective observational study to address the need for, and challenges with, real world pharmacovigilance in multiple sclerosis, BMJ OPEN, Vol: 11, ISSN: 2044-6055
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Nutma E, Gebro E, Marzin MC, et al., 2021, Activated microglia do not increase 18 kDa translocator protein (TSPO) expression in the multiple sclerosis brain, GLIA, Vol: 69, Pages: 2447-2458, ISSN: 0894-1491
To monitor innate immune responses in the CNS, the 18 kDa Translocator protein (TSPO) is a frequently used target for PET imaging. The frequent assumption that increased TSPO expression in the human CNS reflects pro-inflammatory activation of microglia has been extrapolated from rodent studies. However, TSPO expression does not increase in activated human microglia in vitro. Studies of multiple sclerosis (MS) lesions reveal that TSPO is not restricted to pro-inflammatory microglia/macrophages, but also present in homeostatic or reparative microglia. Here, we investigated quantitative relationships between TSPO expression and microglia/macrophage phenotypes in white matter and lesions of brains with MS pathology. In white matter from brains with no disease pathology, normal appearing white matter (NAWM), active MS lesions and chronic active lesion rims, over 95% of TSPO+ cells are microglia/macrophages. Homeostatic microglial markers in NAWM and control tissue are lost/reduced in active lesions and chronic active lesion rims, reflecting cell activation. Nevertheless, pixel analysis of TSPO+ cells (n = 12,225) revealed that TSPO expression per cell is no higher in active lesions and chronic active lesion rims (where myeloid cells are activated) relative to NAWM and control. This data suggests that whilst almost all the TSPO signal in active lesions, chronic active lesion rims, NAWM and control is associated with microglia/macrophages, their TSPO expression predominantly reflects cell density and not activation phenotype. This finding has implications for the interpretation of TSPO PET signal in MS and other CNS diseases, and further demonstrates the limitation of extrapolating TSPO biology from rodents to humans.
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