Introduction: Classifications such as Mild Cognitive Impairment (MCI) and Cognitive Impairment, No Dementia (CIND) are thought to represent the transitory, pre-clinical phase of dementia. However, increasing research demonstrates that MCI and CIND represent nonlinear and unstable entities that do not always lead to imminent dementia. Despite an increase in research examining patterns and predictors of cognitive impairment classification stability, this concept is still poorly understood, and the research remains limited. The present study was designed to address the existing limitations within the literature by utilizing a longitudinal repeated measures design to gain a more thorough understanding of CIND classification stability patterns, as well as identify predictors of future stability. Objectives: The objectives were to i) explore patterns of longitudinal stability in cognitive status across multiple assessments, and ii) investigate whether select baseline variables could predict 6-year cognitive status stability patterns. Methods: Participants included 259 older adults from Project MIND, a six-year longitudinal repeated measures design in which participants were classified as either Normal Cognition (NC) or CIND at each assessment. A latent transition analysis approach was adapted in order to identify and characterize transitions in CIND status across annual assessments. Participants were classified as either Stable NC, Stable CIND, Progressers, Reverters, or Fluctuaters. Multinomial logistic regression was then employed to test whether baseline predictors were associated with cognitive status stability patterns. Results: The sample demonstrated high rates of reversion and fluctuation in CIND status across years of study. Additionally, premorbid IQ, total number of medications, presence of arthritis, and CIND severity at baseline were all significantly associated with select CIND stability outcomes. Conclusion: CIND status was unstable for several years following baseline assessment, and factors such as cognitive reserve may delay or protect against demonstrable cognitive impairment. Further, considering cognitive impairment severity (i.e., single versus multidomain impairment) at the time of initial classification may improve CIND classifications. Continued research on CIND stability is recommended to improve classification methodology and provide a framework for future identification and prevention. / Graduate

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Diabetes (DM) and hypertension (HTN) are prevalent chronic diseases among older adults. For example, in the U.S., 1 in 4 older adults have DM, 3 in 4 have HTN and 1 in 6 have DM and HTN. Moreover, each year, health care costs attributable to DM and HTN are estimated at $327 billion and $131 billion USD respectively. Both diseases also impose tremendous burden on the health and well-being of older adults. For example, gait speed (GS) is reduced in older adults with DM or HTN compared to older adults without DM or HTN. Gait speed is a powerful indicator of health status among older adults. Reduced GS predicts various adverse health outcomes including falls, frailty, cognitive impairment, reduced quality of life, hospitalization and even death. Moreover, adequate GS is required to safely execute daily activities. For example, GS of 1.14 m/s or faster is required to safely cross the street. Reduced GS in older adults with DM or HTN can partly be explained by multimorbidity (e.g., older adults with DM are at increased risk of developing HTN) as well as complications that are frequently associated with DM and HTN. For example, older adults with DM or HTN are at increased risk of developing peripheral artery disease, which causes reduced lower extremity muscle strength and pain, as well as retinopathy, which causes vision impairment. Additionally, older adults with DM are at increased risk of developing peripheral neuropathy, which causes pain and impaired balance. Although the physiological mechanisms of these complications are largely understood, research is needed to determine the extent to which these complications contribute to GS decline among older adults with DM, HTN or DM and HTN. The overarching objective of this thesis was to examine how multimorbidity patterns (i.e., types/combinations of chronic diseases), and sensory and motor impairments impact GS in older adults with DM, HTN or DM and HTN. This thesis also examined how GS changes over time (i.e., trajectories) in this population. This thesis is comprised of 3 manuscripts and was conducted using data from the National Health and Aging Trends Study (NHATS); a large, nationally representative sample of American older adults. Annual data collection began in 2011 and is ongoing. In 2015, the NHATS was replenished with approximately 50% new participants, to account for death and loss-to-follow-up. Therefore, data was analyzed in two cohorts: cohort A (individuals recruited in 2011) and cohort B (individuals recruited in 2015 and individuals recruited in 2011 who remained in the sample at the time of replenishment). In manuscript 1, latent class analysis was performed to identify multimorbidity patterns in older adults with DM, HTN or DM and HTN. Additionally, analysis of covariance (ANCOVA) was conducted to examine differences in GS among these multimorbidity patterns. This study identified a total of nine multimorbidity patterns in cohort A: two patterns in older adults with DM (low multimorbidity and cardiovascular-joint multimorbidity), three patterns in older adults with HTN (low multimorbidity, psychological multimorbidity and cardiovascular multimorbidity) and four patterns in older adults with DM and HTN (metabolic-cardiovascular-psychological-joint multimorbidity, metabolic-bone-joint multimorbidity, metabolic-cardiovascular-joint multimorbidity and metabolic multimorbidity). Additionally, this study identified a total of ten multimorbidity patterns in cohort B: two patterns in older adults with DM (low multimorbidity and joint multimorbidity), four patterns in older adults with HTN (cardiovascular-joint-respiratory multimorbidity, cardiovascular multimorbidity, psychological-joint multimorbidity and joint multimorbidity) and four patterns in older adults with DM and HTN (metabolic-cardiovascular-joint-respiratory multimorbidity, metabolic-psychological-joint multimorbidity, metabolic-bone-joint multimorbidity and metabolic-joint multimorbidity). Overall, multimorbidity patterns with larger numbers of chronic diseases patterns or patterns that included depression or anxiety were associated with the slowest GS. In manuscript 2, multinomial logistic regression was used to conduct state-based analyses which examined the relationship between impairments (i.e., hearing, and vision impairment, pain, balance, and lower extremity strength impairment) and GS transitions (i.e., fast to, intermediate walker, intermediate to slow walker etc.) in older adults with DM, HTN or DM and HTN. Balance and lower extremity strength impairment were associated with an increased risk of GS decline (i.e., transitioning from an intermediate to slow walker). Moreover, older adults with vision, hearing, balance, or lower extremity strength impairment and those who used pain medication at least 5 days/week were more likely to be slow walkers at baseline and remain slow walkers at follow-up. In manuscript 3, group-based trajectory modeling was used to identify longitudinal trajectories of GS in older adults with DM, HTN or DM and HTN. Multinomial logistic regression was then conducted to examine the correlates of these trajectories. This study identified four GS trajectories in both cohorts: i) fast-stable GS, ii) intermediate GS with slow decline, iii) intermediate GS with moderate decline and iv) slow GS with fast decline. Additionally, one trajectory was unique to cohort A: intermediate-stable GS and two trajectories were unique to cohort B: fast GS with slow decline, and intermediate GS with fast decline. In both cohorts, individuals who were older, Black (non-Hispanic), had a higher number of chronic diseases or higher body mass index (BMI) were more likely to belong to a trajectory group with faster GS decline. Conversely, individuals with higher education, or higher baseline GS were less likely to belong to a trajectory group with faster GS decline. From a population health perspective, findings from this thesis can inform large-scale monitoring and management strategies to mitigate GS decline in older adults with DM, HTN or DM and HTN. For example, individuals who are older, identify as Black non-Hispanic or those with a higher number of chronic diseases or higher BMI may benefit from more frequent monitoring of their GS. Moreover, findings from this thesis can be used to determine how older adults with different multimorbidity patterns, or different types of sensory and motor impairments respond to interventions. Lastly, older adults with DM and/or HTN should be educated about the importance of maintaining their GS as they age to prevent adverse outcomes including falls, hospitalization, and premature death. / Thesis / Doctor of Philosophy (PhD) / Diabetes and hypertension are common chronic diseases among older adults globally. Moreover, these two chronic diseases are frequently found in the same individual due to shared risk factors including physical inactivity, and family history. Additionally, older adults with diabetes and/or hypertension are at risk of developing complications including vision loss, heart disease and stroke. These complications often cause impairments (i.e., changes in body structure or function) which also occur with aging including vision and hearing impairment, pain, and balance impairment which may reduce physical function (e.g., walking speed). There is a need for research to examine which other chronic diseases are linked to diabetes and hypertension and the impact of these diseases and disease-related impairments on walking speed among older adults with diabetes and/or hypertension. Moreover, it is important to examine how walking speed changes over time (i.e., trajectories) in older adults with diabetes and/or hypertension. Results from this thesis show that older adults with diabetes and/or hypertension who used pain medication at least 5 days/week, had vision, balance, or lower extremity strength impairment as well as older adults who are female, Black non-Hispanic, had a higher number of chronic diseases and a higher body mass index were at greatest risk of reduced walking speed. On the other hand, higher education and higher baseline walking speed were linked to lower risk of walking speed decline. Older adults who were identified as “high-risk” may benefit from closer monitoring and management of their walking speed to prevent further decline.

Over 6 million people are estimated to have been living with Alzheimer’s Disease (AD) in 2020, with another 12 million living with Mild Cognitive Impairment (MCI). Research has been conducted to evaluate genetic links to AD, but more research is needed on the subject. The Alzheimer’s Disease Neuroimaging Initiative (ADNI) has been conducting a longitudinal study of AD and MCI since 2004 and offering their data to research teams around the world. Diagnostic and demographic data was collected from participants, as well as data regarding single nucleotide polymorphisms (SNPs). SNP data was transformed to a binary format regarding whether the SNP contained the alternative allele for that particular SNP. We performed cross-validation to determine the ideal alpha and lambda values to use in elastic net regularization, which called for LASSO regression, in order to perform feature selection on the SNPs and other predictors, which were systolic and diastolic blood pressure, age, gender, years of education, race, marital status, and handedness. The LASSO regression reduced the number of SNPs from 55,106 to 13 and removed all non-SNP predictors except years of education and marital status. We used simple logistic regression to assess the relationship between variations in the significant SNPs (as well as years of education and marital status) and diagnosis of AD/MCI, utilizing a separate LASSO regression with conditional selective inference to more accurately calculate the significance of the variables. The adjusted odds ratios for the SNPs are 1.59 (95% CI 1.23, 2.05), 2.37 (95% CI 1.81, 3.12), 0.71 (95% CI 0.54, 0.93), 1.59 (95% CI 1.21, 2.09), 0.55 (95% CI 0.38, 0.79), 2.03 (95% CI 1.27, 3.23), 0.31 (95% CI 0.18, 0.50), 0.43 (95% CI 0.30, 0.60), 0.69 (95% CI 0.53, 0.89), 1.95 (95% CI 1.46, 2.60), 1.89 (95% CI 1.22, 2.90), 1.47 (95% CI 1.13, 1.90), and 0.52 (95% CI 0.37, 0.72) for SNPs rs11086694, rs2075650, rs2094277, rs2261682, rs31887, rs4745514, rs4816158, rs4826619, rs6640551, rs6809370, rs7312407, rs919751, and rs9857853, respectively. The SNPs are located in genes that have clinical significance and may be associated with various diseases that affect cognitive performance. The results propose that the alternative alleles for seven SNPs are associated with an increased risk of Alzheimer’s Disease/Mild Cognitive Impairment diagnosis while six SNPs are associated with a decreased risk of diagnosis. This research may have clinical implications and should be further studied.

BACKGROUND: Visual impairment impacts over 15% of Americans over the age of 65, roughly 7.3 million people. Currently there is no statewide model for low vision rehabilitation services that serves individuals across the visual impairment continuum. This dissertation sought to examine the existing eye care service delivery models, identify best practices, and explore perceived barriers and facilitators to access low vision rehabilitation services for older adults in order to inform the development of a revised service delivery model. The model will guide practice and policy change for existing and future services. METHODS: A mixed methods convergent approach was used to achieve the study’s overarching objectives. First, quantitative data from a synthetic estimation, was used to categorize high and low resource communities, which informed the purposeful sampling of focus groups and provided essential data to guide model development. Next, focus groups and one-on-one key stakeholder interviews were held to understand stakeholder perspectives on access to low vision rehabilitation services in both high and low resource communities. Further, one-on-one interviews with focus group participants provided additional quantitative data on individual prioritized barriers. Taken together, qualitative and quantitative research was conducted concurrently and then merged and expanded to inform a low vision rehabilitation focused care delivery model grounded in the Institute for Health Improvement’s Chronic Care Model. RESULTS: Key findings indicate the need for a model of service delivery that provides the full continuum of care, beginning with a low vision eye exam, which is coordinated throughout the community and health systems and addresses the chronic nature of visual impairment. Care should be client-centered and provided when the client is ready to accept services. Lastly, ongoing education to health care providers, consumers, and society will facilitate productive interactions and positive health outcomes. CONCLUSION: The stakeholder-driven low vision rehabilitation focused care delivery model grounded in the Chronic Care Model will provide a structure for service delivery throughout the state. This collaboration with community and health systems, as well as case management, will assist with program sustainability and reach to all adults throughout the state living with VI. / 2020-06-30T00:00:00Z

Students with Visual Impairment (VI) s5ll experience barriers to educa5on despite the right to educa5on s5pulated in the United Na5ons Conven5on on the Rights of Persons with Disabili5es (UNCRPD). Challenges such as delays in the conversion of curriculum content to accessible formats, inaccessible online course sites and teaching and learning that is mostly visual. With the University of Cape Town (UCT) going fully online due to COVID-19 pandemic, it became necessary to explore how equitable access to the curriculum is understood. The research topic is: How do staff and students at UCT understand equitable access to the curriculum for students with VIs? Four conceptual framework components were used. The hidden and enacted curriculum was used to explore hidden curriculum aspects and their effect on the enacted curriculum. Universal Design for Learning (UDL) framework was used to explore enablers such as assis5ve technology (AT) and challenges such as inaccessible content. Eight elements of digital literacies were used to explore access to opportuni5es to acquire digital literacies and the UNCRPD to ensure alignment with the right to educa5on. A Q methodology study was conducted which is a hybrid of both quan5ta5ve and qualita5ve methods. It sta5s5cally groups viewpoints that are significantly similar to or dis5nct from each other, quan5ta5vely into factors, then qualita5vely interprets these factors thema5cally to reveal par5cipant views about the research topic. Data was collected from students with VI, lecturers, staff from Disability Services, ICT Services, Library Services, and the Centre for Higher Educa5on Development using Q sor5ng where par5cipants ranked sixty statements into disagree, neutral and agree. Focus group discussions were used to support the interpreta5on of the factors. Findings revealed that: accessible curriculum is also a technical issue which is not priori5sed at UCT, and lecturers struggle with compe5ng demands such lack of 5me, need for promo5on and research. Accessibility design from the start both for curriculum development and support services is not valued. The right to educa5on for students with VI is par5al, varying their experience of the curriculum. Tes5ng of a course site for accessibility and lack of AT nega5vely affects right to educa5on. This study argues that students with VI do not yet enjoy full par5cipa5on in the curriculum due to lack of understanding of the complexity involved. UDL can help academics move from a deficit view to an asset view of students with VI. UCT should change its opera5onal model to accessibility from the start. Then UCT will move closer to equitable access to the curriculum for students with VI.

No / Visual impairment is an important risk factor for falls. However, relatively little is known about how visual impairment affects stair or step negotiation. The aim of the present study was to determine the effects of blurred vision on the mechanics of landing during stepping down by the elderly. Twelve elderly subjects (72.3±4.7 year) stepped down from three levels (7.2 cm, 14.4 cm and 21.6 cm). Step execution time, ankle and knee joint angular displacements at the instance of ground contact, and vertical landing stiffness and the amount of bodyweight supported by the contralateral (support) limb during the initial contact period were recorded. Measurements were repeated with vision blurred by light scattering lenses. With blurred vision, step execution time increased (P<0.05), knee flexion and ankle plantar-flexion increased (P<0.05), vertical stiffness decreased (P<0.01), and the amount of bodyweight being supported by the contralateral leg increased (P<0.05). These findings suggest that under conditions of blurred vision, subjects were more cautious and attempted to ‘feel’ their way to the floor rather than ‘drop’ on to it. This may have been an adaptation to increase the kinaesthetic information from the lower limb to make up for the unreliable or incomplete visual information. Correcting common visual problems such as uncorrected refractive errors and cataract may be an important intervention strategy in improving how the elderly negotiate stairs.

The purpose of this qualitative study was to explore self-determination in daily life and external programs for youth with visual impairments. To achieve this, the researcher explored three areas that contribute to the development of self-determination based on Wehmeyer’s Functional Theory of Self-determination: capacity, opportunities, and support. All participants in this study participated in Cane Quest, an external program specifically designed for youth with visual impairments. Cane Quest is a long cane competition for youth with visual impairments. These youth independently complete on a route using their orientation and mobility skills while navigating through complex environments such as residential areas, commercial areas, stores, buses, and a college campus. Data were collected through individual interviews, focus group sessions, and document collection. The phenomenological approach was used to analyze the data. Results suggest that youth with visual impairments are facing barriers to capacity, opportunities, and appropriate support in their daily lives. The finding also identified that external programs, like Cane Quest, can provide opportunities and appropriate support for youth with visual impairments to practice and develop self-determination skills. External programs, such as Cane Quest, can be beneficial for youth with visual impairments by filling in some of the gaps that may be occurring in their daily lives.

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