1,721,104 research outputs found
Exploring the Relationship Among Remitted Late-Life Depression, Cognitive Outcomes, and Brain Structures
Full text linkLate-life major depressive disorder (MDD), even in remission (rMDD), is a risk factor for cognitive decline and dementia. Study 1, a systematic review of 47 studies, found that rMDD is associated with cognitive impairment and may increase the risk of mild cognitive impairment (MCI) or dementia, particularly in early-onset cases. These findings highlight the need for interventions to prevent cognitive decline in older adults with rMDD. Study 2 assessed whether baseline magnetic resonance imaging (MRI) measures moderated cognitive outcomes in a randomized controlled trial of cognitive remediation plus transcranial direct current stimulation (CR+tDCS) in 246 participants with rMDD, MCI, or both. Higher overall and regions of interest cortical thickness enhanced the benefits of CR+tDCS on global cognition, executive function, and verbal memory. These findings suggest that cortical thickness may be used to identify older adults with rMDD who are most likely to benefit from CR+tDCS, supporting personalized interventions for dementia prevention in this high-risk population.M.Sc
Optimizing a Clinical Trials Approach to Investigate Cognitive and Physical Health Outcomes in Late-Life Depression
Full text linkLate-life depression (LLD) is a common and multifaceted condition affecting approximately 10% of older adults. More so than depression in younger adults, LLD interacts with physical and cognitive health outcomes in both the short and the long term, necessitating a comprehensive approach to studying and treating this condition. There are bidirectional relationships between LLD and cognitive function and between LLD and physical function that are incompletely understood. Modern clinical trials in LLD need to address current gaps in our understanding of these links, and how they can be therapeutically targeted.
The central aim of this Thesis was to narrow these knowledge gaps through targeted analyses of the extant literature and recent large clinical trial datasets, building the foundation for a pilot clinical trial design intended to launch a new direction of inquiry into the biological basis of LLD and its treatment. The central hypothesis underlying this aim was that LLD clinical trial design could be further optimized by an explicit focus on cognitive and physical health outcomes.
This Thesis work employed a variety of methodological approaches, including systematic review and meta-analysis, exploratory data analysis, and multivariable linear modelling, with a transition towards primary trial design work in the final experimental chapter (Chapter 7). Where appropriate, both a priori and post-hoc subgroup analyses have been performed to better characterize various dimensions of this heterogeneous population, and for the purposes of further hypothesis generation.
Several main findings have arisen from this Thesis work. First, LLD adversely affects cognition during the acute phase of illness, with impacts on executive function that are more pronounced in the setting of treatment resistance. Second, effective antidepressant treatment may lead to recovery from deficits in some cognitive domains but not others. Third, increased physical comorbidity adversely affects some areas of cognitive function and may negatively impact LLD treatment outcomes. And finally, the dopamine system is implicated in the links between LLD, cognition, and physical health, and this system may be pharmacologically manipulated to clinical benefit.
This Thesis provides new insights into the biological underpinnings of LLD. It forms the basis for a promising new avenue of inquiry.Ph.D
Brain-Cognition Associations in Late-Life Depression or Mild Cognitive Impairment: An Analysis of Gray and White Matter Integrity
Full text linkMost older adults with late-life depression (LLD) exhibit cognitive impairment and a third meet diagnostic criteria for mild cognitive impairment (MCI). While LLD is a risk factor for developing Alzheimer’s dementia (AD), the mechanisms remain unclear. In Study 1, we systematically reviewed the literature to synthesize the published associations between structural brain alterations and cognition in LLD or LLD+MCI. The current literature is characterized by limitations: basic cognitive measures, univariate models, small sample sizes, and quasi-absence of participants with LLD+MCI. These findings guided the design of Study 2: we assessed the multivariate associations between structural brain alterations and cognition in a sample (N=283) of participants with LLD, MCI, or LLD+MCI, and controls. Gray matter atrophy in specific regions predicted worse memory, language, and processing speed; global reduced white matter tract integrity predicted worse executive function and processing speed. These findings remained significant in MCI/LLD+MCI, but not LLD or HC groups.M.Sc
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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