1,721,078 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
A pilot study of standardized treatment in geriatric bipolar disorder
No full textThe authors sought to determine the feasibility of treating elderly adults with bipolar disorder under standardized-treatment conditions.
Objective: The authors sought to determine the feasibility of treating elderly adults with bipolar disorder under standardized-treatment conditions. Methods: Thirty-one patients age 60 and older with bipolar disorder were treated in standardized pathways. Mood state was checked at each study visit with the Hamilton Rating Scale for Depression-17 item (Ham-D-17) and the Young Mania Rating Scale (YMRS). Results: De ning "well days" as both Ham-D and YMRS scores of <= 10, the mean percentage of well days was 72.5 (range: 0%-100%) over study participation. Conclusions: Treating older adults with bipolar disorder under standardized treatment is feasible and is associated with low symptom levels. However, most older adults with bipolar disorder do not experience sustained recovery
EEG Features of Working Memory Impairment in Alzheimer’s Dementia and Mild Cognitive Impairment
No full textThe presence of working memory impairments in individuals with Alzheimer’s Dementia (AD) or Mild Cognitive Impairment (MCI) is well-accepted; however, the neurophysiological mechanisms contributing to these impairments have not been fully elucidated. Research has reliably shown that oscillatory activity, driven by repetitive and synchronous activity within and between neuronal populations, plays a significant role in memory functioning and can be accurately captured using electroencephalography (EEG). While resting-state studies have identified aberrant oscillatory activity, mainly in those with AD, there is a paucity of research investigating how EEG activity behaves during cognitive processing. As such, the overall objective of this study was to assess the relationship between oscillatory activity and working memory impairments in AD and MCI, with a focus on three EEG features: theta and alpha power, theta-gamma coupling, and theta phase synchronization. We hypothesized that these EEG features would be most impaired in those with AD, while individuals with MCI would present with less significant impairments. Additionally, we hypothesized that each of these features would be associated with working memory performance. In the first study, we found that the AD group demonstrated the smallest increase in theta power following the onset of the 2-back stimulus; while compared to controls, the MCI group demonstrated a smaller increase in theta power on the most difficult 3-back condition. Similarly, in the second study, the AD group demonstrated the lowest level of theta-gamma coupling followed by MCI and HC groups. Finally in the third study, we found that the AD group demonstrated impaired theta phase synchronization between the temporal region and the rest of the brain, while no differences were found between the HC and MCI groups. Our results also demonstrated that each of the EEG features were associated with working memory performance to varying degrees. Taken together, findings from these studies revealed widespread impairments in EEG activity in AD, along with an intermediate and inconsistent level of impairment in those with MCI. Ultimately, this research advances our understanding of the neurophysiological mechanisms underlying working memory impairments in MCI and AD and may help guide the development of novel interventions in the future.Ph.D
EEG Features of Working Memory Impairment in Alzheimer’s Dementia and Mild Cognitive Impairment
Full text linkThe presence of working memory impairments in individuals with Alzheimer’s Dementia (AD) or Mild Cognitive Impairment (MCI) is well-accepted; however, the neurophysiological mechanisms contributing to these impairments have not been fully elucidated. Research has reliably shown that oscillatory activity, driven by repetitive and synchronous activity within and between neuronal populations, plays a significant role in memory functioning and can be accurately captured using electroencephalography (EEG). While resting-state studies have identified aberrant oscillatory activity, mainly in those with AD, there is a paucity of research investigating how EEG activity behaves during cognitive processing. As such, the overall objective of this study was to assess the relationship between oscillatory activity and working memory impairments in AD and MCI, with a focus on three EEG features: theta and alpha power, theta-gamma coupling, and theta phase synchronization. We hypothesized that these EEG features would be most impaired in those with AD, while individuals with MCI would present with less significant impairments. Additionally, we hypothesized that each of these features would be associated with working memory performance. In the first study, we found that the AD group demonstrated the smallest increase in theta power following the onset of the 2-back stimulus; while compared to controls, the MCI group demonstrated a smaller increase in theta power on the most difficult 3-back condition. Similarly, in the second study, the AD group demonstrated the lowest level of theta-gamma coupling followed by MCI and HC groups. Finally in the third study, we found that the AD group demonstrated impaired theta phase synchronization between the temporal region and the rest of the brain, while no differences were found between the HC and MCI groups. Our results also demonstrated that each of the EEG features were associated with working memory performance to varying degrees. Taken together, findings from these studies revealed widespread impairments in EEG activity in AD, along with an intermediate and inconsistent level of impairment in those with MCI. Ultimately, this research advances our understanding of the neurophysiological mechanisms underlying working memory impairments in MCI and AD and may help guide the development of novel interventions in the future.Ph.D
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
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