Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from PDF title page (viewed Sept. 23, 2009). Additional advisors: Karlene K. Ball, H. Randall Griffith, Daniel C. Marson, Sylvie Mrug, David E. Vance. Includes bibliographical references (p. 59-80).

Dementia is prevalent among elderly people. As the world population ages, it is projected that the number of people affected by dementia may triple in the next 50 years. Over the last two decades, research has focused on identifying potentially modifiable risk factors in development and progression of dementia, such as vitamin B12 and folate. Results concerning the effects of low folate and vitamin B12 on cognitive performance are mixed. The main objective of the present study was to investigate the effects of vitamin deficiency on cognitive functioning in a clinical sample of elderly individuals with cognitive problems using a comprehensive neuropsychological assessment. A retrospective chart-review was performed on the 102 records of patients from the Geriatrics Clinic at the University of North Texas Health Science Center who presented with cognitive deficits. Charts were reviewed to obtain data on vitamin supplementation, vitamin status, history of chronic conditions and other biochemical data. The available database was used to obtain data on neuropsychological assessment. The study demonstrated mild association between vitamin B12 and folate status and cognitive deficits. There appeared to be a higher cut-off level that is above the traditionally used levels for vitamin B12 and folate deficiency concentrations at which cognitive deficits became more pronounced. Clinical applications, limitations and suggestions for future research were discussed.

The purpose of the current study was to explore the relationship between cognitive status and depression in a sample of geriatric patients. Participants included 282 geriatric patients ranging in age from 65 to 96 years who were classified according to diagnosis as: DAT, VaD, MCI, and Norm. All were referred for neurocognitive testing from the Geriatric Assessment Program (GAP) at the University of North Texas Health Science Center (UNTHSC) in Fort Worth, Texas. This study sought to identify factor structures for two versions of the GDS using a geriatric sample of cognitively impaired and intact patients. It then compared these factors to each other to determine whether the GDS-15 is truly a shorter version of the GDS-30. These were then compared to a previously determined factor structure. This study explored whether the four-factors of the GDS-30 are able to differentiate cognitive diagnostic groups. Further, this study sought to identify whether the severity of cognitive decline impacted GDS factor score for each of the cognitively impaired groups. Results revealed a two-factor model of the GDS - 15 and a four-factor model with the GDS - 30. The GDS-15 factors did not differ from the first two factors of the GDS-30. Comparison between the GDS-30 factor structure and that reported by Hall and Davis (in press) revealed no significant differences despite the inclusion of a normal, non-demented group in the current study. Comparisons of subscale scores revealed that DAT patients tended to score lower than the other groups on all but the cognitive impairment subscale. Severity level analyses indicated that as severity of deficits increases, awareness of deficits decreases. This study found that although the GDS-30 is a good screening tool for depression in geriatric patients, it is not particularly useful in differentiating cognitive status group. Also, the GDS-15 was not found to be a good substitute for the GDS-30.

Longitudinal data (N = 263) was used to investigate the bidirectional relationship between engagement (engaged lifestyle activities) and cognition (crystallized & fluid intelligence). Extroversion and openness to experience were also tested as moderators of the relationship between engagement and cognition. Results showed that the relationship between engagement at Wave 1 and cognition at Wave 2 did not differ from the relationship between cognition at Wave 1 and engagement at Wave 2. Testing for moderation with regression indicated that neither extroversion nor openness was moderating the relationship between engagement and cognition in either direction. Structural equation models provided further summary evidence that the relationships among engagement at Wave 1, extroversion, openness, and cognition at Wave 2 were not strong. However, a strong limitation to these results was the measurement error associated with a new measure of engagement.

[Truncated thesis] This thesis is concerned with executive functioning in two different but related ways. The first is as an information processing construct in cognitive psychology. There are many different conceptualisations of the information processing basis of executive functioning but this thesis will pursue the notion that executive functioning is best thought of as adaptation to novelty. In the thesis, this will be operationalised using performance indices (principally reaction time) from a number of information processing tasks. These tasks have typically been used in the literature to index either executive functioning or speed of information processing. Both kinds of tasks are used to tackle the second concern of this thesis, namely, how executive functioning is measured. The data analytic techniques developed in this thesis are based on the hypothesis that executive functioning is the process or processes involved in resolving task novelty and consequently measurement will be enhanced through an analysis of performance changes within tasks as the task changes from novel to familiar. The analysis methods will be based largely on the computation of coefficient of variation of reaction time in successive performance windows across the information processing tasks. An elderly sample was chosen for this thesis because of a history of research that has attempted to determine whether cognitive deficits in the elderly are the consequence of the slowing of information processing speed or to impairment in executive functioning. ... The analysis was driven by the hypothesis that a significant shift in the coefficient of variation would mark a transition from novelty to familiarity in task performance and hence from executive to non-executive phases. Three methods were applied to individual performance curves to determine the point at which for each task this transition occurred. Using criterion measures of variability to separate the task data into two stages, analyses showed, contrary to the hypothesis, that later task performance was more highly associated with executive functioning than in initial task performance. The fourth stage of analysis (Chapter 7) applied confirmatory factor analysis to the newly-formed pre- and post transition data. Evidence was found that the magnitude of the contributions of EF across the pre- and post-criterion phases was stable, failing to support the hypothesis. Finally, structural equation modelling was used to examine how age and intelligence in this elderly sample exerts its influence on task performance and whether EF or IPS was the primary cause of age-related cognitive decline. The results showed that the age and intelligence effects on performance were mediated by the requirement to adapt to novelty. Although there was limited evidence to claim that EF is the primary cause of age-related cognitive decline, ageing effects were only apparent when the participants were adapting to novelty. The thesis concludes that there is some support for the hypothesis that executive functioning is best thought of as the processes underpinning adaptation to novelty. While not a panacea, the analytic techniques developed show promise for future research.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from PDF title page (viewed Sept. 21, 2009). Additional advisors: Michael Crowe, Cynthia Crowley, Virginia G. Wadley, David E. Vance. Includes bibliographical references (p. 31-34).

The aim of this thesis was to investigate inter-individual variability on cognitive task performance in normal older adults. In a review of the cognitive aging literature, the implications of a differential perspective were drawn out in order to establish a theoretical and methodological basis for an investigation into variability. A number of regularly occurring patterns, identified on the basis of available reports in the literature, were used to develop a model of variability (the shuttle model). The empirically-based model was located broadly within a neuropsychological framework, and derived explanatory power from the tenets of brain reserve capacity (BRC) theory. It served to describe the bulge in interindividual variability due to aging (the shuttle bulge), and the shifting occurrence of the bulge in relation to the age axis due to cohort and task-related influences (the shuttle shift). A two phase research study was conducted in order to test hypotheses derived from the model. Phase 1 comprised between-groups analyses of normative data covering a broad range of neuropsychological tests in the domains of attention, memory, language, visual and hand motor skills, in order to examine the progression of variability effects across the adult age range. Phase 2 constituted between and within-groups analyses of normative data from a more limited number of neuropsychological tests. It included the examination of raw score distributions and the characteristics of outliers, and was undertaken to explore more closely the nature of the variability phenomena detected in the first phase of the analysis. Taken together, the results of both phases of the investigation revealed statistically significant variability effects in support of the shuttle model. There was a consistent pattern of increased variability in association with older age regardless of functional modality; frequently, in association with later old age, there was also a subsequent decrease in variability (the shuttle bulge). The age of onset of the initial increase in variability occurred earlier or later (the shuttle shift) as a function of four factors: education, gender, task challenge and age-sensitivity of task. The finding of an earlier onset of variability effects for low education, male gender, high task challenge and high age-sensitivity of task was interpreted in terms of BRC threshold theory. The clinical and social implications of the outcome were discussed with special emphasis on the need for a differential perspective on aging, as a complement to the prevailing normative tradition. It was concluded that the shuttle model has considerable heuristic value. It presents an integrative framework for understanding existing variability data and provides clear indications for future research.

Indiana University-Purdue University Indianapolis (IUPUI) / Dementia studies often collect multiple longitudinal neuropsychological measures in order to examine patients' decline across a number of cognitive domains. Dementia patients have shown considerable heterogeneities in individual trajectories of cognitive decline, with some patients showing rapid decline following diagnoses while others exhibiting slower decline or remain stable for several years. In the first part of this dissertation, a multivariate finite mixture latent trajectory model was proposed to identify longitudinal patterns of cognitive decline in multiple cognitive domains with multiple tests within each domain. The expectation-maximization (EM) algorithm was implemented for parameter estimation and posterior probabilities were estimated based on the model to predict latent class membership. Simulation studies demonstrated satisfactory performance of the proposed approach. In the second part, a simulation study was performed to compare the performance of information-based criteria on the selection of the number of latent classes. Commonly used model selection criteria including the Akaike information criterion (AIC), Bayesian information criterion (BIC), as well as consistent AIC (CAIC), sample adjusted BIC (SABIC) and the integrated classification likelihood criteria (ICLBIC) were included in the comparison. SABIC performed uniformly better in all simulation scenarios and hence was the preferred criterion for our proposed model. In the third part of the dissertation, the multivariate finite mixture latent trajectory model was extended to situations where the true latent class membership was known for a subset of patients. The proposed models were used to analyze data from the Uniform Data Set (UDS) collected from Alzheimer's Disease Centers across the country to identify various cognitive decline patterns among patients with dementia.

This study explored the healthy aging process by: (a) examining the selected demographics of older adults in South Florida; (b) examining technology use of older adults in South Florida; (c) examining the health literacy levels of older adults in South Florida; (d) determining whether a relationship exists between older adults living in South Florida use of technology and their health literacy levels; and (e) evaluating the effects of health literacy as it relates to technology use in older adults in South Florida. Variables explored included health literacy, education, ethnicity, and technology use. The sample study included 102 older adults (age > 60) living in South Florida that had completed profiles on the South Florida Quality Aging Registry, a part of the Healthy Aging Research Initiative (HARI). The sample size represented 22.3% of the total South Florida Quality Aging Registry population. The ethnicities of the participants among the South Florida Quality Aging Registry were African American (17%); Afro Caribbean (7.8%); Hispanic (10.7%); and European American (63.7%). The education mean was 15, indicating that the majority of participants had an education level equivalent to completing high school. The mean health literacy score was 3.88, demonstrating that the majority of the participants had moderate levels of health literacy. The mean technology use score was 7.5 on a scale of one through ten, indicating that the majority of the participants had a moderate level of technology use. Analysis of variance, correlation coefficients, and multiple regression analysis was used to explore the variables that may influence health literacy. There was a statistically significant difference among Afro Caribbean and African American, Afro Caribbean and European American, European American and Hispanic ethnicities related to their health literacy skill level (p < .01). Additionally, there was a statistically significant difference among Afro Caribbean American and European American ethnicities and technology use (p. < .01). / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Past studies showed that older workers maintained a high level of job performance despite declines in physical and cognitive abilities. The present research project aimed at examining the impacts of emotion regulatory and SOC (selection, optimization, and compensation) strategies in explaining how older workers manage to maintain a high level of job performance. Two studies were conducted to assess Chinese insurance sales workers' global and momentary employment of emotion regulatory and SOC strategies at work, and to compare the effectiveness of emotion regulatory and SOC strategies in predicting job performance for younger and older workers. Study 1 was a cross-sectional survey study and consisted of 355 insurance sales workers. Results showed that older adults reported higher employment of elective selection and optimization than did younger workers. Older workers' employment of elective selection and compensation, as well as suppression, was associated with higher job performance, however such association was not found among younger workers. Study 2 was a five-day experience sampling study. It consisted of 87 participants who carried a handheld computer that recorded their momentary employment of emotion regulatory and SOC strategies during their work. Results of the multilevel analyses revealed that older and younger workers varied in their use of cognitive reappraisal, elective selection, and loss-based selection across work-related situations with different levels of task difficulty. Older workers' greater use of the four SOC strategies and suppression in the sampling period was predictive of the post-sampling increase in sales commission. Among these strategies, elective selection contributed the most to the increase in insurance sales among older workers even after accounting for the impact of other strategies. Findings from this research project contribute to the understanding of Chinese workers' psychological adaptation in the face of age-related declines in cognitive abilities. They also revealed cultural differences in the effectiveness of emotion regulatory strategies in predicting job performance of older and younger workers. Moreover, these findings shed light on the types of recommendations that should be given to employers for modifying organizational policies and implementing appropriate training and development programs, to meet with the needs of the aging workforce. / Yeung, Yuen Lan Dannii. / Adviser: Helene H. Fung. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3821. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 76-86). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.