Multiple indices of diffusion identifies white matter damage in mild cognitive impairment and Alzheimer's disease

The study of multiple indices of diffusion, including axial (DA), radial (DR) and mean diffusion (MD), as well as fractional anisotropy (FA), enables WM damage in Alzheimer's disease (AD) to be assessed in detail. Here, tract-based spatial statistics (TBSS) were performed on scans of 40 healthy elders, 19 non-amnestic MCI (MCIna) subjects, 14 amnestic MCI (MCIa) subjects and 9 AD patients. Significantly higher DA was found in MCIna subjects compared to healthy elders in the right posterior cingulum/precuneus. Significantly higher DA was also found in MCIa subjects compared to healthy elders in the left prefrontal cortex, particularly in the forceps minor and uncinate fasciculus. In the MCIa versus MCIna comparison, significantly higher DA was found in large areas of the left prefrontal cortex. For AD patients, the overlap of FA and DR changes and the overlap of FA and MD changes were seen in temporal, parietal and frontal lobes, as well as the corpus callosum and fornix. Analysis of differences between the AD versus MCIna, and AD versus MCIa contrasts, highlighted regions that are increasingly compromised in more severe disease stages. Microstructural damage independent of gross tissue loss was widespread in later disease stages. Our findings suggest a scheme where WM damage begins in the core memory network of the temporal lobe, cingulum and prefrontal regions, and spreads beyond these regions in later stages. DA and MD indices were most sensitive at detecting early changes in MCIa

Using Support Vector Machines with Multiple Indices of Diffusion for Automated Classification of Mild Cognitive Impairment

Few studies have looked at the potential of using diffusion tensor imaging (DTI) in conjunction with machine learning algorithms in order to automate the classification of healthy older subjects and subjects with mild cognitive impairment (MCI). Here we apply DTI to 40 healthy older subjects and 33 MCI subjects in order to derive values for multiple indices of diffusion within the white matter voxels of each subject. DTI measures were then used together with support vector machines (SVMs) to classify control and MCI subjects. Greater than 90% sensitivity and specificity was achieved using this method, demonstrating the potential of a joint DTI and SVM pipeline for fast, objective classification of healthy older and MCI subjects. Such tools may be useful for large scale drug trials in Alzheimer's disease where the early identification of subjects with MCI is critical

Effect of glyceryl trinitrate on haemodynamics in acute stroke: data from the Efficacy of Nitric Oxide in Stroke trial

Background and Purpose: Increased blood pressure (BP), heart rate and their derivatives (variability, pulse pressure, rate-pressure product [RPP]) are associated with poor clinical outcome in acute stroke. We assessed the effects of glyceryl trinitrate (GTN) on haemodynamic parameters, and these on outcome in participants in the Efficacy of Nitric Oxide in Stroke trial.Methods: 4011 patients with acute stroke and raised BP were randomised within 48 hours of onset to transdermal GTN or no GTN for 7 days. Peripheral haemodynamics were measured at baseline (3 measures) and daily (2 measures) during treatment. Between-visit BP variability over days 1 to 7 (as standard deviation) was assessed in quintiles. Functional outcome was assessed as modified Rankin Scale (mRS) and cognition as telephone mini-mental state examination (t-MMSE) at day 90. Analyses were adjusted for baseline prognostic variables. Data are mean difference (MD) or odds ratios (OR) with 95% confidence intervals (CI).Results: Increased baseline BP (diastolic, variability), heart rate and RPP were each associated with unfavourable functional outcome at day 90. Increased between-visit systolic BP variability was associated with an unfavourable shift in mRS (highest quintile adjusted OR 1.65, 95% CI 1.37 to 1.99), worse cognitive scores (t-MMSE: highest quintile adjusted MD -2.03, 95% CI -2.84 to -1.22) and increased odds of death at day 90 (highest quintile adjusted OR 1.57, 95% CI 1.12 to 2.19). GTN lowered BP and RPP, and increased heart rate at day 1; and reduced between-visit systolic BP variability.Conclusions: Increased between-visit BP variability was associated with poor functional and cognitive outcomes and increased death 90 days after acute stroke. In addition to lowering BP and RPP, GTN reduced between-visit systolic BP variability. Agents that lower BP variability in acute stroke require further study

Route of feeding as a proxy for dysphagia after stroke and the effect of transdermal glyceryl trinitrate: data from the efficacy of nitric oxide in stroke randomised controlled trial

Post-stroke dysphagia is common, associated with poor outcome and often requires non-oral feeding/fluids. The relationship between route of feeding and outcome, as well as treatment with glyceryl trinitrate (GTN), was studied prospectively. The Efficacy of Nitric Oxide in Stroke (ENOS) trial assessed transdermal GTN (5 mg versus none for 7 days) in 4011 patients with acute stroke and high blood pressure. Feeding route (oral = normal or soft diet; nonoral = nasogastric tube, percutaneous endoscopic gastrostomy tube, parenteral fluids, no fluids) was assessed at baseline and day 7. The primary outcome was the modified Rankin Scale (mRS) measured at day 90. At baseline, 1331 (33.2%) patients had non-oral feeding, were older, had more severe stroke and more were female, than 2680 (66.8%) patients with oral feeding. By day 7, 756 patients had improved from non-oral to oral feeding, and 119 had deteriorated. Non-oral feeding at baseline was associated with more impairment at day 7 (Scandinavian Stroke Scale 29.0 versus 43.7; 2p < 0.001), and worse mRS (4.0 versus 2.7; 2p < 0.001) and death (23.6 versus 6.8%; 2p = 0.014) at day 90. Although GTN did not modify route of feeding overall, randomisation ≤6 hours of stroke was associated with a move to more oral feeding at day 7 (odds ratio = 0.61, 95% confidence intervals 0.38, 0.98; 2p = 0.040). As a proxy for dysphagia, non-oral feeding is present in 33% of patients with acute stroke and associated with more impairment, dependency and death. GTN moved feeding route towards oral intake if given very early after stroke

Sexual Dimorphism in Healthy Aging and Mild Cognitive Impairment: A DTI Study

Previous PET and MRI studies have indicated that the degree to which pathology translates into clinical symptoms is strongly dependent on sex with women more likely to express pathology as a diagnosis of AD, whereas men are more resistant to clinical symptoms in the face of the same degree of pathology. Here we use DTI to investigate the difference between male and female white matter tracts in healthy older participants (24 women, 16 men) and participants with mild cognitive impairment (21 women, 12 men). Differences between control and MCI participants were found in fractional anisotropy (FA), radial diffusion (DR), axial diffusion (DA) and mean diffusion (MD). A significant main effect of sex was also reported for FA, MD and DR indices, with male control and male MCI participants having significantly more microstructural damage than their female counterparts. There was no sex by diagnosis interaction. Male MCIs also had significantly less normalised grey matter (GM) volume than female MCIs. However, in terms of absolute brain volume, male controls had significantly more brain volume than female controls. Normalised GM and WM volumes were found to decrease significantly with age with no age by sex interaction. Overall, these data suggest that the same degree of cognitive impairment is associated with greater structural damage in men compared with women

The association between increasing oral anticoagulant prescribing and atrial fibrillation related stroke in Ireland

Aims: Recent increases in the number of patients with atrial fibrillation (AF) prescribed oral anticoagulants (OAC) are evident in Ireland and internationally, largely due to the availability of direct oral anticoagulants (DOACs). This study aimed to determine the rate of stroke in the context of increasing anticoagulation utilisation, with a focus on AF-related ischaemic stroke (IS).Methods: Dispensing data for OACs were identified for the period 2010-2018 as well as hospital discharges for IS (2005-2018). Irish National Stroke Register data were used to elucidate the characteristics of patients with acute ischaemic stroke.Results: The number of patients prescribed OACs increased by 94% from 2010-2018 with a significant change from 2013 (β = 2.57, P = .038), associated with a large increase in the number of patients on DOACs. There was 3.3-fold increase in expenditure on OACs nationally from 2013 to 2018, of which 94% was DOAC related. Using the 2013 timepoint, ischaemic stroke rates until 2018 did not show a significant deviation from the previous trend (β = 0.00, P = .898). The percentage of AF-related ischaemic stroke was stable from 2013 to 2017 with a 4.5% decrease in 2018. The percentage of ischaemic stroke patients with previously diagnosed AF decreased from 2013 to 2018; however, there was an increase in the percentage of ischaemic strokes while on OAC in this cohort.Conclusion: Large increases in OAC utilisation have not resulted in changes in ischaemic stroke rates at a national level. The percentage of ischaemic strokes with a previous diagnosis of AF has decreased indicating a possible benefit from greater OAC utilisation. However, the percentage presenting with an ischaemic stroke while on OAC treatment is increasing. The increase in patients presenting with stroke while treated with OAC may largely reflect the national increase in patients prescribed DOACs but the findings raise concerns about treatment failures. The real-world effectiveness of DOACs requires further examination.</div

Prevalence and predictors of continence containment products and catheter use in an acute hospital: A cross-sectional study

Although incontinence is common in hospital, the prevalence and predictors of continence aid use (continence wear and catheters) are poorly described. A one-day cross-sectional study was conducted in a large university hospital assessing consecutive inpatients (≥55) for their pre-admission and current use of continence aids. Barthel Index, Clinical Frailty Scale and Charlson Co-morbidity scores were recorded. Appropriateness was defined by local guidelines. 355 inpatients, median age 75±17 years, were included; 53% were male. Continence aid use was high; prevalence was 46% increasing to 58% for those ≥75. All-in-one pads were the most common, an overall prevalence of 31%. Older age, lower Barthel and higher frailty scores were associated with continence aid use in multivariate analysis. Inappropriate use of aids was high at 45% with older age being the only independent predictor. Continence aids are often used inappropriately during hospitalisation by older patients. Concerted efforts are required to address this issue

Identifying priority interventions for stroke in Ireland through stakeholder engagement to inform population-based modelling: a mixed methods protocol [version 1; peer review: awaiting peer review]

Introduction Improvements in stroke survival have resulted in increasing numbers of people living with stroke, and with a rapidly evolving evidence-base for stroke prevention and management, there is a need for robust data and evidence to inform future policy decision-making. Population-based modelling and economic evaluation of alternative policy options is a useful tool to support decision making. However, this process must be aligned to key stakeholder priorities. The aim of the proposed research is to engage with stakeholders in Ireland to identify their priorities for the development of stroke prevention and management strategies and policies. Methods The design is iterative, based on mixed methods. Phase 1 involves a qualitative approach for initial priority gathering, based on an open-ended online survey (target sample: 100-120) and interviews (target sample: 34-40). Stakeholders will include: 1) stroke survivors and family member/main carers, 2) healthcare professionals (HCPs) providing stroke care and 3) people working in stroke research, policy and advocacy. These data will be analysed qualitatively, with the aim of identifying a long-list of specific interventions. Phase 2 involves an interim priority setting exercise, based on a quantitative online survey. Participants will be asked to rank the interventions on the initial long-list. These rankings will be used to inform a final priority-setting workshop (Phase 3), where a small stakeholder group will decide on the final set of priorities. Discussion The rich and detailed quantitative and qualitative data, based on the views of diverse stakeholders, will be directly relevant to policy makers and service planners involved in developing and improving stroke care in Ireland. The information provided will also be essential to inform the Scenario and Intervention Modelling in Ireland for Stroke (SIMI-Stroke) project, a population-based economic and epidemiological modelling study aimed at identifying cost-effective interventions for stroke across the prevention, acute and post-acute care continuum.</div

Using diffusion tensor imaging and mixed-effects models to investigate primary and secondary white matter degeneration in Alzheimer's disease and mild cognitive impairment.

International audienceWhite matter (WM) degeneration in Alzheimer's disease (AD) and mild cognitive impairment (MCI) may be a key indicator of early damage in AD. Here, we analyzed WM diffusion tensor data using Tract-Based Spatial Statistics in conjunction with mixed-effects models. Four indices of diffusion were assessed in 61 healthy control, 19 non-amnestic MCIs, 14 amnestic MCIs, and 9 AD patients. The aim of the study was to use advanced mixed-effects models to investigate the retrogenesis hypothesis of AD, which suggests that tracts that are late to myelinate in ontogenetic development are the earliest to be affected in AD. Our results show that a number of late-myelinating pathways, including the parahippocampal region and the inferior longitudinal fasciculus, were predominantly affected by changes in WM volume. Conversely, early-myelinating pathways were found to be affected by a combination of both WM and gray matter (GM) atrophy. A model of the entire WM structure of the brain returned GM models for two indices of diffusion, suggesting that more complex regional landscapes of diffusion lie hidden beneath a global analysis of the entire brain. Our results warn against an explanation of white matter damage that points simply to one of two mechanisms: secondary degeneration or direct damage of myelin. We suggest that tracts may be affected by both mechanisms, with the balance depending on whether tracts are early or late-myelinating. A greater understanding of the pattern of WM changes in AD may prove useful for the early detection of AD

Development of a national stroke audit in Ireland: scoping review protocol [version 1; peer review: 2 approved]

Introduction Recent advances in stroke management and care have resulted in improved survival and outcomes. However, providing equitable access to acute care, rehabilitation and longer-term stroke care is challenging. Recent Irish evidence indicates variation in stroke outcomes across hospitals, and a need for continuous audit of stroke care to support quality improvement. The aim of this project is to develop a core minimum dataset for use in the new Irish National Audit of Stroke (INAS), which aims to improve the standard of stroke care in Ireland. This paper outlines the protocol for conducting a scoping review of international practice and guidelines in auditing acute and non-acute stroke care. Objective Identify data items that are currently collected by stroke audits internationally, and identify audit guidelines that exist for recommending inclusion of content in stroke audit datasets. Methods and analysis This scoping review will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews extension for Scoping Reviews (PRISMA-ScR). We will search the following databases: Medline Ovid; Embase; CINAHL EBSCOHost. Grey literature will also be searched for relevant materials, as will relevant websites. Study selection and review will be carried out independently by two researchers, with discrepancies resolved by a third. Data charting and synthesis will involve sub-dividing relevant sources of evidence, and synthesising data into three categories: i) acute stroke care; ii) non-acute stroke care; and iii) audit data collection procedures and resourcing. Data will be charted using a standardised form specific to each category. Consultation with knowledge users will be conducted at all stages of the scoping review. Discussion This scoping review will contribute to a larger project aimed at developing an internationally benchmarked stroke audit tool that will be used prospectively to collect data on all stroke admissions in Ireland, encompassing both acute and non-acute data items.</p