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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Subclinical Vascular Brain Damage, Vascular Risk Factors, and Depression in Successful Cognitive Aging

Warsch, Jessica 01 May 2010 (has links)
Currently, about one in every eight Americans is age 65 or older; by the year 2050, it will be one in five people. Given this “graying” of the population, research into successful aging is of increasing relevance. The question of how to precisely define successful aging, however, has not been completely answered. Likewise, the role of vascular risk factors, subclinical vascular brain damage, and other biopsychosocial characteristics in normal cognitive aging are not well understood. This Dissertation focused on the identification of some of the physiological, behavioral, and social risk factors that distinguish people able to maintain extraordinary health at an advanced age. Specifically, we aimed to create an ecologically valid definition of successful aging that incorporates both physical well-being and cognitive abilities, and to report the prevalence of successful cognitive aging in a population-based multi-ethnic cohort of older adults. We sought to describe how the prevalence varies by several sociodemographic and psychosocial determinants, and to investigate global vascular risk, depressive symptomatology, and MRI markers of subclinical vascular brain damage as correlates of successful cognitive aging. We observed the prevalence of successful cognitive aging to be 37% in the study sample (N=1,162) of a diverse racial/ethnic population in Northern Manhattan (NYC, NY). The prevalence decreased with increasing age; we did not observe any differences by racial/ethnic group, but did note a lower prevalence with lower socioeconomic status. Several social resources and self-reported quality of life were related to successful cognitive aging, and appeared more important than demographic variables alone. We found that the likelihood of successful cognitive aging decreases with increasing global vascular risk score, more severe depressive symptomatology, and greater white matter damage. The field of successful aging requires further study. Consideration of such biopsychosocial factors as socioeconomic status, social support, quality of life, and depressive symptoms alongside novel indicators of disease and disability including global vascular risk and white matter hyperintensity burden is essential. It may lead to a more robust definition of successful cognitive aging replete with opportunities to modify the aging process, as many of the factors investigated in this study are modifiable.
2

Attentional Selection and Reduced Interference Improve Visual Short-term Memory in Mild Cognitive Impairment

Newsome, Rachel 15 December 2011 (has links)
Visual short-term memory (VSTM) is a vital cognitive ability, allowing us to hold online the contents of visual awareness. Healthy older adults have reduced VSTM capacity compared to young adults; however recent evidence suggests that their performance may be improved by the use of a retroactive cue (“retro-cue”). The retro-cue reduces interference from irrelevant items within VSTM. Mild cognitive impairment (MCI) patients have reduced VSTM performance, compared to healthy older adults. Here, we examined whether the use of a retro-cue would increase VSTM capacity in MCI patients. By presenting a retro-cue after a to-be remembered array, we direct attention to the to-be probed location, which reduces interference from other items that are no longer relevant. The present findings suggest that VSTM capacity per se is not compromised in MCI patients, but these patients may be more susceptible to the effects of interference.
3

Attentional Selection and Reduced Interference Improve Visual Short-term Memory in Mild Cognitive Impairment

Newsome, Rachel 15 December 2011 (has links)
Visual short-term memory (VSTM) is a vital cognitive ability, allowing us to hold online the contents of visual awareness. Healthy older adults have reduced VSTM capacity compared to young adults; however recent evidence suggests that their performance may be improved by the use of a retroactive cue (“retro-cue”). The retro-cue reduces interference from irrelevant items within VSTM. Mild cognitive impairment (MCI) patients have reduced VSTM performance, compared to healthy older adults. Here, we examined whether the use of a retro-cue would increase VSTM capacity in MCI patients. By presenting a retro-cue after a to-be remembered array, we direct attention to the to-be probed location, which reduces interference from other items that are no longer relevant. The present findings suggest that VSTM capacity per se is not compromised in MCI patients, but these patients may be more susceptible to the effects of interference.
4

Establishing a rodent (Fischer 344 rat) model of mild cognitive impairment in aging

LaSarge, Candi Lynn 15 May 2009 (has links)
Mild Cognitive Impairment is characterized by age-related decline in a variety of cognitive domains, including reference and working memory and olfactory function. Importantly, declining age-related mnemonic abilities is not inevitable; learning and memory deficits emerge in some people by middle-age while others remain largely cognitively-intact even at advanced chronological ages. The goal of this thesis is to establish a Fischer 344 (F344) rat model with some features of human cognitive aging which can then be utilized to undercover the neurobiological underpinnings of age-related cognitive deficits. Young (6 mo), middle-aged (11 mo), and aged (22 mo) F344 rats were behaviorally characterized in a well-established reference memory version of the Morris water maze task. Indeed, age-related impairments did occur across the lifespan. Moreover, the reference memory protocol used here was sufficiently sensitive to detect a difference in individual abilities among aged F344 rats such that approximately half of the rats performed on par with young while the other half performed outside this range, demonstrating impairment. These data mimic individual differences in declarative memory among aged humans. Subsequently, subsets of rats initially characterized on the reference memory version of the water maze were tested on either a spatial working memory water maze task or an olfactory discrimination task. Despite detecting an age-related delay-dependent decline in spatial working memory, this impairment was not correlated with spatial reference memory. In contrast, a strong and significant relationship was observed among aged rats in the odor discrimination task such that aged rats with the worst spatial reference memory were also the most impaired in their ability to discriminate odors for a food reward. Importantly, this subset of cognitively-impaired rats was not impaired on digging media discrimination problems with identical task demands, nor were they anosmic. These data are among the first to demonstrate a cross-domain cognitive deficit in a rodent model of human aging. Together, the current study both confirms the use of the naturalistic F344 rat model for the study of cognitive deficits within the context of aging and provides the most comprehensive cognitive profile of this rat population to date.
5

The impact of a structured life review process on people with memory problems living in care homes

Morgan, Sarah January 2000 (has links)
The following study describes an investigation into the impact of a life review intervention on individuals experiencing cognitive impairment who were living in care homes. Previous research into the effect of life review and reminiscence has been inconclusive. Various studies have found improvements in depression, selfesteem, and life satisfaction in individuals without cognitive impairment who have participated in these activities. Relatively little research has been carried out with people with cognitive impairment. Seventeen individuals took part in the study and were randomly allocated to one of two groups. Eight individuals entered the experimental group and participated in a structured, individual, life review intervention that culminated in the creation of a life story book. Nine individuals entered a no treatment control group and took part in the pre, post and follow up assessments only. Using four psychometric assessment scales, the two groups were compared on levels of depression, selfesteem, life satisfaction and autobiographical memory prior to, immediately after and at six weeks following completion of the life review. The quantitative results indicated a statistically significant improvement in the experimental group in depression and also in a particular aspect of autobiographical memory relating to the recall of personal factual information. Life satisfaction and self-esteem remained relatively stable throughout the study. Various limitations and strengths of the project anfl intervention model are discussed, as are a number of issues to consider when car7ing out this form of intervention with this population.
6

The effects of methamphetamine on neurocognition in existing and recovering addicts

Van Wyk, Cindy 08 December 2011 (has links)
M.A. / The aim of the present study was to establish the existence of potential cognitive impairment in a group of 14 currently using methamphetamine addicts in comparison to a group of 17 abstinent recovering methamphetamine addicts and a matched control group of 18 participants. The current study was undertaken as methamphetamine abuse has risen dramatically over the past several years (Hart, Ward, Haney, Foltin & Fischman, 2001). This resurgence into popular culture imposes a sense of urgency for understanding the effects of methamphetamine medically and neurologically (Simon et al., 2000; Volkow et al., 2001a). Twenty nine million people consumed amphetamine-type stimulants in the late 1990s, a larger number than that of people using cocaine and opiates combined (World Health Organisation, 2001). South Africa is one of the countries world-wide that is currently experiencing a methamphetamine pandemic. The startling increase of methamphetamine use in South Africa is further exacerbated by the fact that 80 percent of methamphetamine users in the Western Cape are under 21 years of age, according to the South African National Council on Alcoholism and Drug Dependence (SANCA) (Morris & Parry, 2006). Methamphetamine has been established as neurotoxic in chronic doses abused by humans. The resultant deleterious consequences of this drug on cognitive functioning have led researchers to conclude that the observed deficits are as a direct result of methamphetamine’s neurotoxicity (Nordahl, Salo & Leamon, 2003; Vocci & Appel, 2007; Yucel, Lubman, Solowij & Brewer, 2007). Amongst the cognitive functions affected by methamphetamine, preliminary findings indicate that attention, memory and executive functioning may potentially be compromised (Barr et al., 2006). These findings need to be corroborated in the South African milieu using culture fair measuring instruments. Furthermore the possible effects of previous use of methamphetamine in recovering addicts need to be ascertained. A comparative and quantitative ex post facto research design was utilised in the research. Participants were selected according to stringent inclusion and exclusion criteria. A neuropsychological test battery, comprising of pen and pencil tests, was used to assess the cognitive functions of attention, memory and executive functioning in the two experimental groups and the control participants. Statistical analysis was performed on the raw data by the Statistical Consultation Service of the University of Johannesburg. The research was conducted according to a specified code of ethics stipulated for psychological research. Significant results were established between the two experimental groups in comparison to each other and the control group for the cognitive functions of attention and memory. Assessment of executive functioning yielded results in which significant results were observed between the current and recovering users of methamphetamine and between the control group and recovering methamphetamine addicts. There were no significant results detected between the current users of methamphetamine and the control group regarding executive functioning.
7

Self and relative reported executive dysfunction in multiple sclerosis : prevalence and relationship with mood and health status

Atkins, Elisabeth Anice January 2002 (has links)
No description available.
8

Low 25-Hydroxyvitamin D Concentrations and Risk of Incident Cognitive Impairment in Black and White Older Adults: The Health ABC Study

Kilpatrick, Laurel, Houston, Denise K., Wilson, Valerie K., Lovato, James, Ayonayon, Hilsa N., Cauley, Jane A., Harris, Tamara, Simonsick, Eleanor M., Yaffe, Kristine, Kritchevsky, Stephen B., Sink, Kaycee M. 02 January 2018 (has links)
Using data from the Health, Aging, and Body Composition study, we examined whether low 25-hydroxyvitamin D (25[OH]D) concentrations were associated with prevalent or incident cognitive impairment. Serum 25(OH)D concentrations were measured in 2,786 older adults and categorized as <20 ng/mL, 20 to <30 ng/mL, or ≥30 ng/mL. Cognitive impairment was defined as a score >1.5 standard deviations below race and education specific means on either digit symbol substitution test or modified mini-mental state test. Logistic regression determined the odds of cognitive impairment at baseline and year 5 by 25(OH)D category. 25(OH)D concentrations were <30 ng/mL in 57.3% of whites and 84.6% of blacks. After excluding participants with baseline cognitive impairment (n = 340), 13% of whites and 13% of blacks developed cognitive impairment by year 5. In whites, 25(OH)D concentrations <30 ng/mL were not associated with prevalent or incident cognitive impairment. Black participants with 25(OH)D concentrations <20 ng/mL had a higher odds of prevalent, but not incident cognitive impairment (OR (95% CI): 2.05 (1.08–3.91), p = 0.03) compared to participants with 25(OH)D concentrations ≥30 ng/mL. Low 25(OH)D concentrations were associated with twofold higher odds of prevalent cognitive impairment in blacks.
9

The Montreal Cognitive Assessment and the Mini-Mental State Examination as Screening Instruments for Cognitive Impairment: Item Analyses and Threshold Scores

Damian, Anne Mariam 30 April 2012 (has links)
A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Objective: This study was performed to provide a detailed analysis of the MoCA versus the MMSE, including an item analysis and an examination of threshold scores appropriate for use in different clinical settings. Methods: 135 subjects enrolled in a longitudinal clinicopathologic study were administered the MoCA and MMSE. Subjects were classified as cognitively impaired or cognitively normal based on neuropsychological testing and consensus conference diagnosis. Results: 89 subjects were cognitively normal, 46 cognitively impaired (20 dementia, 26 MCI). ROC analysis showed that, for any threshold value selected for the MMSE to identify cognitive impairment, a MoCA value with better sensitivity and specificity could be identified. Recall performed best among individual items on the MMSE, and Orientation performed best on the MoCA. Overall, the best discrimination was obtained using a weighted combination of four items (2*MoCA-Orientation + MMSE-Recall + MoCA-Language + 0.5* MoCA-Visuospatial/Executive; AUC 0.94). A MoCA threshold score of 26 had a sensitivity of 98% and specificity of 52% for identifying cognitive 5 impairment. A MoCA threshold score of 21 had a sensitivity of 57% and specificity of 96%. Conclusions: The MoCA was superior to the MMSE in detecting cognitive impairment. Individual domains on the MoCA and MMSE made substantially different contributions to each instrument’s sensitivity, and a weighted subset of items from both instruments performed best in detecting cognitive impairment. A lower MoCA threshold score may be appropriate in a population with a higher prevalence of cognitive impairment such as a memory clinic.
10

Beta-amyloid protein deposition in the brain and its role in the pathogenesis of Alzheimer's disease

Cairns, Nigel John January 1995 (has links)
No description available.

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