97,263 research outputs found
Cerebral atrophy in mild cognitive impairment and Alzheimer disease: rates and acceleration.
No full textOBJECTIVE: To quantify the regional and global cerebral atrophy rates and assess acceleration rates in healthy controls, subjects with mild cognitive impairment (MCI), and subjects with mild Alzheimer disease (AD). METHODS: Using 0-, 6-, 12-, 18-, 24-, and 36-month MRI scans of controls and subjects with MCI and AD from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database, we calculated volume change of whole brain, hippocampus, and ventricles between all pairs of scans using the boundary shift integral. RESULTS: We found no evidence of acceleration in whole-brain atrophy rates in any group. There was evidence that hippocampal atrophy rates in MCI subjects accelerate by 0.22%/year2 on average (p = 0.037). There was evidence of acceleration in rates of ventricular enlargement in subjects with MCI (p = 0.001) and AD (p < 0.001), with rates estimated to increase by 0.27 mL/year2 (95% confidence interval 0.12, 0.43) and 0.88 mL/year2 (95% confidence interval 0.47, 1.29), respectively. A post hoc analysis suggested that the acceleration of hippocampal loss in MCI subjects was mainly driven by the MCI subjects that were observed to progress to clinical AD within 3 years of baseline, with this group showing hippocampal atrophy rate acceleration of 0.50%/year2 (p = 0.003). CONCLUSIONS: The small acceleration rates suggest a long period of transition to the pathologic losses seen in clinical AD. The acceleration in hippocampal atrophy rates in MCI subjects in the ADNI seems to be driven by those MCI subjects who concurrently progressed to a clinical diagnosis of AD
Using support vector machines with multiple indices of diffusion for automated classification of mild cognitive impairment
No full textFew 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
Assessment of outcome in clinical trials in mild Alzheimer 19s disease: urgent time for a rethink?
No full textIntroduction: A major barrier for clinical trials in Alzheimer's disease is the lack of sensitive clinical endpoints for the early stages. Until recently, regulatory agencies have required demonstration of improvement in two disease domains, cognition plus functional or global status, as the evidence of symptomatic improvement during clinical trials for Alzheimer's disease. However, the model of Alzheimer's disease progression indicates impairment in cognition occurs earlier than changes in function and new draft guidance from the Food and Drug Administration considers change in cognition as an endpoint. The aim of this paper is to assess the outcomes of clinical trials in mild Alzheimer's disease. Short communication: The Alzheimer's disease assessment scale - cognitive subscale is the most widely used assessment of cognition in clinical trials; however, analysis of its psychometric properties, show it lacks the sensitivity to detect change in cognition in mild Alzheimer's disease. There is a need to develop a new outcome measure capable of capturing the subtle changes associated with mild AD in a reliable and valid way. Conclusion: Given the heterogeneity of AD phenotypes, development of a reliable, valid and clinically meaningful outcome measure is complex and challenging and will require discussion and cooperation between researchers, clinicians, industry and patients and their advocates to achieve success
Centella asiatica extracts as green corrosion inhibitor for mild steel in 0.5 M sulphuric acid medium
No full textThe leaf extracts of centella asiatica(CE) was tested as green corrosioninhibitor for mild steel in 0.5 M H2SO4 by using gravimetric, polarization and electrochemical impedance spectroscopy (EIS) measurements. The data obtained from all the three methods are in good agreement with each other. Results indicate that leaf extracts of CE is a good green corrosion inhibitor for mild steel corrosion in 0.5 M H2SO4 solution. The inhibition efficiency was found to increase with increase in CE extracts concentration. A maximum inhibition efficiency of 95.08% was observed for 1200 ppm at 303K. Polarization measurements showed that the CE extracts acts as mixed type of inhibitor.Temperature studies revealed a decrease in inhibition efficiency with increase in temperature which suggests physisrption mechanism. The adsorption characteristics of CEextracts of on mild steel surface obeys Langmuir isotherm. Both kinetic and thermodynamics adsorption parameters were calculated and discussed,and SEM was used to analyse the surface adsorbed film
Early and Differential Diagnosis of Dementia and Mild Cognitive Impairment Design and Cohort Baseline Characteristics of the German Dementia Competence Network
No full textBackground: The German Dementia Competence Network (DCN) has established procedures for standardized multicenter acquisition of clinical, biological and imaging data, for centralized data management, and for the evaluation of new treatments. Methods: A longitudinal cohort study was set up for patients with mild cognitive impairment (MCI), patients with mild dementia and control subjects. The aims were to establish the diagnostic, differential diagnostic and prognostic power of a range of clinical, laboratory and imaging methods. Furthermore, 2 clinical trials were conducted with patients suffering from MCI and mild to moderate Alzheimer's Disease (AD). These trials aimed at evaluating the efficacy and safety of the combination of galantamine and memantine versus galantamine alone. Results: Here, we report on the scope and projects of the DCN, the methods that were employed, the composition and flow within the diverse groups of patients and control persons and on the clinical and neuropsychological baseline characteristics of the group of 2,113 subjects who participated in the observational and clinical trials. Conclusion: These data have an impact on the procedures for the early and differential clinical diagnosis of dementias, the current standard treatment of AD as well as on future clinical trials in AD. Copyright (C) 2009 S. Karger AG, Base
Social Competence and Executive Functioning in Adolescents Following a Mild Traumatic Brain Injury
No full textA traumatic brain injury (TBI) is one of the most common injuries sustained by adolescents and a leading cause of death and long-term disability. The vast majority of these cases are mild and yet they can cause a range of difficulties across multiple domains which can negatively impact upon a person’s social functioning. The aim of this study was to determine whether adolescents who have sustained a mild TBI would differ from their uninjured peers in regards to social competence. A secondary aim was to investigate whether there was a relationship between an adolescent’s level of social competence and their executive functioning abilities.
This investigation involved a population-based sample of 30 young adolescents who had sustained a mild TBI between the age of 12 and 15 years. Parental and/or self-report ratings of behaviour and executive function, as well as a performance-based measure of cognition were explored at 12 months post-injury. These adolescents were then compared to a community recruited, age-matched sample of their TBI-free peers.
A composite scale of social competence based on observable behaviours was formulated. The results showed adolescents with a mild TBI demonstrated greater difficulties with socially competent behaviours compared to their uninjured peers. These difficulties were found to centre around aspect of their behavioural functioning, particularly regarding their regulation and inhibition of behaviour. Higher levels of dysfunction in the mild TBI sample were also found for parental ratings of behaviours associated with executive functions. A relationship between the Social Competence Index and executive function was not found. However, a relationship between the Social Competence Index and composite measures of cognitive functioning was. Suggesting there are more cognitions behind socially competent behaviour than the domain of executive functions alone. These findings highlight the need for post-injury screening for behavioural and social difficulties, with interventions implemented as required, to reduce the risk of on-going social impairment
Treatment for depression following mild traumatic brain injury in adults: A meta-analysis
No full textPrimary objective: Development of depression after TBI is linked to poorer outcomes. The aim of this manuscript is to review evidence for the effectiveness of current treatments.
Research design: Two meta-analyses were undertaken to examine the effectiveness of both pharmacological and non-pharmacological interventions for depression after mild TBI
Method and procedures: PubMed, Medline, PsychInfo, Web of Science and Digital Dissertations were searched and 13 studies located. Meta Analyst Beta 3.13 was used to conduct analyses of pre- vs post-effects then to examine treatment group vs control group effects.
Main outcomes and results: Studies using a pre–post design produced an overall effect size of 1.89 (95% CI = 1.20–2.58, p < 0.001), suggesting that treatments were effective; however, the overall effect for controlled trials was 0.46 (95% CI = −0.44–1.36, p < 0.001), which favoured the control rather than treatment groups.
Conclusions: This study highlights the need for additional large well-controlled trials of effective treatments for depression post-TBI
Grading the intensity of nondental orofacial pain: Identification of cutoff points for mild, moderate, and severe pain
No full textBackground: When assessing pain in clinical practice, clinicians often label pain as mild, moderate, and severe. However, these categories are not distinctly defined, and are often used arbitrarily. Instruments for pain assessment use more sophisticated scales, such as a 0–10 numerical rating scale, and apart from pain intensity assess pain-related interference and disability. The aim of the study was to identify cutoff points for mild, moderate, and severe nondental orofacial pain using a numerical rating scale, a pain-related interference scale, and a disability measurement. Materials and methods: A total of 245 patients referred to the Facial Pain Unit in London were included in the study. Intensity and pain-related interference were assessed by the Brief Pain Inventory. Pain-related disability was assessed by the Chronic Graded Pain Scale. Average pain intensity (0–10) was classified into nine schemes with varying cutoff points of mild, moderate, and severe pain. The scheme with the most significant intergroup difference, expressed by multivariate analysis of variance, provided the cutoffs between mild, moderate, and severe pain. Results: The combination that showed the greatest intergroup differences for all patients was scheme 47 (mild 1–4, moderate 5–7, severe 8–10). The same combination provided the greatest intergroup differences in subgroups of patients with temporomandibular disorder and chronic idiopathic facial pain, respectively. Among the trigeminal neuralgia patients alone, the combination with the highest intergroup differences was scheme 48 (mild 1–4, moderate 5–8, severe 9–10). Conclusion: The cutoff points established in this study can discriminate in pain intensity categories reasonably well, and showed a significant difference in most of the outcome measures used
The stability of rock on mild slopes under wave attack
No full textMomentarily the determination of the static stability of rock on mild slopes can be split in roughly two paths, the empirical and the physical approach. However, both the approaches have their limitations from which one could conclude that neither approach is currently an accurate description of the stability of rock on mild slopes under wave attack. The empirical approach by van der Meer [1988] has to be extrapolated outside its validity region and is deemed to be too conservative by Schiereck and Fontijn [1996]. The physical approaches on which the software XBeach-G[1], runs are capable of globally determining dynamic profile response reasonably well however they cannot accurately determine static stability. From this lack of an accurate approach to determine the stability of rock on mild slopes under wave attack, follows the research question of this thesis: “How should the stability or rock on mild slopes be described?” To determine how to describe the stability of rock on mild slope under wave attack, a test plan was set up. The test plan was split into two parts, firstly the empirical approach and secondly the physical approach. The empirical approach is based around the formula of Van der Meer [1988] for plunging waves. Whereas the physical approach follows the methodology of Xbeach-G. For which the input parameters have been derived by the means of a combination Bubble Image Velocimetry (BIV) and Particle Image Velocimetry (PIV)
Regional coherence evaluation in mild cognitive impairment and Alzheimer's disease based on adaptively extracted magnetoencephalogram rhythms
No full textThis study assesses the connectivity alterations caused by Alzheimer's disease (AD) and mild cognitive impairment (MCI) in magnetoencephalogram (MEG) background activity. Moreover, a novel methodology to adaptively extract brain rhythms from the MEG is introduced. This methodology relies on the ability of empirical mode decomposition to isolate local signal oscillations and constrained blind source separation to extract the activity that jointly represents a subset of channels. Inter-regional MEG connectivity was analysed for 36 AD, 18 MCI and 26 control subjects in delta, theta, alpha and beta bands over left and right central, anterior, lateral and posterior regions with magnitude squared coherence-c(f). For the sake of comparison, c(f) was calculated from the original MEG channels and from the adaptively extracted rhythms. The results indicated that AD and MCI cause slight alterations in the MEG connectivity. Computed from the extracted rhythms, c(f) distinguished AD and MCI subjects from controls with 69.4% and 77.3% accuracies, respectively, in a full leave-one-out cross-validation evaluation. These values were higher than those obtained without the proposed extraction methodology.</p
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