Degree Type

Dissertation

Date of Award

2019

Degree Name

Doctor of Philosophy

Department

Human Development and Family Studies

Major

Gerontology

First Advisor

Jennifer A. Margrett

Abstract

Dementia is a neurocognitive disorder that negatively affects independence and significantly contributes to the global mortality rate. Alzheimer’s disease is the most pervasive type of dementia and is the sixth leading overall cause of mortality in the United States. Although the exact etiologies of Alzheimer’s disease and related dementias (ADRD) are not fully understood, research suggests that it may stem from genetic and environmental factors. There is currently is no cure for ADRD, thus, it would behoove the public health field to identify factors associated with brain health and cognitive performance so that individuals could modify their lifestyles across their life spans in an effort to strengthen cognitive reserves. As such, the current study focused on identifying life span biopsychosocial factors protective against cognitive decline and dementia. Specifically, this study used longitudinal data from the Kuakini Honolulu-Asia Aging Study (HAAS) to test three research aims. The HAAS provides biological and psychosocial data on 8,006 men of Japanese descent across 12 exams spanning from Exam 1 (1965-1968; Mean age = 54.40y, Range = 45-68y) to Exam 12 (2011-2012; Mean age = 93.50y, Range = 91-106y). Aim 1 employed growth curve models to examine biopsychosocial associates of cognitive performance over time [level and slope (changes across Exams 4-6)]. Results suggest that education was consistently and positively associated with baseline cognition as well the slope. There were several cognitive risk factors, indicating that older participants, those who had an APOE-ԑ4 allele, men with greater levels of inflammatory associates (e.g., uric acid, glucose), and those who reported more depressive symptoms at baseline tended to have poorer cognitive performance at baseline along with steeper declines in cognition over time. Aim 2 examined how patterns of cognitive performance were associated with age at ADRD diagnosis through survival analyses. Findings indicated that men who had the greatest declines in cognition tended to be at greater risk for ADRD at a younger age than those with less severe cognitive declines. Aim 3 employed bootstrapping methods to determine if level and change in cognitive abilities mediated the relationship between biopsychosocial factors and ADRD. Results demonstrated that education was positively associated with cognition, whereas age, associates of inflammation, presence of an APOE-ԑ4 allele, and depressive symptoms were negatively related with cognition, both baseline performance and slope. There was no support for mediation by cognition nor were there significant direct relationships between biopsychosocial factors and ADRD. Discussion focuses on practical implications of findings, including noting methods individuals could engage in to strengthen reserves in an effort to maximize cognitive health in later life, as well as offering future directions for research.

Copyright Owner

Hardeep K. Obhi

Language

en

File Format

application/pdf

File Size

193 pages

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