All ETDs from UAB

Advisory Committee Chair

Michael Crowe

Advisory Committee Members

Olivio J Clay

Patricia Sawyer

David E Vance

Virginia G Wadley

Document Type

Dissertation

Date of Award

2013

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Recent literature indicates associations between inflammation, aging, and cognitive function. Inflammatory processes have also been implicated in the onset of pathological and neurodegenerative conditions. Current study aims were to examine the associations between inflammatory biomarkers and cognitive function in older adults, and to explore the interrelationships of inflammatory biomarkers, depressive symptoms, health conditions, and cognitive function. Two studies were utilized for the current project: 1) a cross-sectional sample of sedentary older adults aged 65+ from the Physical and Cognitive Exercise Study (PACES; n=54); and 2) a longitudinal study (UAB Study of Aging) of community-dwelling older African Americans and Caucasians (n=393). Inflammatory biomarkers were obtained from serum blood draws and separated into tertiles of low, middle, and high levels for the analyses. Sociodemographic factors were included as covariates in all statistical models. For PACES, a series of multiple regression models indicated executive function/ reasoning tasks were most strongly associated with serum levels of inflammation, and in particular with biomarkers IL-6 and IFN-g. In the Study of Aging analyses, Caucasian race membership, poorer subjective health, and greater BMI were associated with higher likelihood of elevated levels of serum inflammation. Cross-sectionally, highest tertile levels of IL-6 were significantly associated with MMSE score (ß = -0.102; p≤.05), while lower number of reported depressive symptoms, higher BMI, better subjective health ratings, and use of NSAIDs were all significantly associated with higher MMSE total scores. For longitudinal analyses, models including outcomes of telephone-based MMSE performance across three timepoints found no significant time-by-biomarker classification interactions, indicating that all biomarker tertiles showed similar rates of decline in telephone-MMSE scores over time. Neither IL-6 nor CRP moderated the relationship between vascular-based health conditions and change in telephone-MMSE scores. Younger age, Caucasian race, female gender, greater years of education, fewer depressive symptoms, use of NSAIDs, and better subjective health ratings were all associated with higher telephone MMSE scores over time. Similar findings across both studies indicate high levels of inflammatory biomarkers — particularly IL-6 — are cross-sectionally associated with poorer performance on measures of cognitive function. Fewer depressive symptoms, better subjective health, and use of NSAIDs may be protective against cognitive decline.

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